Inspection and Salvage of Hydraulic Cylinder Components {7562} Caterpillar

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Introduction

Table 1

Revision	Summary of Changes in SEBF8072
47	Updated Illustration 63
46	Updated Effectivity
45	Updated Effectivity
44	Updated Effectivity
43	Updated Effectivity

© 2019 Caterpillar All Rights Reserved. This guideline is for the use of Caterpillar Dealers only. Unauthorized use of this document or the proprietary processes therein without permission may be violation of intellectual property law. Information contained in this document is considered Caterpillar: Confidential Yellow.

This guideline enables dealers and dealer customers to benefit from cost reductions made possible through an established parts reusability and salvage program. Every effort has been made to provide the most current information known to Caterpillar Inc. Since the company makes ongoing product changes and product improvements, this guideline must be used with the latest technical information. Using the latest technical information available from Caterpillar ensures that such changes and improvements are incorporated where applicable.

For questions or additional information concerning this guideline, submit a feedback form in the Service Information System web site. To address an urgent need, use the following to forward your request to Caterpillar Repair Process Engineering:

• Cat Dealer Technical Communicator

• Global Dealer Solution Network

• Cat Technical Representative

• Knowledge Network

Canceled Part Numbers and Replaced Part Numbers

This document may not include canceled part numbers and replaced part numbers. Use NPR on SIS for information about canceled part numbers and replaced part numbers. NPR will provide the current part numbers for replaced parts.

Summary

Often, the replacement of worn or damaged hydraulic cylinder components with new parts is not the best repair option. After being reconditioned and/or salvaged, original parts can be expected to give normal performance and life.

This guideline includes illustrations of used hydraulic cylinder components. Some of the components can be used again with salvage (reconditioning) operations. Additionally, this guideline defines procedures to salvage cylinder components, if necessary. If replacement parts are required, Caterpillar recommends using Caterpillar replacement parts or parts with equivalent specifications.

Never install a part this guideline shows cannot be used again. As with any repair, correct the conditions that caused the original failure or wear.

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Rerodding, straightening, or welding any steering cylinder rod, bowl cylinder rod, or front suspension cylinder rod could result in injury or death. If any of these rods are broken or cracked, the rods must be replaced with a REMAN rod or a new rod. These rods can be ground and plated with chrome if the recommended Caterpillar process that is identified in this document is used.

Important Safety Information

Illustration 1	g02139237

Work safely. Most accidents that involve product operation, maintenance, and repair are caused by failure to observe basic safety rules or precautions. An accident can often be avoided by recognizing potentially hazardous situations before an accident occurs. A person must be alert to potential hazards. This person should also have the necessary training, skills, and tools to perform these functions properly. Safety precautions and warnings are provided in this instruction and on the product. If these hazard warnings are not heeded, bodily injury or death could occur to you or to other persons. Caterpillar cannot anticipate every possible circumstance that might involve a potential hazard. Therefore, the warnings in this publication and the warnings that are on the product are not all inclusive. If a tool, a procedure, a work method, or operating technique that is not recommended by Caterpillar is used, Ensure that the procedure is safe for you and for other people to use. Ensure that the product will not be damaged or be made unsafe by the operation, lubrication, maintenance, or the repair procedures that are used.

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Improper operation, lubrication, maintenance or repair of this product can be dangerous and could result in injury or death. Do not operate or perform any lubrication, maintenance or repair on this product, until you have read and understood the operation, lubrication, maintenance and repair information.

Safety precautions and warnings are provided in this manual and on the product. If these hazard warnings are not heeded, bodily injury or death could occur to you or to other persons.

The hazards are identified by the safety alert symbol which is followed by a signal word danger, warning, or caution. The "WARNING" safety alert symbol is shown below.

Illustration 2	g00008666

This safety alert symbol means:

Pay attention!

Become alert!

Your safety is involved.

The message that appears under the safety alert symbol explains the hazard.

Operations that may cause product damage are identified by "NOTICE" labels on the product and in this publication.

Caterpillar cannot anticipate every possible circumstance that might involve a potential hazard. The safety information in this document and the safety information on the machine are not all inclusive. Determine that the tools, procedures, work methods, and operating techniques are safe. Determine that the operation, lubrication, maintenance, and repair procedures will not damage the machine. Also, determine that the operation, lubrication, maintenance, and repair procedures will not make the machine unsafe.

The information, the specifications, and the illustrations that exist in this guideline are based on information which was available at the time of publication. The specifications, torques, pressures, measurements, adjustments, illustrations, and other items can change at any time. These changes can affect the service that is given to the product. Obtain the complete, most current information before you start any job. Caterpillar dealers can supply the most current information.

Safety

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Sudden movement of the machine or release of oil under pressure can cause injury to persons on or near the machine. To prevent possible injury, perform the procedure that follows before testing and adjusting the steering system.

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Personal injury can result from hydraulic oil pressure and hot oil. Hydraulic oil pressure can remain in the hydraulic system after the engine has been stopped. Serious injury can be caused if this pressure is not released before any service is done on the hydraulic system. Make sure all of the attachments have been lowered, oil is cool before removing any components or lines. Remove the oil filler cap only when the engine is stopped, and the filler cap is cool enough to touch with your bare hand.

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NOTICE
Care must be taken to ensure that fluids are contained during performance of inspection, maintenance, testing, adjusting, and repair of the product. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids. Refer to Special Publication, PERJ1017, "Dealer Service Tool Catalog" for tools and supplies suitable to collect and contain fluids on Cat® products. Dispose of all fluids according to local regulations and mandates.

References

Table 2

Media Number	Title
SEHS9538	Tool Operating Manual,"Using the 9U-6463 Hone Group and Attachments"
NEHS0627	"Tool Operating Manual for the 1U-9001 and 1U-9002 Automatic Hone Tooling"
NEHS0901	"Tool Operating Manual for the 233-2225 Hydraulic Cylinder Hone"
NEHS0927	"Procedures for Using the 250-6597 Cylinder Washer Tank Group"
REHS2689	"Hydraulic Cylinder Honing"
PEKP1020	"Hydraulic Cylinder and Seal Reference Guide"
SEBF9233	"HVOF Identification and Polishing"
SEBF9276	"Thermal Spray Procedure for Hydraulic Cylinder Rods"
SEBF9238	"Fundamentals of Arc Spray for Reconditioning Components"
SEBF9240	"Fundamentals of Flame Spray for Reconditioning Components"
SEBF9236	"Fundamentals of High Velocity Oxygen Fuel (HVOF) Spray for Reconditioning Components"
NENG2500	"Dealer Service Tool Catalog"
PECJ0003	"Hand Tools and Shop Supplies"

To obtain a tool operating manual for the HTA4000Sunnen Hone, contact Sunnen directly. The supplier address can be found under the "Equipment Suppliers" section.

Tooling and Equipment

Table 3

Tooling
Part Number	Part Description
250-6597	Cylinder Washer Gp
1U-8809	Rust Preventative
185-4125	Rust Preventative
222-3121	Rust Preventative
9U-6484	Honing Oil
5P-8615	Honing Oil
222-3117	Brake Cleaner
4C-4804	Penetrating Oil
4C-4805	Developer
1U-9918	Wire Brush
-	Cloth or Wipes
263-7184	Crack Detection Kit

Table 4

Optional Tooling
HTA-4000	Sunnen Hone

Cleaning

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Personal injury can result from air pressure. Personal injury can result without following proper procedure. When using pressurized air, wear a protective face shield and protective clothing. Maximum air pressure at the nozzle must be less than 205 kPa (30 psi) for cleaning purposes.

Wash all dirt, grease, oil, and contaminants from the cylinder assembly. If the cylinder is dirty, a high-pressure washer may be required to remove all the unwanted material. Cleaning the inside and outside of the cylinder is important. To achieve an accurate inspection, the cylinder must be cleaned properly. Proper cleaning also prevents outside contamination from entering the hone oil supply.

If the cylinder is not going to be honed within two days of cleaning, apply a generous coat of 222-3121 Rust Preventive or 1U-8809 Caterpillar 450 Rust Preventative Oil. In EAME, order 185-4125 Caterpillar 450 Rust Preventative Oil. The rust preventative prevents rust from forming on the unfinished portion of the cylinder walls.

Inspection

Perform an inspection on the cylinder before significant time is spent on the honing process. Following the proper inspection process eliminates unnecessary cylinder repairs. Inspect cylinders thoroughly to aid in the decision of future action. These actions may include having the cylinder retubed or purchasing a remanufactured cylinder from Caterpillar.

Cylinder Nomenclature

Illustration 3	g01585543
The three Caterpillar cylinder designs: (A) Bolted Head Cylinder, (B) Threaded Crown Cylinder (C) Threaded Gland Cylinder. (1) Eye (2) Weld Joint (3) Flange (4) Bolt on Head (5) Bolts (6) Tube (7) End Cap (8) External Threads (9) Head (10) Threaded Crown (11) Trunnion Bearings (12) Trunnion (13) Internal Threads (14) Threaded Gland

Tubes

Inspection and Reuse of Tubes

Illustration 4	g03359136
Vertical Scratch with raised (above surface level) edges. Use again after salvaging the tube by honing.

Illustration 5	g03359154
Heavier vertical scratches in the bore. Use again after salvaging the tube by either honing oversize or by retubing if rust pitting is deeper than 0.76 mm (0.030 inch) from the nominal diameter. For a complete explanation of these procedures, refer to “Re-tube” and “Oversize Honing” in this guideline.

Note: Some of the tubes in the Illustrations that follow were cut to show the damage more clearly.

Illustration 6	g03359171
Wear and light rust Use again after salvaging the tube by honing.

Illustration 7	g03359188
Rust in cylinder bore Use again after salvaging the tube either by honing oversize or retubing if rust pitting is deeper than 0.76 mm (0.030 inch) from the nominal diameter. For a complete explanation of these procedures, refer to “Re-tube” and “Oversize Honing” in this guideline.

Illustration 8	g03359202
Heavy rust in cylinder bore Use again after salvaging the tube either by honing oversize or retubing if rust pitting is deeper than 0.76 mm (0.030 inch) from the nominal diameter. For a complete explanation of these procedures, refer to “Re-tube” and “Oversize Honing” in this guideline.

Illustration 9	g03359211
Heavy cylinder bore damage Use again after salvaging the tube by retubing.

Illustration 10	g03359219
Dent in the tube Use again after salvaging the tube by retubing.

Illustration 11	g03359416
Ruptured cylinder tube Use again after salvaging the tube by retubing.

Salvage Procedures

Retube

Cylinders that have dents or heavy scratches inside the bore cannot be used again unless reconditioned by retubing. Retubing is a procedure in which the end cap, eye, flange, and trunnion are removed from the cylinder tube and welded to a new tube. Refer to Illustrations 9,10, and 11.

The recommended material for this procedure is cold drawn-over mandrel (D.O.M.) or seamless SAE 1026 Honed ID (inside diameter) hydraulic cylinder tubing.

1. Measure the damaged cylinder for correct size and length of tubing needed. Also refer to Hydraulic Cylinder & Seal Reference Guide, PEKP1020, for length and bore dimensions. For dealers with approved access to the Hydraulic Information System (H.I.S.) for Cylinder Dimensions, tube dimensions can be obtained after entering the tube part number. To obtain approval, select "Contact Us" on the H.I.S. web screen.

   Note: Make note of the position or make alignment marks with a punch or marker on the eye, end cap, flange, mounting blocks and trunnion for assembly of the new tube.

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   Illustration 12	g03358599
   Use a torch to cut cylinder into sections.

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   Illustration 13	g01251883
   Tube must be long enough to chuck into a lathe.

2. Cut off the end cap, trunnion, and flange sections with a torch or band saw. Make sure that there is enough tube remaining to chuck each section into a lathe. Refer to Illustrations 12 and 13.
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   Illustration 14	g01251887
   Tube in position ready to machine.

3. Put the tube section in the lathe. Machine the weld from the flange, eye, and cap, or trunnion until the part is cut free of tube. Refer to Illustrations 13 and 14.

4. Make necessary repairs to the flange, eye or cap, and trunnion. Refer to the “Welding” section in this guideline for details.
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   Illustration 15	g01621637
   (A) Machined Tube (3) Flange (6) Tube

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   Illustration 16	g01584859
   Typical dimensions to machine the ends of a new tube. Specifications can be different, according to type of tube used. (15) 15° chamfer (16) 1.52 mm (0.060 inch) - cap end (17) 6.35 mm (0.250 inch) radius (18) 9.65 mm (0.380 inch) - head end

5. Machine the new tube to length. Machine the head end and the bottom end (where the end cap will go) to the same specifications as old tube. The end of tube (6) that is welded to flange (3) must also be machined to a slightly smaller diameter (A). Refer to Illustration 15. This machining is done so that flange (3) can slide onto tube (6). Refer to Illustration 16 for dimensions to machine.

   Note: Tube (6) should be slightly longer than the final specification length. This added length allows the end of tube (6) to be machined flush with flange (3) after flange (3) is welded in place.

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   Illustration 17	g01251907
   Use the correct wire or electrode to weld new tube.

6. Assemble the flange, end cap, or eye, and/or trunnion to new tube. Orient the parts with alignment marks made earlier.

7. Weld the end cap or eye, flange, and/or trunnion to new tube. Use solid electrode wire that is acceptable according to AWS class E70S-IB or E7018 electrode. Do not use flux-cored electrode to weld end cap in place. Also, weld any mounting or lifting brackets to tube. Refer to Illustration 17.

8. Welding will cause the tube to shrink by approximately 0.05 mm (0.002 inch) in the welded area. Lightly hone the tube back to the specified size in the following areas: the flange, trunnion, and end cap or eye.

Hone

Hydraulic cylinders are honed to ensure that the proper surface finish is restored on the cylinder walls. Honing also brings the cylinder bore back to the correct size and roundness. Another purpose of hydraulic cylinder honing is refinishing the bore that has been in previous service. Refinishing involves the removal of scratches and/or rust that is on the cylinder walls. An improper surface finish will prevent new seals from providing a good seal on the cylinder wall. The cylinder may leak and unexpected performance might occur. The surface roughness needs to be within a specified range. If the surface is too rough, the seal will not last for the intended life. If the surface is too smooth, proper oil retention on the cylinder walls will be inadequate. The seal may get hot due to friction which is a cause of premature failure. Honing is used to scuff a smooth or glazed cylinder surface. Honing gives the cylinder a texture that will hold oil. Honing also provides lubrication for the piston seal and the wear ring. Honing will also correct noticeable distortion in cylinder bores out of round, bell mouth, barrel, taper, and minor dents.

For more information on hydraulic cylinder honing, refer to Special Instruction, REHS2689, "Hydraulic Cylinder Honing".

Cleaning

The honing process creates a large quantity of abrasive particles that must be cleaned from the cylinder before the cylinder is resealed. The abrasives are either stone particles, the binder used to hold the stone particles together, guide material, or metal shavings from the cylinder bore. Abrasives can cause accelerated wear to hydraulic cylinder seals and other components in the hydraulic system if not properly removed from the cylinder bore.

After honing, allow the honing oil to drain from the cylinder assembly. Properly wash the cylinder assembly inside diameter using the 250-6597 Cylinder Washer available from Dealer Service Tools, or equivalent. Reference the Tool Operating Manual, NEHS0927, "Procedures for Using the 250-6597 Cylinder Washer Tank Group" for operating and repair instructions.

Oversize Honing

Current advances in cylinder seal technology allow for possible cylinder assembly salvage by oversized honing. Usual bore refinishing (glaze removal) increases the ID (inside diameter) of the cylinder assembly less than 0.025 mm (0.001 inch). Oversized honing increases the bore size 0.25 to 0.76 mm (0.010 to 0.030 inch) oversize.

Cylinders that are honed and the inside diameter is not greater than 0.25 mm (0.010 inch) over nominal size can be resealed using standard bore size seals, regardless of operating pressure. Any bore oversized past 0.25 mm (0.010 inch) using standard seals may cause seal extrusion.

Cylinders that operate at pressures up to 20700 kPa (3000 psi) can be honed to 0.76 mm (0.030 inch) oversize and resealed using 0.76 mm (0.030 inch) oversize seals. For cylinders bored 0.76 to 1 mm (0.030 to 0.040 inch) oversized, the 0.76 mm (0.030 inch) oversized seals can be used. Any bore oversized past 1 mm (0.040 inch) using 0.76 mm (0.030 inch) oversize seals may cause seal extrusion.

Cylinders that operate over 20700 kPa (3000 psi) are not recommended for oversize honing.

Depending on the operating pressure, if the bore scratches cannot be removed by honing 0.76 mm (0.030 inch) oversize, the cylinder must be salvaged by retubing.

Before honing a cylinder assembly oversize, check the availability of oversize seals for the cylinder being repaired. Refer to the latest seal kit IRM (Information Release Memo), PSK (Parts Sales Kit), or the Hydraulic Cylinder & Seal Reference Guide, PEKP1020.

Honing Equipment

Caterpillar offers a manual hone and a semi-automatic hone. For specific information about these tools, contact Dealer Service Tools.

Oversize Cylinders

Depending on operating pressure, the dealer may choose to oversize the bore of the cylinder up to 0.76 mm (0.030 inch). Caterpillar has manufactured three different types of cylinders: threaded-gland, threaded-crown, and bolted-head. All three types of oversize cylinders use standard-size rod seals, but use oversize piston seals and wear rings. The three types of cylinders differ in method used to seal the head to the cylinder. The three types are covered in the following sections.

Oversize Identification

After a cylinder has been honed oversize, the cylinder must be identified as having an oversize bore. One identification method is to stamp ".030 OS" on the tube OD close to the open end of the tube. If possible, locate stamp so the stamp can be read after cylinder is installed on machine.

Another method of identifying oversize cylinders is to stamp the amount of oversize on the metal tag that identifies the cylinder group part number. The stamp should be a minimum of 6.4 mm (0.25 inch) high.

Oversize Threaded-Gland Cylinder

Illustration 18	g01592418
Threaded gland with standard head seal (19) Head seal

The head seal for the oversize threaded gland cylinder is the standard O-ring and back-up ring. Refer to Illustration 18.

Oversize Threaded Crown Cylinder

Illustration 19	g01582913
Threaded crown with oval seal (A) O-ring groove (9) Head (20) Oval seal

The head seal for the oversize threaded-crown cylinder is an oval cross-section seal (20). The head seal fits in the lead-in chamfer at the open end of the cylinder. The O-ring and back-up ring groove (A) in head (9) is left empty.

Table 5

Oval Seal Part Numbers for Oversize Threaded Crown Cylinders
Standard Bore Size	Oversize Head Seal
2.50 mm (0.098 inch)	8C-4889
2.75 mm (0.108 inch)	8C-4890
3.00 mm (0.118 inch)	8T-8367
3.25 mm (0.128 inch)	8C-4891
3.50 mm (0.138 inch)	8T-8368
3.75 mm (0.148 inch)	8T-8369
4.00 mm (0.157 inch)	8T-8370
4.25 mm (0.167 inch)	8T-8371
4.50 mm (0.177 inch)	8T-8372
4.75 mm (0.187 inch)	8T-8373
5.00 mm (0.197 inch)	8T-8374
5.25 mm (0.207 inch)	8T-8375
5.50 mm (0.217 inch)	8T-8376
6.00 mm (0.236 inch)	8T-8377
6.25 mm (0.246 inch)	8T-8378
6.50 mm (0.256 inch)	8T-8379
7.00 mm (0.276 inch)	8T-8380
7.25 mm (0.285 inch)	8T-8381
7.50 mm (0.295 inch)	8C-0553
7.75 mm (0.305 inch)	8C-4892
8.25 mm (0.325 inch)	8T-8382
8.50 mm (0.334 inch)	8C-4893
9.25 mm (0.364 inch)	8T-8383
10.00 mm (0.394 inch)	8C-4895
10.25 mm (0.404 inch)	8C-4896
10.50 mm (0.413 inch)	8C-4897
11.50 mm (0.453 inch)	8C-4898

Threaded Crown Cylinder Assembly Chamfer Dimensions

Oversize threaded crown cylinders are sealed by using an oval head seal that locates in the lead-in chamfer of the cylinder bore. Chamfers that do not meet specifications will cause leaks.

Illustration 20	g01583516
(E) Standard bore (F) 0.76 mm (0.030 inch) oversize (H) 9.7 mm (0.38 inch) max. on standard size bore (J) 8.1 mm (0.32 inch) max. on 0.76 mm (0.030 inch) oversize bore (L) 15° (6) Tube (9) Head (21) Oval Head Seal

If the chamfer is too deep, the chamfer can be shortened by machining a maximum of 3.0 mm (0.12 inch) from the end of cylinder tube (6). If the end of the cylinder is machined, ensure that the crown can be fully threaded onto the cylinder. Ensure that the threads do not bottom before the head is seated against the cylinder. If the chamfer is not concentric and perpendicular with the cylinder bore, the chamfer must be machined again.

Oversize Bolted-Head Cylinder

Illustration 21	g01583073
Bolted head with face O-ring seal. (3) Flange (4) Head (22) Groove for Face O-Ring Seal (23) Face O-ring Seal (24) Location of Stock Seal (25) Former location of Oval Seal

The head seal for the oversize bolted-head cylinder is the same oval seal that is used in an oversize threaded-crown cylinder. The oversize bolted-head cylinder is now sealed at the head joint by an O-ring (23). This O-ring (23) provides a more effective seal than the oval head seal. The groove (24) for the stock seal is left empty.

O-ring Part Numbers and Groove Dimensions

Bolt-on head cylinder assemblies that have been honed oversize but lack the flange face O-ring groove can be reworked to add the groove. Machine new grooves according to the dimensions in Table 6. Make the groove concentric and perpendicular to the centerline of the bore. If the flange face of the cylinder assembly is damaged, the cylinder can be salvaged by machining away a maximum of 3.0 mm (0.12 inch) from the face. If the damaged face has the O-ring groove, the groove must be machined deeper by the amount removed from the flange face.

Note: Some cylinder assemblies have been dealer-reworked to add an O-ring groove to the flange face of the head rather than the cylinder. Do not assemble a cylinder that would mate a cylinder and head both having an O-ring groove.

Illustration 22	g01583674
Seal Groove Width Dimensions. Refer to Table 6 for item references and dimensions.

Table 6

Seal Part Numbers and Machining Dimensions
Nominal Bore Diameter	O-ring Part Number	Groove Diameter (A)	Groove Width (B)	Groove Depth (C)	Radius (D)
76.20 mm (3.000 inch)	5P-2931	87.12 mm ± 0.50 (3.43 ± .020 inch)	2.40 ± 0.05 mm (.094 ± .002 inch)	1.33 ± 0.05 mm (.052 ± .002 inch)	0.4 ± 0.05 mm (.016 ± .002 inch)
88.90 mm (3.500 inch)	4F-4097	101.96 mm ± 0.50 (4.014 ± .020 inch)	3.53 ± 0.08 mm (.139 ± .003 inch)	1.95 ± 0.08 mm (.077 ± .003 inch)	0.4 ± 0.10 mm (.016 ± .004 inch)
95.25 mm (3.750 inch)	7X-5494	106.30 ± 0.50 mm (4.185 ± .020 inch)	2.40 ± 0.05 mm (.094 ± .002 inch)	1.33 ± 0.05 mm (.052 ± .002 inch)	0.4 ± 0.05 mm (.016 ± .002 inch)
101.60 mm (4.000 inch)	9X-7357	112.52 ± 0.50 mm (4.430± .020 inch)	2.40 ± 0.05 mm (.094 ± .002 inch)	1.33 ± 0.05 mm (.052 ± .00 inch)	0.4 ± 0.05 mm (.016 ± .002 inch)
107.95 mm (4.250 inch)	6S-3002	121.00 ± 0.50 mm (4.764 ±.020 inch)	3.53 ± 0.08 mm (.139 ± .003 inch)	1.95 ± 0.08 mm (.077 ± .003 inch)	0.4 ± 0.10 mm (.016 ± .004 inch)
114.30 mm (4.500 inch)	9X-7566	127.36 ± 0.50 mm (5.014 ±.020 inch)	3.23 ± 0.08 mm ((.139 ± .003 inch)	1.95 ± 0.08 mm (.077 ± .003 inch)	0.4 ± 0.10 mm ((.016 ± .004 inch)
120.00 mm (4.720 inch)	133-0128	136.00 ± 0.50 mm (5.354 ± .020 inch)	3.53 ± 0.08 mm (.139 ± .003 inch)	1.95 ± 0.08 mm (.077 ± .003 inch)	0.4 ± 0.10 mm (.016 ± .004 inch)
120.65 mm (4.750 inch)	3F-5792	136.45 ± 0.50 mm (5.372 ± .020 inch)	4.75 ± 0.13 mm (.187 ± .005 inch)	2.64 ± 0.13 mm (.104 ± .005 inch)	0.8 ± 0.20 mm (.031 ± .008 inch)
127.00 mm (5.000 inch)	131-3716	137.92 ± 0.50 mm (5.430 ±.020 inch).	2.40 ± 0.05 mm (.094 ± .002 inch)	1.33 ± 0.05 mm (.052 ± .002 inch)	0.4 ± 0.05 mm (.016 ± .002 inch)
133.35 mm (5.250 inch)	2D-8009	149.15 ± 0.50 mm (5.872 ± .020 inch)	4.75 ± 0.13 mm (.187 ± .00 inch)	2.64 ± 0.13 mm (.104 ± .005 inch)	0.8 ± 0.2 mm (.031± .008 inch)
139.70 mm (5.500 inch)	9X-7358	152.76 ± 0.50 mm (6.014 ± .020 inch)	3.53 ± 0.08 mm (.139 ± .003 inch)	1.95 ± 0.08 mm ((.077 ± .003 inch)	0.4 ± 0.10 mm (.016 ± .004 inch)
140.00 mm (5.510 inch)	2K-8257	155.50 ± 0.50 mm (6.122 ± .020 inch)	4.75± 0.13 mm (.187 ± .005 inch)	2.64 ± 0.13 mm (.104 ± .005 inch)	0.8 ± 0.20 mm (.016 ± .004 inch)
152.40 mm (6.000 inch)	8T-6404	165.46 ± 0.50 mm (6.514 ± .020 inch)	3.53 ± 0.08 mm (.139 ± .003 inch)	1.95 ± 0.08 mm (.077 ± .003 inch)	0.4 ± 0.10 mm ((.016 ± .004 inch)
158.75 mm (6.250 inch)	9X-7391	171.81 ± 0.50 mm (6.764 ± .020 inch)	3.53 ± 0.08 mm (.139 ± .003 inch)	1.95 ± 0.08 mm (.077 ± .003 inch)	0.4 ± 0.10 mm (.016 ± .004 inch)
160.00 mm (6.30 inch)	9D-8042	176.15 ± 0.50 mm (6.935 ± .020 inch)	3.53 ± 0.08 mm (.139 ± .003 inch)	1.95 ± 0.08 mm (077 ± .003 inch)	0.4 ± 0.10 mm (.016 ± .004 inch)
165.10 mm (6.50 inch)	9D-8042	179.17 ± 0.50 mm (7.054 ± .020 inch)	3.53 ± 0.08 mm (.139 ± .003 inch)	1.95 ± 0.08 mm (.077 ± .003 inch)	0.4 ± 0.10 mm (.016 ± .004 inch)
170.00 mm (6.690 inch)	9X-7725	187.50± 0.50 mm (7.382 ± .020 inch)	3.53± 0.08 mm (0.139 ± .003 inch)	1.95± 0.08 mm (0.077 ± .003 inch)	0.4 ± 0.10 mm (0.016± .004 inch)
177.80 mm (7.000 inch)	5J-2383	198.98± 0.50 mm (7.834 ± .020 inch)	4.75 ± 0.13 mm (0.187± .005 inch)	2.64± 0.13 mm (0.104± .005 inch)	0.8 ± 0.20 mm (0.031± .008 inch)
180.00 mm (7.087 inch)	5J-2383	196.50± 0.50 mm (7.736 ± .020 inch)	4.75± 0.13 mm (0.187 inch)	2.64± 0.13 mm (0.104± .005 inch)	0.8 ± 0.20 mm (0.031± .008 inch)
184.15 mm (7.250 inch)	5J-2383	198.98± 0.50 mm (7.834± .020 inch)	4.75 ± 0.13 mm (0.187± .005 inch)	2.64± 0.13 mm (0.104± .005 inch)	0.8 ± 0.20 mm (0.031± .008 inch)
190.50 mm (7.500 inch)	3J-0634	211.68 ± 0.50 mm (8.334± .02 inch)	4.75 ± 0.13 mm (0.187± .005 inch)	2.64± 0.13 mm (0.104± .005 inch)	0.8 ± 0.20 mm (0.031± .008 inch)
196.85 mm (7.750 inch)	3J-0634	209.47 ± 0.50 mm (8.247 ± .020 inch)	4.75 ± 0.13 mm (0.187± .005 inch)	2.64± 0.13 mm (0.104± .005 inch)	0.8 ± 0.20 mm (0.031± .008 inch)
200.00 mm (7.874 inch)	5P-3092	225.00± 0.50 mm (8.858± .020 inch)	7.40 ± 0.20 mm (0.291± .008 inch)	3.95 mm (0.155 ± .008 inch)	1.6 ± 0.4 mm (0.063 ± .016 inch)
209.55 mm (8.250 inch)	4K-6804	224.38± 0.50 mm (8.834± .020 inch)	4.75 ± 0.13 mm (0.187± .005 inch)	2.64± 0.13 mm (0.104± .005 inch)	0.8 ± 0.20 mm (0.031± .008 inch)
215.90 mm (8.500 inch)	1T-0132	241.22 ± 0.50 mm (9.497 ± .020 inch)	4.75 ± 0.13 mm (0.187± .005 inch)	2.64± 0.13 mm (0.104± .005 inch)	0.8 ± 0.20 mm (0.031± .008 inch)
220.00 mm (8.661 inch)	1M-9015	253.92 ± 0.50 mm (9.997± .020 inch)	9.35± 0.25 mm (0.368 ± .010 inch)	5.20 ± 0.25 mm (0.205 ± .006 inch)	1.6 ± 0.4 mm (0.063 ± .016 inch)
234.95 mm (9.250 inch)	5S-3676	253.92 ± 0.50 mm (9.997± .020 inch)	4.75 ± 0.13 mm (0.187± .005 inch)	2.64± 0.13 mm (0.104± .005 inch)	0.8 ± 0.20 mm (0.031± .008 inch)
254.0 mm (10.000 inch)	3S-3074	276.15 ± 0.50 mm (10.872 ± .020 inch)	7.40 ± 0.20 mm (0.291± .008 inch)	3.95 mm (0.155 ± .008 inch)	1.6 ± 0.4 mm (0.063 ± .016 inch)
266.70 mm (10.500 inch)	5P-2236	288.85± 0.50 mm (11.372 ± .020 inch)	7.40 ± 0.20 mm (0.291± .008 inch)	3.95 mm (0.155 ± .008 inch)	1.6 ± 0.4 mm (0.063 ± .016 inch)
279.40 mm (11.000 inch)	130-9108	310.50± 0.50 mm (12.224± .020 inch)	7.40 ± 0.20 mm (0.291± .008 inch)	3.95 mm (0.155 ± .008 inch)	1.6 ± 0.4 mm (0.063 ± .016 inch)
292.10 mm (11.500 inch)	6V-3263	314.25± 0.50 mm (12.372± .020 inch)	7.40 ± 0.20 mm (0.291± .008 inch)	3.95 mm (0.155 ± .008 inch)	1.6 ± 0.4 mm (0.063 ± .016 inch)
317.50 mm (12.500 inch)	130-9109	360.50 ± 0.50 mm (14.193 ± .020 inch)	7.40 ± 0.20 mm (0.291± .008 inch)	3.95 mm (0.155 ± .008 inch)	1.6 ± 0.4 mm (0.063 ± .016 inch)
330.20 mm (13.000 inch)	130-9110	381.50± 0.50 mm (15.020 ± .020 inch)	7.40 ± 0.20 mm (0.291± .008 inch)	3.95 mm (0.155 ± .008 inch)	1.6 ± 0.4 mm (0.063 ± .016 inch)
342.90 mm (13.500 inch)	130-9110	381.50± 0.50 mm (15.020± .020 inch)	7.40 ± 0.20 mm (0.291± .008 inch)	3.95 mm (0.155 ± .008 inch)	1.6 ± 0.4 mm (0.063 ± .016 inch)

Cylinder Heads

Nomenclature

Illustration 23	g01622492
Cylinder Head nomenclature (bolted head). (26) O-ring seal and back-up ring head seal groove (27) Wiper seal counterbore (28) Head wear band groove (29) Buffer seal groove (30) U-cup seal groove

Inspection and Reuse of Heads

Illustration 24	g03396036
Light scratches in the bore Use again

Illustration 25	g03396038
Heavy scratches in the bore Use again after salvaging the bore by welding and machining.

Salvage of Heads

Some cylinders can develop wear behind the U-cup seal. Cylinders also develop wear between the U-cup seal and the wiper seal. The worn areas can be machined to allow more room for welding. The seal grooves can then be machined back into place. If the U-cup seal is extruded, this repair should be considered. Seal extrusion is a factor of gap, temperature, and pressure. Typically, cylinders are engineered to have approximately 0.20 mm (0.008 inch) total clearance between the rod and the lands inside the head. If the gap gets too large, the temperature gets too high or the pressure gets too high, seal extrusion can occur. In certain circumstances, a cylinder can operate with more than 0.20 mm (0.008 inch) total clearance. Information from the field has shown that cylinders can operate with as much as 0.30 mm (0.012 inch) to 0.38 mm (0.015 inch) total clearance. If the U-cup seal has a backup ring, the clearance can be even more. Too many variables exist for Caterpillar to give a dimension at which a head should be salvaged. The decision to repair should be made after the head has been disassembled.

Illustration 26	g01452053

The area behind the U-cup seal shown in black in Illustration 26 should be removed by machining. Machine a radius in the corner to allow for weld penetration. Build up the area by welding. Machine the groove back to the correct dimensions.

Installation of Head Wear Ring

More recent design of hydraulic cylinder heads includes a groove for a nylon wear ring. This wear ring prevents contact between the chrome rod and the hardened bore of the head. Heads not having the wear ring can easily be updated by machining a groove for the wear ring.

Numerous publications list the wear ring that is used with each head. Refer to Hydraulic Cylinder & Seal Reference Guide, PEKP1020 to select the proper wear ring.

The first machining operation requires the head bearing bore to be machined to 0.33 mm (0.013 inch) larger than the diameter of the rod. This diameter is the same diameter as the land between the U-cup and buffer seal.

Machining dimensions for the new wear ring groove can be calculated as follows:

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Illustration 27	g01252089
Measure the thickness of the wear ring selected and record the measurement.

1. Measure the thickness of the wear ring selected with a rounded anvil micrometer and record the measurement. Refer to Illustration 27.

2. Measure the diameter of the chrome hydraulic cylinder rod and record this measurement.

3. Add two times the thickness measurement found in Step 1 to the diameter measurement found in Step 2.

4. Add 0.10 mm (0.004 inch) to the value obtained in Step 3.

The value obtained in Step 4 is the diameter of the groove, which must be machined in the head for the new wear ring installation.

Illustration 28	g01252092
Measure the width of the wear ring selected.

The groove length is determined by measuring the width of the wear ring and adding 0.30 mm (0.012 inch) to that measurement. Refer to Illustration 28.

Illustration 29	g01252128
Check the run-out of the bore with an indicator to make sure that the groove will be concentric to the bore. The Total Indicator Reading (TIR) must not exceed 0.05 mm (0.002 inch).

Illustration 30	g01252131
Check the runout of the flange with an indicator to make sure that the groove will be perpendicular to the flange. The Total Indicator Reading (TIR) must not exceed 0.05 mm (0.002 inch).

Illustration 31	g01252135
Carbide cutting tools are required to machine the hardened surface of the bore.

Machining of the groove can be accomplished by using an engine lathe that has the chuck capacity to hold the head. Secure the head in the chuck. Measure the head with an indicator to make sure that the groove is concentric and perpendicular to the center-line of the bore. Refer to Illustrations 29 and 30. The total indicator reading (TIR) must not exceed 0.05 mm (0.002 inch) on the bore or the flange face. Corners of the groove must be square with the groove and have a maximum of 0.76 mm (0.030 inch) radius at the intersection of the groove diameter and the side of the groove. Carbide cutting tools are required to machine the hardened surface of the bore. Refer to Illustration 31.

Cylinder Head Wear Band Reuse

Illustration 32	g01588113
Example of a metal wear band removed for clarity.

If a cylinder develops an early hour leak, reuse of the cylinder head wear band may be possible. Never reuse seals. Seals can be easily damaged during removal. Therefore, all seals should be replaced with new seals.

In the normal life span of a cylinder, the head wear band will develop normal wear along with the seals. Typically, the wiper seal will wear out before the wear band. All high hour cylinders should have all the seals and the wear band replaced after disassembly.

Note: Do not remove the metal wear band of the cylinder head for inspection. The metal wear band will be destroyed if removed.

Check the wear band for damage. Look for cracks, broken edges, or scratches. If any damage is found, do not reuse the wear band. If none of these issues are found, the metal wear band may be reused.

Piston and Nut

Inspection and Reuse of Pistons

Illustration 33	g03396041
Light Scratches Use again after removing any sharp or raised edges with emery paper and/or file.

Illustration 34	g03396346
Light Scratches Use again after removing any sharp or raised edges with emery paper and/or file.

Illustration 35	g01252209
Remove raised and/or sharp edges with a file.

Illustration 36	g03358889
Remove sharp edges with 180 grit emery paper.

Illustration 37	g03396354
Piston with heavy scratches Use again after raised and/or sharp edges are removed with emery paper and/or file.

Illustration 38	g01252241
Piston after raised and/or sharp edges were removed. Use again

Note: Do not decrease the diameter across the piston more than 0.13 mm (0.005 inch) maximum. If a piston is undersize to this maximum amount, do not use the piston with a tube that is honed 0.25 mm (0.010 inch) oversize.

Illustration 39	g03396356
Heavy damage Do not use again

Reuse of Nuts

Illustration 40	g01252261
Piston retaining nut with nylon lock. Use Again Two types of piston retaining nuts with a nylon lock are shown. These nuts can be used again up to seven times. Make a mark on the exterior of the nut each time to indicate the number of times the nut has been used.

Rods

Nomenclature

Illustration 41	g01585375
Parts of a typical cylinder rod. (31) Rod Eye (32) Rod (33) Piston (34) Nut

Inspection and Reuse of Rods

Illustration 42	g03396434
Heavy scratches Use again after the rod is salvaged by chrome plating or HVOF spraying, grinding, and polishing.

Illustration 43	g06038728
Light scratches cannot be felt with a fingernail. Use again

Illustration 44	g06038730
Light scratches cannot be felt with a fingernail. Use again

Illustration 45	g03396441
Scored rod Use again after the rod is salvaged by chrome plating or HVOF spraying, grinding, and polishing.

Note: Rods too deeply scored to be salvaged by chrome plating or HVOF spraying and grinding can be salvaged by welding. Salvage welding is acceptable for all rods except for rods used in steering cylinders, scraper bowl cylinders, and front suspension cylinders on trucks. If the scored area is small, the rod can also be salvaged by selective plating or selective HVOF spraying.

Illustration 46	g03396445
Light pitting in the chrome plating or HVOF spraying that cannot be felt with a fingernail. Use again after the rod is salvaged by chrome plating or selective HVOF spraying, grinding, and polishing.

Illustration 47	g03396449
Pitting Use again after salvaging the rod by stripping, grinding, chrome plating or HVOF spraying and polishing.

Illustration 48	g03396455
Heavy pitting Use again after salvaging the rod by stripping, grinding, chrome plating and polishing.

Illustration 49	g06038729
Light pitting in the chrome plating can be felt with a fingernail. Use again after the rod is salvaged by chrome plating or HVOF spraying, grinding, and polishing.

Illustration 50	g06038731
Dent in the rod surface indicated by the arrow. Use again Use again after the rod is salvaged by selective plating or selective HVOF spraying.

Note: Selective plating or selective HVOF spraying is only practical for the repair of small areas. For example, small areas of dents or pitting can be salvaged by this method.

Illustration 51	g01585434
Typical damage to a cylinder rod. (35) Metal transfer (36) Pitting (37) Dents

Individual dents (37) and small areas of pitting (36) can be salvaged by selective plating or selective HVOF spraying. Metal transfer (35), where metal has moved from one surface to another, must be salvaged by polishing. Refer to Illustration 51.

Illustration 52	g06038963
Pieces of the chrome plating or HVOF spraying have come away from the rod. Use again after salvaging the rod by stripping, grinding, chrome plating or HVOF spraying and polishing.

Illustration 53	g06038984
Pieces of the chrome plating or selective HVOF spraying have come away from the rod. Use again after salvaging the rod by stripping, grinding, chrome plating or selective HVOF spraying, and polishing.

Illustration 54	g06038990
Pieces of the chrome plating have come away from the rod. Use again after salvaging the rod by stripping, grinding, chrome plating and polishing.

Illustration 55	g06218455
Inspect the machined radii and grooves on the piston shank region of the cylinder rod. Liquid dye penetrant or magnetic particle inspection methods may be helpful in identifying cracks.. Do not use again if cracks are found.

Liquid Penetrant Testing (PT)

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Personal injury can result from improper handling of chemicals. Make sure you use all the necessary protective equipment required to do the job. Make sure that you read and understand all directions and hazards described on the labels and material safety data sheet of any chemical that is used. Observe all safety precautions recommended by the chemical manufacturer for handling, storage, and disposal of chemicals.

Refer to Tooling and Equipment Table 3 for part numbers.

• Cleaner: Removes dirt before dye application and dissolves the penetrant making possible to wipe the surface clean.

• Penetrant: This solution is highly visible, and will seep into openings at the surface of a part with capillary action.

• Developer: Provides a blotting action, bringing the penetrant out of the discontinuities and providing a contrasting background to increase the visibility of the penetrant indications.

• Wire Brush: Removes dirt and paint.

• Cloth or Wipes: Use with cleaner and for other miscellaneous uses.

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Illustration 56	g06107074
Typical example of pre-cleaning area.

1. Preclean inspection area. Spray on cleaner / remover to loosen any scale, dirt, or any oil. Wipe the area to inspect with a solvent dampened cloth to remove remaining dirt and allow the area to dry. If there is visible crack, remove paint using paint remover or wire brush.
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   Illustration 57	g06107081
   Typical example of applying penetrant.

2. Apply penetrant by spraying to the entire area to be examined. Allow 10 to 15 minutes for penetrant to soak. After the penetrant has been allowed to soak, remove the excess penetrant with clean, dry wipe.
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   Illustration 58	g06107088
   Typical example of removing excess penetrant.

3. The last traces of penetrant should be removed with the cleaner solvent dampened cloth or wipe. Allow the area to dry thoroughly.
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   Illustration 59	g06107094

4. Before using Developer, ensure that it is mixed thoroughly by shaking can. Hold can approximately 8-12 inches away from part, apply an even, thin layer of developer over the area being inspected. A few thin layers are a better application method than one thick layer.
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   Illustration 60	g06084042
   Typical example of cracks found during a liquid penetrant examination.

5. Allow the developer to dry completely for 10–15 minutes before inspecting for cracks. Defects will show as red lines in white developer background, refer to Illustration 60. Clean the area of application of the developer with solvent cleaner.

Surface Finish Inspection

When an HVOF coated component has not failed at time of disassembly, the surface roughness of the component must be measured. If the surface finish does not meet the specification, the component should be repolished and checked again. After repolishing, the following inspection procedure should be conducted:

• Place component on rollers, in a lathe, or hang vertically.

• Clean the inspection area with isopropyl alcohol and a lint free cloth.

• Holding an LED pen light less than 1 ft from the surface and at an approximately 30 degree angle, look for any shiny sparkles. If any are seen, circle the area with a permanent marker or paint pen.

• Hold a ball point pen at approximately a 45 degree angle and lightly drag the tip across the marked areas. Reject the part if a pit is felt when moving the pen across the surface.

Illustration 61	g06038724
Holding the LED pen light less than 1 ft from the surface and at an approximately 30 degree angle.

Illustration 62	g06038694
Holding the ball point pen at approximately a 45 degree angle.

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Rerodding, straightening, or welding any steering cylinder rod, bowl cylinder rod, or front suspension cylinder rod could result in injury or death. If any of these rods are broken or cracked, the rods must be replaced with a REMAN rod or a new rod. These rods can be ground and plated with chrome if the recommended Caterpillar process that is identified in this document is used.

Illustration 63	g06404391
Bent rod Use again after salvaging the rod by straightening.

Note: Some bent rods can have small cracks on the surface. Do not use bent rods with cracks. Also, the maximum amount a rod can be bent and still be straightened is 3.18 mm (0.125 inch) measured over a 610 mm (24.0 inch) length.

Illustration 64	g01252379
The chrome plating or HVOF spray, has been removed because the rod is bent. Do not use again Do not straighten the rod. The rod is too short and thick. For a complete explanation of the procedure, refer to the "Procedure for Salvaging Cylinder Rods (Rerodding)" section in this guideline.

Illustration 65	g01252387
Bent rod Do not use again do not straighten the rod. The rod is bent too much. For a complete explanation of the procedure, refer to the "Procedure for Salvaging Cylinder Rods (Rerodding)" section in this guideline.

Illustration 66	g01252390
Broken rod Use again after salvaging the rod by rerodding.

Inspection and Reuse of Eyes

Illustration 67	g01252393
Damage to the eye is in the bearing area. Use again after salvaging the eye by welding and machining.

Procedure for Salvaging Cylinder Rods (Rerodding)

Cylinder rods that are badly bent or broken can be salvaged by rerodding. Rerodding is a procedure by which a new rod is welded to the original eye. Basically, the old rod is cutoff, and a new rod is machined to the same specifications. The new rod is then welded to the eye portion of the damaged rod.

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Rerodding, straightening, or welding any steering cylinder rod, bowl cylinder rod, or front suspension cylinder rod could result in injury or death. If any of these rods are broken or cracked, the rods must be replaced with a REMAN rod or a new rod. These rods can be ground and plated with chrome if the recommended Caterpillar process that is identified in this document is used.

General Information

Acceptable Rod Material

The following SAE steels can be used in the salvage of hydraulic cylinder rods.

• SAE 1045 Pre-Chromed and Induction Hardened

A preferred material for rerodding is SAE 1045. The material supplied should have a minimum tensile strength of 861845 kPa (125000 psi) and 689476 kPa (100000 psi) yield strength

• SAE 1045

The material supplied should have a minimum tensile strength of 675686.48 kPa (98000 psi) and a 406790.84 kPa (59000 psi) psi yield strength.

Note: SAE 1045 is acceptable as rerod material only if the completed rod is processed according to the following:

1. The finished rod should have an induction hardened layer 1.3 mm (0.05 inch) to 2.5 mm (0.10 inch) deep with a minimum hardness of 50 on the Rockwell C (Rc) hardness scale.

2. The chrome plate should be no less than 0.018 mm (0.0007 inch) thick with a hardness of Rc 70.

3. The hardness of the inner core of the medium carbon rod should be 18 to 35 Rc

Previously, SAE 1141, SAE 1144, SAE 1144 STRESSPROOF®, and SAE 1144 FATIGUEPROOF® were recommended as acceptable rerod steels. The recommendation is removed, because SAE 1144 steels are resulfurized and do not weld correctly.

Cutting Pre-chromed Rod (SAE 1045)

Illustration 68	g01622882
(A) Weld Repair Area (B) Stroke Line (C) End of Rod to Stroke Line

Cylinder rods that have been in service have a stroke line (B) located near the eye of the rod. The stroke line (B) is where the wiper seal rests when the rod is fully retracted. This line will be visible. Area (A) is the area on the rod where the wiper seal does not contact. Measure Distance (C) from the end of the cylinder rod to the stroke line (B) before the rod is cut. Record this measurement.

Pre-chromed hydraulic cylinder rod is an induction-hardened, medium carbon steel. The machining of pre-chromed rod will include cutting through all of the heat treatment and chrome plate discussed above under SAE 1045. The most difficult part of the operation will be cutting through the chrome and induction hardened layers. This process will require special tooling.

The rod must be rigidly chucked in the lathe with the area to be machined located as close to the chuck as possible. Support the tool with minimal overhang. Since the chrome is of such hardness, a hot-pressed ceramic cutting insert must be used. The insert must be oriented at a 45 degree side cutting edge angle to minimize the wear notch.

The machine rpm should be set to produce a cutting speed in the range of 85 to 98 surface meters per minute (280 to 320 surface feet per minute). The machine feed rate should be set for 0.13 mm (0.005 inch) to 0.18 mm (0.007 inch) per revolution.

Note: Do not use coolant on hot-pressed ceramic inserts. Thermal shock will cause the insert to shatter.

Cutting deeper than 3.0 mm (0.12 inch) using the ceramic insert is not necessary. The hot pressed ceramic insert number SNG454T1 is available through major tooling suppliers. After the hardened and chrome layers have been removed, conventional carbide tooling with coolant can be used to finish machining the part.

For dealers with approved access to the Hydraulic Information System (H.I.S.), obtain Cylinder Dimensions by entering the part number. Also access to rod machining dimensions can be obtained after entering the rod part number. To obtain approval, select "Contact Us" on the H.I.S. web screen.

Eye Preparation

Note: Rods over 114 mm (4.5 inch) diameter are tubular. Tubular rods are easier to cut with a chop saw rather than a torch.

Illustration 69	g01252409
Do not cutoff the rod too near the eye.

1. Measure 100 mm (4.0 inch) from the rod eye, and cut the remainder of the rod off with a torch. This step will produce a 100 mm (4.0 inch) stub. Refer to Illustration 69.

2. Temper (heat) the surface of the stub with the torch until the stub becomes red. Let the stub cool naturally.

3. Weld a 100 mm (4.0 inch) long steel rod to the eye opposite the stub. Be sure that the new steel rod is approximately the same diameter as the original rod.

4. Install the eye on a lathe. Chuck on the 100 mm (4.0 inch) stub of the original rod. Machine the welded rod until the rod is concentric with the 100 mm (4.0 inch) stub.

5. Turn the eye around and chuck on the welded rod that was machined on the lathe.

6. On larger and heavier eyes, machine the end of the rod for a center. Larger eyes need the added support.
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   Illustration 70	g01588693
   (A) Weld Repair Area (B) Stroke Line (C) End of Rod to Stroke Line (D) End of Rod to Eye of Rod

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   Illustration 71	g01622907
   (B) Stroke Line (E) Weld Repair

   Note: Whenever possible, all weld repairs (E) should be made past the stroke line (B) in area (A). The distance from the end of the rod to the weld repair area (E) should be longer than Dimension (C) that was measured earlier. The wiper seal should not contact the repair area. No further machining or chroming will be necessary if the repair area is made in area (A). The final length (D) of the repaired rod must still be the proper length.

7. Machine the stub on the rod eye so that the weld repair area can be made past the stroke line if possible.
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   Illustration 72	g01252416
   After the welded rod is machined, chuck the rod in the lathe to machine the stub.

8. Machine the stub to approximately one third the diameter of the original rod. Machine a standard thread and a 30 degree welding chamfer from the base of the threads to the outside diameter of the rod. Refer to Illustration 72.

Illustration 73	g01591555
Use these dimensions as a general guide to machine the stub correctly. (M) 101.6 (4.00) (N) 30 degree (O) 1/3 x Diameter Q (P) 3/4 x Diameter Q (Q) Diameter (R) 1 x Diameter Q (38) Standard thread (39) Tack weld

Note: If the rod is gun drilled, dimension (O) may need to be larger due to the gun drilled hole inside the threaded area. Refer to Illustration 73.

Illustration 74	g01252427
The finished product

Preparation of the Rod

1. Measure the original rod from the center of the eye to the opposite end.

2. Machine the piston end of the new rod to the same specifications as the old rod. Be sure clearance between the shaft and piston is 0.08 mm (0.003 inch) or less. Ensure that the piston seat is perpendicular to the center of the rod within 0.05 mm (0.002 inch) TIR.
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   Illustration 75	g01252428
   Rod in position to machine.

3. In the eye end of the rod, machine a threaded hole that is the same diameter and pitch as the thread machined on the eye. Machine a 30 degree welding chamfer from the outside diameter of the rod. The eye end of the rod must be machined so the length of the rod will be correct when the eye is installed.
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   Illustration 76	g01252430
   Eye in position on the rod.

4. Assemble the eye to the rod.

Rod and Eye Preparation Considerations for Position Sensing Cylinders

Caterpillar uses position sensing cylinders (PSC) in various applications. These cylinders have a gun drilled hole the entire length of the rod. The same process can be used to rerod a PSC as described in the two previous sections. However, slight variations may be required due to the gun drilled hole.

1. Machine the stub to approximately one third the diameter of the original rod. Machine a standard thread and a 30 degree welding chamfer from the base of the threads to the outside diameter of the rod.

   Note: Dimension (O) may need to be larger than one third the original diameter of the rod to have adequate material thickness to thread.

2. The second thing to consider when rerodding a PSC is alignment of the gun drilled hole. The new rod and the stub shaft on the eye must be aligned properly to avoid a lip inside the gun drilled hole. If a lip exists, the stem of the sensor can catch on the lip and damage the sensor. The gun drilled hole must be smooth and seamless.

Weld Procedure for Rerodding

Illustration 77	g01252470
Protection on the first 100 mm (4.0 inch) to 130 mm (5.0 inch) of the new rod during the welding procedure.

1. Put a cover of material over the first 100 mm (4.0 inch) to 130 mm (5.0 inch) of new rod. This step will protect the rod from weld spatter during welding.

2. Weld the rod to the eye with either dual shield wire (flux cored) with the same specification as ASW class E70T-1, E71T-1, or E7018 electrodes. Before welding, heat the rod to a temperature between 150 °C (302 °F) and 200 °C (392 °F). This step will prevent cracks. Refer to the “Welding” section in this guideline for more information.

3. Remove the stub from the rod eye. After removal of the stub, grind this area of the eye until smooth.

Finishing the Rod after Chrome Application

1. The rod is ready if the steel rod used was SAE 1045 pre-chromed, and if the weld is outside of the closed stroke position. If the weld is inside the closed stroke position, the rod should be machined to the correct diameter.
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   Illustration 78	g01252479
   An application of chrome

2. Typically, an initial application of approximately 0.08 mm (0.003 inch) of chrome is applied to conventional cylinders and hoist cylinders. An application of approximately 0.14 mm (0.006 inch) of chrome is applied to truck struts. Depending on the required rod diameter, as much as 0.25 mm (0.010 inch) of chrome can be applied. Refer to Illustration 78.
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   Illustration 79	g01252490
   Grind the rod to size.

3. Grind the rod to size. The amount of chrome on the rod surface after the rod is ground will typically be 0.03 mm (0.001 inch) for conventional cylinders and hoist cylinders. The final chrome thickness for truck struts should be approximately 0.09 mm (0.004 inch).
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   Illustration 80	g01252504
   Polish the rod

4. Wet polish the rod with a 400 grit silica carbide belt. Surface finish must be .20 Ra µm 8 Ra microinch to .40 Ra µm 16 Ra microinch. Refer to “Polishing Chrome” in this guideline for details.

Note: The finished rod diameter is 0.05 ± 0.04 mm (0.002 ± 0.002 inch) under the nominal (standard) rod diameter.

Chrome Plating and Grinding

Chrome plating is discussed here as one of many alternatives for cylinder rod repair.

Chrome Stripping

The chrome on a component being salvaged can be removed mechanically or chemically. The following information describes the necessary procedure for mechanical removal.

Belt grinding with a diamond belt can be implemented by attaching a belt grinding machine to the cross slide of a lathe. The in-feed adjustment will control the amount of load on the component and grinding belt. The feed of the cross slide will control the feed rate of the belt grinder along the component. Some wheel grinders can be converted to belt grinders by substituting a contact wheel for the stone wheel and installing a belt idler assembly.

Chrome removal can be performed at a rate of 0.025 mm (0.001 inch) to 0.038 mm (0.0015 inch) per pass at a traverse rate of 0.66 m/min (26 in/min) with the proper set-up and tooling. 966F or 967F aluminum oxide belts, made by 3M, should be used for chrome stripping. Chrome stripping should be done wet.

Preparation for Chrome Plating

Illustration 81	g01252556
Grind the rod undersize in preparation for chrome plating.

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Rerodding, straightening, or welding any steering cylinder rod, bowl cylinder rod, or front suspension cylinder rod could result in injury or death. If any of these rods are broken or cracked, the rods must be replaced with a REMAN rod or a new rod. These rods can be ground and plated with chrome if the recommended Caterpillar process that is identified in this document is used.

1. Install the rod in an external grinder. For conventional rods and hoist rods, grind the rod to a maximum of 0.08 mm (0.003 inch) undersize if necessary to remove all surface damage. For truck struts a maximum of 0.14 mm (0.006 inch) can be removed. If grinding does not remove all surface damage, the rod must be built up with spot weld. Then, machine the rod to the standard size before chrome plating. Refer to the "Welding" section in this guideline for complete instructions.
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   Illustration 82	g01252558
   Put a cover of protection where necessary.

2. Put tape, stop-off lacquer, or wax on all surfaces of the rod which do not need chrome plating.

3. Install the rod in a fixture for plating. Use auxiliary anodes and thieves, as needed, to control the build-up of plating.

4. Clean the rod as follows:

   1. Remove grease with solvent. This removal is optional and can be done before tape, stop-off lacquer, or wax is used.

   2. Soak clean with alkaline. This cleaning is also optional.

   3. Electroclean with alkaline [anodic 200 ASF (amps per square foot)].

   4. Wash thoroughly with hot water.

   5. Etch with 50% to 60% sulfuric acid (H2SO4) anodic 1 to 1.5 ASI (amps per square inch).

   6. Wash thoroughly with cold water.

5. Put the rod in the plating bath immediately after the cleaning procedure.

Application of Hard Chrome Plating

Illustration 83	g01252562
Rod installed in a fixture, ready for plating.

1. Make sure that the plating bath mixture is 225 to 227 g/liter (20 to 37 oz/gal) of chromium trioxide (CrO3). The acid-to-catalyst total ratio must be from 90:1 to 110:1. The temperature of the plating bath must be 55 °C (131 °F) to 60 °C (140 °F).

2. Put the rod into the plating bath. Keep the rod there until the rod is the same temperature as the bath.

3. Turn the current from zero potential to a current density of 2.0 to 3.0 ASI for all conductive surfaces. This step will take from 30 seconds to 1 minute for the current density to get to this level.

4. Plating must be constant and long enough to build a chrome deposit that results in a diameter of more than the acceptable, finish-machined diameter. A surface deposit of 0.25 mm (0.010 inch) to 0.36 mm (0.014 inch) is desired.

5. After the chrome plating is complete, remove the rod and wash the rod thoroughly with water.

6. Remove the rod from the fixture, and remove all protection (wax, stop-off lacquer, or tape).

7. Put the rod into an oven at a temperature of 150 °C (302 °F) for 3 hours. The rod must be put into the oven no more than 1 hour after the rod is removed from the plating bath. This step must be done to prevent cracks in the chrome plating.

8. Remove the rod from the oven, and let the rod cool slowly to room temperature.

Chrome Grinding Procedure

1. Install the rod in an external grinder, and grind to size. There will be approximately 0.03 mm (0.001 inch) of chrome on the rod surface of a conventional cylinder and hoist cylinder after grinding. There will be approximately 0.09 mm (0.004 inch) of chrome on the rod surface of a truck strut after grinding.

2. Grind the chrome plating carefully to prevent heat or pressure damage to the plating. Grind with a Norton No. 32-A-80-K5-VBE or similar aluminum oxide, 80 grit vitrified bond grinding wheel. Use a large volume of cutting fluid, either heavy-duty synthetic or light, soluble oil. Use wheel speeds of 1980 to 2590 surface meters per minute (6500 to 8500 surface feet per minute) and a medium to high work speed to prevent heat damage.

3. Conventional Cylinders and Hoist Cylinders: After the grinding operation is complete, be sure that the surface finish is Ra = 0.20 µm Ra = 8 microinch to Ra = 0.40 µm Ra = 16 microinch. Also, the rod can be polished, if necessary. Refer to “Polishing Chrome” in this guideline for details.

4. Truck Strut: After the grinding operation is complete, be sure that the surface finish is Ra = 0.10 µm Ra = 4 microinch to Ra = 0.15 µm Ra = 6microinch.

Selective Chrome Plating

Many times when a cylinder has a seal failure, the cause is a small nick, scratch, or pit on the rod surface. Repair of the nick, scratch, or pit is necessary before the rod can be put back into service. The repair can be made most easily by a procedure known as selective plating. In this procedure, a small surface can be plated with a given metal. Copper, nickel, and cobalt are the most common metals used on chrome plated cylinder rods.

Selective plating is not a replacement for bath chrome plating. But just as bath chrome plating is best for the repair of large areas, selective plating is especially practical for the repair of small areas.

Illustration 84	g01252584
Selective plating is a good repair method for small areas.

Selective plating has many steps and must be done correctly by personnel with special training. Training is available from manufacturers of selective plating equipment.

There are five basic steps in the procedure:

1. Preparation of the surface

2. Selection of the correct tools and power settings

3. Masking

4. Procedure to work out plating thickness

5. Surface finishing

The step-by-step procedures will be different according to the type of equipment, type of failure, and type of solution used. For complete details on the procedure and training available, contact the selective plating equipment manufacturer. Refer to the list of suppliers at the end of this guideline.

Polishing Chrome

Polishing is necessary only to remove light scratches or to get a desired surface finish. Polishing chrome may be done after applying new chrome or after grinding chrome to size.

1. Install the rod in an external grinder or a polishing lathe.
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   Illustration 85	g01252592
   Rotation of the polisher must be in this direction.

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   Illustration 86	g01252595
   Use the correct grit belt to polish.

2. Wet polish the chrome with a 400 grit silica carbide belt. The correct belt will give the desired conventional cylinder or hoist cylinder a finish of Ra = 0.20 µm Ra = 8 microinch to Ra = 0.40 µm Ra = 16microinch or Ra = 0.10 µm Ra = 4 microinch to Ra = 0.15 µm Ra = 6 microinch for truck struts. Refer to Illustration 86.

3. Polish only during rotation. Do not polish in one location for extended periods of time.

High Velocity Oxygen Fuel (HVOF)

The following sections concerning HVOF discuss identifying HVOF on a rod, stripping HVOF off a rod, and general dimensions when applying HVOF. For complete details of the entire process as recommended by Caterpillar, refer to Table 7 and Special Instruction, SEBF9236, "Fundamentals of HVOF Spray for Reconditioning Components".

HVOF Identification

Before a repair option can be decided upon, identify the material on the rod. The difference between HVOF and chrome is not obvious at a glance. One way to identify HVOF is by visual inspection. HVOF will be present in the weld area between the rod and the eye. The HVOF in this area will not be polished and will be a dull gray color and will also be rough to the touch. If the weld area is chrome plated, the appearance will be shiny and smooth to the touch.

Illustration 87	g01274314
Visible HVOF on a conventional cylinder rod.

The visual description above also applies to suspension cylinders, struts, and hoist cylinders. The HVOF will be present near the bottom of a strut where the diameter tapers smaller. The HVOF will be present on the end of a hoist cylinder where the piston bolts on.

Illustration 88	g01274316
Area where HVOF will be visible on a strut.

Illustration 89	g01274317
Visible HVOF on a hoist cylinder.

For more information on identification of HVOF coating, refer to Special Instruction, SEBF9233, "HVOF Identification and Polishing".

HVOF Stripping

Illustration 90	g02729079
Finishers Tech SG-6 Belt Grinder mounted on a lathe.

Some cylinder rods are coated with HVOF. The HVOF can be stripped before new HVOF is sprayed on.

Belt grinding with a diamond belt can be implemented by attaching a belt grinding machine to the cross slide of a lathe. The in-feed adjustment will control the amount of load on the component and grinding belt. The feed of the cross slide will control the feed rate of the belt grinder along the component. Some wheel grinders can be converted to belt grinders by substituting a contact wheel for the stone wheel and installing a belt idler assembly.

The removal of an HVOF coating from a piece should be done with a M125 or M250 grit diamond belt from 3M. A diamond belt should only be used until the breakthrough of the steel substrate is apparent. If the diamond belt is used after this point, carbon will be drawn out of the diamond particles by the steel. The belt will stop working. At first exposure to steel, a Cubic Boron-Nitride (CBN) belt should be installed and used to remove the rest of the HVOF.

Coolant with a rust and bacteria inhibitor is required for the HVOF stripping operation. Hard water may require treatment, since materials can interfere with rust inhibitors and other coolant additives. The coolant should be flooded into the contact area between the abrasive and the component.

For adequate filtration, the lathe pump should pipe the coolant to an auxiliary filtering system. The filtering system must be at least 50% efficient for 10 micron particles. A filter tank/pump set up using an automatically advancing paper roll element is preferable for handling large volumes of fluid.

For complete and detailed instructions on stripping, grinding, and polishing/superfinishing chrome and/or HVOF, refer to Special Instruction, SEBF9276, "Thermal Spray Procedures for Hydraulic Cylinder Rods".

Application of HVOF

The application of HVOF on the rod should result in a diameter of more than the acceptable finished diameter. For conventional cylinders and hoist cylinders, an initial spray deposit of approximately 0.13 mm (0.005 inch) is desired.

For truck struts, an initial spray deposit of approximately 0.22 mm (0.008 inch) is desired.

Coating Repairs

The following guidelines should be used when repairing a blemish on an HVOF coated component:

1. If the coating thickness is less than 0.51 mm (0.020 inch), the coating should be completelyremoved and returned to the surface texturing operation.

2. If the coating thickness is over 0.51 mm (0.020 inch), then the following steps should be followed:

   1. Remove 0.13 mm (0.005 inch) of coating thickness.

   2. Heat the component to 177° C (350° F) for 3 hours to remove all oils from the surface of the coating.

   3. Apply a degreasing agent to the surface of the coating and dry with clean shop air.

   4. Apply the HVOF Coating.

HVOF Finishing

The approximate finish thickness of HVOF on conventional cylinders and hoist cylinders is 0.076 mm (0.003 inch). The approximate finish thickness of HVOF on truck struts is 0.17 mm (0.01 inch).

Illustration 91	g02759157
Supfina 210 Super Finisher

Illustration 92	g02759158
Finishers Tech SF-4 Super Finisher

HVOF coatings may be finished by using a conventional wheel grinder or by using a belt grinder. The most economical method of finishing an HVOF coating is belt grinding. Belt grinding is twice as fast as conventional wheel grinding.

Belt finishing for most components is usually a two-step process. The first step is to grind the HVOF coating by using a 3M Trizact M70 diamond belt. This grinding will remove most excess material and remove any taper from the component. The second step uses the super finisher to grind the component to the proper size and the proper surface finish. A 20 micron film should be used for super finishing.

Use of the super finisher has three important purposes. The super finisher removes blemishes that the belt grinder leaves on the surface. Second, the super finisher produces a slight crosshatch in the coating. This finish is desirable because the finish helps to lubricate the seals to extend seal life. The super finisher also leaves a more polished surface appearance.

The belt grinder can be mounted on a good quality lathe by mounting the belt grinding machine to the cross slide. The in-feed adjustment and the feet rate can be controlled by the lathe. The super finisher can also be mounted to a lathe. The super finisher can be combined with a rear-mount belt grinder together on the lathe. This arrangement will allow both operations to be performed on the same machine.

An HVOF coating can be ground at a rate of 0.04 mm (0.002 inch) to 0.05 mm (0.002 inch) per pass at a traverse rate of 4.76 mm (0.188 inch) per revolution with the proper set-up and tooling. A pass is defined as the belt grinder making one trip in one direction for the length of the component. The HVOF coatings can be superfinished at a rate of 0.01 mm (0.001 inch) to 0.04 mm (0.002 inch) per pass at a traverse rate of 635 mm (25 inch) per minute.

Table 7

HVOF Coatings for Conventional Cylinder Rods, Hoist Cylinder Rods, and Truck Struts
Surface Finish	Using a 5 micron stylus: Ra = 0.076 µm (3.000 µin) to 0.203 µm (8.000 µin) OR Rz = 0.70 µm (27.559 µin) Note:Either scale can be used to measure the surface finish, however, Ra and Rz do not equate to each other physically or mathematically as they measure different surface profiles. Only one of these measurements needs to be met.
Finish Thickness	As Required
Finishing Allowance	0.025 mm (0.001 inch) to 0.037 mm (0.002 inch) per side
Machining Equipment Type	Lathe with Grinder attachment or Cylindrical Grinder
Finishing and Superfinishing Equipment Type	Diamond Belt Grinding and Superfinishing
Grinding Equipment	Finishers Tech Super G-6 Belt Grinder or equivalent CNC Cylinder Grinder
Recommended Abrasive	3M Trizact Diamond Cloth Belts 663FC (70 micron)
Superfinishing Equipment	Supfina210, IMPCO, GEM, or equivalent
Recommended Abrasive	3M Diamond Microfinishing Film 675L (20 Micron)

Procedure for Straightening Rods

Some bent rods can be used again after straightening. Before straightening, inspect the rod to obtain the following information.

Illustration 93	g01252641
The rod can have a gentle (A) or sharp (B) bend.

1. Type of bend (gentle or sharp). Refer to Illustration 93.

2. Location of bend.

3. Amount of bend.

4. Type of rod (solid or tubular).

5. Whether or not more salvage operations will be necessary beyond straightening.

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Rerodding, straightening, or welding any steering cylinder rod, bowl cylinder rod, or front suspension cylinder rod could result in injury or death. If any of these rods are broken or cracked, the rods must be replaced with a REMAN rod or a new rod. These rods can be ground and plated with chrome if the recommended Caterpillar process that is identified in this document is used.

The maximum amount of bend a cylinder rod can have and still be straightened is 3.18 mm (0.125 inch) measured over a 610 mm (24.0 inch) length. Any more than this length and the rod must be salvaged by rerodding.

Cylinder rods that are bent at the eye or just below the eye cannot be straightened. The best salvage method for a bend in this location is rerodding. Tubular rods with a gentle bend can be straightened. However, the ram from the straightening press may cause a flat area on the rod surface. A flat area on the rod surface is acceptable if more salvage operations are necessary like building up the rod with weld or chrome plating.

Rods that are bent have other surface damage that needs repair. If more salvage operations are needed, the need to straighten the rod to the final specification is not necessary. If chrome plating or HVOF spraying is necessary, straighten to 0.36 mm (0.014 inch) TIR or less. If welding is necessary, straighten to 0.76 mm (0.030 inch) TIR or less. Many times, a rod that must be salvaged by welding, chrome plating, or HVOF does not need to be straightened as a separate operation: the grinding procedure will straighten the rod instead.

1. Heat the rod in an oven for 90 minutes. Do not use a torch. Using a torch can cause the rod to become too hot in some areas and not hot enough in others. The rod is ready to be straightened when the rod temperature is between 150 °C (302 °F) and 260 °C (500 °F). The recommended temperature is 232 °C (450 °F). Use a thermometer to check the temperature.
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   Illustration 94	g01252662
   100 ton straightening press

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   Illustration 95	g01252667
   150 ton straightening press

2. Put the rod in position on a hydraulic press. Use a 100 ton press for small diameter rods, under 127 mm (5 inch), and a 150 ton press for large diameter rods 127 mm (5 inch) and over. A 150 ton press will do the job for all sizes of rods. Refer to the list of straightening press suppliers at the end of this guideline. Refer to Illustrations 94 and 95.

3. Use a dial indicator to find where the rod is bent the most.

4. If no more salvage operations are needed after the rod is straightened, put a crankshaft bearing between the rod and press ram. Putting a crankshaft bearing between the two parts protects the surface.

5. Put a small amount of force on the cylinder rod where the bend is greatest, and then release the press ram. Measure the amount of TIR in the rod. The rod must be straight to 0.25 mm (0.010 inch) TIR or less measured over the complete length of the rod. If the rod is not, increase the force on the press ram, and repeat the straightening procedure until the rod has the correct straightness. Preferably, straighten the rod a little beyond zero, turn the rod and straighten the rod back to zero from the other side.

Welding

Most of the parts on hydraulic cylinders and rods can easily be salvaged with a special type of welding. This welding process is basically a build-up procedure (adding layer on top of layer). Any of the four methods can be used.

1. Shielded Metal Arc (stick)

2. Gas Metal Arc (MIG)

3. Flux Cored Arc

4. Submerged Arc

The procedure will be different according to the method used and the part. The following general information applies to all procedures.

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Rerodding, straightening, or welding any steering cylinder rod, bowl cylinder rod, or front suspension cylinder rod could result in injury or death. If any of these rods are broken or cracked, the rods must be replaced with a REMAN rod or a new rod. These rods can be ground and plated with chrome if the recommended Caterpillar process that is identified in this document is used.

General Information

Voltage Current and Polarity

The voltage, current, and polarity must be set correctly to produce the required weld deposits.

The voltage controls the shape and size of the weld bead. The weld bead gets flatter as the voltage is increased.

The current (or amperage) controls the rate of weld deposit. The higher the amperage, the higher the rate of deposit. Remember, a high rate is desired because the higher rate decreases the amount of time needed for reconditioning. The use of high amperage to get high deposit rates is limited because of the heat factor. As the amperage goes up, the heat input is increased. The type of current can be either direct (DC) or alternating (AC). Generally, DC is used.

The polarity controls the penetration (depth) of the weld. If the electrode is positive (reverse polarity), there is more penetration. Welding is done with direct current and electrode positive (DCEP).

Preheating Procedure

Cylinder rod assemblies must be preheated to a temperature between 150 °C (302 °F) and 260 °C (500 °F) to prevent cracks due to high carbon content of the rods. Small rods, 114 mm (4.5 inch) diameter and smaller, must be heated completely. Large rods, over 114 mm (4.5 inch) diameter, only require preheating of the area where the weld is to begin. Welding produces enough heat in large rods to maintain the correct temperature range and prevent cracking.

If the welding procedure is interrupted and the rod assembly temperature drops below the required pre-heat temperature, the rod must be preheated again. After preheating again, welding can then be resumed. (Measure the temperature with a thermometer or with a temperature stick).

Conventional hydraulic cylinders (lift, tilt, steering) should be replaced and not repaired. Cylinder housings for off-highway truck suspensions can have damage repaired by welding and must be preheated to at least 93 °C (200 °F) before welding.

Cleaning Procedure

All foreign material like oil, grease, water, paint, rust, dirt, and scale must be removed before the foreign materials are heated by the welding operation. This gas can cause porosity in the weld deposit. Water or rust can cause a condition known as “hydrogen enbrittlement”. The result of this condition is cracking in the weld deposit. Remove oil and grease with solvent. Remove paint, rust, dirt, and scale with a wire brush or glass beads.

Welding Material

Recommendations for the type of electrodes and wires to use will be different, according to the application, procedure, and material. Table 8 gives some basic recommendations.

Table 8

WELDING MATERIALS
Covered Electrode for Shielded Metal Arc Procedure
AWS E6013	An all position general-purpose electrode. Use to weld parts together.
AWS E7018	An all position, medium penetration, and medium deposit electrode. Use for weld build-up in areas of high load.
AWS E7024	A flat position, light penetration, and high deposit electrode. Use for general weld build-up.
	4.75 mm (0.187 inch) Diameter
	5.50 mm (0.216 inch) Diameter
	6.30 mm (0.248 inch) Diameter
Flux-Cored Electrode Wire for Flux-Cored Arc Procedure
AWS E71T-1	For flat and horizontal position, medium penetration, high deposit rate applications. Use to weld parts together and general weld build-up.
	Type II 70	1.15 mm (0.045 inch) Diameter
		1.60 mm (0.063 inch) Diameter
	Type 7000	1.60 mm (0.063 inch) Diameter
		1.15 mm (0.045 inch) Diameter
	Type 7100	1.15 mm (0.045 inch) Diameter
		1.30 mm (0.051 inch) Diameter
		1.60 mm (0.063 inch) Diameter
Solid Electrode Wire for Gas Metal Arc Procedure
AWS E70S-3	Use to weld parts together in flat and horizontal position with CO2. Use for general weld build-up with 75% Ar + 25% CO2 or 98% Ar + 2% O2
	Type-Spoolare85	1.15 mm (0.045 inch) Diameter
	Type-L50	0.90 mm (0.035 inch) Diameter
		1.15 mm (0.045 inch) Diameter
		1.60 mm (0.063 inch) Diameter
		2.00 mm (0.079 inch) Diameter
AWS E70S-6	Use to weld parts together in flat and horizontal position with CO2. Use for general weld build-up with 75% Ar + 25% CO2 or 98% Ar + 2% O2
	Type Supfina 88	0.90 mm (0.035 inch) Diameter
		1.30 mm (0.051 inch) Diameter
Flux and Wire Combination for Submerged Arc Welding of Rods
AWS EL12	For weld build-up of cylinder rods.
	2.40 mm (0.094 inch) Diameter

Note: The combination of Lincoln Wire L-60 and Lincoln Flux A-96-S will give a matensite type 420 stainless steel surface. A minimum of two passes is needed. Three passes will give a surface hardness of Rockwell C52-54.

Refer to Cat Hand Tools and Shop Supplies, PECJ0003 for other weld wire.

Welding Cylinder Rod Eyes

1. Build up the face of the eye first if the eye is damaged. Use an E7018 electrode.
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   Illustration 96	g01253179
   Salvage of a rod eye.

2. Build up the bore of the eye using a 276-2066 Automatic Bore Welder with E7024 weld wire (electrode) or an E7024 stick electrode. European Union-compliant, CE marked 276-2067 Automatic Bore Welder or 276-2068 Automatic Bore Welder can also be used.
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   Illustration 97	g01253182
   Eye welded circumferential.

3. Weld either across the eye or circumferential . Refer to Illustration 97.
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   Illustration 98	g01253185
   Horizontal milling machine in use.

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   Illustration 99	g01253188
   Vertical milling machine in use.

4. Machine the bore and the face to original size. The sequence of machining is not important, but the face and the eye must be machined perpendicular to each other. Use a horizontal or vertical milling machine. Refer to Illustrations 98 and 99.

Welding Cylinder Rods

Illustration 100	g01253189
Welded cylinder rod.

At times, rods are damaged beyond the point where the rods can be ground to a maximum of 0.36 mm (0.014 inch) undersize and then chrome plated. These rods can be built up by one of two methods.

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Rerodding, straightening, or welding any steering cylinder rod, bowl cylinder rod, or front suspension cylinder rod could result in injury or death. If any of these rods are broken or cracked, the rods must be replaced with a REMAN rod or a new rod. These rods can be ground and plated with chrome if the recommended Caterpillar process that is identified in this document is used.

1. Build up the rod with a mild steel weld deposit. Use the gas metal arc procedure, machine, and chrome plate.

2. Build up the rod with a stainless steel weld deposit. Use the submerged arc procedure, and machine to size. No chrome plating is necessary.

Automatic welding equipment is necessary for both methods.

Method 1 - Procedure for Gas Metal Arcing

1. Grind the rod undersize until all damage has been removed.

2. Where welding is to begin, preheat the area to a temperature between 150 °C (302 °F) and 260 °C (500 °F).
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   Illustration 101	g01253214
   Rod in position for gas metal arc procedure.

3. Build up the rod with weld.

   1. Use 1.6 mm (0.063 inch) diameter solid electrode wire (AWS classification E70S-1B). Use a shielding gas of 98% Argon and 2% Oxygen. Use direct current with electrode positive (DCEP).

   2. Overlap the bead from one revolution to the next by 50%.

      Note: A single weld pass will produce enough build-up. More passes are permissible if needed.

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   Illustration 102	g01253216
   Machine the rod back to finish size.

4. Machine the rod to finish size. Refer to Illustration 102.

5. Chrome plate the rod. Refer to “Chrome Plating and Grinding” in this guideline for more information.

Method 2 - Procedure for Submerged Arcing

1. Grind the rod undersize to remove all damage. Grind to a minimum of 1.5 mm (0.06 inch) undersize.

2. Where welding is to begin, preheat the area to a temperature between 150 °C (302 °F) and 260 °C (500 °F).
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   Illustration 103	g01253221
   Submerged arc welding.

3. Build up the rod with weld.

   1. Use 1.27 mm (0.050 inch) solid electrode wire (AWS classification EL12), Lincoln L60. Use Lincoln Flux A96S. Use direct current with electrode positive (DCEP).

   2. Overlap the bead from one revolution to the next by 50%.

      Note: Two passes, minimum, are needed to give a stainless steel composition with a hardness of Rockwell C52-54.

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   Illustration 104	g01253224
   Use a large volume of cutting fluid when grinding.

4. Grind the rod to finish size. Use a Norton No. 32-A-80-1CS-VBE or similar aluminum oxide, 80 grit vitrified bond grinding wheel. Use a large amount of cutting fluid, either heavy-duty synthetic or light soluble oil. Use wheel speeds of 1980 to 2590 surface meters per minute (6500 to 8500 surface feet per minute) and a medium to high work speed to prevent heat damage. Plunge-grind all high points first, and then traverse-grind to finish size with a maximum stock removal of 0.05 mm (0.002 inch) per pass.

5. Polish the rod to a surface finish of 0.4 Ra µm (16 Ra microinch) to 0.8 Ra µm (32 Ra microinch). Use a 220 grit abrasive belt.

Miscellaneous Salvage Welding

Salvage of a Broken Trunnion

Weld the broken piece into place, and build up the bearing surfaces with weld. Then, machine the inside of the bore.

Illustration 105	g01253237
Broken piece from the trunnion has been welded back into position.

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NOTICE
Do not salvage broken lift cylinder trunnions on any scraper bowls, wheel loaders, or track loaders. These trunnions are heat treated for strength, and welding will destroy this special characteristic.

Salvage of Damaged Cylinder Rod Ends

Build up the damaged cylinder rod end with weld. Then, machine the diameter and recut the thread.

Illustration 106	g01253249
Salvage of the piston end of the cylinder rod.

Illustration 107	g01253251
Salvage of the piston end of the cylinder rod.

Salvage of Damaged Cylinder Assembly Ends

Build up the damaged cylinder end with weld. Then, machine the bore to original size.

Illustration 108	g01253254
Salvage of the tube. Build up the end with weld (only the end of the tube was damaged).

Illustration 109	g01253255
Same cylinder tube as the tube shown in Illustration 108 after the tube has been machined to size.

Reconditioning check valve seat of Truck Strut Rods

At truck strut rebuilds inspect the seat of the internal check valve on the front suspension rod. This check valve is set up as an internal cushion and can have erratic actuation depending on conditions.

Conditions such as bad haul roads, overloading, or under charged struts can cause the check ball to strike against check valve seat. This can cause seat damage and allow oil to bleed past check valve.

If any damage is visible upon inspection, reface valve seat to 30°

Illustration 110	g06037118

Machine the valve seat to clean up any damage, minimizing the depth to allow for multiple repairs. Machining depth depends upon damage. Maximum machining depth of 1.5 mm for 40 ton through 100 ton. Maximum machining depth of 3.0 mm for 130 ton through 400 ton. Only machining until the valve seat is cleaned up should allow for more machining to be done on next rebuild.

Note: Mark repair depth of check valve on top of rod in between bolt holes. This will easily identify check valve depth at next rebuild. Indicate with an engraving tool the depth in mm that the check valve was taken to. Example R26.5 for taking 1.5 mm off the check valve seat.

Equipment Suppliers

Surface Finish Analyzers

Taylor Hobson Ltd
PO BOX 36
2 New Star Road
Leicester, LE4 9JQ England
www.taylor-hobson.com
Tel: (0) 166 276 37, Fax: (0) 116 246 0579

United States:

Taylor Hobson Inc.
1725 Western Drive
West Chicago, IL 60185 USA
Tel: (1) 630 621 3099, Fax: (1) 630 231 1739

Japan:

Mitutoyo Corporation Head Office
(Overseas Sales)
20-1 Sakado 1-choma, Takatsu-ku
Kawasaki-shi, Kanagawa-ken 213 Japan
Tel: (81) 044 813 8230, Fax: (81) 044 813 8231

High-Speed Polishers

K W Products
305 Mears Blvd.
Oldsmar, FL 34677
Tel: (1) 813 855 7817

Peterson Machine Tool Inc.
1100 North Union Street
Council Grove KS 66846
www.petersonmachine.com
Tel: (1) 316 634 6699
Fax: (1) 620 767 6415

Straightening Presses

Dake Corporation
724 Robbins Road
Grand Haven, MI 49417 USA
www.dakecorp.com
Tel: (1) 800 937 3253, Fax: (1) 800 846 3253

Eitel Presses
97 Pinedale Industrial Road
Orwigsburg, PA 17961 USA
www.eitelpresses.com
Tel: (1) 570 366 0585, Fax: (1) 570 366 2536

Selective Plating Equipment

Liquid Development Company Inc.
3748 East 91st Street
Cleveland, Ohio 44105
Tel: (1) 216 641 9366, (1) 800 321 9194,
Fax: (1) 216 641 6416

Sifco Selective Plating
World Headquarters
5708 E. Schaaf Road
Cleveland, Ohio 44131-1308 USA
Tel: (1) 216 524 0099, (1) 800 765 4131
Fax: (1) 216 524 6331

Hydraulic Cylinder Hones

Caterpillar Dealer Service Tools
501 SW Jefferson Ave
Peoria, IL 61630 USA
dealerservicetool_hotline@cat.com
(1) 800 542-8665

Sunnen Products Co.
7910 Manchester Rd
St. Louis, MO 63143
Tel: (1) 314 781 2100, Fax: (1) 314 781 2268