Specifications and Reusability for Hydraulic Gear Pumps and Motors{5061, 5073} Caterpillar

Off-Highway Truck/Tractor: All

Articulated Truck:

725 (S/N: AFX1-UP)

730 (S/N: AGF1-UP)

735 (S/N: WWC1-UP; B1N1-UP; AWR1-UP)

735B (S/N: L4D1-UP; T4P1-UP)

740 (S/N: WWD1-UP; AXM1-UP; B1P1-UP; AZZ1-UP)

740 EJECTOR (S/N: B1R1-UP; AZZ1-UP)

740B (S/N: L4E1-UP; T4R1-UP)

740B EJECTOR (S/N: L4F1-UP; T4S1-UP)

Landfill Compactor:

836 (S/N: 3RL1-UP; 7FR1-UP)

836G (S/N: BRL1-UP; 7MZ1-UP)

836H (S/N: BXD1-UP)

Excavator:

225 (S/N: 61X1-UP)

225B (S/N: 2ZD1-UP)

235B (S/N: 7WC1-UP; 1FD1-UP)

235C (S/N: 2PG1-UP; 3WG1-UP; 4DG1-UP)

235D (S/N: 8KJ1-UP)

245 (S/N: 95V1-UP; 84X1-UP)

322L (S/N: 9RL1-UP)

330B (S/N: AME1-UP; 6DR1-UP)

5080 (S/N: 6XK1-UP; 8SL1-UP)

5090B (S/N: CLD1-UP; SJY1-UP)

5110B (S/N: AAA1-UP; AAK1-UP; AAT1-UP)

5130 (S/N: 7TJ1-UP; 5ZL1-UP)

5130B (S/N: 4CS1-UP)

5230 (S/N: 7LL1-UP)

5230B (S/N: 4HZ1-UP)

M325C (S/N: XJA1-UP; PAN1-UP)

W330B (S/N: AME1-UP)

Load Haul Dump:

R1700 II (S/N: 4LZ1-UP)

R1700G (S/N: SBR1-UP; 8XZ1-UP)

R2900 (S/N: 5TW1-UP)

R2900G (S/N: GLK1-UP)

Motor Grader:

24H (S/N: 7KK1-UP)

24M (S/N: B9K1-UP)

Pipelayer:

578 (S/N: 8HB1-UP)

583R (S/N: 2XS1-UP)

589 (S/N: 31Z1-UP)

Track-Type Loader:

963 (S/N: 11Z1-UP; 18Z1-UP; 21Z1-UP)

977 (S/N: 57D1-UP)

Track-Type Tractor:

5 (S/N: 57D1-UP)

6 (S/N: 57D1-UP)

8D (S/N: 54F1-UP)

D10R (S/N: AKT1-UP)

D11N (S/N: 4HK1-UP; 74Z1-UP)

D11R (S/N: AAF1-UP; 8ZR1-UP; 9TR1-UP; 9XR1-UP; 7PZ1-UP)

D11T (S/N: AMA1-UP; GEB1-UP; TPB1-UP; MDG1-UP; JEL1-UP; JNS1-UP)

D5B (S/N: 5LD1-UP; 8HD1-UP)

D5E (S/N: 9RG1-UP)

D6D (S/N: 6HC1-UP; 7XF1-UP; 7YK1-UP; 9FK1-UP; 74W1-UP; 75W1-UP; 19X1-UP)

D6E (S/N: 8FJ1-UP)

D6G Series 2 (S/N: P6G1-UP; 2MJ1-UP; 3SR1-UP; C6X1-UP; P6X1-UP)

D6K Series 2 (S/N: WMR1-UP; RST1-UP)

D6R Series III (S/N: GMT1-UP)

D7H Series II (S/N: 2SB1-UP; 4AB1-UP; 79Z1-UP; 80Z1-UP)

D7H (S/N: 77Z1-UP)

D7R (S/N: 2HR1-UP)

Underground Articulated Truck:

AD30 (S/N: CXR1-UP; DXR1-UP)

AD45 (S/N: BKZ1-UP)

AD45B (S/N: CXM1-UP)

AD55 (S/N: ANW1-UP; DNW1-UP)

AD55B (S/N: JNW1-UP)

AE40 II (S/N: 1ZZ1-UP)

Wheel Dozer:

834B (S/N: 7BR1-UP; 92Z1-UP)

834G (S/N: BPC1-UP; 6GZ1-UP)

834H (S/N: BTX1-UP)

854G (S/N: A4W1-UP; 1JW1-UP)

854K (S/N: H9K1-UP; H8M1-UP; 2211-UP)

Wheel Loader:

950G Series II (S/N: BAA1-UP; AYB1-UP; AYL1-UP; AYS1-UP)

962G Series II (S/N: BAB1-UP; BAC1-UP; BAD1-UP; AYE1-UP; AYG1-UP; AXS1-UP; AXY1-UP)

966F (S/N: 1YX1-UP)

966G Series II (S/N: AXJ1-UP; ANT1-UP; AWY1-UP; ANZ1-UP)

972G Series II (S/N: AXC1-UP; AXE1-UP; AXN1-UP; AWP1-UP; AXP1-UP; ANY1-UP)

980C (S/N: 63X1-UP)

980F Series II (S/N: 5XJ1-UP; 4RN1-UP; 8JN1-UP)

980F (S/N: 8CJ1-UP)

980G Series II (S/N: AXG1-UP; AWH1-UP)

980G (S/N: 9CM1-UP; 2KR1-UP)

980H (S/N: MHG1-UP; A8J1-UP; KZL1-UP; JMS1-UP)

988B (S/N: 50W1-UP)

988F Series II (S/N: 2ZR1-UP)

988F (S/N: 8YG1-UP)

994 (S/N: 9YF1-UP)

994D (S/N: 3TZ1-UP)

994F (S/N: 4421-UP)

994H (S/N: DWC1-UP)

Introduction

Table 1

Revision	Summary of Changes in SEBF8073
13	Updated Introduction
12	Added "Think Safety" graphic. Updated Effectivity. Updated photos.
11	Updated Effectivity.
10	Updated to Add Arrows to Photos.
09	Updated Reference Table.

© 2015 Caterpillar All Rights Reserved. This guideline is for the use of Cat dealer 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 Reuse and Salvage Guideline contains the necessary information to allow a dealer to establish a parts reusability program. Reuse and salvage information enables Cat dealers and customers to benefit from cost reductions. Every effort has been made to provide the most current information that is known to Caterpillar. Continuing improvement and advancement of product design might have caused changes to your product which are not included in this publication. This Reuse and Salvage Guideline must be used with the latest technical information that is available from Caterpillar.

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

• Cat Dealer Technical Communicator

• Dealer Solution Network

• Cat Technical Representative

• Knowledge Network

Canceled Part Numbers and Replaced Part Numbers

This document may 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

This guideline shows visual examples of worn hydraulic pump and motor parts used on Caterpillar machines. Specifically, the guideline shows illustrations of gear pump and motor parts which cannot be used again without salvage operations. All specifications previously included in Special Instruction, SEBF8074, "Specifications for Reusable Hydraulic Gear Pump and Motor Components" are now incorporated into this guideline.

Parts that can be used again according to this guideline can be expected to give normal performance until the next overhaul.

Important Safety Information

Illustration 1	g02139237

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.

Improper operation, lubrication, maintenance, or repair of this product is dangerous. Improper methods could result in injury or death.

Do not operate or perform any lubrication, maintenance, or repair of this product, until you understand 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.

Hazards are identified by a safety alert symbol. Safety alert symbols are followed by a signal word such as "Warning" that is shown below.

Illustration 2	g02662636

The following is the meaning of the above safety alert symbol:

• Pay Attention!

• Become Alert!

• Your Safety is Involved.

The message that appears under the warning explains the hazard. The message will be written or pictorially shown.

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. Therefore, the warnings in this publication and on the product are not all inclusive. If a tool, a procedure, a work method, or an operating technique that is not recommended by Caterpillar is used, ensure that the procedure is safe for all personnel around the machine. Ensure that the product will not be damaged or that the product will not be made unsafe by the operation, lubrication, maintenance, or repair procedures.

All of the information, specifications, and illustrations that are in this publication are based on information that was available at the time of publication. The following information could change at any time: specifications, torque, pressures, measurements, adjustments, illustrations and other items. These changes can affect the service that is given to the product. Obtain the most current and complete information before you start any job. Cat dealers have the most current information that is available.

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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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, NENG2500, "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.

• Do not install a part again if this guideline shows that the part cannot be used again.

• Do not use a part again if the part has wear or damage that is not shown in this guideline.

• When looking to see if a given part is reusable, be sure to remember the "cause and effect" relation to other parts. Generally, failure wear or damage to one part can affect the performance of connected parts. There is light wear on the bearing diameter of the gear shaft. The wear is from contaminants which are embedded in the Teflon material that coats the bearing bores. The condition of the bearing is not easily seen at this early stage. If a new bearing is not installed, the wear will gradually increase and cause failure.

• Most of the illustrations in this guideline are of pumps and not motors. While pumps have a different purpose than motors, wear and damage characteristics are similar in both. Normally, the guideline makes salvage procedures the same in both unless other procedures are given.

• Specifications needed to recondition gear type hydraulic pumps and motors are given in the "Service Manual" and in this guideline.

• Metal spray is an acceptable method of restoring a surface to the original size. Each step in the procedure is critical in achieving the desired coating bond and the surface finish.

• Ordering information and technical support on the Loctite Fixmaster Aluminum Liquid and other Loctite products is available at www.useloctite.com/Caterpillar.

References

Table 2

References
Media Number	Title
PECJ0003	"Cat Hand Tools and Shop Supplies"
NENG2500	"Dealer Service Tool Catalog"
REHS1832	"Bench Test Procedure for Gear Pumps"
SEBF8355	"Cleaning Guide Equipment and Chemical Recommendations Reference Manual"
SEBF9236	"Fundamentals of High Velocity Oxygen Fuel (HVOF) Spray for Reconditioning Components"
SEBF9238	"Fundamentals of Arc Spray for Reconditioning Components"
SEBF9240	"Fundamentals of Flame Spray for Reconditioning Components"
SEBF2110	"Thermal Spray Procedures for Pump Drive Gear Inside Diameter"
SEBF2156	"Thermal Spray Procedures for Gear Shafts for Gear Pumps"
SEBF2129	"Thermal Spray Procedures for Tyrone Drive Shaft (Pump Gear)"
PEGJ0075	"Cat Loctite Global Crossover List"
SEBF8074	"Specifications for Reusable Hydraulic Gear Pump and Motor Components"
SEHS8428	"Repair Procedure for Tyrone Gear Pumps"

Tooling and Equipment

Table 3

Tooling and Equipment
Part number	Part Description
262-9732	180 Grit Crocus Cloth
262-9740	400 Grit Crocus Cloth
7B-0337	Surface Plate
NA	Optical Flat
NA	V-Block
6V-6050	Ultrasonic Cleaner Group
6V-6060	Ultrasonic Cleaner Group
9S-3500	Master Repair Insert Kit
9S-3700	Master Repair Insert Kit
NA	Loctite ODC_Free Cleaner & Degreaser or Teroson FL+
NA	Loctite Aluminum Liquid or Putty
NA	Loctite Silicone Lubricant (Aerosol)
NA	Loctite 629 Retaining Compound

Procedure for Cleaning

Before a part is inspected, wash in a clean solvent that is made from petroleum. Wash each part separately. If several parts are washed together, there is a possibility that a machined surface can be damaged. Use compressed air to dry the part. Put hydraulic oil on the part to prevent rust or corrosion. Put the part in a clean container. Use a lint-free towel to clean the part before assembly. Be sure to put oil on all of the parts during assembly.

Procedure for Inspection

Gear pumps and motor parts have wear patterns that can be seen but not felt by a fingernail or pencil lead after salvage procedure. This type of wear has no effect on the performance of the part. Unless stated in this guideline, parts cannot be used again that have wear patterns felt with a fingernail or pencil lead after the salvage procedure. Throughout this guideline, the fingernail or pencil lead inspection will be used to determine if a part can be used again.

Procedure for Touch Lapping

The touch lapping procedure is used on some parts to salvage that part. The touch lapping procedure will not give a part a "like new" surface or surface flatness. The procedure is used only to remove discoloration and small surface marks.

Use 4/0 emery polishing paper. Refer to Special Publication, PEJC0003, "Cat Hand Tools and Shop Supplies". Put the emery paper on a ground surface plate so the paper is smooth. Do not use any other surfaces.

Wash the part in a clean solvent. Let the part dry at room temperature. Put hydraulic oil on the part and then put the part in a clean container.

1. Wet the emery paper with a clean solvent made of a petroleum base.

2. Place the part on the emery paper with the surface to be "touch lapped" on the paper.

3. Move the part in a pattern like a number "8". More than ten complete number "8" patterns is not necessary. Refer to Illustration 3.

4. Wash the part in a clean solvent. Let the part dry at room temperature.

5. Put hydraulic oil on the part, and then put the part into a clean container.

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NOTICE
When you handle or put pump and motor parts in storage, care must be taken to prevent damage to the machined surfaces.

Illustration 3	g02552199
Touch lapping procedure used on a piston slipper face.

Pump and Motor List

This guideline is to be used only for gear pump and motor part numbers listed in Table 4.

Table 4

Pump and Motor Coverage List by Group and Part Number
Group/Model	Part Number
1/P1	3G-9669 (1), 9J-3471, 9J-5617, 4T-7388, 235-4849 (2), 383-2607
2/P2	3G-4466, 7J-8030 (3), 7J-8199, 8J-1568, 8J-1762, 8J-4513 (3) (4), 8J-9299, 9J-7900, 9J-8226, 4T-0338, 9T-5140, 1U-2033, 1U-2034, 1U-2102, 1U-2781
3/HP7	6E-3524, 3G-900 (3), 9J-5764, 4T-4188 (3), 4T-5533 (5), 4T-6066 (6), 9T-5199. 6E-5883 (3) (7), 244-3304 (3) (7), 201-1489 (3) (7), 159-0869 (8), 188-4433, 188-4455, 230-5571, 111-8399 (3) (6) (7) (9), 134-9865 (3) (6) (10), 140-0087, 143-2701 (6), 145-3997 (3) (6), 145-6021 (3) (6), 147-9538, 150-3346 (3) (6) (11), 153-9509 (3) (6)191-0984 (3) (6), 190-8756 (3) (6) (7), 228-4838 (3) (6) (12), 159-4575 (3) (7), 139-2454 (3), 186-5460 (3) (7), 145-3996 (3) (7), 159-4632 (7), 166-4131 (6), 169-8563 (6) (12), 170-6521 (6), 171-8892 (3) (6) (13) 175-6253 (3) (6), 186-5430 (6) (20), 188-3304 (6) (20), 191-0135 (3) (6), 203-9024 (3) (6), 209-9024 (3) (6), 212-5948218-2167 (6), 218-2168 (6), 223-3749 (6), 223-3755 (3) (6) (14), 230-7132 (6), 230-7133 (3) (6), 237-3960 (3) (6), 237-7419 (6) (20), 244-5447 (6), 246-7926 (6), 280-7490 (3), 281-0106 (6), 256-3682 (6),281-8288 (6) (15), 284-3536 (6) (7), 292-9964 (3) (6), 299-5363 (6), 210-4846 (6) (20), 260-3947 (6)303-9323, 318-2590 (6), 310-4846 (6) (20), 354-6918 (6), 3G-5867 (2) (7), 358-4403 (6)
4/HP8	6E-4182, 3G-1710, 3G-2640, 3G-8635, 6E-5294 (3) (6)9J-0809, 4T-9351 (2) (6), 9T-5764 (16), 9T-5956 (2) (5) (17), 227-9383 (2) (6), 228-4838 (3) (6) (7), 145-6021 (3) (20). 175-0008 (3), 255-5478 (6) (7), 267-7463 (6) (20), 295-0778 (3) (6), 375-0678 (6), 157-4761 (3) (7)
5/P16	6E-1288, 6E-2168, 6E-4345, 9T-1489, 9T-1619, 9T-2794, 9T-2844,9T-4704, 9T-8998 (6), 9T-9932, 087-1615, 121-7514 138-1750 (18), 148-8570, 169-4661, 180-9490, 195-8747, 302-5412
6/20	6E-0456 (3), 6E-0867, 6E-0869, 103-4891, 6E-2046, 6E-2871 (3), 6E-4191 (6), 6E-4772, 3G-0302 (3), 3G-1145 (3), 3G-1233, 3G-1686 (3), 3G-2243 (3), 3G-2858, 3G-2875 (3), 3G-3302 (3), 3G-4661, 3G-4768, 3G-5958 (3), 3G-5995, 3G-6002 (3), 3G-6856, 3G-7428, 3G-7429, 3G-7611 (3), 3G-8177 (3), 3G-9891, 4T-0380, 4T-2497, 4T-4093, 4T-5614 (3), 4T-8713, 6E-1983 (19), 6E-3719 (3) (20), 3G-7610 (3) (20), 3G-5867 (3) (20), 4T-4944 (3) (20), 4T-5615 (3) (20), 159-4575 (3) (20), 130-5643, 248-6240 (3), 248-6241 (3), 3G-5995
6/20 Cont.	6E-6046, 6J-8600, 6J-8700, 7J-4882, 8J-2059 (3), 8J-3632, 8J-3634, 8J-3635, 8J-3809 (2), 8J-3812, 8J-5945, 9J-0476, 9J-0729, 9J-1294 (21), 9J-1295, 9T-1250, 9T-9843 (22), 9T-9909, 9J-1783 (2), 9J-1810, 9J-4983, 9J-1297 (23), 9J-5763 (2), 9J-6398, 9J-7115, 9J-7902, 9J-7903, 9J-7904, 9J-8767, 9J-8769 (2), 9J-8771, 9T-0315, 9T-0937, 9T-1488, 9T-3698, 9T-5557, 9T-6577 (2), 9T-6813 (5), 9T-8987, 9T-9839 (2), 1U-1625, 1U-1779 (2), 244-3304 (2) (12)142-1638 (2), 6E-5652 (2), 6E-5883 (2) (12)169-4621 (2) (6), 4T-2590, 9T-1295, 6E-6045, 134-4795, 203-4892 (3)111-8399 (23), 159-4575, 177-0472, 9J-1297, 116-7341, 207-1273, 9T-7465 (2) (12), 9T-9909, 9J-0455 (2) (12), 227-9383 (2) (12), 3G-5867 (2) (12), 145-3997 (2) (6), 6E-5294 (2) (12), 229-7228, 179-3625, 201-1489 (2) (12) (24), 142-2829 (2) (12), 375-0678 (3)
7/25	6E-0868, 6E-3421 (3) (7), 3G-2753, 3G-5863 (3), 3G-5864 (25) (3), 3G-5865 (3) (26), 3G-5866 (3) (27), 3G-5867 (3) (7), 3G-5868, 3G-5869, 3G-5870, 3G-5878, 3G-5887 (28),137-5169 (29), 9J-5637, 9T-3216 (3) (30), 199-6105 (3) (31), 4T-2606 (3), 4T-4944 (3) (7), 4T-5615 (3) (7), 4T-8756, 9T-1185, 9T-3216 (3), 9T-5715 (3), 9T-7414 (3), 9T-7465 (3) (7), 9T-7468 (3) (3), 9T-8920 (3), 9J-0455, 6E-6045, 101-9974, 103-4892 (3) (32)109-3421, 3G-7610 (3) (6), 142-2829 (2) (6), 208-5478 (3), 199-6106 (3), 211-6626 (3)
8/THP7	3G-9007 (3), 4T-0337 (3), 4T-4188 (3), 9T-5484 (6) , 151-3171
9	1U-0544, 145-3997 (3) (20)

( 1 )	Canceled replaced by 4T-5617 on T260 and T400.
( 2 )	Canceled replace by 383-2607.
( 3 )	Tandem pump
( 4 )	Canceled, replaced by 8J-8809.
( 5 )	Canceled, replaced by 9T-6813.
( 6 )	Ferrous (iron) pump.
( 7 )	Front Pump.
( 8 )	Canceled replaced by 230-5571.
( 9 )	Canceled replace by 244-3304.
( 10 )	Canceled replaced by 153-9509.
( 11 )	Canceled replaced by 190-8756.
( 12 )	Canceled replaced by 230-7132.
( 13 )	Canceled replaced by 223-3755.
( 14 )	Canceled released by 230-7133.
( 15 )	Canceled replace by 354-6918.
( 16 )	Canceled replaced by 6E-4182.
( 17 )	Canceled replace by 6E-5294
( 18 )	Canceled replaced by 148-8570
( 19 )	Canceled replaced by 103-4891.
( 20 )	Rear pump.
( 21 )	Canceled replaced by 9T-9843.
( 22 )	Canceled replace by 6E-4772.
( 23 )	Canceled replaced by 9T-9909.
( 24 )	Canceled replaced by 284-3536.
( 25 )	Canceled replaced by 3G-7610.
( 26 )	Canceled replaced by 9T-5715.
( 27 )	Canceled replaced by 9T-7414.
( 28 )	Canceled replaced by 137-5169.
( 29 )	Canceled replaced by 159-0869.
( 30 )	Canceled replaced by 9T-7468.
( 31 )	Canceled replaced by 208-5478
( 32 )	Canceled replaced by 199-6106.

Specifications

Measure the gear bore diameter to verify the pump group or the motor. If the pump is identified as a Group 1 or Group 2 component, refer to Table 5. Measure the gear width to identify the pump. If the pump is not identified as a Group 1 or 2 component, refer to Table 6.

Illustration 4	g01281466

Measure the pressure plate bearing bore diameter. Check the dimension against Table 6 to see if the part is acceptable.

Table 5

Maximum Gear Bore Diameter (8)	Pump and Motor Group No.	Reference Gear Width	Minimum Bushing Support Thickness (9) (10)
Group 1
31.07 mm (1.223 inch)	4T-7388, 3G-9669	15.24 mm (0.600 inch)	20.68 mm (0.814 inch)
	9J-5617, 9J-3471	19.05 mm (0.750 inch)	18.77 mm (0.739 inch)
Group 2
44.86 mm (1.766 inch)	9J-7900, 1U-2034, 4G-0557	15.24 mm (0.600 inch)	28.52 mm (1.122 inch)
	9J-7901	27.94 mm (1.100 inch)
	8J-1568, 8J-4513 (2)	21.59 mm (0.850 inch)	31.70 mm (1.248 inch)
	8J-1762, 1U-2781, 9J-8226, 7J-8199	38.61 mm (1.520 inch)	34.87 mm (1.373 inch)

( 8 )	Measure the gear track on both sides of housing or plate.
( 9 )	Can machine 0.1 mm (0.004 inch) under minimum if gear plate thickness or body depth is adjusted. On Groups 1 and 2, if bushing supports are refaced, all must be the same length within 0.03 mm (0.001inch)
( 10 )	Refer to Illustration 68

Table 6

Maximum gear Bore Diameter (8)	Pump and Motor Group Number	Minimum Pressure Plate Thickness (9)	Standard Pressure Plate Bearing Bore Diameter (11)	Maximum Reuse Pressure Plate Bore Diameter (11)
61.03 mm (2.403 inch)	9	6.71 mm (0.264 inch)	33.36 ± 0.04 mm (1.313 ± 0.001 inch)	33.40 mm (1.315 inch)
64.92 mm (2.556 inch)	6	6.71 mm (0.264 inch)	33.36 ± 0.04 mm (1.313 ± 0.001 inch)	33.40 mm (1.315 inch)
80.95 mm (3.187 inch)	7	7.92 mm (0.312 inch)	41.69 ± 0.04 mm (1.641 ± 0.001 inch)	41.73 mm (1.643 inch)
77.41 mm (3.048 inch)	3	7.86 mm (0.310 inch)	46.06 ± 0.04 mm (1.813 ± 0.001 inch)	46.10 mm (1.815 inch)
91.53 mm (3.604 inch)	4	7.90 mm (0.311 inch)	49.64 ± 0.04 mm (1.954 ± 0.001 inch)	49.68 mm (1.956 inch)
77.41 mm (3.048 inch)	3 Ferrous	10.82 mm (0.426 inch)	46.06 ± 0.04 mm (1.813 ± 0.001 inch)	46.10 mm (1.815 inch)
91.53 mm (3.604 inch)	4 Ferrous	10.87 mm (0.428 inch)	49.64 ± 0.04 mm (1.954 ± 0.001 inch)	49.68 mm (1.956 inch)
50.78 mm (1.999 inch)	5	4.69 mm (0.184 inch)	25.78 ± 0.04 mm (1.015 ± 0.001 inch)	25.91 mm (1.020 inch)
50.78 mm (1.999 inch)	5 Ferrous	6.68 mm (0.263 inch)	26.92 ± 0.04 mm (1.060 ± 0.001 inch)	27.00 mm (1.063 inch)
44.83 mm (1.765 inch)	8 Ferrous	4.69 mm (0.184 inch)	21.33 ± 0.04 mm (0.840 ± 0.001 inch )	21.41 mm (0.843 inch)

( 11 )

Refer to Illustrations 63 and 64.

Flange, Plate, and Body Assemblies

Nomenclature

Illustration 5	g01281605
Flange assembly for Groups 1 and 2 (front) (1) Pilot diameter (2) Seal bore (3) Mounting face

Illustration 6	g01281611
Flange assembly for Groups 1 and 2 (rear) (4) Body face (5) Seal groove

Illustration 7	g01281612
Flange assembly for Groups 3 and 4 (front) (6) Mounting face (7) Weep hole plug (8) Pilot diameter (9) Seal bore

Illustration 8	g01281614
Flange assembly for Groups 3 and 4 (rear) (10) Bushing (11) Body face (12) Alignment dowel hole (13) Seal groove

Illustration 9	g01281618
Flange assembly for Groups 6 and 7 (front) (14) Mounting face (15) Pilot diameter (16) Seal bore (17) Weep hole plug

Illustration 10	g01281620
Flange assembly for Groups 6 and 7 (rear) (18) Body face (19) Seal groove (20) Bushing (21) Alignment dowel

Illustration 11	g03397793
Flange assembly used in iron pump bodies for Groups 5 and 8 (front). (22) Mounting face (23) Seal bore (24) Pilot diameter

Illustration 12	g01281631
Flange assembly used in iron pump bodies for Groups 5 and 8 (rear). (25) Bushing (26) Body face (27) Seal face

Illustration 13	g01281635
Plate assembly used in aluminum pump bodies (through bores). (28) Gear bore (29) Seal face

Illustration 14	g01281639
Plate assembly for Groups 5 and 8 (iron body) (30) Seal groove (31) Gear bore

Illustration 15	g01281644
Body assembly (blind bores) on the left. Plate assembly (through bores) on the right. (32) Gear bore (33) Bearing (34) Seal face

Note: Not all plate assemblies have gear bores.

Procedure for Cleaning

Remove lip seals and remove weep hole plugs first. Wash flanges, plates, and bodies with clean solvent made from petroleum. Try to clean inner surfaces. Be sure that the seal drain passages are clean on the flange assemblies equipped with weep hole plugs. Remove all sealant from seal grooves or the seal will not work correctly. If the sealant cannot be removed with the solvent and a brush, use glass beads. Use beads of 80 to 150 micron (size 10) with 585 ± 35 kPa (85 ± 5 psi). Early flanges were equipped with metallic seal drain valves, which are made of Viton material. Before installing a new seal drain valve, a steel sleeve must be installed in the drain valve passage first.

Procedure for Inspection

Mounting Face

Illustration 16	g01281666
Fretting on the mounting face can be an indication that the face is bent.

Use Again after the face is measured and the measurement is found to be acceptable.

Illustration 17	g01281673
A comparison between two dimensions near the pilot diameter and near the mounting bolt hole will show if the face is acceptable or not.

Use Again only if the difference between the two dimensions is 0.5 mm (0.02 inch).

Seal Bore

Illustration 18	g03397676
Light scratches in the seal bore

Use Again

Note: This type of damage will not result in seal case to bore leakage if an application of Loctite 620 Retaining Compound is applied. The compound is put around the joint between the seal case and the bore when installing a new seal.

Illustration 19	g03397681
Damage in the seal bore

Use Again after the bore is salvaged according to the correct procedure. Refer to ""Procedure for Salvaging Seal Bore" " in this document.

Bushing

The bronze used in bushings is porous. The porosity allows the Teflon overlay to get pushed into these holes during manufacturing. Gradual wear in the load zone will cause more of the bronze to show through. The bushing can still be used again because the surface is a mix of bronze and Teflon. The bronze shows through when the Teflon in the non-load zone of the bushing becomes worn. The surface will be rough, but the bushing can be used again. Refer to Illustration 21.

The height of the bushing in the flange assemblies for Groups 6 and 7 projects above the body face 5.71 ± 0.12 mm (0.225 ± 0.005 inch), as shown in Illustration 10.

The height of the bushing in the flange assemblies for Groups 5 and 8 is flush to 0.13 mm (0.005 inch) recessed from the body face, as shown in Illustration 12.

Illustration 20	g01282710
Fretting in the outside diameter of the bushing in the seal area.

Use Again

Illustration 21	g01282717
Typical example of bushing wear in which the bronze shows through Teflon.

Use Again

Illustration 22	g01282721
Scored and spalled

Do not use again

Note: Bushings in Illustrations 21 and 22 were cut to show the condition more clearly.

Illustration 23	g03353876
Damage to the Teflon on the inside diameter of the bushing.

Do not use again

Illustration 24	g01282726
The bushing has turned in the bore.

Do not use again

Inspect the bushing bore for out of round after the bushing is removed. If the bushing bore is out of round by more than 0.05 mm (0.002 inch), do not use the casting again. A bushing bore that is out of round is a clear sign that the gear track is too deep. The casting in which the gears track must be replaced.

Bushings are installed with the seam no more than 1.5 mm (0.06 inch) from a line through the center of the bushing bores toward the dowel pin holes.

The installation of new bushings will affect the efficiency of the unit. The new bushings will cause the gears to move to a new position where the tips of the gear teeth will no longer be in contact with the worn gear track. The movement is one important reason to test the efficiency of rebuilt pumps to be sure that the pumps are acceptable according to specifications.

Table 7 lists the tooling used to remove and install the sleeve bearings. The tool chart lists tooling for either single or tandem version pumps manufactured after 1979. Pumps produced before 1979 require different bearing assembly tools because the stake location varies. These pumps do not have date codes. Measure the stake location dimension in the housing. Refer to Table 8 to determine which staking sleeve is needed. Tools for noncurrent pumps are fabricated tools (FT) because there are fewer older pumps than current pumps. Refer to Special Instruction, SEHS8428, "Repair Procedure for Tyrone Gear Pumps".

Illustration 25	g01282733
Tooling needed for pump repairs. (35) Bushing Remover (36) Bearing puller group (37) Bearing installer group

Table 7

Tooling needed to remove and install bearings
Pump model	20 Series	25 Series	HP-7 Series	HP-8 Series
Group #	8T-0875	8T-9134	-	-
Collet Assembly	8T-0871	8T-9135	-	-
Shaft	8T-0873	8T-9136	-	-
Bolt	9F-2773	9F-2773	-	-
Washer	5P-1075	5P-1075	-	-
Bearing Remover	8T-9137	135-7275	8T-9122	8T-9127
Bearing Installer
Group #	8T-0880	8T-9133	135-7275	8T-3057
Punch Assembly	8T-0874	8T-9129	8T-9124
Cap	8T-0876	8T-9131	8T-9125
Staking Shaft	8T-0877	8T-9132	8T-9126
Staking Tool	8T-0878	8T-0878	8T-0878	8T-0878
Set Screw	1K-6979	1K-6979	1K-6979	1K-6979

Illustration 26	g01283498
Location of staking dimensions. (38) Sleeve bearing (39) Pump housing (40) Stake location dimension

Table 8

Staking Dimensions
Pump Series	Stake Location Dimension	Staking Sleeves Pt. No.
20 Current Former	15.09 ± 0.13 mm (0.594 ± 0.005 inch) 32.64 ± 0.13 mm (1.285 ± 0.005 inch)	8T-0877 FT-2145
25 Current Former	41.40 ± 0.13 mm (1.629 ± 0.005 inch) 48.46 ± 0.13 mm (1.903 ± 0.005 inch)	8T-9132 FT-2146
HP-7 Current Former	41.40 ± 0.13 mm (1.629 ± 0.005 inch) 48.34 ± 0.13 mm (1.903 ± 0.005 inch)	8T-9126 FT-2143
HP-8 Current Former	41.40 ±0 .13 mm (1.629 ± 0.005 inch) 65.74 ±0 .13 mm (2.588 ± 0.005 inch)	1U-6601 8T-3028

Gear Track

The maximum allowable depth in the gear track for an aluminum pump body is 0.38 mm (0.015 inch) on the low-pressure side of the unit.

The maximum allowable depth in the gear track for an iron pump body is 0.3 mm (0.011 inch) on the low-pressure side of the unit.

Illustration 27	g01283984
Burr on the edge of the gear track

Use again

Use again after burr is removed from gear track with a knife or similar sharp instrument.

Erosion or gradual wear on the low-pressure side of the gear track will not affect the performance unless the wear has extended to the high-pressure side. Extended damage will result in a loss in efficiency. How much loss cannot be determined without testing. Test these castings after assembly to be sure that the level of efficiency is acceptable. Pumps with this condition will run at a higher noise level.

Illustration 28	g03397691
Erosion in the gear track

Use again

Note: Use again unless erosion is extended to the high-pressure side.

Illustration 29	g03397694
Gear track in iron pump body shows normal wear with some discoloration.

Use again

Illustration 30	g03353884
Damage caused by foreign material

Use again

Note: Use again unless damage is extended to the high-pressure side.

Illustration 30 shows damage caused by foreign material in the low-pressure side of the gear track. The damage will not have a negative effect on performance unless the damage has extended to the high-pressure side. Again, extended damage can cause a loss in efficiency. Therefore, test the castings after assembly.

Seal Groove

Illustration 31	g03397695
Sealant in the seal groove

Use again

After sealant is removed, refer to ""Procedure for Cleaning" " in this document for details.

Illustration 32	g01284159
Damaged seal groove

Do not use again

Illustration 33	g03397696
Damaged seal face

Do not use again

Illustration 34	g01284163
Damage across the O-ring seal area of the seal face

Do not use again

Note: Similar damage across the O-ring groove can cause leakage, as can tool chatter in the bottom of the O-ring groove. Do not use if the part has either one of these types of damage.

Threaded Hole

If the bolt cannot be tightened to the correct torque specifications, there is a possibility that the threaded hole is damaged.

Illustration 35	g03397800
Pieces of aluminum in the threads of this bolt are an indication that the threaded hole is damaged.

Use again

Use again after aluminum is removed with a wire brush.

Illustration 36	g03397801
Damage threaded hole

Use again

Use again after an insert from 9S-3500 (UNF) or 9S-3700 (UNC) Master Repair Insert Kit.

Miscellaneous

Illustration 37	g01284182
Side clearance can be felt in the dowel hole.

Do not use again

Note: Do not reuse mating piece.

Illustration 38	g03353900
Crack in the casting flange

Do not use again

Illustration 39	g03397807
Crack in the casting flange

Do not use again

Illustration 40	g03397809
Crack in the casting flange

Do not use again

Illustration 41	g03353919
Crack in the gear body

Do not use again

Illustration 42	g01284190
Crack in the seal area of the port

Do not use again

Procedure for Salvaging the Seal Bore

Most types of damage in the flange, plate, or body assembly are either acceptable as is or not at all. Generally, if the part is not usable as is, salvage is not practical, except if there is seal bore damage. Refer to Illustrations 18 and 19.

Note: Follow the manufacturers directions carefully in the use of Loctite products. Refer to the ""Safety" " section.

The procedure to salvage seal bores is as follows:

• Remove any raised metal in the bore with 180 grit crocus cloth.

• Make sure that the bore is free of oil and dirt and that the bore is dry. (Use Loctite ODC-Free Cleaner & Degreaser or Teroson FL+ or similar solvent to remove oil permit the bore. Dry thoroughly).

• When the part is at room temperature (21 °C (69.8 °F), put a layer of Loctite Silicone Lubricant (Aerosol) on the outside diameter of the seal cases.

• Put an application of Loctite Aluminum Liquid or Putty on the damaged area. Be careful not to get any Loctite Aluminum Liquid or Putty into the seal drain passage.

• Install the seal in the bore. Do not install the flange assembly for 2 hours.

Illustration 43	g01284194
Be sure that the bore is clean and dry.

Illustration 44	g01284195
Put Loctite Silicone Lubricant (Aerosol) on the outside diameter of the seal case.

Illustration 45	g01284200
Seal bore ready to install.

Gear Shaft

Nomenclature

Illustration 46	g01284202
Gear shaft nomenclature (41) Tooth profile (42) Tooth face (43) Bearing areas (44) Seal area (45) Spline

Procedure for Cleaning

Wash gears with a clean solvent that is made from petroleum. Clean gears carefully to avoid damaging bearing areas. Washing is not necessary to remove any discoloration from the gears. The discoloration is caused by oil and is acceptable.

Procedure for Inspection

Shaft Seal Area

Illustration 47	g03397700
Grooves in the seal area can be felt with a fingernail.

Use again

Use again after the seal area is salvaged according to the correct procedure. Refer to ""Procedure for Salvaging the Shaft Seal Area" " in this document.

Illustration 48	g03354338
Corrosion in the seal area

Use again

Use again after the seal area is salvaged according to the correct procedure that is found in ""Procedure for Salvaging the Shaft Seal Area" ".

Illustration 49	g03397704
Splines show signs of interference.

Use again

Use again after installation is adjusted to stop interference.

Note: Do not use a shaft again if the shaft has a twisted spline.

Illustration 50	g03397707
Fretting in the splines can be felt with a fingernail.

Do not use again

Do not use again if fretting exceeds 0.31 ± .06 mm (0.012 ± 0.002 inch).

Illustration 51	g03397710
Light spline damage

Use again

Illustration 52	g03397712
Heavy spline damage

Do not use again

Bearing Area

Illustration 53	g03398360
Bearing area shows wear caused by contaminants.

Use again

Use again after scratches are removed with 400 grit crocus cloth and motor oil.

Illustration 54	g03354008
Corrosion in the bearing area and tooth face

Use again

Use again after scratches are removed with 400 grit crocus cloth and motor oil.

Note: If corrosion has caused pitting in the shaft, do not use the part again.

When reconditioning the bearing, install the bearing in a lathe for operation. Use a flat file behind the crocus cloth to polish bearing and tooth face areas. Refer to Illustrations 54 and 54.

Tooth Face

Illustration 55	g01510356
Scratches on the gear tooth face

Use again

Use again after most of the scratches and all the burrs are removed with 400 grit crocus cloth and motor oil. Install in a lathe for the operation. Use a flat file behind the crocus cloth to polish tooth face area. Refer to Illustration 55.

Note: The area between the journal and the tooth face valley must not contain any scratches.

Tooth Profile

Illustration 56	g03354023
Heavy damage on a tooth profile

Do not use again

Illustration 57	g01284250
(46) Wear on tooth tip for Groups 3 and 4 and Groups 5 and 8. Normal break-in wear on tip of tooth. Refer to Table 9 for specific pump model allowances −0.16 ± 0.03 mm (−0.006 ± 0.001 inch.)

Use again

Use again if material wear from tip is less than 0.25 mm (0.01 inch).

Table 9

Minimum Allowable Wear for Gear Tips
Pump Series	New Diameter	Min. Wear Allowed
HP16	53.19 mm (2.094 inch)	52.96 mm (2.085 inch)
FP14	44.75 mm (1.762 inch)	44.53 mm (1.753 inch)
FP16 P16	50.70 mm (1.996 inch)	50.47 mm (1.987 inch)
FP20	64.59 mm (2.543 inch)	64.36 mm (2.534 inch)
FP25	80.87 mm (3.184 inch)	80.64 mm (3.175 inch)
FP7	77.32 mm (3.044 inch)	77.09 mm (3.035 inch)
FP8	91.44 mm (3.600 inch)	91.21 mm (3.590 inch)
FL7	77.32 mm (3.044 inch)	77.09 mm (3.035 inch)
SL7	77.32 mm (3.044 inch)	77.09 mm (3.035 inch)
HP7	77.32 mm (3.044 inch)	77.09 mm (3.035 inch)

Illustration 58	g01421091
Light wear on tooth profile

Use again

Illustration 59	g03354032
Heavy wear on tooth profile

Do not use again

Illustration 60	g01284256
Profile of gear teeth shows heavy wear.

Do not use again

Shaft

Illustration 61	g03397811
Light damage to the end of the shaft

Use again

Procedure for Salvaging the Shaft Seal Area

Grooves in the seal area that can be felt with a fingernail, as shown in Illustration 48, can be removed to make the part usable again.

Note: Follow the metal spray manufacturers directions carefully in the application of metal spray to the shaft seal area.

The procedure to salvage shaft seal area is as follows:

1. Measure the shaft outside diameter at the seal area and the shoulder radius (if present) and make a note of each dimension.

2. Refer to Special Instruction, SEBF9236, "Fundamentals of High Velocity Oxygen Fuel (HVOF) Spray for Reconditioning Components", Special Instruction, SEBF9238, "Fundamentals of Arc Spray for Reconditioning Components", and Special Instruction, SEBF9240, "Fundamentals of Flame Spray for Reconditioning Components" for the correct salvage procedures.

3. Grind the seal area to the diameter measured in Step 1 to 0.05 mm (0.002 inch). The surface finish must be 0.40µm to 0.80µm (16 microinch to 32 microinch). The wheel radius must be the same or greater than the shoulder radius measured in Step 1.

Illustration 62	g01516780
Seal area has been metal sprayed. The next step is to grind.

Pressure Plate

Nomenclature

Illustration 63	g03357709
Pressure plate nomenclature (former design). Refer to Table 6 for dimensions. (47) Bronze face (48) Bearing bore diameter

Illustration 64	g01284416
Pressure plate nomenclature (new design). See Table 6 for dimensions. (49) Bearing bore diameter (50) Backup ring groove

Illustrations 63 and 64 show a comparison between the former design and the new design pressure plates in the pumps used on 943, 980C, 988D Loaders and the front pump on D11N Tractors (Groups 5 and 8). The new design pressure plate has a recessed area for the backup ring. These pressure plates cannot be interchanged.

Procedure for Cleaning

Wash pressure plates with clean solvent made from petroleum. Be especially careful not to damage the bronze face during the procedure. Washing is not necessary to remove oil discoloration. Remove carbon deposits with the 6V-6050 Ultrasonic Cleaner Group or 6V-6060 Ultrasonic Cleaner Group .

Procedure for Inspecting

Illustration 65	g03397724
Carbon deposits on the bronze face

Use again

Use again after the carbon is removed by ultrasonic cleaning and if the plate is not bent. Check thickness according to Table 6.

Small surface marks on the bronze face can be removed by a procedure known as "Touch Lapping". Follow the touch lapping procedure provided in this document.

Illustration 66	g01284427
To see if the plates are flat, hold the plates with bronze surfaces turned toward each other. If a 0.18 mm (0.007 inch) feeler gauge fits between the plates, the plates are too bent and no longer acceptable.

Illustration 67	g03397727
Scratches in the pressure plate

Use again

Illustration 68	g01284434
Step in the pressure plate

Use again

Use again if the step can be removed by touch lapping and if the plate has an acceptable thickness according to Table 6.

Illustration 69	g03397729
Erosion is near the pressure equalization chamfer

Use again

Illustration 70	g03354048
Smearing on the bronze face

Use again

Use again after smearing is removed by touch lapping.

Illustration 71	g03354063
Pitting on the pressure plate

Use again if the plate has an acceptable thickness according to Table 6.

Miscellaneous Parts

Procedure for Cleaning

Clean miscellaneous parts, such as bushing supports, couplings, isolation plates, and support rings, with clean solvent made from petroleum.

Note: Never use seals again. Use new seals.

Procedure for Inspecting

Illustration 72	g03397789
Damaged coupling

Use again

Use again if more than 75 percent of the length of each spline is still in acceptable condition.

Illustration 73	g01284445
Wear on the gear face of the bushing support (measure thickness).

Use again

Use again after wear is removed by touch lapping and if the part has an acceptable thickness according to Table 5.

Illustration 74	g03354076
Tip of isolation plate is broken off

Do not use again

Illustration 75	g03354223
Isolation plate damaged during assembly.

Procedure for Testing

This break-in test procedure should be used for rebuilt medium-pressure gear pumps.

After replacing the ring or center sections of the 20, 25, HP7, HP8, FP7, or FP8 Series Gear Pumps, go through a break-in test. The procedure for pumps with aluminum bodies is different than the procedure for pumps with iron bodies.

Note: Failure to use the correct procedure, aluminum or cast iron, could result in severe damage to the pump and hydraulic system.

Procedure for Aluminum Bodies

Illustration 76	g01284465
Aluminum cycle with chip removal. Gear pumps with aluminum bodies. (51) Pressure (psi) (52) Speed (rpm) (53) 2400 rpm (54) Approx. 30 seconds (55) 90 cycles, 60 seconds (56) Time (57) Read flow rate (58) Stop the pump (59) Vent load Valve (60) Start the pump (61) Increase pressure

Note: A 17225 kPa (2500 psi) system pump is shown in Illustration 76. Pumps in systems with pressure settings other than 17225 kPa (2500 psi) would use break-in pressures that would be 3445 kPa (500 psi) above normal system pressure.

1. Refer to Illustration 76. Operate the pump at 2400 rpm.

2. Slowly increase the pressure from 0 to 3445 kPa (500 psi) above the relief valve pressure in a 30 second period.

3. Cycle the pressure between the relief pressure plus 3445 kPa (500 psi) and 0 kPa (0 psi) 90 times in the next 60 seconds using a hand outlet valve or solenoid valve.

4. Increase the pressure to the application relief valve pressure and read the flow rate. The pass/fail flow rate is based on a minimum 92 percent volumetric efficiency. For narrow gear width units in a given series, the minimum allowable volumetric efficiency can be as low as 88 percent.

5. Stop the pump.

6. Vent the load valve.

7. Accelerate the pump to 2400 rpm.

8. Increase the pressure to the application relief valve pressure.

9. Stop the pump.

10. Vent the load valve.

11. Accelerate the pump to 2400 rpm.

12. Stop the pump motor.

Procedure for Iron Bodies

Illustration 77	g01284481
Iron cycle with chip removal. Gear pumps with iron bodies. (62) Pressure (psi) (63) Speed (rpm) (64) 2400 rpm (65) Time (66) Off pressure time ( 1 to 3 seconds) (67) Increase pressure rate of 100 psi/sec (68) Read flow rate

Note: The pressure must be increased gradually from 0 to 3445 kPa (500 psi) above the application relief valve pressure, with pauses every 1723 kPa (250 psi) increase where the pressure is off for one to 3 seconds.

1. Refer to Illustration 77. Operate the pump at 2400 rpm.

2. Increase the pressure from 0 to 3445 kPa (500 psi) at a rate of approximately 689 kPa/second (100 psi/second).

3. Decrease the pressure to 0 kPa (0 psi) for 1 to 3 seconds.

4. Rapidly return the pressure to 3445 kPa (500 psi) and then gradually increase the pressure 1723 kPa (250 psi) at approximately 689 kPa/second (100 psi/second).

5. Decrease the pressure to 0 kPa (0 psi) again for 1 to 3 seconds.

6. Continue the pattern of increasing the pressure 1723 kPa (250 psi) at a time and returning the pressure to 0 kPa (0 psi) for about 3 seconds. Do this procedure until a pressure equal to the relief valve pressure plus 3445 kPa (500 psi) is reached.

7. Decrease the pressure to 0 kPa (0 psi) once more before returning the pressure to the application relief valve pressure.

8. Read the flow rate. The pass/fail rate is based on 92 percent volumetric efficiency. For the narrow gear width units in a given series, the minimum allowable volumetric efficiency can be as low as 88 percent.

9. Return the pressure to 0 kPa (0 psi).