Inspection, Maintenance, and Repair of Operator Protective Structures (OPS) and Attachment Installation Guidelines for All Earthmoving Machinery, If Equipped {7323, 7325} Caterpillar

Caterpillar Products

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Introduction

This Special Instruction is intended for all Caterpillar machines with a certified OPS, including Hydraulic Excavators (HEX) from 6 to 50 tons. This Special Instruction is also intended for Tip-Over Protective Structures (TOPS) for Excavators under 6 tons ( Mini HEX) and Falling-Object Protective Structures (FOPS). This Special Instruction is not intended for Operator Protective Guards (OPG) on HEX or OPS on forestry machines.

Hereinafter Rollover Protection Structures (ROPS), FOPS, or TOPS will be referred to as OPS for the remainder of this instruction.

This Special Instruction applies to Caterpillar, Inc produced machines. Caterpillar, Inc. will now require that any proposed changes to an OPS be presented to the Global Dealer Solution Network (GDSN) for approval. This action should be done before any modifications or attachments are applied to the OPS. If there are questions concerning current modified OPS structures, submit a service request ticket to the GDSN.

This Special Instruction is to be used ONLY by Cat dealers as a guide for OPS service without voiding the Certification. The OPS is designed and certified to provide protection for the machine operator. This protection is in accordance with the applicable requirements stated on the certification plate attached to the structure.

Note: Any damage, modification, or repair to the OPS not permitted by these specific instructions will void the Caterpillar Inc. OPS Certification.

Depending upon the specific OPS design, some modifications or repairs beyond the limits in these guidelines may be permitted upon authorization from Caterpillar Inc. Approval must be obtained for each OPS to exceed these guidelines without voiding the certification. Submit a GDSN ticket for any questions.

Reference: Refer to the Parts Manual, Service Manual, Operation and Maintenance Manual for your machine.

Inspection

Visually inspect the OPS at least every 1000 service hours or as recommended in the Operation and Maintenance Manual. Repair or replace according to the guidelines given in this document.

Permitted Repair

Loose or missing bolts:

Replace any bolts that are not Grade 8 and tighten to the recommended torque specifications shown in the Service Manual and Operation and Maintenance Manual. Use the correct part number for the bolts as shown in the Parts Manual.

Worn or damaged rubber mounting pads:

If the mounting pad cannot be visually inspected for wear, replacement is necessary if the OPS rattles (makes noise). Submit a GDSN ticket with photos and data with any questions.

Cracks in welds or parent metal of the structure:

Cracks in the welds can be repaired as shown in the "Repairs" section of this Special Instruction. Parent metal cracks that originate from welds less than 13 mm (0.512 inch) can also be repaired. Refer to the "Repairs" section of this Special Instruction. Parent metal cracks not originating from the welds CAN NOT be repaired.

Replacement is Necessary

Bent, deformed or broken OPS legs or mounting brackets:

Repairs cannot be made and replacement of the OPS and/or mounting brackets is necessary.

Note: DO NOT weld reinforcement plates on OPS legs.

Cracks in cast mounting pads:

Repair welds are not permitted in castings. A cracked weld between castings can be repaired.

Corrosion

Photos must be submitted via GDSN for an engineering judgment if rust pitting is found on the structure. The OPS must be replaced if the structure is rusted through entirely.

Machine Overturn

If a machine has experienced a tip over or rollover, the OPS certification is voided if there is any visible permanent damage. The OPS certification is voided if the OPS mounting brackets, legs, or roof structure members are deformed. If there is a question, any OPS deformation must have a photo taken shown with a straight edge and submitted via GDSN. Cracks or weld failures can be repaired if cracks or weld failures are within the guidelines established in this Special Instruction. Replacement of all OPS mounting bolts (OPS structure and OPS mounts) is necessary. Studs installed in the case or frame to fasten the OPS will not need to be changed when there is no visual damage.

Machine Fire

OPS that have experienced a fire can be used again. A visual inspection of the OPS structural members must be done. There should not be any evidence of permanent deformation or discoloration of the paint or metal from the heat of the fire.

Repairs

Use the following guide to determine if repairs can be made, and for the correct repair procedure:

1. Repairs can be made to cracks in the welds of the OPS.

2. Repairs can be made to cracks in the parent metal. Repairs can only be made, provided the crack originates from a weld, and does not exceed 13 mm (0.512 inch) in length. Cracks in parent metal not originating from the welds, or that exceed 13 mm (0.512 inch) generally cannot be repaired.

   Note: Contact Caterpillar Inc. and submit a ticket to GDSN for guidance on repair of any cracks outside these guidelines.

3. If the OPS roof cover plate or sheet metal attached to the OPS member is damaged, repairs may be made.

4. The final determination of reparability of a crack, other than what is discussed above, is based on the following:

   (A) The accessibility for making the groove preparation

   (B) The accessibility for the proper welding angle

   (C) The accessibility for restoring the surface to the surfaces original contour

Crack Preparation

1. Cracks must be removed completely with an air carbon arc torch or similar tool.

2. When a crack is removed with an air carbon arc torch or similar tool, ensure that the procedure does not cover up the cracks. A dye-penetrant can be used to check if the crack is removed down to solid metal.

   Note: All slag or foreign material must be removed from the crack before a check is made with a dye- penetrant.

   Show/hide table

   Illustration 1	g02224134
   (aa) 90 degree minimum (ab) Width (ac) Depth

3. Width (ab) must be two times as wide as depth (ac). If the crack extends through the plate, refer to the "Welding Procedure" section in this Special Instruction.

4. The groove angle will vary depending on the procedure used to make the groove. V-grooves, U-grooves, or other radius preparation can be used.

Preheating

1. The OPS prewelding temperature must be no less than 16° C (60° F).

   Note: Many hours in a heated building may be required for an OPS to reach the required prewelding temperature. The number of hours will depend on if the OPS has been exposed to lower temperatures. The number of hours will also depend on the actual temperature and length of exposure.

2. Avoid intensive local preheating. Torch heating may be used to raise the weld repair area to prewelding temperature. Move the torch over a wide area in the vicinity of the repair location when torch heating is used. The required preweld temperature has been reached if the repair area is warm to the touch immediately before starting the repair.

Weld Quality

Note: The quality of a welding repair is dependent on the skill of the welding operator and the materials used for the repair. All welds must conform to the standards shown in AWS specifications for qualified welds (AWS D1.1-83).

1. Only low hydrogen welding is permitted. All welds must be smooth, free of gas holes or cracks and have no undercuts and overlaps.

2. Use one of the recommended welding processes and type of electrodes that follows:

   (A) Shielded Metal Arc Welding (SMAW). Use a covered electrode that meets the American Welding Society Class E7018. An electrode with a core diameter of 3 mm (0.118 inch) is recommended for the root (first) pass.

   (B) Gas Metal Arc Welding. Use a bare electrode that meets American Welding Class E70S2, E70S3, E70S6, or E70S1B.

3. All electrodes must be dry. Follow the manufactures instructions on handling and storage to prevent moisture absorption.

   Note: The repair surface must be clean. Remove all foreign material before welding. All slag and foreign material must be removed after each pass of multipass welds and tie-ends before making a following pass or weld connections.

4. More than one weld pass must be used if the groove preparation is more than 5 mm (0.197 inch) deep. Each pass must be cleaned and inspected before the pass is covered with an additional pass. Care must be used with each pass to prevent unfused areas between layers and at the deposit and base metal interface.

5. A good root (first) pass is important. Care must be used to prevent the containment (trapping) of slag or the formation of voids or root porosity.

6. Any defect in the root pass or following passes must be corrected before the next weld is made (in the same groove).

7. Any weld defect must be ground out, cleaned, and welded again. Welding to cover a welding defect is not allowed.

8. The weld toe geometry must be free from undercut, cold laps, and poor transitions after the weld deposit is ground flush with the adjacent surface.

9. After grinding the weld deposit flush with the plate surface, unfused lengths around the weld deposit perimeter can be detected by using a dye-penetrant.

Welding Repair Check List

1. Is this type of repair allowed?

2. Clean the repair area metal to remove all foreign material.

3. Make a groove to remove the crack down to solid metal.

4. Clean the groove to remove all foreign material.

5. Weld the prepared area.

6. Correct all weld and weld reinforcement defects.

Welding Procedure

(1) If the crack is less than the plate thickness:

(A) Clean the repair area to remove all foreign material.

Illustration 2	g02224195
Before welding (ad) 1.5 mm (0.059 inch)

(B) Make a groove to remove the crack down to solid metal or to the backup strip (if present).

(C) Remove all foreign material from the groove.

(D) Weld the crack as shown in the "Weld Quality" section in this Special Instruction.

Illustration 3	g02224253
After welding

(E) Grind the weld smooth and even with the original surface.

(2) If the crack is all the way through the plate, and has access from both sides:

(A) Clean the repair area to remove all foreign material.

(B) Make a groove over the crack on one side to a depth of one-half the plate thickness.

(C) Clean the groove to remove all foreign materials.

(D) Weld the crack as shown in the "Weld Quality" section in this Special Instruction.

(E) Make a groove over the crack on the opposite side to a depth including the root of the first weld made in item 2.D.

(F) Clean the groove to remove all foreign material.

(G) Weld the crack as shown in the "Weld Quality" section in this Special Instruction

(H) Grind the weld smooth and even on both sides.

(3) If the crack is completely through the plate, and access is from one side only:

(A) Clean the repair area to remove all foreign material.

(B) Cut a groove over the crack to the dimension shown above.

(C) Clean the groove to remove all foreign material.

(D) Weld the crack as shown in the "Weld Quality" section in this Special Instruction.

(E) Use a technique and welding machine settings to penetrate and fuse the ungrooved portion of crack. Without burning through, produce a uniform weld on the backside, as shown above.

(F) Grind the weld smooth and even with the original surface.

OPS Attachment Installation Guidelines

Note: This Special Instruction applies to Caterpillar, Inc produced machines. Caterpillar, Inc. will now require that any proposed changes to an OPS be presented to the GDSN for approval. This action should be done before any modifications or attachments are applied to an OPS. If there are questions concerning current modified OPS structures, contact the GDSN.

1. Clamps or bonding are the preferred methods to fasten attachments to the OPS. Submit a GDSN ticket with total mass of attachment for Product Group engineering approval.

2. The roof cover plate is the preferred location for mounting attachments. The body canopy is the preferred location on trucks.

3. The attachments should not transmit reactive forces to the structure in case of tip over. Air conditioners, mirrors, and lights, meet this requirement. Hydraulic cylinders, water tanks, or other mechanical devices do not.

4. Do not connect hydraulic cylinders, booms, water tanks, or other massive equipment to the OPS.

5. Do not drill or cut an OPS with a torch except on the cab sheet metal and/or roof cover plate.

6. Do not cut or drill any structure cross members for the roof or on the support legs.

7. Any holes in the roof cover plate must be closed to prevent object penetration in the event of a machine rollover.

8. Welding should be done on the enclosure sheet metal, on the roof cover plate or on the roof cross members that are not OPS members. Do not put extensive welds on unsupported areas of the roof cover plate.
   Show/hide table

   Illustration 4	g02223135
   Rear view (A) Roof cover plate (B) Combined gusset and leg thickness (C) Center line

9. Welds are permitted on the top end of the legs where the gussets are welded to the legs. Welds are permitted only where the total width of the leg and gusset is more than 1 1/4 times the leg width. For example, if the leg is 127 mm (4.999 inch) wide. Welds are permitted only above the point where the total gusset and leg thickness is 158 mm (6.220 inch) or more.
   Show/hide table

   Illustration 5	g02223134
   (ae) 150 mm (6 inch) no weld area (af) Width (ag) 1/3 width (C) Center line (G) Welds not permitted (H) Welds parallel to (C) permitted in this area

10. Welds may be permitted on the OPS legs and structure cross members. Welds are permitted if the welds are parallel to the axis and in the middle 1/3 of the width. The weld must also be at least 150 mm (6 inch) from any significant change in the cross section.