- Off-Highway Truck:
- 777D (S/N: AGC1-UP; FKR1-UP)
- 777F (S/N: JRP1-UP; JXP1-UP)
Introduction
ReferenceSpecial Instruction, REHS1841, "General Welding Procedures"
ReferenceSpecial Instruction, REHS4445, "Servicing the Suspension Cylinders for Off-Highway Trucks"
ReferenceDisassembly and Assembly, RENR3365
ReferenceDisassembly and Assembly, RENR8311
The following instructions provide the needed information to invert the rear suspension cylinders on certain 777 Off-Highway Trucks.
Note: If needed, the following procedure can be completed on only one rear suspension cylinder. A configuration of one cylinder installed "rod up" and the other cylinder installed "rod down" is acceptable.
The following manuals will be referenced in the procedure:
- 777D Disassembly and Assembly, RENR3365
- 777F Disassembly and Assembly, RENR8311
Safety
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. You must determine that the tools, procedures, work methods, and operating techniques are safe. You must determine that the operation, lubrication, maintenance, and repair procedures will not damage the machine. Also, you must determine that the operation, lubrication, maintenance, and repair procedures will not make the machine unsafe.
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Personal injury or death can result from sudden suspension cylinder movement. Sudden movement, up or down, can cause the clearance above your head to change rapidly. Read all warning labels on the suspension cylinders before servicing. Do not check the oil in the suspension cylinder until all the nitrogen pressure has been released. Do not, under any condition, remove valves, cover or plugs from the cylinder unless the rod is fully retracted and all the nitrogen pressure is released. Do not stand under the machine when testing or adjusting the suspension cylinders. |
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Personal injury or death can result from improper lifting or blocking. When a hoist or jack is used to lift any part or component, stand clear of the area. Be sure the hoist or jack has the correct capacity to lift a component. Install blocks or stands before performance of any work under a heavy component. Approximate weights of the components are shown. Clean all surfaces where parts are to be installed. |
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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. |
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High Pressure Cylinder. Do not remove any grease fitting, valve or plug until the truck is supported and pressure is relieved or the truck may drop suddenly, resulting in personal injury. Suspension groups should only be serviced by properly trained personnel who have read and understand the service manual procedure to relieve pressure and to charge cylinders. |
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Dry nitrogen is the only gas approved for use in the suspension cylinders. Charging the suspension cylinders with oxygen gas will cause an explosion. This danger will not happen if nitrogen cylinders with standard CGA (Compressed Gas Association, Inc.) Number 580 Connections are used. When you order nitrogen gas, be sure that the cylinders are equipped with CGA No. 580 Connections. Do not use color codes or other methods of identification to tell the difference between nitrogen cylinders and oxygen cylinders. Never use an adapter to connect your nitrogen charging group to a valve outlet used on both nitrogen, oxygen or other gas cylinders. Be sure you use dry nitrogen (99.8% purity). |
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| NOTICE |
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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. |
Machine Preparation
- Move the machine to a hard level surface.
- Avoid sudden steering inputs when you are parking the machine.
- Apply the service brakes in order to stop the machine.
- Move the transmission control lever to the PARK position.
- Turn the engine start switch to the OFF position in order to stop the engine.
- Turn the battery disconnect switch to the OFF position.
- Disconnect the battery. Refer to Operation and Maintenance Manual, "Battery or Battery Cable - Inspect/Replace" for additional information disconnecting the battery.
- Chock the front wheels and the rear wheels. Refer to Disassembly and Assembly, "Wheel Chock (Front and Rear) - Remove and Install".
- Release the pressure from the system. Refer to Operations and Maintenance Manual, "System Pressure Release".
Procedure
| Required Parts | |||
| Item | Qty | Part Number | Description |
| 1 | 1 | 469-6517 | Valve Block |
| 2 | 1 | 8M-4435 | O-Ring Seal |
| 3 | 2 | 8T-5005 | Bolt |
| 4 | 2 | 8T-4121 | Hard Washer |
| 5 | 3 (1) 4 (2) |
372-1181 | Valve As |
| 6 | 1 | 114-3361 | O-Ring Seal |
| 7 | 1 (1) | 129-1029 | Check Valve Gp |
| 8 | 1 (1) | 033-6039 | O-Ring Seal |
| 9 | 1 (1) | 030-0167 | Backup Ring |
| 10 | 1 (1) | 228-4929 | Block |
| 11 | 2 (1) | 4L-7124 | Bolt |
| 12 | 2 (1) | 5P-0537 | Hard Washer |
| 13 | 1 (1) | 3J-1907 | O-Ring Seal |
| 14 | 1 (1) | 221-3416 | Pressure Sensor Gp |
| 15 | 6 | N/A | Plug 3/8 - 18 Thread (3) |
| 16 | 2 | 2H-5001 (4) | O-Ring Seal |
| 17 | 1 | 3J-1907 (4) | O-Ring Seal |
| 18 | 1 | 4J-1151 (4) | Backup Ring |
| 19 | 1 | 8J-8900 (4) | Wear Ring |
| 20 | 1 | 9X-7354 (4) | Lip Type Seal |
| 21 | 1 | 243-4567 (4) | Backup Ring |
| 22 | 1 | 243-4572 (4) | O-Ring Seal |
| 23 | 1 | 330-6822 (4) (5) | Buffer Seal As |
| 24 | 1 | 433-5904 (4) | U-Cup Seal |
| 25 | 1 | 279-2269 | Film |
| 26 | 1 | 279-2271 | Film |
| ( 1 ) | If the machine is equipped with TPMS |
| ( 2 ) | If the machine is not equipped with TPMS |
| ( 3 ) | Fabricated |
| ( 4 ) | Part of the 451-5832 Hydraulic Cylinder Seal Kit |
| ( 5 ) | If head design allows use |
- Remove the rear suspension group from the machine and completely disassembly the suspension cylinders.
Note: Refer to Disassembly and Assembly, "Rear Suspension (Cylinder) - Remove" and Disassembly and Assembly, "Rear Suspension (Cylinder) - Disassemble" for information to remove and disassemble the rear suspension cylinders.
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| Illustration 1 | g03795690 |
Typical view of the rear of the 777 | |
- Clean and inspect the condition of all the parts. Thoroughly inspect the finish on the cylinder bores and the rod surfaces. If there are any visible signs of damage or wear to the rod finish, the part must be reworked.
Note: Refer to Reuse And Salvage Guidelines, SEBF8194, "Specifications for Rear Suspension Cylinder Components Used in Off-Highway Trucks" for specification information for the rear suspension cylinders.
- Machine the center cap according to the specifications in Illustration 3.
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| Illustration 2 | g03818080 |
View of the holes in the center cap | |
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| Illustration 3 | g03795736 |
(A) 30 mm (1.18 inch) diameter spotface (B) 11 mm (0.433 inch) diameter hole (C) 14.5 mm (0.571 inch) diameter hole 18 mm (0.708 inch) deep. 5/8-18-2B thread 15 mm (0.591 inch) deep. (D) 5 mm (0.197 inch) radius (E) 8.7 mm (0.342 inch) diameter hole 22 mm (0.866 inch) deep (two places). M10 X 1.5-6G thread 18 mm (0.708 inch) deep. Use a bottom tap to cut threads. (F) 12.7 mm (0.5 inch) diameter hole (G) 5 mm (0.197 inch) radius (two places) (H) Spot face until full cleanup on hole (A) (J) 64 mm (2.51 inch) (maximum) (K) 75 mm (2.95 inch) (minimum) (L) 95 mm (3.74 inch) (M) 120 mm (4.72 inch) (minimum) (N) 25 mm (0.98 inch) (P) 50 mm (1.96 inch) (minimum) (R) 60 mm (2.36 inch) (maximum) (S) 185 mm (7.28 inch) and not to exceed 190 mm (7.48 inch) (T) 95 mm (3.74 inch) | |
- Secure block (1) and O-Ring seal (2) to the center cap by using two bolts (3) and two hard washers (4) .
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| Illustration 4 | g03795781 |
(1) 469-6517 Valve Block (2) 8M-4435 O-Ring Seal (3) 8T-5005 Bolt (4) 8T-4121 Hard Washer | |
- If the machine Is Equipped with a Truck Payload Measurement System (TPMS), secure two valve assemblies (5), check valve group (7), O-Ring seal (8), and backup ring (9) onto valve block (1). Refer to Illustration 5.
If the machine is Not Equipped with a Truck Payload Measurement System (TPMS), secure three valve assemblies (5) onto valve block (1). Refer to Illustration 6.
Note: Installation torque on valve assemblies (5) is 13.6 ± 0.6 N·m (120 ± 5 lb in).
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| Illustration 5 | g03818313 |
(1) 469-6517 Valve Block (5) 372-1181 Valve As (7) 129-1029 Check Valve Gp (8) 033-6039 O-Ring Seal (9) 030-0167 Backup Ring | |
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| Illustration 6 | g03818314 |
(1) 469-6517 Valve Block (5) 372-1181 Valve As | |
- If the machine Is Equipped with a Truck Payload Measurement System (TPMS), secure block (10) to valve block (1) by using two bolts (11) and two hard washers (12). Secure pressure sensor group (14) with O-Ring seal (13) to block (10) .
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| Illustration 7 | g03818316 |
(1) 469-6517 Valve Block (10) 228-4929 Block (11) 4L-7124 Bolt (12) 5P-0537 Hard Washer (13) 3J-1907 O-Ring Seal (14) 221-3416 Pressure Sensor Gp | |
- Secure valve assembly (5) with O-Ring seal (6) to the top of the cap.
Note: Installation torque on valve assembly (5) is 13.6 ± 0.6 N·m (120 ± 5 lb in).
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| Illustration 8 | g03818317 |
(5) 372-1181 Valve As (6) 114-3361 O-Ring Seal | |
- Using low strength bolts, fabricate six plugs (15) .
Note: Cut the bolt to the correct length and add a slot for a flat-head screwdriver.
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| Illustration 9 | g03818116 |
Plug (15) 3/8-18 Thread (A) 12 mm (0.472 inch) (B) 3 mm (0.118 inch) (C) 3 mm (0.118 inch) | |
- Machine and rework the rod assembly.
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| Illustration 10 | g03818040 |
(15) Plug (A) 90 Degrees (six places) (B) 15 mm (0.59 inch) Diameter hole (six places) | |
Note: Machining and rework to the four outside holes is optional. Machining and rework to the two inside holes must be completed. Refer to Illustration 10 for the machining dimensions.
- Insert six plugs (15) into the rod assembly.
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| Illustration 11 | g03818246 |
(15) Plug | |
- Prepare the area for welding.
Note: Refer to Special Instruction, REHS1841, "General Welding Procedures" prior to performing any welding on the machine.
Fill the remainder of the six holes with plug weld.
Note: Preheat to 232° C (450° F). Use "GMAW" or Low Hydrogen 7018. Grind the area flush.
Remove any weld splatter.
- Thoroughly clean the parts again and repaint, as needed.
- Using all new seals, reassemble the reworked suspension cylinders.
Note: Refer to Disassembly and Assembly, "Rear Suspension (Cylinder) - Assemble" for information to assemble the rear suspension cylinders.
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| Illustration 12 | g03818173 |
(16) 2H-5001 O-Ring Seal (17) 3J-1907 O-Ring Seal (18) 4J-1151 Backup Ring (19) 8J-8900 Wear Ring (20) 9X-7354 Lip Type Seal (21) 243-4567 Backup Ring (22) 243-4572 O-Ring Seal (23) 330-6822 Buffer Seal As (If head design allows use) (24) 433-5904 U-Cup Seal | |
| NOTICE |
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Do not reuse old seals. |
- Install the reworked suspension cylinders with the rod down.
Note: Refer to Disassembly and Assembly, "Rear Suspension (Cylinder) - Install" for information to install the rear suspension cylinders.
Note: Each suspension cylinder has two holes for grease fittings. The grease fittings may require relocation.
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| Illustration 13 | g03818303 |
Typical view | |
| NOTICE |
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Ensure that the blocks on the suspension cylinders face away from the tires when installed. |
- Reinstall the cover onto the bottom of the suspension cylinders without a clamp on the bottom (rod end).
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| Illustration 14 | g03797013 |
View of the inverted rear suspension with cover | |
| NOTICE |
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Do not secure the cover to the bottom (rod end) of the suspension cylinders. |
- Remove the existing film, and replace with film (25) and film (26) .
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| Illustration 15 | g03818250 |
(25) 279-2269 Film (26) 279-2271 Film | |
- Charge the suspension cylinders. Refer to Special Instruction, REHS4445, "Servicing the Suspension Cylinders for Off-Highway Trucks" for instructions.