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Personal injury or death could result when towing a disabled machine incorrectly. Block the machine to prevent movement before releasing the brakes. The machine can roll free if it is not blocked. |
- Place the shift control lever in the P position.
- Chock the wheels.
- Hook up the towing machine. Refer to Operation and Maintenance Manual, "Towing the Machine" for the guidelines.
- Check the steering and the service brake on the disabled machine. If the steering or braking needs assistance, use an Auxiliary Power Unit (APU) as a separate hydraulic source. An APU that is designed to use with this machine is available through your Cat dealer. Consult your Cat dealer for further information on the selection and the proper operation of an APU.
Only a limited amount of steering is provided by the secondary steering system. Park the truck in a safe location before the secondary steering energy is depleted. The steering system accumulators provide a limited amount of stored hydraulic pressure for secondary steering capability. The stored hydraulic pressure is exhausted by a small amount of steering system oil flow that keeps the oil warm and by steering wheel action by the operator. The stored hydraulic pressure will be exhausted faster as the steering wheel action by the operator is used to a greater magnitude, duration, or frequency. Refer to Operation and Maintenance Manual, "Operator Controls" for more information on the secondary steering system.
Note: When the engine start switch is moved to the OFF position, solenoid valves will fully deplete the brake oil pressure from the brake accumulators and the steering oil pressure from the steering accumulators.
- Apply the service brake pedal on the disabled machine to check the braking. If the brakes are functioning, release the brakes.
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NOTICE The parking brake must be fully released. Partial brake engagement and brake damage could occur if proper hydraulic pressure is not maintained.
Do not allow the parking brake release pressure to drop below
3445 kPa (500 psi) when the towed machine is moving.Show/hide table
Illustration 1 g03441425 - Push and hold the park brake (2) switch until the Advisor display indicates that the parking brake is released and the hydraulic brake pressure is
3800 kPa (550 psi) - Turn the steering wheel. Confirm that the front wheels turn as the steering wheel is turned.
- Remove the wheel chocks.
- Move the shift control lever to the N position. Make sure that the engine start switch remains in the ON position.
- Pull the disabled machine with the towing machine.
- During towing, continue to monitor the hydraulic pressure on the Advisor display. Do not continue to tow the machine if the hydraulic brake pressure is below
3445 kPa (500 psi) . As the parking brake release oil pressure decreases, depress the brake release switch. Momentarily hold the brake release switch to provide adequate brake oil pressure and prevent the engagement of the parking brake.
Limping Home a Machine with Final Drive and/or Drive Motor Failure
Perform the following procedure on machine with a final drive that is damaged or a drive motor that is locked up. This procedure can only be used when the other final drive and drive motor are functional.
- Make sure that the shift control lever is in the P position and stop the engine.
- If the machine is loaded, empty the body. Lower the body.
- Chock the wheels.
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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.
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Illustration 2 g03135477 - Remove cover (1) from the final drive/drive motor to be disabled.
- Remove the axle shafts. Refer to Disassembly and Assembly, UENR2271, "794 AC Off-Highway Truck Power Train", "Axle Shaft - Remove".
- Remove any damaged power train components that may rotate when the machine is moved.
Note: When there is failure of the final drive, clean the system before the machine is moved. Debris in the wheel can cause extensive damage when the wheel is rotated.
- Replace the final drive cover.
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NOTICE If the axle shaft is removed without disabling the drive motor, permanent damage to the drive motor will occur if the shift control lever is moved out of the P position with the engine running.
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Illustration 3 g06344239 - Disable the drive motor through the settings menu in Advisor. Refer to Operation and Maintenance Manual, "Monitoring System" for information on Advisor. The drive motors can also be disabled through ET
Note: The drive motor will become disabled after the engine start switch is cycled.
- Start the engine.
- Remove the chocks from the wheels.
- Check the steering by turning the steering wheel to the right and to the left.
- Check the braking by applying the service brake pedal.
- Verify on the Advisor display that the designated drive motor is disabled and move the shift control lever to the D position.
- Drive the empty machine to a repair location. Do not use the retarder control with a disabled drive motor, the disabled drive motor will not provide any retarding capability. Use the service brake to slow and stop the machine.
Note: The machine speed will be limited to
11 km/h (7 mph) during single drive motor operation - Make sure that none of the power train components are causing additional damage.
