- Wheel Loader:
- 914G (PIN: 7ZM1-UP; 9WM1-UP)
- Integrated Toolcarrier:
- IT14G (PIN: 1WN1-UP; 8ZM1-UP)
The information in this section has been updated. Replace the referenced section of the Operation and Maintenance Manuals with the information in this article.
For additional information, see Service Magazine, SEPD0533, 17 July 2000, "New Crossover Relief Valves Are Used in the Hydrostatic Pump Group".
Towing with a Stopped Engine
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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 work tools have been lowered to the ground, and the 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 machine. Be prepared to collect the fluid with suitable containers before opening any compartment or disassembling any component containing fluids. Refer to Special Publication, NENG2500, "Caterpillar Tools and Shop Products Guide"for tools and supplies to collect and contain fluids in Caterpillar machines. Dispose of all fluids according to local regulations. |
When the disabled machine's engine is stopped, perform the following steps before you tow the machine.
- Engage the parking brake and chock the wheels.
- Reverse the hydraulic steering hose connections on one cylinder only.
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| Illustration 1 | g00415378 |
- Ensure that the pump has cooled before performing the procedure.
- Activate the bypass mode of the crossover relief valves in order to allow free circulation of the oil while the machine is being towed.
Note: There are two types of relief valves that can be used for this application. The two types of relief valves have different adjustments for activating the bypass mode. An instruction for each type of relief valve is provided at the end of this section. Be sure to use the correct instruction for the type of relief valves on your machine.
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| Illustration 2 | g00720361 |
- Secure the tow bar to the disabled machine.
- Remove the wheel blocks and release the parking brake.
Note: Do not tow the machine faster than 2.0 km/h (1.2 mph).
- After towing is complete, deactivate the bypass mode for the crossover relief valves and tighten the valves to the specified torque. The torque specifications are provided at the end of this section.
| NOTICE |
|---|
Release the parking brake to prevent excessive wear and damage to the parking brake system, when towing the machine. The procedure for manual release of the parking brake is outlined in the next topic, Parking Brake Manual Release. |
- Reconnect the hydraulic steering hose connections that were reversed in Step 2.
Note: Ensure that the hydraulic steering hoses are connected correctly before operating the machine. The steering system will not function when the hoses are reversed.
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Personal injury or death can result from a brake malfunction. Be sure all necessary repairs and adjustments have been made before a machine that has been towed to a service area, is put back into operation. |
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Activating the Bypass Mode for the Crossover Relief Valves on Machines with the 152-9143 Relief Valves
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| Illustration 3 | g00720142 |
- Remove the protection cap (1) from the 152-9143 Relief Valves. See Illustration 3.
- Unscrew hex head screw (2) on both of the relief valves. This will release the valve cartridge, which allows free circulation of the oil during towing.
Note: Do not adjust the external hex nut (3). This is the locking nut for set screw (5), which is the adjustment for the relief pressure setting. Any adjustment of the hex nut can loosen the hex head screw (2). This can result in changes to the relief pressure setting and in activation of the bypass mode. If adjustments are made to the relief pressure setting with the hex nut (3), always check in order to ensure that the hex head screw (2) is tightened to the correct torque. See Table 1 for the torque specifications.
- Replace the protection caps on the relief valves.
Activating the Bypass Mode for Crossover Relief Valves on Machines with the 123-7550 Relief Valves
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| Illustration 4 | g00720150 |
Hold the nut (2) and turn the adjustment nut (1) counterclockwise for 1 to 2 turns. This will release the valve cartridge, which allows free circulation of the oil during towing. See Illustration 4.
Torque Specifications for Crossover Relief Valves
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| Illustration 5 | g00720267 |
| Location | Torque |
| A | 10 N·m (7.4 lb ft) |
| B | 10 N·m (7.4 lb ft) |
| C | 20 N·m (14.8 lb ft) |
| D | 150 N·m (111 lb ft) |
| E | 100 N·m (74 lb ft) |