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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. Follow the recommendations below, to properly perform the towing procedure. |
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When you are towing the machine, the cross over relief valves must be adjusted. If the cross over relief valves are not adjusted, the hydraulic pump will be damaged. |
These towing instructions are for moving a disabled machine for a short distance at low speed. Move the machine at a speed of 2 km/h (1.2 mph) or less to a convenient location for repair. These instructions are only for emergencies. Always haul the machine if long distance moving is required.
Shields must be provided on both machines. This will protect the operator if the tow line breaks or the tow bar breaks.
Do not allow an operator to be on the machine that is being towed unless the operator can control the steering and/or the brakes.
Before you tow the machine, make sure that the tow line or the tow bar is in good condition. Make sure that the tow line or the tow bar has enough strength for the conditions that are involved. The strength of the tow line or of the tow bar should be at least 150 percent of the gross weight of the machine that is being towed. This pertains to a disabled machine that is stuck in the mud and to towing a disabled machine on a grade.
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| Illustration 1 | g00475586 |
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| Illustration 2 | g00415700 |
When you tow the machine from the front, attach the tow line to the tow eyes on the frame. When you tow the machine from the rear, attach the tow line to the towing pin.
Do not use a chain for pulling a disabled machine. A chain link can break. This may cause personal injury. Use a wire cable with ends that have loops or rings. Place an observer in a safe position in order to watch the pulling procedure. The observer can stop the procedure, if necessary. The procedure should be stopped if the cable starts to break. Also, stop the procedure if the cable starts to unravel. Stop pulling whenever the towing machine moves without moving the towed machine.
Keep the tow line angle to a minimum. Do not exceed a 30 degree angle from the straight ahead position.
Quick machine movement could overload the tow line or the tow bar. This could cause the tow line or the tow bar to break. Gradual, steady machine movement will be more effective.
Normally, the towing machine should be as large as the disabled machine. Make sure that the towing machine has enough brake capacity, enough weight, and enough power. The towing machine must be able to control both machines for the grade that is involved and for the distance that is involved.
You must provide sufficient control and sufficient braking when you are moving a disabled machine downhill. This may require a larger towing machine or additional machines that are connected to the rear of the disabled machine. This will prevent the machine from rolling away out of control.
All situation requirements cannot be listed. Minimal towing machine capacity is required on smooth, level surfaces. Maximum towing machine capacity is required on inclines or in poor conditions.
When any towed machine is loaded, this machine must be equipped with a brake system that is operable from the operator compartment.
Consult your Caterpillar dealer for the equipment that is necessary for towing a disabled machine.
Towing with a Running Engine
If the engine is running, the machine can be towed for a short distance under certain conditions. The power train and the steering system must be operable. Tow the machine for a short distance only. For example, pull the machine out of mud or pull the machine to the side of the road.
The operator on the towed machine must steer the machine in the direction of the tow line.
If the steering system is inoperable use the secondary steering system to steer the machine. Refer to Operation and Maintenance Manual, "Secondary Steering".
Comply with all of the instructions that are outlined in this topic.
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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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 3 | 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 4 | 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.
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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 5 | g00899107 |
- Remove the protection cap (2) .
- Unscrew hex head screw (3) 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 (4). This is the locking nut for set screw (1), which is the adjustment for the relief pressure setting. Any adjustment of the hex nut can loosen the hex head screw (3). 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 (4), always check in order to ensure that the hex head screw (3) is tightened to the correct torque.
- Tighten hex head screw (3) on both of the relief valves to a torque of 10 N·m (7.4 lb ft).
- 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 6 | g00899112 |
- Remove the protection cap from the relief valve.
- 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.
- Tighten adjustment nut (1) to a torque of 10 N·m (7.4 lb ft).
- Replace the protection caps on the relief valves.