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Personal injury or death can result from sudden machine movement. Sudden movement of the machine or release of air pressure or oil pressure can cause injury to persons on or near the machine. To help prevent possible injury before testing and adjusting any air system or hydraulic system, perform the procedure in the Testing and Adjusting, "General Information" section. |
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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, "Caterpillar Dealer Service Tool Catalog" for tools and supplies suitable to collect and contain fluids on Caterpillar products. Dispose of all fluids according to local regulations and mandates. |
Note: Before you perform any operation checks, open the drain valves in order to release any water in the air tanks. Water lowers the capacity of the air tanks. When the capacity of the air tanks is lowered, the air compressor can operate continually. Close the drain valve. Start the engine. Operate the machine until the machine is at the normal operating temperature.
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Location of drain valve for air tank | |
Operation checks can be used to find the source of air leakage in the air system and in the brakes. Operation checks can also be used to diagnose the reasons for bad performance in the air system and in the brakes.
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Do not check for leaks with your hands. Pin hole (very small) leaks can result in a high velocity oil stream that will be invisible close to the hose. This oil can penetrate the skin and cause personal injury. Use cardboard or paper to locate pin hole leaks. |
Note: It is possible to hear the sound of air leakage. Air leakage can be observed by applying soapy water to connections, to valves and to hoses.
- Start the engine and allow the air pressure to reach the cutout pressure. Stop the engine.
Note: The governor cutout pressure is equal to
815 ± 35 kPa (120 ± 5 psi) . If the governor cutout pressure is not correct, see the Systems Operation/Testing And Adjusting, "Air Compressor Governor - Test and Adjust" that is located in this manual.Note: Include all hoses, lines and connections in your investigations.
- Check from the air compressor to the air tanks. The check should include the air compressor governor and the air dryers.
- Check for air leakage at the drain valves of the air tanks. Check for air leakage at the relief valves for the air dryers and for the air tanks.
- Check all hoses, lines and connections between the following components: the air tanks, the air start relay and the air starting motor group.
- Check all hoses, lines and connections between the following components: the circuit for the horn and the solenoid for the air starting motor group .
Note: While you check for air leakage, check the exhaust passages for restrictions. (The restrictions may be from mud or from dirt.) A restriction in an exhaust passage will slow down the release of pressure air during normal operation. A restriction in an exhaust passage may even prevent the release of pressure air during normal operation.