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Sudden movement of the machine or release of oil under pressure can cause serious injury to persons on or near the machine.
To prevent possible injury, perform the procedure that follows before testing and adjusting the hydraulic system.
Personal injury or death can result from escaping fluid under pressure.
Escaping fluid under pressure, even a very small pin-hole size leak, can penetrate body tissue and cause serious injury and possible death. If fluid is injected into your skin, it must be treated by a doctor familiar with this type of injury.
Always use a board or cardboard when checking for a leak.
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.
Note: Permit only one operator on the machine. Keep all other personnel away from the machine or in the operator's sight.
- Move the machine to a smooth, horizontal location that is away from operating machines and away from personnel.
- Place the transmission direction and speed control in the NEUTRAL position and in any speed position. Engage the steering and transmission lock lever.
- Engage the parking brake. Place wheel blocks in front of the wheels and behind the wheels.
- When the work tool is raised for testing or for adjusting, make sure that the work tool is supported correctly. Also, make sure that the work tool is fully in the DUMP position. The lift circuit has high oil pressure when the lift arms raise the front of the machine.
Note: Do not stop the machine with the front of the machine off the ground unless this is required for a test. Lower the machine to the ground and stop the engine.
- If the machine is equipped with the ride control system, with the engine running, press and hold the ride control switch in the SERVICE position and ensure the ride control indicator is illuminated. Move the joystick control lever to the FLOAT position. This will relieve all of the hydraulic pressure in the ride control accumulator.
Note: If the ride control indicator does not illuminate when the ride control switch is in the service position, identify the root cause before proceeding.
- Stop the engine.
- Install the steering frame lock.
- Move the joystick control lever through the full range of travel. This will relieve any pressure that may be present in the implement hydraulic system.
- Move the steering control several times in both directions to release the pressure in the steering system.
- Release the braking system oil pressure.
Reference: Refer to Systems Operation, Testing and Adjusting, Braking System, "System Pressure - Release" for the machine that is being serviced.
- Depress the breaker relief valve on the hydraulic tank to release the pressure in the hydraulic tank.
Illustration 1 g00912063 (1) Pressure tap (for the rod end of the tilt cylinder)
- Connect a 177-7861 Hose As and an 8T-0860 Pressure Gauge to pressure tap (1). If there is any pressure on the gauge, move the joystick control lever to all positions until all the pressure is removed from the system.
Illustration 2 g00912064 (2) Pressure tap (for the head end of the tilt cylinder)
- Connect a 177-7861 Hose As and an 8T-0860 Pressure Gauge to pressure tap (2). If there is any pressure on the gauge, move the joystick control lever to all positions until all the pressure is removed from the system.
- The pressure in the hydraulic system has now been released. The lines, fittings and components can be removed.
- Remove the test equipment.