LINK 2924856 - Caterpillar

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 attachments have been lowered, 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.
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, "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.
Specifications
Table 1
Pilot Oil Pressure
Date Equipment ID Code
Pressure Specification Actual
Low Idle 3450 345 kPa (500 50 psi) Introduction
This test will check the pilot oil pressure reducing valve. Refer to the Systems Operation, Testing and Adjusting, "Machine Preparation for Troubleshooting".Required Tools
Illustration 1 g01623868
Table 2
Tool Item Part Number Description Qty
B 198-4240 Digital Pressure Indicator Gp
B1 198-4234 Digital Indicator 1
B2 251-9600 Pressure Sensor Gp (0 to 68,900 kPa (0 to 10,000 psi)) 1
B3 198-4236 Adapter Cable As 1 Test Preparation
Bring the engine to normal operating temperature and move the machine to a smooth, horizontal location. Move the machine away from other operating machines and away from personnel. Place the transmission direction control switch in the NEUTRAL position. Engage the parking brake. Lower the bowl to the ground. Retract the ejector cylinder and disengage the cushion hitch. Shut off the engine and turn the engine start switch to the ON position. Place chocks in front of the wheels and behind the wheels.
Perform the following steps prior to the pilot pressure diminishing. The procedure should be performed no more than 1/2 hour after the engine has been shut off.
Move the control levers through the full range of travel. This movement of the levers will relieve any pressure that may be present in the hydraulic system. Turn the engine start switch to the OFF position.
Slowly loosen the filler cap for the hydraulic oil tank to release the pressure
Illustration 2 g03720509
Rear of the implement control valve
(1) Test port
Remove the dust cap from test port (1) and attach Tooling (B).Test Procedure
Start the engine and run the engine at low idle.
Put the bowl on the ground and lower the apron.
Move the joystick control to the bowl RAISE position. The digital pressure indicator should read 3450 345 kPa (500 50 psi).Note: The pilot oil pressure should also read 3450 345 kPa (500 50 psi) when the joystick control is in any of the following positions:
Bowl LOWER position
Bowl RAISE position
Ejector FORWARD position
Ejector REVERSE position
Apron RAISE position
Apron LOWER position
Remove the test equipment.Adjustment