PUMP GP-CHARGE 2935440 - Caterpillar

Release of Hydraulic Pressure from Multiple Hydraulic Circuits
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.
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.
Perform the following Steps to release the hydraulic pressure from multiple hydraulic circuits of the main hydraulic system.
Position the machine on level ground.
Illustration 1 g02137969
Fully retract the stick cylinder rod. Adjust the position of the bucket so that the bucket is parallel to the ground. Lower the boom until the bucket is flat on the ground. Refer to Illustration 1.Note: Perform Step 3 through Step 6 immediately after the engine is shut off. This action is to insure adequate pilot system pressure is available to release the pressure in the hydraulic circuits.
Shut off the engine.
Turn the engine start switch to the ON position without starting the engine.
Place the hydraulic activation control lever in the UNLOCKED position.
Move only the joysticks or the pedals of the hydraulic circuit that requires service to the FULL STROKE positions. This action will release the high pressure only in that hydraulic circuit. This action will also release any pressure that might be present in the pilot hydraulic circuit.Note: If the hydraulic circuit requiring service requires the activation of a switch for operation, activate the necessary switches for the operation of the hydraulic circuit.
Place the hydraulic activation control lever in the LOCKED position.
Start the engine.
Place the hydraulic activation control lever in the UNLOCKED position. Do not move any joysticks or pedals from the NEUTRAL position during this step. Do not activate any switches during this Step.
Return the hydraulic activation control lever to the LOCKED position.
Shut off the engine.
Repeat Steps 4 through 11 for each additional hydraulic circuit that requires service.
After releasing the hydraulic pressure in each of the desired hydraulic circuits, place the hydraulic activation control lever in the LOCKED position.
Turn the engine start switch to the OFF position.
Illustration 2 g02275615
Filler cap
(A) LOCK position
(B) PRESSURE RELEASE - START position
(C) PRESSURE RELEASE - END position
(D) OPEN position
Release the pressure that may be present in the return hydraulic circuit with the following procedure. Refer to Illustration 2 for filler cap positions.
Turn the filler cap counterclockwise and move the arrow from position