PLUG 5437643 - Caterpillar

Sudden movement of the machine or release of oil under pressure can cause injury to persons on or near the machine.To prevent possible injury, perform the procedure that follows before testing and adjusting the hydraulic system.
Park the host machine on a smooth, level surface. Move away from other operating machines and away from personnel. Lower the work tool to the ground. Stop the engine.
Permit only one operator on the host machine. Keep other personnel away from the host machine or in the operator's sight.
Engage the parking brake. Place chocks in front of the tracks or wheels and behind the tracks or wheels.
When the work tool is raised for testing or for adjusting, make sure that the work tool is supported correctly. The lift circuit has high oil pressure when the lift arms raise the work tool.Note: Do not stop the host machine with the work tool off the ground unless this is required for a test. Lower the work tool to the ground and stop the engine.
Follow the procedure in the Operation and Maintenance Manual of the host machine to relieve any pressure within the auxiliary hydraulic lines. For Caterpillar Skid Steer Loaders, use the following procedure.
Turn the engine start switch key to the ON position. Do not start the engine.
Disengage the parking brake.
Operate the auxiliary hydraulic control back and forth for several times in order to relieve hydraulic pressure within the auxiliary hydraulic lines.
Turn the engine start switch key to the OFF position.
To relieve all of the pressure in the hydraulic oil tank, slowly loosen the filler cap.Note: All hydraulic pressure must be released before any hydraulic components are worked on.
Install the filler cap.During a diagnosis of the hydraulic system, remember that correct oil flow and correct pressure are necessary for correct machine operation. The pump output increases as the engine speed increases and vice versa. Oil pressure is caused by resistance to the flow of oil.