BREATHER AS 2932147 - Caterpillar

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.
Illustration 1 g00477489
Housing for the Plunger of the Main Control Valve (1) Nut. (2) Threaded plunger.The main control valves are activated by pilot oil pressure. The pilot control valves are able to modulate the movement of the main control valve spool. This is done by controlling the amount of pilot pressure that is sent to the spool. The initiation pressure is the point when the main valve stem begins to move.Adjustment of the Valve Stem Modulation
One end of the valve spool is being checked. A pilot line is connected to that end of the valve spool. Install a 0 to 4150 kPa (0 to 600 psi) pressure gauge in the pilot line.
Start the engine. Run the engine at high idle. Ensure that the hydraulic oil is at the operating temperature.
Slowly move the tilt pilot control valve to the DUMP position. Note the pressure gauge reading at the moment that the bucket begins to move.
The pressure should be 860 70 kPa (125 10 psi).
If the pressure is not correct, stop the engine.
Nut (1) is on the valve spool at the end that was checked. Loosen nut (1) on the end of the valve spool. Turn plunger (2) clockwise in order to increase the initiation pressure. Turn the plunger counterclockwise in order to decrease the initiation pressure. Tighten nut (1) .
Repeat Steps 2 through 4.
If the pressure is not correct, repeat Steps 5 through 6.
When the pressure is correct, remove the gauge and the additional test equipment.