PIN AS 4E1799 - Caterpillar

Sudden movement of the machine or release of air 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 air system and brakes.
Start the tractor engine and allow the air pressure to reach the cut-out pressure 965 34 kPa (140 5 psi).
Read the cut-out pressure on the test gauge. See Testing and Adjusting, "Air Pressure Gauge - Test" for the installation of the gauge.
Push the brake pedal rapidly for several times.
Read the cut-in pressure on the test gauge.
The cut-in pressure should be 793 kPa (115 psi) minimum. The cut-out pressure should be 965 34 kPa (140 5 psi).
Illustration 1 g00724498
View of the Left Side of the Tractor Engine (1) Air compressor (2) Governor cover
If necessary, adjust the air compressor governor:
Remove cover (1) on the top of the governor.
Loosen the locknut on the adjustment screw.
Turn the adjustment screw counterclockwise in order to raise the cut-out pressure. One turn of the adjustment screw changes the pressure approximately 140 kPa (20 psi). The cut-in pressure will change the same amount.
If the adjustment screw does not change the cut-out pressure, the unloading valves in the air compressor are not working correctly.
If the difference between the cut-in pressure and the cut-out pressure is not correct, the governor is not working correctly.