VMAC - Vehicle Mounted Air Compressors
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VMAC Knowledge Base: kb.vmacair.com
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Figure 44 — Adjusting the Unloader Valve
(engine base plate removed for clarity)
☐
Rotate the “Pressure Adjustment Screw” counterclockwise in 1/8 turn
increments.
☐
While securely holding the “Pressure Adjustment Screw”, tighten the “Pressure
Adjustment Locknut”.
☐
Test the system and repeat the steps above (if necessary) until the system
unloads at 140 psi.
Pressure
Adjustment Screw
Pressure Adjustment
Locknut
☐
While securely holding the “Pressure Adjustment Screw”, loosen the “Pressure
Adjustment Locknut” (Figure 44).
Each 1/8 rotation of the “Pressure Adjustment Screw” is equivalent
to approximately 5 psi.
The unloader valve is sensitive to very small adjustments.
To prevent inadvertently rotating the “Pressure Adjustment Screw”,
hold the “Pressure Adjustment Screw” securely when tightening
loosening or tightening the “Pressure Adjustment Locknut”
