Key Components of a Complete Assembly
Pressure Switch (The "Brain"): This mechanical device controls the motor. It switches the compressor ON when pressure drops below a certain level (cut-in) and OFF when the desired high pressure is reached (cut-out).
Auto/Off Lever/Knob: A manual switch to turn the unit on for automatic operation or off completely.
Adjustable Springs: Inside the switch, these allow setting the specific cut-in and cut-out pressure points.
Contacts: These connect/disconnect the power to the motor.
Unloader Valve: Frequently integrated into the switch box, this releases trapped air from the pump cylinder when the motor stops, allowing the compressor to start again without load.
Pressure Gauges (The "Eyes"):
Tank Pressure Gauge: Indicates the current pressure stored in the tank.