Campbell Hausfeld MDR-4P-100-135 pressure switch is a four-port control switch rated for a 100–135 psi operating range, intended for use with Campbell Hausfeld air compressors. It features an unloader valve that vents residual pressure when the compressor stops, reducing startup load on the pump. The model MDR-4P-100-135 provides the specific four-port configuration and unloader function for compatible Campbell Hausfeld equipment.
