pilot valves are used in compressed air systems to actuate another device using a pneumatic (air) signal. pilot valves always work in conjunction with another device. examples of usage include - actuating a throttle control to slow down or speed up and engine - opening and closing a discharge valve to vent air to the atmosphere - operating intake unloaders in the compressors head. Pilot valves operate in a set pressure range. The range has an unload setting and a load setting. As a compressor operates in this range, it is said to by cycling. At the unload setting, the pilot valve opens and actuates another device (throttle control, discharge valve). At the load setting, the pilot valve closes and returns the compressor to normal operation. NEED A THROTTLE CONTROL CABLE??? Visit our store for numerous sizes and ratings on throttle control cables. we do combine shipping on all of our products. Pilot Unloader Valve For Air Compressors 1/4 FPT inlet - 1/8 outlet Manual Hand Unloader 30-40 PSI Adjustable Up or Down 1/4 FNPT Inlet & 1/8 FNPT Discharge Outlet 250 PSI MAX OPERATING PRESSURE, 15f to 350f Temp rating, Pilot Valve UPC 691023899391 Brand Name conrader Unit Count 1.0 Count Item Weight 0.47 Pounds Manufacturer EDGE CONRADER Model Number RCB-HU Material Type Brass, Stainless Steel Inlet Connection Size 0.25 Inches Inlet Connection Type National Pipe Tapered Outlet Connection Type FNPT Manufacturer Part Number RCB-HU Manufacturer Warranty Description 90 days from date of purchase