The Bendix+ LP-3 low pressure indicator is a safety device designed to give an automatic warning to the driver whenever air pressure in the air brake system is below the safe minimum for normal vehicle operation. It is usually used to operate an electrical buzzer or warning light, or both, which are audible or visible to the driver. Two styles of low pressure indicators are currently manufactured. The Bendix+ LP-3 low pressure indicator consists of a die cast body, nylon cover and employs a spring loaded o-ring diaphragm and piston. The LP-3 indicator is available with either one terminal or two. The single terminal unit utilizes a metallic gasket between body and case to ground the lower contact strip. The two terminal unit utilizes a phenolic insulating gasket to isolate both terminals from the vehicle frame.The electrical contacts provided in the LP-3 indicator remain closed by spring force until the air brake system pressure below the diaphragm is above the setting (force) of the low pressure indicator spring. The setting of the indicator and piece number is marked on a label on the valve body. If a label is not present, then the vehicle manual should be consulted for the proper setting. The nominal setting of most indicators is 60 psi; however, pressure settings may vary depending upon the vehicle.