The valve in an oil or hydraulic circuit that opens to release excess fluid pressure and return fluid to the feed side of the pump.

A pressure sensitive switch used to provide a signal voltage to an instrument, lamp or electronic control module.

A supercharger using the exhaust pressure waves to boost the inlet air pressure. This supercharger uses a drum with longitudinal drillings that is rotated in time with the engine and ported to match inlet and exhaust pressure waves together.

A spray gun equipped with a separate paint container that is pressurized and connected to the spray gun by means of a solvent-resistant fluid hose, in addition to the normal air hose.

A brake shoe that has a leading edge making first contact when applied. Also leading shoe.

The low tension (primary circuit) coil of wire in an ignition coil.

The first coat of paint applied to a substrate. Depending on the formulation of a particular primer, its function can be to provide any combination of">adhesion, build, scratch-filling, ground coating and corrosion resistance.

An undercoat which improves adhesion of the topcoat, by sealing off old painted surfaces that have been sanded; usually does not require sanding when dry.

Lifting fuel into the system components to remove air.

A manually operated pump that lifts fuel into the system.