Friday, 23 April 2021, 12:14 PM
Site: IMI eLearning
Course: IMI eLearning (IMI eLearning)
Glossary: Automotive Glossary

Valve Lifter

Cam follower or tappet.

Valve Margin

The thickness of the valve head between the valve face and the head surface.

Valve Needle

The control pin in, for example, a fuel injector. The needle works against an accurately shaped component to control flow.

Valve Overlap

The term used to describe the angle of crankshaft rotation when the inlet and exhaust valves are both open.

Valve Seat

The bevelled surface annular face in the cylinder head that closes each port and into which a valve seats and seals the port.

Valve Seat Insert

A steel insert fitted in aluminium and some iron cylinder heads to form a durable seating for the inlet and exhaust valves.

Valve Spring

The spring that closes and holds closed the valve. It fits around the valve stem above the guide and between the cylinder head and valve spring retainer.

Valve Stem

The shaft of a valve.


A flat component used as part of a pump that moves a liquid or fluid.

Vane Pump

A type of positive displacement pump formed by an eccentric rotor driving two or more vanes fitted inside a housing. The eccentricity of the rotor and vanes forms the pumping chambers of the vane pump.