A valve that sets its position depending on the difference between two pressures, for example, two fuel pressures or fuel pressure and manifold pressure.

Valves that operate under the control of TWO external pressures or the difference (differential) between them.

See Digital Converter.

A number.

A signal current with either an 'on' or 'off' voltage. Digital instruments which show a numerical value.

Electronic devices that convert analogue signals to digital or digital signals to analogue.

A liquid which increases the capacity of a solvent for the binder. Diluents cannot dissolve the binder themselves. They are usually used to control viscosity or flash-off times.

A switching relay that results in a resistor being connected in series with dipped lights when ignition and sidelights are switched on. This safety feature as used on some vehicles – but not all.

An electronic one way valve with polarity bias manufactured from a semiconductor material.

A collection of diodes that act as a rectifier. A minimum of six diodes in the pack are needed for a three phase alternator.