Glossary “vacuum modulator” Definition:
Component of the air-temperature sensor that regulates the amount of vacuum signal that is applied to the servo motor. It may also refer to a device which is used on some A/T to regulate shift points and or and pressure to engine torque and demands on the vehicle.

Glossary “vacuum motor” Definition:
1). Device having a chamber containing a vacuum diaphragm used to create movement in a component, such as a heated air-intake blend door, when engine vacuum is routed to the chamber. 2). Device designed to provide mechanical control by the use of a vacuum.

Glossary “vacuum gauge” Definition:
Analog or digital instrument used for measuring vacuum.

Glossary “vacuum hose” Definition:
A rubber like, plastic or nylon hose used to transmit vacuum.

Glossary “vacuum hydraulic power unit” Definition:
Unit consisting of a vacuum brake cylinder or chamber, hydraulic cylinder(s), and control valve in which driver effort is combined with force from the cylinder piston or chamber diaphragm to displace fluid under pressure for actuation of the brake (s).

Glossary “vacuum dump valve” Definition:
Valve that mechanically releases vacuum from the speed control servo when the brake pedal is depressed.

Glossary “vacuum diaphragm” Definition:
The thin, rubberized, flexible disc in vacuum regulator, valve or modulator.

Glossary “vacuum differential valve” Definition:
A valve used in the Thermactor system with catalyst to cut off vacuum to the air bypass valve during deceleration.

Glossary “vacuum diverter valve” Definition:
Term used for vacuum switching device.

Glossary “vacuum check valve” Definition:
1). An air-operated mechanical device that closes a vacuum line to the vacuum reserve tank whenever the manifold vacuum pressure falls below the reserve vacuum pressure. 2). In a power-brake system, a one-way valve on the power brake boost that maintain vacuum within the unit when vacuum supply drops.

Glossary “vacuum control valve” Definition:
A ported vacuum switch. Controls vacuum to other emission devices during engine warm-up. The 2-port types simply open when engine coolant reaches their pre-determined calibration temperatures. The 4-port types open likewise, since they are nothing more than two, 2-port types in one housing. The 3-port types switch the vacuum source to the center port from the top or the bottom ports. Most VCV’s respond to a sensing bulb immersed in engine coolant by utilizing a wax pellet principle.

Glossary “vacuum controlled temperature sensing valve” Definition:
A valve that connects the manifold vacuum to the distributor advance under hot-idle conditions.

Glossary “vacuum delay valve” Definition:
Orifice controlled valve which delays a vacuum signal to a diaphragm, such as in the distributor vacuum advance unit.

Glossary “vacuum canister” Definition:
Tank like enclosure to serve the requirements of vacuum-actuated accessories.

Glossary “vacuum chamber” Definition:
Term used for vacuum canister or vacuum reserve tank.

Glossary “vacuum check relay” Definition:
Mechanical, air-operated device that closes off a vacuum line to a port whenever the manifold vacuum pressure falls below the applied vacuum pressure.

Glossary “vacuum booster” Definition:
Power bbrake actuating mechanism that uses vacuum on one side of a diaphragm as a power source to amplify braking force.

Glossary “vacuum brake booster” Definition:
Device that uses vacuum to amplify the braking force.

Glossary “vacuum advance control” Definition:
An emissions-control system component that allows vacuum advance only during certain modes of engine operation.