c

compression stroke

Glossary “compression stroke” Definition:
Movement of the piston from BDC to TDC, immediately after the intake stroke. The upward movement of the piston squeezes the A/F mixture into the combustion chamber. In diesel applications, only air is compressed during this stroke. This is the second stroke in the four-stroke cycle.

compression ratio (CR)

Glossary “compression ratio (CR)” Definition:
1). Measurement of volume compressed inside an engine cylinder. If compressed to 1/10 of its original volume, the compression ratio is 10 to 1. 2). The ratio of the volume in the engine cylinder with the piston at bottom dead center compared (BDC) to the volume at top dead center (TDC)

compression braking

Glossary “compression braking” Definition:
Slowing of a vehicle restricting a diesel engine exhaust flow, such as that provided by a Jake brake. It is a misnomer that a gasoline engine will slow the vehicle by compression braking; actually, vacuum causes the braking effect.

compression gauge

Glossary “compression gauge” Definition:
A gauge used in the spark plug hole of the cylinder head to measure cylinder compression pressures of a gas engine. Removing the glow plug from a diesel engine allows for the installation of higher pressure rated compression gauge used to measure cylinder compression.