Usually the top two rings in the piston, they form a seal between the piston and cylinder wall to compress the air fuel mixture in the cylinder.
A scale of temperature measurement with the boy point of water at 212F and the freezing point at 32F
On OHC overhead cam engine the equivalent of a rocker arm.
A signal that varies the ratio of on-time to off-time, resulting in a square wave that can range between zero and 100; in a process, the ratio of on-time to total cycle time; in fuel injectors, the percentage on-time to total cycle time; in solenoids, the percentage of on-time to total cycle time.