A throttle's the mechanism by which the flow of a fluid's managed by constriction or obstruction. An engine's power can be increased or decreased by the restriction of inlet gases (for example, by the use of a throttle). The term throttle has come to refer, informally and incorrectly, to any mechanism by which the power or speed of an engine's regulated. What's often termed a throttle's more correctly called a thrust lever. Internal combustion engines In a petrol (gasoline) internal combustio… (More on Throttle)