Lever resistance (or load). It is common to call the input force "the effort" and the output force "the load" or "the resistance." This allows the identification of three classes of levers by the relative locations of the fulcrum, the resistance and the effort: These cases are described by the mnemonic "fre 123" where the fulcrum is in the middle for the 1st class lever, the "r"esistance is in the middle for the 2nd class lever, and the effort is in the middle for the 3rd class lever. The lever is a movable bar that pivots on a fulcrum attached to
Lever tumbler lock move. Typically, the belly of the lever is cut away to various depths to provide different combinations, or the gate is cut in a different location, to provide differs. A lever will have "pockets" (or "gates") through which the bolt "stump" (or "post" or "fence") moves during unlocking. There has not always been universal agreement about which variants of the basic design merit the terms "lever lock" or "detainer lock" or both. Some authors use the term "detainer lock" to refer specifically to variants where the gates are "open" (i.e. at the edge of the lever), rather than "closed" (i.e.