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A lever is a simple machine consisting of a beam or rigid rod pivoted at a fixed hinge, or fulcrum. A lever is a rigid body capable of rotating on a point on itself. On the basis of the locations of fulcrum, load and effort, the lever is divided into three types. It is one of the six simple machines identified by Renaissance scientists.
Wheel and axle motion (e.g. screwdrivers, doorknobs): A wheel is essentially a lever with one arm the distance between the axle and the outer point of the wheel, and the other the radius of the axle. Typically this is a fairly large difference, leading to a proportionately large mechanical advantage.
The lever is a movable bar that pivots on a fulcrum attached to or positioned on or across a fixed point. The lever operates by applying forces at different distances from the fulcrum, or pivot. The location of the fulcrum determines a lever's class. Where a lever rotates continuously, it functions as a rotary second-class lever.
The idea of a simple machine originated with the Greek philosopher Archimedes around the 3rd century BC, who studied the Archimedean simple machines: lever, pulley, and screw. [2] [13] He discovered the principle of mechanical advantage in the lever. [14]
The toggle-link action used in the iconic Winchester Model 1873 rifle, one of the most famous lever-action firearms. A lever action is a type of action for repeating firearms that uses a manually operated cocking handle located around the trigger guard area (often incorporating it) that pivots forward to move the bolt via internal linkages, which will feed and extract cartridges into and out ...
Crank and slotted lever Quick Return mechanism (used in shapers) Fixed piston mechanism (used in hand pumps) Two revolute joints and two prismatic joints: It is denoted as PRRP, [2] and is constructed by connected two sliders with a coupler link. The doubler slider refers to all arrangements in this type. Examples of 2R2P linkages include:
The force on a screw is not usually applied at the rim as assumed above. It is often applied by some form of lever; for example a bolt is turned by a wrench whose handle functions as a lever. The mechanical advantage in this case can be calculated by using the length of the lever arm for r in the above equation.
A lever arm uses the fulcrum to lift the load using and intensifying an applied force.In practice, conditions may prevent the use of a single lever to accomplish the desired result, [1] e.g., a restricted space, the inconvenient location of the point of delivery of the resultant force, or the prohibitive length of the lever arm needed.