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English: Within the human body there are 3 types of levers. The first class lever which can be seen, is located in the head. The second class lever is located within the leg. Finally, the third class lever is located in the arm.
An example of a simple open chain is a serial robot manipulator. These robotic systems are constructed from a series of links connected by six one degree-of-freedom revolute or prismatic joints, so the system has six degrees of freedom. An example of a simple closed chain is the RSSR (revolute-spherical-spherical-revolute) spatial four-bar linkage.
The lever is operated by applying an input force F A at a point A located by the coordinate vector r A on the bar. The lever then exerts an output force F B at the point B located by r B. The rotation of the lever about the fulcrum P is defined by the rotation angle θ in radians. Archimedes lever, Engraving from Mechanics Magazine, published ...
A common example is the traditional sash window lock, where the cam is mounted to the top of the lower sash, and the follower is the hook on the upper sash. In this application, the cam is used to provide a mechanical advantage in forcing the window shut, and also provides a self-locking action, like some worm gears , due to friction.
The different types of levers in the human body. These levers consisting of First Class Lever, Second Class Lever, and a Third Class Lever. The list below describes such skeletal movements as normally are possible in particular joints of the human body.
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:
For example, a bench vise consists of a lever (the vise's handle) in series with a screw, and a simple gear train consists of a number of gears (wheels and axles) connected in series. The mechanical advantage of a compound machine is the ratio of the output force exerted by the last machine in the series divided by the input force applied to ...
Examples of rope and pulley systems illustrating mechanical advantage. Consider lifting a weight with rope and pulleys. A rope looped through a pulley attached to a fixed spot, e.g. a barn roof rafter, and attached to the weight is called a single pulley. It has a mechanical advantage (MA) = 1 (assuming frictionless bearings in the pulley ...