A mechanism is a device designed to transform input and motion forces into a desired set of output forces and motion. Mechanisms generally consist of moving components such as gears and gear trains, belt and chain drives, cam mechanisms and followers, and couplings, as well as friction devices such as brakes and clutches, and structural components such as frame, fasteners, Bearings, springs, lubricants and seals, as well as a variety of specialised machine elements such as stretch marks, nails and nails. The German scientist Tableaux provides the definition of "a machine is a combination of resistant bodies arranged in such a way that by their means the mechanical forces of nature can be forced to do the work accompanied by a certain movement." In this context, their use of the machine is generally interpreted as a mechanism. The combination of strength and motion defines power, and a mechanism is designed to handle the power to achieve a desired set of forces and motion. A mechanism is usually a part of a larger mechanical process or system. Sometimes an entire machine can be referred to as a mechanism. Examples are the steering mechanism in a car, or the winding mechanism of a wristwatch. Multiple mechanisms are machines.
Types of Mechanisms
From the time of Archimedes to the Renaissance, mechanisms constructed from simple machines, such as the lever, the pulley, the screw, the wheel and the shaft, the wedge and the inclined plane were considered. It was Reuleaux who focused on the bodies, called links, and the connections between these bodies called kinematic pairs or joints.
To use geometry to study the motion of a mechanism, its links are modeled as rigid bodies. This means that the distances between points on a link are assumed to not change as the mechanism moves, that is, the link does not flex. Therefore, the relative motion between points on two connected links is considered to be the result of the kinematic pair joining them.
Kinematic pairs or joints are considered to provide ideal constraints between two links, such as single point constraint for pure rotation, or restriction of a line for pure slip, as well as pure rolling without slip and contact Punctual with the slip. A mechanism is modeled as a set of rigid bonds and kinematic pairs. Kinematic pairs
Reuleaux calls the ideal connections between the kinematic pair of links. He distinguished between the upper pairs being said to have line contact between the two links and lower pairs having area contact between the links. J. Phillips [4] shows that there are many ways to build pairs that do not fit into this simple. Planar mechanism
A plane mechanism is a mechanical system that is limited so that the point paths in all bodies of the system lie in planes parallel to a plane of earth. The axes of rotation of the articulated articulations that connect the bodies in the system are perpendicular to this plane of earth. Spherical mechanism
A spherical mechanism is a mechanical system in which the bodies move in such a way that the trajectories of points in the system are in concentric spheres. The axes of rotation of the articulated joints that connect the bodies in the system pass through the center of these circles. Space Mechanism
A spatial mechanism is a mechanical system that has at least one body moving in such a way that its point paths are general spatial curves. The axes of rotation of the articulated articulations that connect the bodies in the system form lines in the space that do not intersect and have different common norms. Gears and gear trains
The transmission of rotation between cogwheels in contact can be traced back to the Antikythera mechanism of Greece and the Chinese wagon pointing south. Illustrations by Renaissance scientist Georgius Agricola show gear trains with cylindrical teeth. The implementation of the involution tooth produced a standard gear design that provides a constant speed ratio. Some important features of gears and gear trains are:
• The ratio of the matching gear pitch circles defines the speed ratio and the mechanical advantage of the gear set.
• A planetary gear train provides high gear reduction in a compact package.
• It is possible to design gear teeth for gears that are not circular, but transmit the torque smoothly.
• Chain and belt drive speed ratios are calculated in the same way as gear ratios. See the bicycle gear. Cam mechanisms and followers
A cam and follower is formed by the direct contact of two specially shaped links. The transmission link is called cam (see also the cam shaft) and the link that is actuated through the direct contact of its surfaces is called follower. The shape of the cam contact surfaces and the follower determine the movement of the mechanism. In general, the energy of a cam follower mechanism is transferred from the cam to the follower. The camshaft is rotated and, in accordance with the cam profile, the follower moves up and down. Slightly different types of cam eccentrics are now also available, in which energy is transferred from the follower to the cam. The main benefit of this type of cam follower mechanism is that the follower moves a bit and helps to rotate the cam 6 times longer length of the circumference with a 70% force. Linkages
A Linkage is a collection of links connected by joints. Generally, the links are the structural elements and the joints allow movement. Perhaps the most useful example is the four-bar planar link. However, there are many more special links:
• The Watt link is a four-bar link that generates an approximate straight line. It was critical for the performance of its design for the steam engine. This link also appears on the vehicle suspensions to prevent side-to-side movement of the body relative to the wheels. See also Parallel Movement.
• The successful linking of Watt leads to the design of approximate similar links in a straight line, such as the Hoeken link and the Chebyshev link.
• The Peaucellier joint generates a true straight line from a rotating entry.
• The Sarrus link is a spatial link that generates straight-line motion from a rotating input.
• Klann's link and Jansen link are recent inventions that provide interesting walking moves. They are respectively a link of six bars and one of eight bars. Mechanisms of flexion
A bending mechanism consisted of a series of rigid bodies connected by conforming elements (bending bearings also known as bending joints) which is designed to produce a geometrically well defined movement upon application of a force.