Question

Different types of mechanisms and how they work

Answer 1

A mechanism is a device designed to transform input forces and movement into a desired set of output forces and the movement. Mechanisms generally consist of moving components such as gears and gear trains, belt and chain drives, cam and followermechanisms, and linkages as well as friction devices such as brakes and clutches, and structural components such as the frame, fasteners, bearings, springs, lubricants and seals, as well as a variety of specializedmachine elements such as splines, pins and determinate motion."[3] In this context, his use of machine is generally interpreted to mean mechanism.

The combination of force and movement defines power, and a mechanism is designed to manage power in order to achieve a desired set of forces and movement.

A mechanism is usually a piece of a larger process or mechanical system. Sometimes an entire machine may 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 MechanismsEdit

From the time of Archimedes through the Renaissance, mechanisms were considered to be constructed from simple machines, such as the lever, pulley, screw, wheel and axle, wedge and inclined plane.

Kinematic pairs, or joints, are considered to provide ideal constraints between two links, such as the constraint of a single point for pure rotation, or the constraint of a line for pure sliding, as well as pure rolling without slipping and point contact with slipping. A mechanism is modeled as an assembly of rigid links and kinematic pairs.

Kinematic pairsEdit

Reuleaux called the ideal connections between links kinematic pairs. He distinguished between higher pairs which were said to have line contact between the two links.

Lower pair: A lower pair is an ideal joint that has surface contact between the pair. A prismatic joint, or slider, requires that a line in the moving body remain co-linear with a line in the fixed body. A cylindrical joint requires that a line in the moving body remain co-linear with a line in the fixed body.

[5] Higher pairs: Generally, a higher pair is a constraint that requires a line or point contact between the elemental surfaces. For example, the contact between a cam and its follower is a higher pair called a cam joint. Similarly, the contact between the involute curves that form the meshing teeth of two gears are cam joints..

Planar mechanismEdit

A planar mechanism is a mechanical system that is constrained so the trajectories of points in all the bodies of the system lie on planes parallel to a ground plane. The rotational axes of hinged joints that connect the bodies in the system are perpendicular to this ground plane.

Spherical mechanismEdit

A spherical mechanism is a mechanical system in which the bodies move in a way that the trajectories of points in the system lie on concentric spheres. The rotational axes of hinged joints that connect the bodies in the system pass through the center of these circle .

Spatial mechanismEdit

A spatial mechanism is a mechanical system that has at least one body that moves in a way that its point trajectories are general space curves. The rotational axes of hinged joints that connect the bodies in the system form lines in space that do not intersect and have distinct common normals.

Gears mechanism
The transmission of rotation between contacting toothed wheels can be traced back to the Antikythera mechanism of Greece and the south-pointing chariot of China. Illustrations by the. A planetary gear train provides high gear reduction in a compact package.It is possible to design gear teeth for gears that are non-circular, yet still transmit torque smoothly.The speed ratios of chain and belt drivesare computed in the same way as gear ratios. See bicycle gearing.

Cam and follower mechanism
Cam follower Mechanism- Force is Applied From Follower To CamA cam and follower is formed by the direct contact of two specially shaped links. The shape benefit of this type of cam follower mechanism is that the follower moves a little bit and helps to rotate the cam 6 times more circumference length with 70% force.

LinkagesEdit

See also: Linkage
Theo Jansen's kinetic sculptureStrandbeest. A wind-driven walking machine.A linkage is a collection of links connected by joints. elements and the joints allow movement. Perhaps the single most useful example is the planar four-bar linkage. However, there are many more special linkages:

Flexure mechanismsEdit

A flexure mechanism consisted of a series of rigid bodies connected by compliant elements (flexure bearings also known as flexure