Coupling,各种联轴器,英文版的

Shaft couplings will be used under the following conditions: 1. With shafts having collinear axis, that is, axis in the same straight line, rigid or flexible couplings of various form are used. 2. With shafts having intersecting axis, a Universal Coupling is employed. 3. With shafts whose axes are parallel and at a relatively small distance apart, the double slider crank principle of mechanism is used. A shaft coupling should have the following requirements: 1. It should be easy to connect or disconnect. 2. It should transmit the full power of the shaft. 3. it should hold the shafts in perfect alignment. 4. It should have no projecting parts.
This flexible-disk coupling contains at least one disk attached at its outside to one of the two rotary parts connected therewith and is splined adjacent its inside periphery to the other of said parts. The splines let the disk expand naturally under centrifugal stress, independently of said other part. They have preferably straight radical profiles, so that the increased expansion of the disk avoids backlash. The couplings may be used in pairs, as common-place, or also singly. The flexible disks are subjected to various stresses, of which the stress set up by centrifugal inertia is a major component. It is customary to rigidly weld the disks at their inner portion to one of the two parts connected by the coupling. The invention departs from this custom. It lets the disks expand naturally without being tied to the expansion of said one part. As this decreases the stress on the disks it enables them to carry increased load.
Metallic Disk coupling
Universal Flexible Couplings/ Hooke's Couplings
In cases where the angular or offset misalignment of the shaft reaches values which cannot be accommodated by flexible couplings, a different type, known as Hooke’s coupling or universal Flexible coupling can be applied to good advantage. It is named after Robert Hook , who developed the device. The universal coupling is used for two shafts whose center lines form a large angle , as 5 to 15 degrees, or even 30 degrees. The joint itself has no torsional flexibility nor can it accommodate any parallel misalignment. This coupling is widely used in agricultural machinery, machine tools and automobiles. It consists of two fork mounted on the shaft end, either with the help keys or screwed on the shaft ends. There is a center piece through which pass two pins whose axes are at right angles to each other.
Unprotected type flange coupling
Protected type flange coupling
Flexible Couplings
It is nearly impossible completely to eliminate all chance misalignment between the shafts of separately built machines, and such misalignment of shafts always leads to eventual failure of bearings or fatigue failure of shafts. The relative position of the connected shafts, inaccurate at the outset due to inevitable errors of manufacturing, is in course of time aggravated by deformations caused by the working load, temperature fluctuations, the uneven sinking of foundations or supports, etc. In such cases ineffective rigid couplings are replaced by flexible couplings. Therefore the purpose of a flexible coupling is to allow for imperfect alignment of two joining shafts, or to absorb impact from the fluctuation of torsional moment or of angular speed.(因此，一个弹性联轴器的目的是允许两个连接轴的不完美的对齐，或吸收扭矩或角速 度波动的冲击力。)These couplings are rigid under torsion, but, allow the correction of errors in the alignment of drive shafts. They are widely used in the fields of robotics or automatisms, because they are excellent for very accurate system piloting. They are also known as "precision couplings“.
Coupling
A coupling is termed as a device used to make permanent or semi-permanent connection where as a clutch permits rapid connection or disconnection at the will of the operator.
Shaft couplings are used in machinery for several purposes the most common of which are following:
1. To provide for the connection of shafts of units that are manufactured separately such as a motor and a generator, and to provide disconnection for repairs or alterations. 2. To provide for misalignment of the shafts or to introduce mechanical flexibility. 3. To reduce transmission shock loads from one shaft to another. 4. To introduce protection against overloads. 5. To alter the vibration characteristics of rotating units.