An industrial clutch or a brake simply transmits torque in accordance with its geometry, apply force, and coefficient of friction. It can be difficult to comprehend how important this is to the drive train stress levels and clutch or brake heat loads unless the system mass effects are considered. The torque that can be transmitted by a clutch is a function of its geometry and the magnitude of the actuating force applied as well the condition of contact prevailing between the members. The applied force can keep the members together with a uniform pressure all over its contact area and the consequent analysis is based on uniform pressure condition.
Two basic types of clutch
The two basic types of clutch are the coil-spring clutch and the diaphragm-spring clutch. The difference between them is in the type of spring used. The coil spring clutch uses coil springs as pressure springs while the diaphragm-spring clutch uses a diaphragm spring. The coil-spring clutch has a series of coil springs set in a circle. At high rotational speeds, problems can arise with multi coil spring clutches owing to the effects of centrifugal forces both on the spring themselves and the lever of the release mechanism. These problems are obviated when diaphragm type springs are used, and a number of other advantages are also experienced.
An industrial clutch could also be a positive or friction clutch. With positive clutches, the engaging clutch surfaces interlock to produce a rigid joint that are suitable for situations requiring simple and rapid disconnection, although they must be connected while shafts are stationary and unloaded. The engaging surfaces are usually of jaw type. The jaws may be a square jaw type or spiral jaw type. They are designed empirically by considering the compressive strength of the material used. Friction industrial clutches work on the basis of the frictional forces developed between two or more surfaces in contact. Friction clutches are usually over the jaw clutches due to their better performance. There is a slip in a friction clutch but it also has its advantages. The friction surfaces can slip during the engagement which enables the system to pick up and accelerate the load with minimum shock. They can be used at high engagement speeds since they do not have jaw or teeth. Lastly, there is smoother engagement due to the gradual increase in normal force.