Билет 10 friction clutches

The object of a friction clutch is to connect a stationary machine part to a rotating part, to bring it up to speed, and to transmit the required power with a minimum of slippage. In certain cases a friction clutch serves as a safety device by slipping when the torque transmitted through it exceeds a safe value, thus preventing the breakage of parts in the transmission train.

Friction clutches may be divided into two main groups, according to the direction of the acting force: axial clutches and radial or rim clutches.

Axial clutches which have the contact pressure applied in a direction parallel to the axis of rotation. Axial clutches, in turn, can be subdivided into: cone clutches, disk clutches, and combined cone and disk clutches.

In rim clutches the contact pressure is applied upon a rim in a radial direction. These clutches, like brakes, may be subdivided into band clutches and block clutches, also into external, internal, and combined internal-and-external clutches.

Magnetic clutches are usually of the disk type.

A friction clutch used to connect two shafts is often termed a clutch coupling or friction coupling.

The factors which must be taken into consideration in deciding what type of clutch is to be used are: torque, rotative speed, available space, and frequency of operation.