Design Principles

At Clark Electric Clutch, Clutches and Brakes of our own manufacture are friction devices with torque being transmitted across steel “pole faces”. These faces are brought together under electro-magnetic force by applying a 24 Volt to the Clutch or Brake coil. Sandwiched between these faces is an asbestos-free friction ring. Very little torque is actually transmitted via this ring, it is there purely to limit the wear on the actual pole faces.

It is a misconception that as the metal pole faces are touching, the Clutch (or Brake) is worn out. Any machining of the pole faces to prevent contact, will introduce an air gap between them and effectively greatly reduce the amount of torque that the Clutch will transmit. This principle applies equally to the Brake. It is for this reason that a friction ring, inner rotor (Clutch), brake fixed pole (Brake) or drive ring only cannot be fitted when servicing or repair work is carried out.

Although metal pole faces are used, our Clutches & Brakes are designed for continuous slipping, such as found in tension control applications but, under controlled conditions and within specific parameters. Although heat will be generated during this process, each model of Clutch & Brake has a heat dissipation value, which, is used in calculations to determine its suitability for a particular tension control application. Please consult with Clark Electric Clutch for your tension control applications.

Selection Table*

Selection table

* Please note this table should only be used as a guide line. For more information and confirmation of your choice please contact Clark Electric Clutch.

Useful Formulae & Conversion

To pick up load:
Nm. x 0.737 = lbf ft
lbf ft. x 1.36 = Nm.
Kgm. x 9.81 = Nm.
Kw. x 1.34 = HP;
To bring to rest:
J = moment of inertia (kgm)
n=rpm & t=time (secs.)