Multi-function electromagnetic tooth clutches
Precision machined teeth are the key to performance
Electromagnetic tooth clutches manufactured by Mönninghoff have at their heart precision-machined teeth that can be varied to achieve different performance and functions. Standard teeth are optimised for high torque transmission but many alternatives are possible, for example torque limiting, single position synchronising and single direction. Clutches and brakes can be manufactured with customised teeth to achieve application-specific performance. Product details and technical advice are available through Techdrives, www.techdrives.co.uk
Electromagnetic tooth clutches transmit torque without slip. Standard designs are engaged by application of a dc voltage, usually 24V. The transmitted torque and the permissible engagement speed depends on the design of the engagement teeth. The Ruhr-based specialist Mönninghoff use tooth rings where one is made from hardened bronze. This prevents magnetic flux passing through the teeth and improves the engagement and wear characteristics. Both stationary field and slip ring designs are available – the most popular and adaptable version has a bearing mounted stationary field coil and torque ratings from 20 to 2200 Nm. Engagement of the clutch is generally done at standstill or low speeds. This again depends on the tooth design and stiffness of the system.
Standard clutches use 200 to 300 small symmetrical teeth which are economical to manufacture and give easy engagement. By adjusting the tooth angle to make them more shallow, clutches can be prepared to release at a pre-defined torque. As the teeth are thrown apart under torque load, such clutches can be used as torque limiters that are very fast acting and therefore sensitive.
The tooth pattern can be made asymmetrical so that the relationship between input and output is synchronised. This allows one engagement position per revolution, and further variants can engage at 2, 4 or more positions. Changing from standard to saw shaped teeth allows higher engagement speeds but in a single direction – torque transmission in the reverse direction is minimal.
Mönninghoff tooth clutches and brakes find varied application in areas such as printing, bookbinding, barrier doors and test machinery. Beyond the tooth form, other options include clutch couplings, spring applied clutches, pneumatic actuation and zero backlash models. Technical advice is available through Techdrives.