Mechanical clutches still outperform electronics

Although electronic overload devices may have improved, Mayer reckons that only mechanical torque-limiting clutches can provide extremely rapid and reliable overload protection.

Long-term experience in the application of torque-limiting clutches in machine tools, packaging machines, extruders etc, by Mayr Antriebstechnik suggests that even with the current responsive electronic motor controls available, only Mayr backlash-free mechanical torque-limiting clutches are able to offer extremely rapid and reliable overload protection.

Electronic overload devices used to be slow compared to mechanical torque-limiting systems.

With substantial improvements in servomotors and controls this gap has been reduced, with the motors and controls now available being more responsive and dynamic.

Some machinery manufacturers may argue that with today's control technology it is no longer necessary to use mechanical torque limiters to protect a machine against the costly damage and downtime caused by jams or collisions.

In order to evaluate this situation Mayr Antriebstechnik has undertaken research on the stopping times of various types of drive under overload or collision condition.

When applied to an actual collision test on a machine, the maximum motor torque is applied after 15-20ms, and the fastest motor would take approximately 30ms to come to a complete stop.

A Mayr EAS backlash-free torque-limiting clutch in a similar situation reacts in 3ms, disconnecting the driver and driven components, thus minimising any damage due to an overload or collision.

It is not normally possible for an electronic device to improve on the instantaneous Mayr EAS backlash-free principle The Mayr EAS backlash-free principle uses springs with special negative rate characteristics together with a unique torque transmission system of a balls interfacing two indents rather than the conventional splined system where fretting occurs.

This keeps preset torque within an acceptable setting tolerance and ensures that even under highly dynamic drive conditions, the clutch will always disengage in an overload situation.

Three basic types of EAS backlash-free torque-limiting clutch are available: ratcheting (multiposition) autoreset, synchronous (single-position 360 degrees) autoreset, and complete disengage manual (external) reset.

EAS backlash-free clutches cover the torque range 0.65-2800Nm.

This comprehensive range includes various hub/shaft fixing methods together with a wide variety of shaft couplings, either backlash-free or flexible elastomeric types.

Back to top