Only the rear motor of tandem drives has a shaft end available to which an encoder can be attached. However, a speed signal is required from the front motor for synchronising purposes in tandem operations or as motor feedback data in single-motor operations (decoupled mode of operation). This is often generated via an encoder driven by a toothed belt, but typical disadvantages of this solution (tension, alignment, wear etc.) have a negative impact on the quality of the signal and lead to increased servicing costs. The better solution is a special encoder that can be attached directly to the shaft of the front motor without having to separate the tandem motors.
To be able to mount an encoder where there is no shaft end available Johannes Hübner Giessen installed its bearing-free, MAG-G magnetic encoders. Consisting of half shells they can be retrofitted at any point of a rotating shaft. The staggered design of the 2+2 half-shells ensures the construction is suitable for applications with high centrifugal forces and rapid reversing movements. Not only does the bearing-free version offer protection against shaft currents, it is wear free and also suitable for large shaft diameters. Thanks to its slim design width of just 30 mm the MAG-G system is easy to integrate in legacy solutions.