Case story: Tandem motors

Heavy Duty Sensoric

INDUSTRY Steel and rolling mills

FIELD Hot and cold rolling mills

APPLICATION Tandem motors

Uninterrupted processes and the quality of the rolled steel are of huge significance in rolling mills. A crucial factor is the drive technology, with a variety of drive concepts in use across the industry. Motors are also used in tandem for coilers as well as reversing mills to be able to operate with lower or higher drive power according to the material to be rolled.


Only the rear motor of tandem drives has an 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. A special encoder that can be attached directly onto the shaft of the front motor without having to separate the tandem motors is the better solution.

Huebner solution:

To be able to mount an encoder where there is no shaft end available Johannes Huebner Giessen installed its bearing-free, MAG-G magnetic encoders. Consisting of half shells they can be retro-fitted to any point of a rotating shaft. The staggered design of the 2+2 half-shells ensure the construction is suitable for 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 existing solutions.


Magnetic encoder system MAG-G, consisting of


  • Pulse wheel with staggered half shells
  • Bearing-free design
  • IP 67 rated scanning head with encapsulated electronics


Customer benefits

High quality signals thanks to direct attachment


  • Requires no high-maintenance belt drive
  • Retrofit where no shaft end is available
  • Protection against shaft currents


Certified quality

TÜV PROFIZERT - Zertifikat DIN EN ISO 9001:2008

Known Consignor (LBA)


Hübner Foundation