The Challenge range of Shaft Mounted Speed Reducers (SMSRs) stands tall amongst the crowd.

Packed full of attention to detail, the Challenge SMSRs deliver performance in the harshest of applications.

Shaft mounted drives remove the need for couplings, mounting plinths and have infinitely variable ratios due to the belt drive. They are also incredibly simple to fit and can be mounted in any position as no motor base is required.

Challenge manufactures two versions; the metric based SMSR and the imperial (inch) based TXT.


  • Available in sizes B to L
  • Grip-Loc hubs available for simple installation and removal
  • Includes complete torque arm assembly
  • Interchangeable with most other manufacturers
  • Production line manufacturing guarantees tolerances and consistent quality.
  • Gears produced on German manufactured hobbing centres to achieve the highest quality helical gear components.
  • Pinions; 8620 steel
  • Gears; 20MnCr5 steel
  • All gears are ground
  • Final heat treatment includes gas carburising to a depth of 1mm, then grinding to DIN class 6.
  • Castings crack tested
  • All units test run prior to final quality control checks
  • Full traceability guaranteed with unique Challenge serial number.
  • Backstops also available to prevent reversing
  • Drive ratios exceed 150:1 with a belt drive
  • Double lipped oil seals used throughout
  • Standard ball and cylindrical roller bearings used – in stock around the world


Challenge TXT range of Shaft Mount Reducers are inch in design for America and other inch dimension countries and have power ratings to ISO standards.

  • Eight gear case sizes, from size 2 to size 9
  • Maximum power up to 150hp,
  • Nominal gear ratios are 15:1 and 25:1.
  • A wide choice of final driven speeds can be determined by the use of an appropriate input belt drive.
  • Twin Tapered Output Hub for ‘easy-on, easy-off’ fitting 2. Precision High Quality Gearing
  • Computer designed helical gears, strong alloy materials for high load capacity, case carburized for long life, ground profile, crown tooth profile, in conformance with ISO 1328-1997. 98% efficiency per stage, smooth quiet operation with several teeth in mesh.
  • Housing from close grain cast iron construction. Excellent vibration dampening and shock resistance features. Precision bored and dowelled to ensure accurate in-line assembly.
  • Backstops: anti-run back devices are available for all sizes
  • Strong alloy steel shafts, hardened with ground on journals, gear seatings and extensions, for maximum load and maximum torsional loads. Generous size shaft keys for shock loading.

Torque Arm Assembly included for easy adjustment of the belt.