Technical information

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The torus gear is the first planar-spiral-gear used for industrial applications. One gear step consists of two gear wheels: the torus wheel and the crown wheel. On the planar side of the torus wheel is the spiral tooth. The minimal number of teeth is one. The crown wheel is on the outgoing side of the gear. The teeth on the lateral area are similar to the ones of a spur gear.



Function Torus


Function evolvent


The spiral tooth profile on the torus gear has, contrary to common planar spiral gears with a straight-line tooth profile, a circular form. The tooth follows the geometry of the partner wheel, called the curve wheel. The Torus gear is considered to be a real helical gear, as it has no rolling contact (the teeth have no rolling contact). Therefore, the profile shape of the tooth has no geometric limitations (involute form etc.). It can be freely defined and adapted to the individual application.


An in-house developed calculation module is applied for the configuration of a specified torus gear. This calculation module is based on normalized calculations for worm gears.  The geometry is mapped with latest 3D-CAD software and loads can be virtually simulated.




Samples can be tested on a test unit, developed in co-operation with the college of applied science Fribourg Switzerland. The test unit provides information about load collectives such as wear, rigidity, efficiency, transmission- and repetition accuracy.







The manufacturing of the gear teeth is based on the virtual CAD model. The geometry will be transferred to the high precision production machine by an in house developed postprocessor. Sophisticated software supervises the manufacturing process and the 5-axes tool compensation.
For customers intending to produce large quantities of the torus gear, have the possibility to acquire a license for manufacturing the parts in their own facility.