Deutsch     English (UK)

The planar spiral gearbox

TorusGear Planar spiral gearboxHighest possible quality and precision, limited weight, simple construction and minimal space requirement makes the TorusGear highly efficient.

With the TorusGear a new and unique gearbox was developed and patented. This new and unique gearbox has excellent characteristics compared to existing gearboxes.

One gear step is the Torus wheel with spiral shaped tooth and the curve wheel with the curved tooth shape. The contact surface and the load on the material can be substantially reduced with the novel gearing module.

The TorusGear is the first „Planar-Spiral Gear“ which is technically mature to be used for industrial applications.


The technical superiority of the TorusGear compared to conventional gearboxes can be described as follows:
The load is spread over a large contact surface and meshes with several teeth. Almost double the torque can be applied, compared to conventional worm gearboxes of the same size! The compact design and the excellent efficiency make it possible to obtain high gear ratios in only one step.

getriebe torus kraft
Load distribution TorusGear
getriebe normal kraft
Load distribution evolvent
The efficiency remains, irrespective of the gear ratio, almost constant. This means that the TorusGear reaches at high gear ratios, above 100:1, a substantial higher efficiency, compared to the worm gear, where the efficiency factor reduces with increasing gear ratios.

wirkunsgrad torusGear
plus High Gear Ratios
With worm gearboxes, high ratios can only be realised with multiple gear stages or motors with low speeds (750 rpm or 1000 rpm), or a combination of the two options. Additional gearbox stages have a negative influence on the level of efficiency, and require more components, the immediate results of which are lower efficiency and higher costs. The same applies to the option of motors with lower speeds. Electric motors with speeds of 750 rpm or 1000 rpm are respectively approx. 250% and 160% heavier, and cost almost 99% and 33%, respectively, more than an electric motor with a speed of 1500 rpm. At an input speed of 750 rpm and a ratio of 200:1, a worm gearbox achieves the same output speed as a TorusGear with an input of 1500 rpm and a ratio of 400:1.
The TorusGear can be down sized where a higher torque is not needed. Wight and space of the gearbox can be reduced.
The unique design of the TorusGear simplifies the adjustment or elimination of backlash. A built in spring preload eliminates backlash for life time.
plusQuiet running
Noise emissions can almost be removed by eliminating backlash and optimizing the design of the tooth shape. The teeth do not roll on each other, they slide.
plusHigh Operational Reliability
The low number of moving parts increases the operational reliability. Safety related functions can be maintained after a tooth break, as several teeth are meshing at the same time on the TorusGear.
plusEasy Assembly
The simple and very compact gear unit design consisting of only the torus wheel, the curve wheel and the housing allow an easy and short assembly process.

You have any questions?

We will be glad to help you.


Nidec Graessner GmbH & Co. KG
Kuchenaecker 11
72135 Dettenhausen
   +49 7157 123 0
  +49 7157 123 212

Agencies Germany

de  Contact persons

Nidec Graessner worldwide

Our network of experts overseas

graessner weltweit