Roller gearing

The principle question in the development of roller gear was whether a connection based on clear rolling, closing with shape can be realized between bodies of revolution, through mediation of rolling bodies.

Article (HU): Preliminary ideas and the base principle of roller gear

The base condition of geometrical scaling is clean rolling: the rolling element is driven along a scalar track between the gearing elements to be connected. The arcs taken by rolling elements in a given time located in roller tracks in the connected groove pairs are equal and the tangent plane pairs placed in the point of contact are parallel at each moment.

Besides taking into consideration the condition of clean rolling, input parameters (like distance of axes, angle of axes, transmission, dimensions of the rolling element, relative rotational directions, a point of the track of rolling element moving between the gearing element and the geared element, the direction of charge transmission) define the geometry of gearing elements and their grooves.

Operation principle
In roller gear, rolling elements move along a well-defined track (connection track) between the gearing body and the geared body, while rolling in their grooves. The rolling elements exiting the connection are driven back into the beginning of the connection track, where they re-enter between the gearing element and the geared element.

Video on operation: Operation of roller gearing

Article (HU): Operation principle of roller gearing

Design possibilities
With the help of roller gearing, all types of axis arrangements can be realized: parallel, skew, intersecting, therefore the axes can be parallel, skew or intersecting, layouts can be used with internal teething or external teething or rack gearing with wheel of axis parallel to the plane of the rack or having an angle with the plane of the rack. Thus, the design engineer obtains large design liberty in case of selecting roller gear during the design. On one side, the main benefit of this gear is that its efficiency is independent from the arrangement of axes. In addition, the facts that the dimension proportion of the gearing body and the geared body is independent from the transmission and the relative rotational direction can be selected freely also conribute to flexible designability of the solution.


  • No risk or seizure
  • The efficiency is independent from the arrangement of axes
  • In case of larger transmissions, the roller gear can be even by 45% smaller than traditional angle gears of the same chargeability, due to the fact that the dimension scale of wheels can be selected within broad limits.
  • The dimension scale between the gearing body and the geared body is independent from the transmission
  • The relative rotational direction can be selected freely without any intermediate wheels, as a parameter added to calculations
  • As a consequence of the advantages listed above, the deisng engineer has a large design liberty
  • Due to high static efficiency (low static friction) the initial torque is very low
  • The number of teeth being connected simultaneously may exceed 20.
  • Due to large number of connections, the mean of errors approach zero, thus the gear becomes precise.
  • The elimination of backslash can be performed easily, through flexible tightening similar to the relation between then ball screw and the nut.
  • The gear is not sensitive to lubrication or temperature

Article (HU): The advantages of roller gearing


Application areas

Due to several advantages of roller gear, like its cold tolerance and its insensitivity to lubrication, it can be applied in aviation, in space travel and in vaccum technique excellently. Furthermore, applications in the pharmaceutical and food industries also emerge where the products must not be polluted by any foreign materials (i.e. lubricants).

Article (HU): Possible application areas of roller gear

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