Pack and Pinion Rotary Actuators for power generation, power plants and presses



Rack and Pinion Rotary Actuators for highest demands on torque

The rack and pinion actuator is ideal for the highest demands on torque. It permits extensive swivelling where there is restricted building room in an axial direction. Additional options are as numerous as for the helical principle. The rack and pinion actuator requires considerably larger dimensions compared with the rotary vane motor to transfer two torques of equal size. This is created and transferred through a rack and pinion piston located diagonally to the propelling tappet developed with a pinion. The lateral forces arising from the teeth and affecting the back of the piston opposite are counterbalanced hydraulically or supported by rolling bearings depending on design. This rotary actuator is particularly suitable for high torque.

Actuators operating on this principle are used in cement factories, in the tyre industry, in power stations, in the steel industry and in rudder movement, for example.


The rack was originally a vertically mounted technical device with teeth, usually made of metal, to hang items in different heights. So seen in the kitchen, where the temperature in pots over open fires was regulated by changes in altitude on the rack.
As part of the progressive industrialization racks were used as machine elements. They are generally used to implement a rotary motion into linear motion or vice versa.

With rack actuators, the rack is a straight machine element with a number of uprisings, the teeth, in which a gearwheel interacts. This is how the tilting of a Bessemer converter is done by the help of a rack rotary actuator. The piston Hz (i.e. feed or procedure) of a rack rotary actuator is calculated according to the mean circumference of the ring gear of the drive gear and its speed n to Hz = π × d × n.

With the rack and pinion rotary actuators, the rotational axis of the gear is orthogonal to the displacement direction of the toothed rack.

Examples of movement transformations:

  • Generating a rotational movement by displacing the rack to a hydraulic cylinder
  • Generating a rectilinear motion by an electric motor


Our rotary actuators may be used throughout industry, e.g. in construction machines, machine tools, bending machines, mould carriers, foundry, mining, agricultural and packaging machines, transfer lines, handling technology, fittings, ship construction, automotive and ventilation technology, power station valves and many more. Rack and Pinion Rotary Actuators are used in Steel- and Power Production, in Power Stations, the Tyre Industry and Ship Building Industry.