The compact size in combination with the highly precise production geometry of the integrated sprags result in outstanding performance characteristics.

Clamping angle and clamping curve

The contact surfaces on the clamping curves close in linear contact to a defined clamping angle α with the rotationally symmetric connecting parts.

The functional criteria of a sprag type freewheel clutch must be met along the clamping curve:

μ > tan α

μ = static friction coefficient
α = clamping angle

If the tangent of the clamping angle is smaller than the coefficient of static friction µ, the sprags will be in static friction contact with the connecting parts when a load is applied.

Clamping angle 


bearing steel 100 Cr6 (material number: 1.3505)
Hardness: HRC = 60+4 (HV = 700+100)

Connecting parts:

The geometry of the clamping curve is designed for connecting parts made of steel – raceways in other materials are not permissible.

Sprags series 400

The small sprag size permits high sprags density and thus maximum performance in a minimum of space. The low inertia of sprags also makes it possible to achieve extremely high indexing frequencies of up to 60 Hz. 

  • Height (radial) in idle position: 4 mm
  • Widths: 5 / 8 mm (for tension spring), 8 mm (for meander spring)
  • Clamping curve geometry: logarithmic spiral
  • Clamping angle: constant
  • Sprag characteristic: lift off inner ring at high speed
Series 400 with height 4 mm 

Sprags series 8000

To achieve maximum torque capacity with the larger sprags series 8000, the profile was adjusted with a slightly higher clamping angle. Due to the center of gravity’s position the design is not lifting off and provides indexing reliability even in high speed applications.

  • Height (radial) in idle position: 8.33 mm
  • Widths: 13 / 16 / 22 mm (for tension spring)
  • Clamping curve geometry: compound circles
  • Clamping angle: increasing
  • Sprag characteristic: press towards inner ring at high speed 
Series 8000 with height 8.33 mm