How Torque Limiters Work
Share & Bookmark
R+W torque limiting couplings are ball detent style overload couplings. They protect drive and driven mechanical components from damage associated with torque overloads.
- backlash-free torque transmission is accomplished by a series of steel balls (4) nested in hardened detents (5).
- Disc springs push against an actuation ring (3) keeping the balls nested.
- The disengagement torque is adjustable by means of an adjustment nut (1).
- In the event of an overload, the actuation ring (3) moves axially allowing the balls to come of the detents separating the drive and driven elements.
- The movement of the actuation ring (3) can be sensed by means of a mechanical switch or proximity sensor (6) triggering the drive to shut down.
Torque Limiter: Single-position / Multi-position
In a torque overload, for the single-position design (standard) and multi-position design, the spring disengages to allow the balls to come out of their detents separating the drive and driven elements. Very low residual spring pressure remains so that the copling will re-engage once the torque is reduced below the overload setting.
At the load holding version the drive and driven elements are only allowed limited rotation in order to achieve a movement of the actuation ring. Re-engagement may only be effected at low speed.
Torque Limiter: Full-disengage
With this design, when a torque overload is detected, the disc spring completely flips over and places no residual spring pressure on the actuation ring. The drive and driven elements are completely separated.
Re-engagement of the coupling is not automatic and must be performed manually (Picture 3a, 3b).
The R+W full-disengage torque limiting coupling can be re-engaged in six different positions or every 60 degrees with low „press-in” force (E). Marks on the actuation ring and body (13) of the coupling must line up and indicate the re-engagement points.
As of size 150 and up the re-engagement can be done with 2 lever which will be supported at a recess on the adjustment nut (picture 3b). Screwdrivers can be used as a lever.
Max. misalignment of Torque Limiters
Angular misalignment Δ Kw - Axial misalignment Δ Ka - Lateral misalignment Δ Kr
Exact alignment of the R+W Torque Limiter considerably increases the service life of the metal Bellows.
Reducing or eliminating lateral misalignment eliminates the radial loading of the adjacent bearings, increasing service life and reducing heat.
For drives running at high speed it is recommended to align the coupling with a dial indicator.
Max. misalignment values see data table. Axial misalignment between 1-2 mm.