Torque Limiting—Safety Element Module

Construction
The Brunel Torque Limiting Module is constructed from the finest quality materials. Many of the vital components are made from high quality tool steels, through hardened to Rockwell C62, and precision ground to close tolerances.

Normal Operation
The flange connection is driven by a large steel ball (2), located in the detent pocket (1), which is retained by a plunger (3). This in turn is retained axially by means of a system of angled races (5,7) biased by pressure from the Belleville springs (4), acting on a circle of balls (6).

Disengagement
On overload, relative angular movement between the flanges imparts a tangential force (Fu) on the large steel ball, forcing it clear of the detent pocket back against the plunger. This in turn causes the plunger to be forced through the circle of balls overcoming the spring loading on the angle races. In this position, the balls are resting on the large diameter of the plunger, and once this condition is reached the flanges are completely free to rotate independently. A suitable switch can be incorporated in the assembly to switch off the drive motor or operate a warning device when the Torque Limiting assembly disengages. After first ensuring that the drive is isolated, resetting is a simple matter of first realigning the flanges and then tapping each module plunger back with a soft mallet to allow the circle of balls to return to their original position and the large steel ball to return to its location in the detent pocket. Detent Pockets Internally & externally adjusted modules can be through hole or blind hole detent fixing (See spec sheets). The type of detent fixing is dependant upon the design constraints. The mechanical clearance in the Module assembly should be eliminated by pre-loading the detent pocket (1) against the driving ball (2).
Detent Pockets
Internally & externally adjusted modules can be through hole or blind hole detent fixing (See spec sheets). The type of detent fixing is dependant upon the design constraints.
The mechanical clearance in the Module assembly should be eliminated by pre-loading the detent pocket (1) against the driving ball (2).
Selection
To apply the modules in the form of a torque limiter it is necessary to determine the quantity of modules needed for the required torque capacity at a specific radius from the axis of rotation.

No. of modules =

Torque (Nm) x 1000

Fu (N) x radius (mm) x K

K = 0.65 for General Applications.

Brunel Torque Limiting Modules have been specifically designed to provide overload protection for applications where very high torque’s are transmitted, and to extend the range covered by Brunel Type JAB units.

The modular system provides facilities for virtually unlimited torque capacity and lends itself to many transmission applications – chain, belt and gear drives, or shaft-to-shaft gear or flexible coupling drives.

The maximum release torque depends on the number and size of Torque Limiting Modules that can be incorporated, and the size of the unit that can be accommodated within the confines of the installation. Internally & Externally adjusted modules provide repeatability better than 5%, however Externally adjusted modules are preferred when the application is required to operate within minimal variations between static & dynamic disengagement.