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 flanges X and Y are 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 6,8 biased by pressure from the Belleville springs 5, acting on a circle of balls 7.

Disengagement

On overload, relative angular movement between flanges X and Y 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. Resetting is a simple matter of first re-aligning the flanges X and Y 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 have through hole or blind hole detents (see diagrams left and on page 16). The type of detents is dependent upon the design constraints.

All modules are required to be preloaded. In the case of the through hole module this is done by tightening the set screw at the base of the detent pocket. In the case of the blind hole module this is done by the means of shims under the module.

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.