Mechanical overload safety

The trend in industry is to design and incorporate more automation into production processes. Machines are becoming more accurate, requiring a higher degree of precision. They are becoming faster, using servo and DC drive technology, and they are more rigid to withstand the dynamic loads necessary to increase capacity and productivity.
Machine downtime in an automated production environment is very costly. Broken components, expensive technicians, and long lead times for custom components can make the difference between operating profitably or not.
A linear motion overload safety system is a mechanism that cooperates with the coupler during force transferring. Once the maximum force setting is exceeded the coupler starts to slip which causes a change of the final position of the lever arms (crank and rocker). In the above figure a simple example of a linear overload safety is shown. The lever arm (crank) apply a force to a second one (rocker) by means of a rod end link (coupler). The link is secured on the lever arm with a slotted end part. The system link-slotted end through the slot it can move for a small distance (depends on slot dimensions). A tension spring constantly through a spring holder pulls the above system closer to the lever arm. The preload of the tension spring is adjustable from a movable spring holder. The lever arm pushes upwards the link without any slippage (end of slot). When the lever pulls down the link and something blocks the movement (jamming, damage) the spring extends under the large forces and the actual length of the increases. This increasing of length protects the machine from damage. This mechanism is ideal in situations where the movements are small or the jam can cause only small deviations on standard dimensions (small clearance passage, small product dimensions). There are many designs of overload safety systems but all have the same principle: Eliminate or reduce overloads.