Series 51 geared cam limit switches are universal mechanical switching devices that have been designed for use in conjunction with cam discs based on a specific angle of rotation for indication of a large number of shaft revolutions.  These cam discs serve to operate mechanical contacts. 

Geared cam limit switches are used wherever specific ranges of travel cannot be directly limited by switchgears but only indirectly via measurements of the angle of rotation.  A classic example of such an application is limitation of the hook travel of crane hoisting gear.

The use of geared cam limit switches is the most efficient alternative especially where there is a danger to person or property and the use of positive opening switching contacts is required according to VDE 0660 T200, EN 60947 T5-1, IEC 947-5-1.

The particular advantages of 51 series geared cam limit switches are as follows:

• Patented planetary gearing
• Low friction planetary gearing with irreversible, self-locking worm adjustment of the cam discs.
• Fixed cam adjustment in housing: The adjusting worms of the cam discs are arranged so that they can be accessed from the same direction as the contact connections for optimal accessibility in confined conditions.  Adjustment is possible during operation. The simplicity and accuracy of the cam adjustment is unparalleled.
• Modular design: The consistent use of the same components for the gearing and housing guarantees economical and flexible manufacture and assembly.
• Patented block adjustment: The adjustment of all switching contacts jointly is made possible by a single adjusting worm (black) without the switching points of the individual switching contacts being altered with respect to each other.
• Large cam disc diameter: This means good adjustability and high switching point repeat accuracy.