The Model 956 Circuit Controller meets the rigorous demands of the rail industry – high sensitivity, reliability, and rugged strength to withstand great mechanical stress under a wide range of environmental conditions. The Model 956 consists of four sets of front-back contacts housed in a cast-aluminum cover. A mechanical linkage to the controller actuates the contacts. Thus, the controller may be used to integrate the positions of various devices with suitable control circuits. Commonly used with switches to detect switch positions, Model 956 controllers can also detect the positions of the derails, bridge locks, slide detectors, etc. They can shunt track circuits as well as control relay circuits.