The 803-B8 Style B Rotating Cam Limit Switch is a circuit control device with a standard left shaft extension and internal timing and dwell adjustments that are designed by Allen-Bradley and used with heavy-duty machinery with dedicated operational cycles in applications where the machine motion corresponds to shaft rotation. The device has an adjustable cam mounted on a rotating shaft which produces actuation as the shaft rotates, and this device is built for long-lived industrial applications. It has 8 heavy-duty control circuits with 10A snap action (1 Normally Closed and 1 Normally Open) contacts, and 8 independent cam assemblies with variable cam segments. The 803-B8 has a rotating shaft with a 150 RPM base shaft speed on which the rotating cam is mounted, and it has a spring-loaded cam roller assembly mounted on a contact base. The shaft connects to machine parts via a keyway (shaft slot), and when the shaft rotates, the cam lobes (adjustable upper cam segments) activate the circuit as they brush against the cam roller.

The 803-B8’s circuit de-activates when the cam valley (lower cam segment) pass the cam roller, and the cam activation duration (dwell time) which is determined by the length of the cam lobes is at the maximum value when the cam lobes offset, and it is at the minimum when they align. It has a timing (when cam activates circuit) determined by the position of the shaft-mounted cam, with reference to the keyway position and it has internal adjustments for both timing and dwell time. The 803-B8 is a Style B device with the standard left shaft extension and an indoor NEMA Type 1 rated enclosure. It has functional temperature limits of -30 to 66 degrees Celsius (-22 to 150 degrees Fahrenheit) without impeding the contact performance, and it is stored at a range of -30 to 93 degrees Celsius (-22 to 200 degrees Fahrenheit). The device weighs approximately 16.3 kilograms (36 pounds), and it is shipped with aggregate dimensions of 311.2 x 144.5 x 200 millimeters (12.25 x 5.69 x 7.88 inches).