The 803-F412RH Rotating Cam Limit Switch is a heavy-duty circuit control device by Allen Bradley that is used in repetitive machine operations where the shaft rotation corresponds to the machine’s motion. The 803-F412RH is specially designed for long-life and heavy-duty operations and it is suitable for assembling, packaging, and steel forming applications. The device has 4 snap action contact blocks (10A N.C., N.O.), a spring-loaded cam roller, a rotating shaft with 150 RPM maximum shaft rotation speed and an over-sized ball bearing, 4 cam assemblies, and a keyway for connecting the shaft to machines. The cam assemblies have 2 adjustable segments (lobe and valley), and the circuit activates when the lobe pushes against the cam-roller and it de-activates when the valley passes through the cam-roller. The 803-F412RH has a dwell time which corresponds to the size of the lobes, and the device can achieve maximum dwell time when the lobes of the cam segments offset at a maximum angle and the minimum dwell time is achieved when both lobes are aligned.

The 803-F412RH comes with a timing angular degree that is determined by the position of the cam on the shaft with reference to TDC and the machine control and operations are determined by the settings of both the dwell time and the timing of each circuit. The 803-F412RH and all Style F devices have external dwell time settings and timing settings that can be adjusted by using a screwdriver while the machine is in motion, and it also has a customized right-hand shaft extension. It has an operating temperature range of -30 to 66 degrees Celsius (-22 to 150 degrees Fahrenheit), with storage limits of -30 to 93 degrees Celsius (-22 to 200 degrees Fahrenheit), and it is enclosed in a water-tight, dust–tight, and oil-tight NEMA Type 13 rated enclosure. The 803-F412RH weighs approximately 5.4 kilograms (12 pounds), with a 446.1 millimeters x 82.6 millimeters x 177.8 millimeters (17.56 inches x 3.25 inches x 7.0 inches) shipping volume, and it is CE, UL, and CSA-certified.