The 803-P12 Rotating Cam Limit Switch is a heavy-duty circuit control switch by Allen-Bradley that is used with machinery with repetitive operation cycles in a long-life application where the motion directly correlates with shaft rotation. It uses a shaft-mounted cam for operation and when the shaft rotates the cam mechanically actuates the contacts. The device has 12 circuits with cam-opened double block contacts and a rotating shaft with oversized ball bearings and a 400 RPM base speed. The 803-P12 also has a cam-roller assembly that is mounted on the base contact, with 12 independently-operated cam assemblies that have adjustable lobes and valleys, and when the shaft rotates, the lobes activate the circuits as the shaft pushes against the cam-roller. The circuit is de-activated when the valley passes by the cam-roller assembly, and the total duration of the activation (dwell time) is determined by the size of the lobes, and it has its maximum value when the lobes are angularly offset, and it has its minimum value when the lobes perfectly align.

The 803-P12 has a set activation timing which is measured in degrees, which is determined by the position of the cam with respect to the keyway (slot in the shaft)/TDC, and like all Style P devices, it has a minimum and a maximum cam duration of 11 and 349 degrees, respectively. The device has a high-speed internally-adjusted dwell and timing, which determines the machine’s control settings, and it has a standard right shaft extension. The device has a factory-rated operating temperature range of -30 to 66 degrees Celsius (-22 to 150 degrees Fahrenheit), with a non-operating range of -30 to 93 degrees Celsius (-22 to 200 degrees Fahrenheit), and it comes in an indoor-rated NEMA Type 1 enclosure. The 803-P12 weighs approximately 19.1 kilograms (42 pounds) with a shipping volume of 483.3 x 181 x 138.1 millimeters (19.04 x 7.12 x 5.44 inches), and with CE, CSA, and UL certifications.