The 803-F312X Rotating Cam Limit Switch with a Double Shaft Extension is a heavy-duty circuit control device by Allen-Bradley used with machinery that has repetitive operation cycles and long-life and heavy-duty operations where shaft rotation correlates with machine motion. This device, like all Allen-Bradley Bulletin 803 cam switches, makes use of cam-actuated contacts mounted on a rotating shaft, and it is suitable for both steel forming and packaging/assembly operations. The 803-F312X has 3 snap action block contacts, 3 cam assemblies with adjustable lobes and valleys (higher and lower segments), a rotating shaft with a 150 RPM base shaft speed, and a spring-loaded cam-roller assembly. The 803-F312X has a higher cam segment (lobe), which activates the device circuit as it brushes with the cam-roller, and a lower cam segment (valley) which de-activates the circuit as it passes by the cam-roller, and the activation duration (dwell time), is determined by the lobe size.

The device has a 10A snap action contact with single pole/double throw (1 N.C., 1 N.O.) block contact with 12A/1.2A MAKE/BREAK ratings at a 600V Maximum AC contact rating, and when the lobe brushes over the cam-roller, the contact snaps, and the Normally-Closed (N.C.) contact opens and the Normally-Open (N.O.) contact closes. The 803-F312X has a timing (in angular degree) which is determined by the position of the shaft-mounted cam, relative to the position of the Keyway. The device, like all Style F devices, has a minimum and maximum cam duration of 12 degrees and 348 degrees, respectively. It has an external timing and dwell time adjustment, which can be set with a screwdriver while the machine is in motion, and the setting of the timing and the dwell time (both maximum and minimum) determine the machine’s operation. The 803-F312X comes with a double shaft extension, and it has a working temperature range of -30 to 66 degrees Celsius (-22 to 150 degrees Fahrenheit), and a storage temperature range of -30 to 93 degrees Celsius (-22 to 200 degrees Fahrenheit). It weighs around 5.4 kilograms (12 pounds), with dimensions of 446.1 millimeters x 82.6 millimeters x 177.8 millimeters (17.56 inches x 3.25 inches x 7.0 inches), and it has CE, CSA, and UL-certifications.