The 803-B84 Rotating Cam Limit Switch by Allen-Bradley is a heavy-duty circuit control device in the Style B line that is used with machines that have dedicated operation cycles, and it is also used in heavy-duty, and long-life operations, where machine motion is correlated to shaft rotation. It makes use of a shaft-mounted cam with a switch that can rotate in both directions and on any plane, and the cam actuates contact as the shaft rotates. The 803-B84 has 8 snap action contacts with Normally Open and Normally Closed (NC and NO) contact, and with 12A/1.2A MAKE/BREAK contact ratings at 600 Volts AC maximum voltage and a 10A carrying current. It also has a 150 RPM rotating shaft speed with over-sized ball bearings, and a spring-loaded cam roller. The 803-B84 comes with 8-cam independently-operated assemblies with adjustable segments and a keyway (shaft slot) which connects the rotating shaft to move machines. The circuit is activated when the cam roller brushes against the lobe (higher cam segment), and the duration of the circuit activation (dwell time) is determined by the size of the lobes, and it is at the maximum duration when the adjacent lobes offset at a maximum angle, and at the minimum when both lobes exactly align.

The circuit de-activates as the valley (lower cam segment) passes by the cam roller, and it has a timing measured in degree, which is determined by the position of the position of the cam with reference to the keyway. The 803-B84 has a cam duration range of 14 degrees to 346 degrees, and it has as standard left shaft extension. It has an internal cam dwell and timing adjustment, which is done with the machine stopped, and both settings and adjustments determine machine control and operations. The 803-B84 has a NEMA Type 4, 13 oil-tight and dirt-tight enclosure, and a working temperature range of -30-66 degrees Celsius (-22 to 150 degrees Fahrenheit), with a non-operating/storage range -30 to 93 degrees Celsius (-22 to 200 degrees Fahrenheit). The device has a total shipping volume of 311.2 millimeters 144.5 millimeters x 200 millimeters (12.25 x 5.69 x 7.88 inches), with a net weight of 16.3 kilograms (36 pounds), and it is CE, CSA, and UL-certified.