The 803-P8LH Rotating Cam Limit Switch by Allen-Bradley is a circuit control switch for industrial machinery with repetitive operating cycles that are used in applications where machine motion directly correlates with shaft rotation. Its cam mechanism is shaft-mounted, and it is designed for heavy duty/long life operations like metal forming, injection molding, and packaging and assembling processes. The 803-P8LH has 8 heavy-duty circuits, with cam-opened 25A NC contact which has 30A/3A MAKE/BREAK AC contact ratings at 600V AC, and a 1A DC contact rating at 230 to 250 Volts DC, and it has a base rotating shaft with a 400 RPM maximum shaft speed, and an over-sized shaft ball bearing. The 803-P8LH has 8 independently-operated cam operators, with adjustable segments (lobes and valleys), which rotate as the shaft rotates, and it has a spring-loaded cam roller assembly that is mounted on a 25A N.C contact. The circuit activates when the cam lobes brush against the cam roller, opening contact 1 and 2 of the NC contact, and the circuit deactivates as the cam valley glides past the cam roller.

The 803-P8LH has a duration of cam activation (dwell time), which depends on the size of the lobe, and the angular alignment of the cam lobes, and when the cam lobes perfectly align, the dwell time is minimum, but when they are offset at the maximum angle, the dwell is maximum. The 803-P8LH’s timing settings determine when the rotating cam activates the circuit, and it is measured in degrees, and determined by the position of the shaft-mounted cam relative to the keyway/top dead center. The device’s internal dwell time and timing settings determine the machine’s operations, and it has a set timing range of 11 to 349 degrees. The 803-P8LH has a left-hand shaft extension modification, and it is enclosed with a NEMA Type 1 indoor enclosure, and its functional 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). It weighs about 10 kilograms (22 pounds), with dimensions of 483.3 by 181 by 138.1 millimeters, and it is CE, CSA, and UL-certified.