The Allen-Bradley 803-P3 switch is a rotating cam limit switch that is part of Allen-Bradley’s Bulletin 803 series. It is manufactured to perform heavy-duty operations over a long period of time without wearing out. If installed and used properly, the 803-P3 limit switch will last for years and need minimal maintenance.

The 803-P3 rotating cam limit switch has between 2 and 12 independent cam operators and assemblies. The high position of the cam segments is called the lobe, and the lobe activates the 803-P3’s circuit by pushing against the cam roller. The low position of the cam segments is called the valley, which passes the cam roller without activating the 803-P3’s circuit. The lobe is essential to determining the 803-P3 rotating cam limit switch’s dwell time, which is the length of time that the cam lobe activates the circuit for, and the length of the dwell time is determined by the position of the 803-P3’s cam segments and by the size of the switch’s cam lobes. When both of the 803-P3’s 2 cam segments are aligned, the cam limit switch experiences its minimum dwell time, whereas when both of the cam segments are offset from each other at the biggest angle that the 803-P3 allows, the device experiences its maximum dwell time. The 803-P3 rotating cam limit switch also has activation timing that is measured in degrees and is determined by the cam activating the shaft and by where the cam is on the shaft relative to the keyway (a slot in the 803-P3’s shaft that connects the driven shaft to the machine.)