The 803-A4R is a Rotating Cam Limit Switch from Allen Bradley’s 803 product family. This rotating cam limit switch is a heavy duty circuit device made for control purposes on machinery with a repetitive operating cycle. It initiates contact actuation at determined positions while its shaft rotates. The shaft supports ration in both clockwise and in counter-clockwise directions and its axis can be positioned at any surface level. The 803-A4R is designed for long life and for operation in harsh conditions. The 803-A4R is a “style A” rotating cam limit switch, with a 150 RPM maximum shaft speed and a cam duration, settable in the range of 14 to 346 degrees. It has 4 independent cam-roller assemblies mounted to the contact base, which actuate 25A rated control circuits. A type 1 industrial enclosure is implemented on this limit switch and shaft rotation is conducted over a twenty to one (20 - 1) gear ratio reducer. A shaft extension is located on a left side of the device when viewed at the front face.

This rotating cam limit switch model has internal timing and dwell adjustments. Settings are made easy over angular degree scales visible on the shaft or on the cam mounting plate. This setting is can only be conducted when the device is in an idle (non-operational) state. The Allen-Bradley 803-A4R has outer dimensions (without the shaft) of 200.1 x 144.5 x 199.4 millimeters (7.88 x 5.69 x 7.85 inches). The product’s weight is around 10 kilograms (22 pounds). And its operating temperature range is -30 to 66 degrees Celsius (-22 to 150 degrees Fahrenheit). Note that the production of the 803-A4R Rotating Cam Switch ceased in 2007.