Allen Bradley's 803-A4RE Rotating Cam Limit switch is a device used in industrial sensory applications. The main purpose of the 803-A4RE switch is to initiate functions at a variety of points, in order to sense rotating machines and open or close contacts for the different angles of the machinery’s rotation. This series of Cam Limit switch is available in six different styles, with the 803-A4RE switch being Style “A”, as indicated by the “A” letter after the dash. This heavy duty type Cam is adjustable both internally and externally, can be mounted in any type of panel, and can rotate in either direction. Its applications commonly include things such as punch presses, lock operations or waterway gate operations, steel forming, heavy metal, assembling, and packing operations, and injection molding machine operations. This style “A” Limit Switch has an N.C. (Normally Closed) double-break contact with a continuous current of 25 A. What a Normally Closed contact does is allow the cam lobe to engage with the cam-roller in order to open the contact, which is usually closed (hence called a Normally Closed contact). It has up to 12 independent cam operators or as few as 2. Its enclosure can be Types 1, 4, and 13, and it has a left shaft extension standards. Its shaft speed can accelerate to 150 RPM at maximum. This unit has four circuits.

The 803-A4RE has an operating temperature of  –30 to 66 degrees Celsius (–22 to 150 degrees Fahrenheit) and should be stored between –30 and 93 degrees Celsius (–22 to 200 degrees Fahrenheit), provided there is no frozen water or other frozen liquids present. The 803-A4RE limit switch has an internal timing and dwell adjustment system. These adjustments can only be made while the device is unmoving. Making an adjustment will require the user to remove the cover of the device and loosen its cam bolts, then to rotate the cams to the desired position. This device contains a scale on its mounting plate, allowing the user to measure exactly where the adjustment should be set. Once all the necessary adjustments have been made, the user should tighten the bolts and replace the cover.