A plate cam is a guide device used in many different mechanical apparatuses. It is used to ensure the fluid movement of a particular part of the device, especially in instances where the movement of the part has to be in two different directions simultaneously. For instance, if a certain torsion or tension rod has to move within a mechanical device in both a circular and vertical up-and-down motion, a plate cam is often used to perform both of these functions simultaneously.
Plate cams can also be used in linear applications. There, the plate is turned on its side, with the part of the device utilizing the plate cam only traveling one path. The path is determined by the profile of the plate on the plate cam. The most common example of this sort of mechanism is the merry-go-round, where the horses are attached to plate cams that make them raise and lower as the turntable spins around the motor.
The device is able to function as such because in a flat plate cam, the plate portion of the apparatus is tilted. One side of the plate is higher than the other and is attached to the cam rod used as the axis that spins the plate. The torsion or tension rod that is attached to the plate cam is attached through bushings and clasps to one side of the plate, and as the plate spins around the axis, the rod is moved according to the tilt while traveling around the axis. This allows the plate cam to attain a multi-directional function.
The linear plate cam, however, is turned on its side, so that the profile of the plate itself, whether it be shaped like a teardrop or any other form, is what the tension or torsion bar is attached to. As the plate spins on the axis point, the torsion bar is moved according to the profile of the plate. This causes the raising and lowering of the position of the torsion bar without requiring it to travel in a circle around the plate’s axis.
Plate cams are also capable of allowing a sliding motion around the contour of the plate, without the tension or torsion rod or anything other than the axis being attached to it for the cam to function properly. The problem with these types of cams, however, is that the moving part is unattached to the plate which can allow for slippage. This is why the attached form of the device is the most popular in mechanical applications.