Cams are also used for cutting machines, or in tracing apparatus where it would be impossible to use ordinary mechanism. All such forms are special, requiring care and study to make their movements co-relate with the other parts of the mechanism that they are connected up with.
Simple Cams.—[Fig. 88] shows a form of the most simple character, used, with some modifications, to a larger extent than any other. It is called the heart-shaped cam, and is the regular type.
[Fig. 89] is an elliptical cam, which is also regular. What is meant by regular is a form that is the same in each half portion of its rotation.
[Fig. 90] is a double elliptic, which gives a regular movement double the number of times of that produced by the preceding figure, and the differences between the measurements across the major and minor axes may vary, relatively, to any extent.
Wiper Wheels.—Wiper wheels are cams which give a quick motion to mechanism, the most common form being the single wiper, as shown in [Fig. 91].