The double wiper cam, [Fig. 92], has, in some mechanism, a pronounced difference between the lengths of the two fingers which form the wipers.
The form of cam shown in [Fig. 93] is one much used in iron works for setting in motion the tilt hammer. Only three fingers are shown, and by enlarging the cam at least a dozen of these projecting points may be employed.
Cam Sectors.—[Fig. 94] shows a type of cam which is designed for rock shafts. The object of this form of cam is to impart a gradually increasing motion to a shaft. Assuming that A is the driving shaft, and B the driven shaft, the cam C, with its short end D, in contact with the long end E of the sector F, causes the shaft B to travel at a more accelerated speed as the other edges G, H, approach each other.
Cylinder Cam.—[Fig. 95] shows one form of cylinder A with a groove B in it, which serves as a means for moving a bar C back and forth. The bar has a projecting pin D, which travels in the groove.
This form of movement may be modified in many ways, as for instance in [Fig. 96], where the drum E has a sinuous groove F to reciprocate a bar G to and fro, the groove being either regular, so as to give a continuous back and forth movement of the bar; or adapted to give an irregular motion to the bar.
Double Cam Motion.—Cams may also be so arranged that a single one will produce motions in different directions successively, as illustrated in [Fig. 97]. The horizontal bar A, hinged at B to the upper end of a link C, has its free end resting on the cam D.