In this example, Fig. 85, is introduced a follower with a flat surface, its path being perpendicular to its working face. The length of its path 06 is the same as before, and is divided into six equal divisions.
The point of original contact 0 being chosen, the original radius OC is drawn perpendicular to it; the radii CX and CB, limiting the arcs of rise, rest, and fall, are then drawn in their proper relation to CO, and the arcs of rise and fall subdivided as before.
The intersections R1, R2, R3, R4, etc., of the rotating arcs with the several position of the radii, are found as before. The rotated positions of the follower in this case are obviously represented by drawing perpendiculars to the several radii through the points R1, R2, R3, R4, etc.
Fig. 85. Diagram of Cam with Flat Follower Perpendicular to Working Face.
The cam should be tested by the tracing-cloth method.
Pressure lines are drawn at the points of contact between the cam and the follower, by erecting perpendiculars to the face of the follower at these points. As in the case of the pointed follower, there is considerable friction due to the sliding of the cam along the follower face. This friction produces a side thrust perpendicular to the path of the follower, and modifies the pressure lines slightly. If it were not for this friction, the pressure line obviously would always be perpendicular to the follower face, acting at a point on the follower face some distance to one side of the original point of contact 0. By taking the distances R1 U1, R2 U2, R3 U3, etc., to the several contact points, and rotating them back, the manner in which the point of contact between the cam and the follower moves along the face of the follower during its travel can be conveniently studied; it is seen that the point of contact during the arc of rise moves to the right of the original radius, and gradually swings back again until, at the point 6, it is on the line of the original radius. During the arc of rest, the point of contact remains at point 6; during the arc of fall, it moves to the left of the original radius, finally coming back again to the original point of contact 0.