Distributor-Plunger Drive

Fig. 15 Plunger & roller:

Input-shaft rotation is transferred to the distributor plunger by dogs on the input shaft and cam plate meshing with a yoke, Fig. 15.
By virtue of the roller ring and cam plate, whose surface rides on the rollers, the input shaft's pure rotation is converted into rotary-reciprocating motion. The plunger is set into the cam plate with its cylindrical fitting piece, and its position relative to the cam plate fixed by a lug.
The plunger is forced up towards its top dead center position by the cam surface, two symmetrically arranged return springs force it back down again towards its bottom dead center. These springs are backed by the distributor head and act on the plunger by way of a spring link. In addition, the springs prevent the cam plate from separating from the rollers under high acceleration. So that the plunger is not displaced from its centered position, the return springs are matched precisely to each other.