[1] A single dwell cam mechanism has a motion function which follows a dwell-rise-fall sequence that repeats.
A single dwell linkage takes advantage of the behavior of a link with a stationary revolute (hinge) or prismatic (sliding) joint and its interaction with special coupler curves.
The concept for linkage dwell mechanisms is that a node located at the center of the circular arc segment of a coupler curve will remain relatively stationary.
If the approximate straight lines are parallel, a pin and slider similar to that used in a scotch yoke mechanism can be used.
Although using the arc-based approach–the other method used for single-dwell linkages–is theoretically possible, it is significantly more difficult to execute and is impractical in practice, as both approximated arcs must share a circle of the same radius.
[5] The actual dwell time will depend on the length of the approximate circular arc or straight line in the coupler curve.
The cams in this application are usually phased 90 degrees apart allowing a pause in the up/down movement of the dog while it is being moved forwards/backwards.