... sur-face in contact—for example, knife-edged, flat-faced, curved-shoe, or roller; (3) interms of the follower motion—such as dwell-rise-dwell-return (D-R-D-R), dwell-rise-return ... motion—such as dwell-rise-dwell-return (D-R-D-R), dwell-rise-return (D-R-R), rise-return-rise (R-R-R), or rise-dwell-rise (R-D-R); and (4) interms of the constraining of the follower—spring ... geometry of the follower thatTcr = |-tan-',(^-f -l) (40.30)where a = I8-R0 - Rr. For y > ycr, the cam-follower system is self-locking, and motionis impossible....