| 摘要 |
A steppable mechanism is described comprising a cam member formed with a series of interconnecting cam slots symmetrically arranged in a closed loop around a central axis, and a follower pin movable within the slots to effect a rotary movement of the cam member in stepped increments in a predetermined forward direction. Each of the cam slots is of decreasing depth in the forward direction of rotation of the cam member such that at each juncture of one slot with the next, the end point of the slot traversed is higher than the starting point of the next slot in the forward direction to thereby define a shoulder between the two slots blocking the return movement of the pin in the traversed direction and constraining its movement only into the next slot in the forward direction of rotation. Also described are valve constructions including the steppable mechanism for actuating the valve at a predetermined step thereof.
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