| 摘要 |
An eccentric shaft is rotatably mounted in a frame, in which a ram is vertically and slidably mounted. First and second connecting rods are provided, each of which has an inner end rotatably mounted on the eccentric shaft. The first and second connecting rods are arranged to perform mutually opposing motions in response to a rotation of said eccentric shaft. The frame carries first and second slot-defining members, which are disposed on opposite sides of the eccentric shaft and define first and second guide slots, respectively. The latter are horizontally aligned and arranged to guide the outer ends of the first and second connecting rod means, respectively. In addition, first and second ball crank levers are disposed on opposite sides of the eccentric shaft and pivoted to the ram. The first and second bell crank levers have first and second output arms, respectively, which are operatively connected to the ram, and first and second guide arms, respectively, which extend at an angle to said output arm. The guide arms are formed with substantially vertical first and second guide slot members, respectively, which are arranged at the outer ends of the first and second connecting rods, respectively.
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