SERVO UNIT FOR ADJUSTING STROKE OF RECIPROCATIVE PUMP

PURPOSE:To facilitate maintenance of a servo unit for adjusting the stroke, by transmitting the amount of displacement of a lead screw in the form of a rotational amount to a rotary shaft fixed to the servo unit through a coupling member. CONSTITUTION:In a servo unit 54 for adjusting the stroke of a reciprocative pump 10 a cam 24 is fitted on a crank shaft 16 coupled with a drive motive for rotation, and a plunger 26 is connected through a connecting rod. A lead screw 30 is coupled to one end of this crank shaft 16, and the stroke of the plunger 26 is adjusted by rotationally moving this lead screw 30. A rotary sleeve 36 is coupled to the top of this lead screw 30 using a fixture 37, and a gear thereon 38 meshes with a worm gear on an operational shaft 40 of a speed reduction gear 50. Thus the rotation of a servo motor 52 is transmitted to the lead screw 30, and the amount of its displacement is transmitted in the form of rotational amount to rotary shaft 70 of the servo unit 54 through a removable key 34 and a rotary disc 72. This enables removal from the reciproca tive pump to ensure that the maintenance is performed easily.