GB1389077A - Drive mechanisms - Google Patents

Abstract

1389077 Operating clutches ROTORK Ltd 14 March 1973 [23 March 1972] 13630/72 Heading F2L An actuator for selectively connecting to an output shaft 14 (e.g. for operating a valve) either a manual drive (e.g. from a hand wheel 28) or a power drive (e.g. a reversible electric motor connected to a shaft 33 with a worm 34 in mesh with a wheel 35) comprises a clutch member 49 rotationally fast with the shaft 14 along which it is axially slidable (e.g. by virtue of keys 50 with radial end parts 52, 56) between a first position engaging the power drive (e.g. by the key parts 56 engaging short segmental axial projections 55 on the wheel 35) to which it is resiliently biased (e.g. by a spring 54) and a second position engaging the manual drive to which it is movable by rotation manually (e.g. by a lever) of part having an arm 92 engaging the clutch member 49 via a cam surface (e.g. the conical face of 49 in Fig. 1 or the face 94 on the arm 92) so that the line of action of the force thereby transmitted lies at a constant angle to the axis of the clutch member. To rotate the arm 92 the lever may have two flats 70, 71 giving a lost motion drive, the lever being spring biased to the power drive position. To maintain the manual drive position, the arm 92 may either have a resilient finger (83), Fig. 3 (not shown), fixed to it in the position of the part 100 in Fig. 4, which snaps over the upper edge of the wheel 35 and acts as a strut until the wheel 35 is rotated, or the part 100 may snap over this upper edge compressing the spring 101, rotation of the wheel causing the part 100 to pivot about a pin 98 against the bias of a spring 102, allowing a return to the position of Fig. 4. The output shaft 14 may be rigid with a further wheel 87 to drive a worm 88 on a shaft controlling limit switches for the electric motor.