GB1434278A - Limit stop device for valve and other actuating mechanisms - Google Patents

Abstract

1434278 Stopping in definite positions; one-way brakes MASTERGEAR CO Ltd 19 Aug 1974 [18 Aug 1973] 39140/73 Heading F2E A limit stop mechanism incorporates a driving shaft 1, Fig. 1, a driven shaft 2 geared to it, a toothed locking wheel device 4 fixed on the driving shaft 1, a lead screw 5 coupled to the driven shaft 2 to be rotatable therewith and presenting an abutment 8 or 9 each end, and a double-ended detent 10, Fig. 2, mounted on, engaging by a screw thread with the lead screw 5, the detent 10 having two pellets 10A, 10B, alternatively engageable with the teeth of the locking device when the detent is swung about the axis of the lead screw in one direction or the other. As shown, the toothed locking wheel device 4 includes two coaxial locking wheels 4A, 4B, each formed with single action ratchet teeth, each presenting one steep ratchet face, the steep faces on the two wheels facing in opposite circumferential directions, the two wheels are approximately opposite respective abutments at opposite ends of the lead screw. In operation, when rotation of the driven shaft 2 is taking place between the ends of the range of movement permitted, the detent 10 moves along the lead screw 5 in one direction or the other depending on the direction of rotation of shaft 2; there is no interference between detent 10 and locking wheel device 4 because centring springs 11, Fig. 2, are provided. When the driven shaft has reached one end of its permitted rotational movement, detent 10 comes up against, e.g. abutment 9, so it must rotate thereafter with the lead screw, whereupon a pallet (e.g. 10A) engages a tooth of wheel 4A, thus locking shaft 1 against further rotation. In Fig. 3 (not shown) lead screw 5 is on a spindle geared to shaft 2.