GB927931A - Improvements in or relating to torque responsive devices and mechanisms incorporating such devices - Google Patents

Abstract

927,931. Retractive switches. EGERTON SMITH ENGINEERS Ltd., G. E. SMITH, and R. CHANTLER. June 19, 1959 [June 20, 1958; Nov. 21, 1958 ; Dec. 15, 1958; April 2, 1959], Nos. 19910/58, 37630/58, 40443/58 and 11316/59. Class 38 (5). [Also in Groups XIX, XXIV, XXVI, XXIX, XXX, XXXV and XL (b)] A torque-responsive mechanism comprises at least one twistable bar offset from the axis of the mechanism, one end of the or each bar being fixed and the other end being connected to a part of the mechanism to which a load may be applied, thereby twisting the bar so that, e.g. a switch is actuated. In one form, a driving shaft 1, Fig. 1 (Provisional 19910/58), carries an eccentric 5 around which slides a planetating pinion 4 meshing a ring gear 3, studs 6 on the planet pinion sliding in diametrically opposite slots 10 in an Oldham-type centre piece 9 cooperating with studs 8 on a driven shaft 2, the reaction of the load placed upon the shaft 2 tending to turn the ring gear 3 and a lever 18 fast on the free end of a torsion bar 16 fixed at its other end 17. A crank 21 at the free end of the torsion bar 16 may actuate an indicating device, or a device controlling a motor driving the shaft 1. A radially projecting pin 13 on the ring gear 3 lies in a slot 14 in a stationary casing 12 to limit the movement of the ring gear. As applied to a valve-operating device, the driven shaft 2 is fast with a bevel gear 27, Fig. 2 (Provisional 19910/58), meshing a bevel pinion 25 secured through a hollow sleeve 23 to a shaft 21 connected to the valve stem. Rotation of the ring gear 3 against the bias of the torsion rod 16 when the valve has been closed, actuates a control device 44 which switches off an electric motor 32. In another construction, a driving shaft 1, Fig. 5 (Provisional 19910/58), is formed with a worm 51 meshing a worm wheel 52 on a driven shaft 53, loading the shaft 53 tending to cause axial movement of the drive shaft 1 which acts through levers 18 fast upon the free ends of torque bars 16 to change the state of a switch 68 controlling a prime mover. In another construction, a rack 72, Fig. 6 (Provisional 19910/58), is slidden axially by a pinion 71 against the bias of torsion bars 16 having at their free ends levers 18 engaging slots in the rack, contacts 74, 75 being closed to shut-off a controlled prime mover. An electric motor having a rotor 76, Fig. 8 (Provisional 19910/58), is shown having its stator 78 rotatable within a easing 79 against the bias of a torsion bar 16 having at its free end a lever 18 coacting with a notch on the outer periphery of the stator casing. On overload of the electric motor, the stator 78 rotates and twists a torsion bar 16 so electric contacts 80 will switch off the motor.