GB500209A - Improvements in winches, more particularly intended for aircraft - Google Patents

Abstract

500,209. Winches. AIR EQUIPMENT. Aug. 4, 1937, No. 21474. Convention date, Aug. 8, 1936. [Class 78 (v)] A winch driven by epicyclic gearing is coupled to its driving motor by a centrifugal clutch which is disengaged when the motor is stopped or is rotating slowly, and is only coupled up when the motor attains a pre-determined speed, the winding drum being free to rotate in both directions when the clutch is disengaged. Fig. 1 shows an electric or other motor 3 the shaft 36 of which carries a.plate 37 supporting radially slidable friction headt 44 which engage the' interior of a cup 45 mounted on a shaft 14 coaxial with the motor shaft. A sun-wheel 28 on the shaft 14 meshes with a planetary pinion 24 riding in a ring 27 on a cylinder 17 loosely rotatable about the shaft 14. Integral with the pinion 24 is a slightly smaller pinion 25 riding in a ring 29 on the cable drum 8. The cylinder 17 and the drum 8 'are both supported by ball-bearings. 9 running on a fixed sleeve 6. The sleeve 6 and the cylinder 17 are provided with dog teeth 31, 30 which are engageable by an annulus of teeth 33 on a plate 32, the teeth 30, 31 being of different heights so that the cylinder 17 is always engaged. The plate 32 is pressed by springs 41 away from a member 42 bearing against the cylinder 17, and is forced towards same by the centrifugal action of heads 40 having tails 39 riding in a groove 38 around the loose boss 35 of plate 32. In order to retard the unwinding of the cable, when the motor 3 is stopped and the load is falling, a brake is provided which may consist of a leaf spring 48 riveted to the cylinder 17 and provided with a friction pad at its outer end which rubs against the inside of the sleeve 6 Alternatively a hydraulic brake comprising a slidable but non-rotatable annulus 54, Fig. 3, threaded on an extension 51 of the drum 8 may be provided. Flap-valves 56 allow easy movement of the annulus toward the drum, i.e. when winding-on, but close when the drum rotates in the opposite direction. Narrow, grooves 57, varying in cross-section along their length, allow leakage of the liquid to permit slow movement of the drum. An auxiliary chamber 58 provided with flap-valves 59 contains a reserve of liquid to compensate for leakage. Instead of brakes, a torsion spring 60, a torsion bar, an elastic cord, &c. may be provided, connecting the drum to its casing, to store energy for part or the whole of the rotation of the drum. The winch may be modified for chain connection to the load by making the drum end 10 a means for attachment thereto of a sprocket wheel 8a, the drum grooves being abolished and the drum acting merely as a centering member in an epicyclic speed-reduction gear-box.