GB563929A - Improvements in or relating to jack screws particularly for aircraft cowls - Google Patents

Abstract

563,929. Screw-and-nut gearing. STEVENS, A. H. (Lear Avia, Inc.). March 14, 1942, No. 3396. [Class 80 (iii)] [Also in Groups X, XXV, XXXII and XXXIII] Consists in screw-and-nut gearing particularly applicable to the operation of ventilating flaps on the cowl of aircraft engines. Flaps 23, Fig. 2, are spaced around a cowl 20. Each flap is resiliently connected to one end of a jack screw 25, the other end of which is resiliently connected to a stationary gear-box 26. These boxes are mounted on a ring 27 and are actuated by flexible shafts 28 from an electric motor 31 preferably embodying features described in Specification 549,552. The jack, screw, Fig. 3, comprises a screw 32 flexibly coupled to gearbox 26 through a cup 33, and a coacting sleeve 34 flexibly coupled to a cup 35 secured to the flap 23. By arranging the sleeve adjacent the flap, the screw 32 is protected from dust &c. carried by the air stream. The motor drives a worm 41, Fig. 5, gearing with a worm-wheel 43 secured to a shaft 44 coupled to the flexible shafts 28. Sleeve 34, Fig. 8, has a ring 51 with flange 53 forced thereon, and a retainer ring 54 is press fitted into cup 35, the rings being bonded to rubber 50. The flange 53 is sufficiently large to prevent the sleeve dropping through the aperture 56 in the base of the cup. The screw 32 is secured to the cup 33 in a similar manner and the cup is connected by screws 74 to a flanged member 73 integral with the shaft 72, Fig. 12, of a gear unit. In this unit a worm-wheel 75 on shaft 72 is driven by a worm coupled to the flexible shafts 28. In modified forms of connection of sleeve and screw to the cups 35, 33 respectively, the flanged rings 51, 67, Fig. 8, are replaced by thick barrelshaped rings. The screw 32 works in a long nut 61, Fig. 8, of tough material, e.g. tobin bronze, the nut being secured by swaging over the end of the sleeve at 62. A nut 64 on the end of the screw prevents the latter from being pulled out from the sleeve.