GB1435493A - Aerials - Google Patents

Abstract

1435493 Aerials CRATER CONTROLS Ltd 14 May 1973 [18 May 1972] 23489/72 Heading H4A A power operating aerial lift, which may be used for extending and retracting a telescopic aerial fitted to a car, comprises a flexible elongate push-pull actuating element 23 which is provided over all or part of its length with a toothed rack section 25. A pinion 20 cooperates with the said rack section, which is kept in mesh by a guiding wall portion 26 of a housing. A partition 1 divides the housing into a drained portion 2, and a sealed portion 3. A high-speed reversible permanent magnet motor 5 in the portion 3 has a shaft 6 extending through the partition 1 to a small spur gear 7, which drives the pinion 20 through spur gears 8, 9, 10, 19. The gear 10 is splined to a shaft 11, upon which the gear 19 is rotatable, and a slipping clutch assembly is interposed between the two gears. This comprises balls 16 which are contained in apertures in the face of the gearwheel 10 and which, when transmitting drive, are pressed into recesses 17 in a disc 18, which is integral with the gear 19. Pressure is applied to the balls by a spring 14, via a plate 12, and it may be adjusted by movement of a backing plate 13 by means of a nut 15. The element 23 is extended and retracted through an axial opening in an upstanding cylindrical connection 24 on which the aerial may be mounted. Within the housing, the element 23 is coiled on the interior of a freely rotatable drum 27. The shaft 11 extends into the portion 3 of the housing and carries a worm 22. This meshes with a worm-wheel (31), Fig. 4 (not shown), provided with a pair of pins for operating limit switching means having terminals 36, 37. The housing and the gears may be made of a plastics material such as nylon.