GB1223614A - Push-pull apparatus - Google Patents

Abstract

1,223,614. Supports for vehicles. ELEKTROAKUSZTIKAI ES VILLAMOSSAGI KTSZ. 25 March, 1968, No. 14328/68. Heading B7J. [Also in Divisions B8 and H4] A push-pull apparatus comprises telescopic elements, operable by a push-pull cable which is secured at one end to one of the elements and at the other end to a drum which is connected to a reversible drive, and a limit switch. The drum has a groove for receiving the cable, into which it is guided by a ring which fits radially into the groove, and has a width or axial dimension which is greater than that of the groove. As described, a telescopic aerial comprises elements 12, Fig. 1, and is raised and lowered by means of a push-pull cable 2 which is secured at one end in a sleeve 13 disposed in the lower end of the inner telescopic element, and is secured at the other end in a groove in a drum 1. The aerial is retracted into a retaining tube 15 which is mounted on a water-tight housing 24 containing the drum 1 and associated operating means. The retaining tube 15 carries a locking screw 16 for securing the device to a vehicle body, and at its end has a closure cap 14 containing a packing ring 17a for receiving in watertight manner an end member 17b of the aerial. The housing 24 comprises two halves or covers between which is a mounting frame 23 with a sealing ring 29, Fig. 6, intermediate, the whole being held together by screws 30. The drum 1 is driven by a reversible electric motor 5 through gearing including a worm gear 4, Fig. 1. The cable 2 is fed in or out of the groove in the drum 1 through a cable-introduction ring 3, Fig. 6. The motor 5 is supplied through a reversing relay 10 and a limit switch, which changes over when the aerial has been fully extended or retracted. The coil of the relay 10 may be actuated by a switch which is ganged with the operating switch of a radio set in the vehicle. The limit switch comprises fixed contacts 26, 27, Fig. 4, and a moving contact 25 which is actuated by a switching drum 7. A spring 6 has two extending legs, and pressure on either causes the other to turn the drum 7 from one position to another against force exerted by a retaining spring 19. An extension of a shaft 28, on which the drum 1, Fig. 6, is fixed, and on which the drum 7 rotates, has a disc 18 fixed to it. There is a projection on the disc 18 which co-operates with a projection on a free-running disc disposed between the disc 18 and the drum 7, and the whole space therebetween is occupied by other free-running discs having similar projections. In this way, lost motion is provided between the disc 18 and the last free-running disc corresponding to the revolutions of the drum 1 required fully to extend or retract the telescopic aerial (Fig. 5, not shown). The projection on the last freerunning disc engages the appropriate leg of the spring 6, Fig. 4, and operates the limit switch. A push-pull apparatus of the kind described may be adapted as a vehicle lifting device, the housing of the apparatus being provided with rails or other means for attachment to the vehicle. The projecting end of the inner element of the telescopic arrangement may carry a balljointed disc provided with claws, and a reinforcing outer guide sleeve may be included.