Patent GB-803222-A (GB)
Title: Apparatus for testing wheel skid-sensing device
Inventor: SIMMONS JOHN
IPC: B60T8/74
Filed: 1955-07-16
Abstract: 803,222. Testing anti-skid brake devices. DUNLOP RUBBER CO. Ltd. July 11, 1956 [July 16, 1955], No. 20632/55. Class 103 (1). Apparatus of a portable form for testing wheel skid sensing devices of the kind described in Specification 676,708 so that the efficiency of such devices may be checked at airfield workshops which do not have extensive test facilities, comprises a stand 2 having located therein, at appropriate heights, platforms 3, 4 and 5 supporting respectively a fluid reservoir 6, a speed change assembly 7 and a variable speed control 8. The electric motor 9 drives through a V-belt 35 a pulley 34 which, in combination with a pulley 40, coupled by a further V-belt 42 to a pulley 43 provides a continuously variable ratio speed change mechanism between the motor and pulley 43. The change of ratio is obtained by operation of a hand lever 21 which, by raising or lowering the spindle 41 acts to alter the radius at which the V-belts 35 and 42 engage the inner radial surfaces of the pulleys 34 and 40. The central member 67 being axially movable on the hub member 62. The pulley 43, as seen in Fig. 6, is arranged to drive a shaft 88 by torque transmitted through friction lining annulus 124 and disc 122, the shaft 88 having secured to it for rotation therewith through flange 183, the drum 86 against which the inertia device 1 to be tested is adapted to be engaged by operation of a control handle 102, as shown in Fig. 1. The drum 86 may be braked at any time by operation of a suitably positioned lever 153, Fig. 1, which acts through a triangular shaped member 147, Fig. 7, to move the disc 122 so as to engage an annulus 131 with an annulus 155 of friction material secured to the fixed plate 154. In operation, the motor 9 is started and the shaft 88 and drive 87 run up to a predetermined rate as registered on the tachometer dial 163. The lever 102 is adjusted to apply the tyre 16 of the housing 15 of the inertia device to the inner surface of the rotating drum 87. When the inertia device has been accelerated up to the speed of the drum 87, the drum is braked by operation of hand lever 153 to bring the annulus 131 against the fixed friction annulus 155. When the drum 87 is braked, inertia causes a fly-wheel 199 within the drum to lag with respect thereto so that through the action of ball and ramp mechanism a rod 165 is moved axially within the shaft 88 against spring 167 to close a micro-switch 180. As may be seen from the circuit in Fig. 12, closing of micro-switch 180 causes the operation of the interval timer 213 on the instrument panel 13. A similar interval timer 415 is operated by a pressure switch responsive to a drop in pressure caused by the inertia control device operating to pass fluid to exhaust. The time taken for the inertia mechanism 1 to come to rest from the application of the brake can be read on the interval timer 213, the time taken by the driven member to come to rest, after the closing of the inlet valve, can be read from timer 415. The difference between the two times being the time taken between the applica. tion of the brake and the closing of the inlet valve, providing a guide to the efficiency of the inertia device. In another similar apparatus described, the variable radial pulley arrangement for alteration of the speed ratio between the motor and pulley 43 is replaced by a conventional gear-box. Specifications 683,490 and 706,351 also are referred to.