GB699375A - Control means for air-operated windscreen wiper actuating mechanisms - Google Patents

Abstract

699,375. Compressed-air engines. LUCAS (INDUSTRIES), Ltd., J. July 1, 1952 [July 3, 1951], No. 15737/51. Class 122(iii) In a compressed air operated windscreen wiper mechanism embodying a parking valve a manually operable lever actuates the parking valve and also opens a spring-loaded air supply valve moved by its spring to its closed position under the control of a reciprocatory part of the mechanism. Two spaced pistons b reciprocable in cylinders a are connected by a bar c having thereon a rack d engaging a pinion e that imparts oscillatory motion to the wiper arm. Compressed air is supplied to a chamber f via a spring-loaded poppet air valve k and is admitted alternately to the cylinders a by a distributing valve loaded with an over-centre spring h and moved by a rocker g actuated by tappets i on the bar c. The stem of the air valve k engages a notch t in the bar c when the pistons are in the parked position and the air valve is opened by one end of a manually operable lever o whose other end carries a rack q engaging a complementary rack r on a pivotally mounted parking valve associated with the distributing valve. In the position shown the wiper is parked and to operate it the lever o is rotated clockwise to open the air valve k, disengage the valve stem from the notch t and move the parking valve to its inoperative position by the racks q, r. The wiper mechanism then operates in the normal manner until the lever o is returned to its initial position thus releasing the air valve and returning the parking valve to its operative position. Due to obstruction by the bar c; however, the valve k remains open and the pistons continue to move until the parking position is reached when the notch t comes opposite the valve stem and allows the valve to be closed by its spring m.