Self parking pneumatic windscreen wipers - with parking piston on one end of reciprocating piston controlled by double valve

摘要

The windscreen wiper is operated pneumatically by a reciprocating piston driving a reciprocating cam drive. The wipers are controlled by double valve elements when connected to an air supply. One end of the double piston cylinder is fitted with a hole through which a control rod pushes on the double piston. The control rod is coupled to a parking piston sliding a separate chamber at the end of the cylinder housing. One side of the parking piston is continuously vented while the other side is coupled to the air supply when the wipers are switched off. This parks the wipers in a setting right off the windscreen. The system is especially useful in trains and heavy vehicles, which are cleaned by heavy industrial cleaning equipment.