Windscreen wiper drive for stacker truck used in explosion prone atmosphere - is driven by spring-return hydraulic cylinder cycled by interconnected oil pressure actuated pilot and main directional valves

摘要

The pivoted windscreen wiper (1) is oscillated to-and-fro by a single-acting, spring-return hydraulic cylinder (4) supplied from a hydraulic power unit (10) of the stacker truck. The cyclic flow of oil into and out of the cylinder (4) is controlled by a pilot oil pressure actuated main directional valve (15) which operates in conjunction with a pilot directional valve (20). This switches in response to the pressure in the cylinder chamber and in turn switches the main valve (15). The cyclic motion of the cylinder can be varied by throttles (28,29) which regulate the response time of the pilot and main valves. USE/ADVANTAGE - Simple hydraulic windscreen wiper drive for stacker truck used in explosion prone atmosphere satisfies conditions for safe operation.