Jack for turning reversible plough - is designed to reverse automatically at end of closing stroke using valves tripped at end of stroke

摘要

A reversible plough is turned by successive closing and opening strokes of a jack. Oil admitted at (6) into chamber (2) of the jack acts on piston (4) to close the jack, chamber (3) being connected to tank via passages (23, 20) chamber (16) and orifice (21). Near the end of the stroke valve (9) is depressed and allows oil in chamber (2) to pass through passages (8, 24, 19) to orifice (17) where it acts on valve (15) to lift it. Orifice (18) is now opened so oil from pipe (25) passes via channel (22) and passages (20, 23) into chamber (3), valve (15) now sealing the orifice (21). The jack now starts to extend on the rod area, whereupon valve (9) reseats sealing chamber (2) from chamber (3).