GB1414288A - Control circuits - Google Patents

Abstract

1414288 Excavators POCLAIN 29 March 1974 [5 April 1973] 14116/74 Heading E1F [Also in Divisions F1 and F2] If a lever 53, Fig. 1, is moved to the left in the Fig., interlinked valves 5, 33 are moved to their first positions in which a chamber 7 of an actuator 4 is supplied from a pump 1 and fluid from a chamber 9 returns freely to a reservoir 3. Fluid from a chamber 31 returns to the reservoir through pipes 34, 35, 32. This allows a spring 27 to depress a piston 29 so that pushers 25, 26 bear on slides 10, 16 to keep pipes 8, 19 open. In the two other positions of the valve 5 the pipe 8 must be perfectly sealed except when feeding fluid to the chamber 9. This is achieved by feeding fluid under pilot pressure to the chamber 31 through pipes 38, 34 to raise the piston 29 so that slides 10, 16 are held up by a spring 18, thus blocking pipes 8, 19. In the third position of the slide 5 automatic piloting of the slide 10 is provided. Fluid from the pump 1 flows through pipes 11, 8 to slide 10 where it is stopped, and into a guide 14. The latter moves the slide 10 to open pipe 8 so that fluid can enter the chamber 9 and fluid from chamber 7 can return through pipes 6, 12. As soon as pressure falls in the pipe 8, e.g. when valve 5 is moved to its second position, slide 10 is moved by the spring 18 to close pipe 8. The circuit shown in Fig. 3, (not shown) operates in a similar manner.