| 摘要 |
<p>1,231,935. 935. Hydraulic motor control circuits. ROBERT BOSCH G.m.b.H. April 23, 1969 [April 24, 1968], No.20722/69. Heading F1P. [Also in Division F2] The spool 19 of a reversing valve is urged to a neutral position by a double acting spring device 34, and is moved to provide the deserved flow and return connections to ram 17 by selectively connecting the ends of cylinder 27 to pressure fluid inlet 13 via orifice 43 and electromagnetically actuated pilot valves 45, 47. With both pilot valves open spool 19 is hydraulically free but is centralized by device 34 so locking ram 17. Energizing valve 45 closes the path between chamber 39 and outlet 14 so that pressure is applied to both chambers 37, 39 causing differential piston 36 to move spool 19 to the left. If now valve 47 is energized, a spool 19 is locked hydraulically and flow to ram 17 continues until valves 45, 47 are de-energized whereupon spool 19 is returned to its neutral position by device 34 and ram 17 is locked in its new position. To reverse the action of ram 17 valve 47 is energized so that fluid can only flow to chamber 37 thereby moving the spool to the right. According to a modification (not shown) the pilot valves are of single bent type. .</p> |
