| 摘要 |
1324860 Hydraulic pressure system CATERPILLAR TRACTOR CO 24 Aug 1970 [29 Sept 1969] 40668/70 Heading F1P A pair of pumps 11, 12, e.g. on articulated earth moving equipment, for selectively driving a remote motor M at one of two speeds, each has its output 23, 31 connected via an orifice 63, 73 in a movable member 61, 71 of a pilot valve 14, and a pilot flow passage 19, 21, to an annular chamber 51, 52 in a main control valve 16 which has a spool 41 movable to connect one, 51, both, or neither chambers 51, 52 to a drain line 22. Each movable member 61, 71, when its pilot flow passage 19, 21 is'connected to drain line 22, moves upwardly to connect the associated pump outlet 23, 31 to a drain passage 27 via orifices 64, 76. When its pilot flow passage 19, 21 is closed, the movable member 61, 71 moves downwardly as shown, and the output of the associated pump 11, 12 is directed via line 33 to the motor M which has a single supply line and drain line. A by-pass 38 prevents cavitation in the motor during over-run, and the valve 14 has a pressurerelief valve 81. Additional pressure fluid may be supplied to the motor via a line 32. |
