GB1330566A - Hydraulic control device for a drive mechanism - Google Patents

Abstract

1330566 Earth graders DEERE & CO 19 April 1971 [18 March 1970] 24544/71 Heading E1F [Also in Division F1] A grader circle 40 Figure 2 is rotated about a vertical axis by two reciprocating hydraulic motors 46, 48 pivotably mounted at 62, 64 between upper and lower horizontal plates (58, 60) Fig. 3 (not shown) and connected by 90‹ out of phase rods 54, 56 to a crankshaft 70 connected by gearing (78, 80) to circle 40; supply to and exhaust from motors 46, 48 being effected by a reversing valve 82 of the sliding spool type actuated by cams 170, 172 pivotable with motors 46, 48. Reversing valve 82 has a generally rectangular body 84 mounted on the upper plate 58 so as to be disposed half forwardly and half rearwardly of a line through pivot pins 62, 64. First and second pairs of upper and lower vertically spaced valve bores 86, 88 Fig. 4 and 90, 92 extend lengthwise, through the forward and rearward halves of body 84. For convenience of representation the first pair of bores 80, 80 are seen at the top, bottom of Fig. 4 in a plane common with the second pair of upper and lower bores 90, 92. The upper bores 86, 90 are inter-connected by a passage 96, and bores, 86, 88 have medial inlet and outlet parts 98, 100 respectively. Bores 86, 88, 90, 92 are respectively interconnected by right control parts 112, 116, 114, 118 and by respective left control ports 120, 124 122, 126. Control ports 112, 118 are connected by a duct 130 to each other and to a work port 128 of actuator 46 whilst control ports 114, 116 are connected by a duct 134 to each other and to an actuator work port 132. The left hand control ports 120, 122, 126, 124 are similarly connected to the work ports 136, 140 of actuator 48. The right and left control ports are selectively connected to inlet and outlet ports 98, 100 by valve members 144 each of which includes a parted sleeve 146 in which slides a valve actuating plunger 162 having their outer ends in abutment with portions of wedge-shaped cams 170, 172. In operation and with a directional control valve 110 in the position shown, fluid delivered by a pump 104 flows round the periphery of both unseated valves 144 in bore 86 and through ducts 130, 138 to work ports 128, 136 to retract motors 46, 48 which exhaust through ducts 134, 142 and past valves 144 in bore 88 and through valve 110 to a return 108. At this time valves 144 in bores 90, 92 are seated since their corresponding actuating stems engage a recussed portion of the cams. When motor 46 is half retracted cam 170 will be in its intermediate position in which it has just released stems 162 in bores 86, 88 but has not yet shifted stems 162 in bores 90, 92. However motor 48 as is further extends rotates motor 46 enough for a cam 170 to shift stems 162 in bores 90, 92, thereby connecting work parts 128, 132 respectively to exhaust and supply through bores 90 and 92.