GB1306325A - - Google Patents

Abstract

1306325 Hydraulic motor control circuits RUSTON-BUCYRUS Ltd 19 April 1971 [24 Feb 1970] 21116/71 Heading F1P A blast hole drill comprising a mast 6 Fig.1 operating means 7 mounted on a platform 5 which is rigidly secured to and above a crawler 1 is raised so that the crawler is free of the ground during drilling and is subsequently lowered so that the crawler supports the substructure 5 and 7 during transport to a different location by means of a front double acting hydraulic jack 2 Fig.2 having its axis lying in the vertical plane in which lies the longitudinal axis 8 of platform 5 and by means of two rear jacks 3, 4 on either side of axis 8 rotate axes lie in a vertical plane which intersect platform 5 to form a transverse axis 9; control of the fluid supply to jack 2 or the exhaust therefrom being effected a solenoid operated proportioning valve 17 responsive to electric signals generated by a level sensor 30 and fluid control for jacks 3, 4 being similarly effected by a proportioning valve 24 operated by a solenoid 39 responsive to electric signals generated by a level sensor 31 whereby during raising and lowering of the drill apparatus the platform 5 is automatically maintained level. To raise platform 5 so that crawler 1 is clear of the ground a manual switch 47 is closed to energise a solenoid 45 and move a closed centre distributing valve 12 to the left so as to connect a pump 13 to the inlet 16 of valve 17 which latter distributes 1/3 of the pump delivery to jack 2 and the remainder to valve 24 which then supplies jacks 3, 4 equally. Assuming platform 6 remains level the solenoid 20 of valve 17 remains unenergized but in the event of uneveness of ground resulting in platform tilting about axis 9 a pendulum tapping of a resistance 34 of sensor 30 delivers a signal through an amplifier 35 and closed switches 40, 41 to solenoid 20 which then positions valve 17 to correct the tilt. Simlarly when the platform tilts about axis 8 solenoid 29 of valve 24 receives signals from sensor 31. When platform 5 is raised sufficiently that the jacks take about 80% of the load i.e. when the crawler is about to leave the ground, series arranged fluid pressure responsive switches 56 to 58 in series with a time delay 60 open a switch 61 in series with the closed manual switch 47 thereby closing valve 12 after such an interval that the crawler is clear of the ground. To lower the apparatus from the drilling position a manual valve 49 is closed which thus energizes solenoid 48 to move valve 12 to its reverse position and also energizes a coil 50 which opens switches 40, 41, 43, 44 and closes switches 52 to 55. The pump delivery is thus connected to the rod ends of the jacks and the head ends thereof discharge through valves 12, 17, 24 to a sump 11. When the crawler touches the ground a momentary pressure rise in line 15 opens a switch 62 to de-energize solenoid 48 of valve 12.