Japanese Patent JPS5345475

B1

1,222,104. Excavators. ORENSTEIN-KOPPEL UND LUBECKER MASGHINENBAU A.G. 6 March, 1968 [10 March, 1967], No. 10912/68. Heading E1F. [Also in Division F1] A control system for an excavator (not shown) comprises two pumps 1, 2 each connected to an associated pre-set relief valve 16, 15 which delivers pressure-relieved hydraulic fluid through a check valve 17, 19 and through lines 18, 20 neutral-positioned slide valves 9, 10 controlling associated motors 3, 4, 5 to a common line 21 which passes successively through neutral-positioned slide valves 12, 14, 13 for controlling associated actuators 6, 8, 7 whereby on opening any of one of valves 12, 14, 13 the pressure-relieved output of both pumps becomes blocked resulting in closure of both relief valves 15, 16 thereby rendering the output pressure of both pumps available to a selected actuators 12, 13 or 14. Motors 3, 4 propel the excavator, motor 5 pivots it and actuators 6, 7, 8 serve to operate a jib, dip arm and grab respectively. In operation and with valves 9, 10, 11, 13, 14 in neutral operation of any one of valves 12, 13, 14 say valve 12 in either direction, e.g. to the left connects the pressure delivery line 26 of pump 1 through a branch line 27 to the upper end of actuator 6 the lower end of which is connected to reservoir 25. At the same time the delivery of pump 2 passes along lines 28, 29, 30, 31, check valve 32 and 33 and is added to the delivery of pump 1 to assist in supplying the actuator 6. If now valve 13 is also displaced in either direction, e.g. ito the left pump 2 instead of delivering to actuator 6 delivers to the underside of actuator 7. Similarly with valve 12, 14 in neutral and valve 13 open both pumps supply actuator 7 and with valves 12, 13 in neutral and valve 14 open both pumps supply actuator 8. Only two of the three actuators can operate together and even though all three valves 12, 13, 14 may be operated valves 12, 13 are connected to their respeotve pumps whilst valve 14 is starved.

JP1516968A

December 06, 1978

March 09, 1968

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E02F9/22; E21B11/04; F15B11/17; (IPC1-7): F15B11/16

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