Power plants – Pressure fluid source and motor – Servo-motor having externally operated control valve sets...
Patent
1987-05-15
1988-12-06
Garrett, Robert E.
Power plants
Pressure fluid source and motor
Servo-motor having externally operated control valve sets...
60484, 60486, 212198, F16D 3102
Patent
active
047888202
ABSTRACT:
A hydraulic circuit for a large crane furnished with a counterweight carriage detachably connectable to the swivel unit of the crane. The hydraulic circuit includes first and second variable displacement pumps for supplying the working fluid to a hydraulic motor for driving the swivel unit and a hydraulic motor for driving the counterweight carriage, respectively, first and second control circuits including valves for controlling the respective discharge rates of the first and second variable displacement pumps, respectively, in accordance with a signal pressure provided by a third control valve for controlling the operation of the swivel unit and the counterweight carriage, a hydraulic circuit for joining the flows of the working fluid discharged from the first and second variable displacement pumps when the swivel unit is operated without the counterweight carriage, and a changeover mechanism for selectively changing the state of the first flow control circuit so that the discharge rate of the first variable displacement pump is regulated properly according to the operating condition of the swivel unit. The discharge rates of the first and second variable displacement pumps are regulated so that the counterweight carriage is driven for movement in perfect synchronism with the swivel motion of the swivel unit.
REFERENCES:
patent: 1943196 (1934-01-01), Ward
patent: 4203290 (1980-05-01), Burckardt
patent: 4529094 (1985-07-01), Wadsworth
patent: 4599855 (1986-07-01), Seelman
patent: 4614275 (1986-09-01), Zenno
patent: 4627238 (1986-12-01), Mayr et al.
Mobilhydraulik, Load-Sensing-Ventile zur Optimierung Hydraulischer Systeme, Von Dipl-Ing. E. Weschenfelder, dhf 3/87, p. 66.
Load-Sensing in der Mobilhydraulik, Grundlagen, Eigenschaften und Einsatzgrenzen, 1986, pp. 916, 918, 919.
Hidaka Sachio
Sakai Hiroaki
Garrett Robert E.
Kabushiki Kaisha Kobe Seiko Sho
Williamson Mark A.
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