| CPC E02F 9/2203 (2013.01) [E02F 3/43 (2013.01); E02F 9/2221 (2013.01); E02F 9/2225 (2013.01); F15B 11/163 (2013.01); F15B 21/14 (2013.01); F15B 2211/20515 (2013.01); F15B 2211/30525 (2013.01); F15B 2211/30535 (2013.01)] | 20 Claims |
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1. A construction machine comprising:
a first implement function operable by a first actuator;
a second implement function operable by a second actuator; and
a hydraulic system for controlling the first and second actuators in response to operator controls, the hydraulic system comprising:
a four-quadrant open-circuit pump;
a pressure line connected with the pump to be pressurized by the pump;
a tank line in communication with a fluid reservoir;
a first circuit including a first directional flow control valve in command of the first actuator to control the first implement function;
a second circuit in parallel with the first circuit, the second circuit including a second directional flow control valve in command of the second actuator to control the second implement function; and
a load sense line,
wherein the first circuit includes a disabled pressure compensator that is incapable of performing pressure compensation between the load sense line and the first directional flow control valve, and
wherein the load sense line is connected to the second directional flow control valve with a pressure compensator.
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15. A method of controlling a construction machine, the method comprising:
driving a variable displacement pump with a prime mover to charge a pressure line of a hydraulic system having a first control valve with an extend position configured to selectively connect a first actuator for a first implement function to the pressure line and a second control valve with an extend position configured to selectively connect a second actuator for a second implement function to the pressure line;
setting the second control valve into the extend position, and providing load sensing with a pressure compensator to throttle flow through the second control valve while extending the second actuator;
setting the first control valve into the extend position, and providing load sensing solely by control of the variable displacement pump without any pressure-compensating throttling of flow through the first control valve, while extending the first actuator; and
maintaining the first control valve in the extend position in which energy is recovered by the prime mover through the pump while retracting the first actuator.
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