Patent ID: 7325398

Claim:
A closed circuit hydraulic system for a work vehicle, comprising: a hydraulic cylinder, the hydraulic cylinder having a first chamber and a second chamber; a bidirectional variable displacement hydraulic pump, the bidirectional variable displacement hydraulic pump in fluid communication with the hydraulic cylinder, the bidirectional variable displacement hydraulic pump selectively pumping and directing to the first chamber to extend the hydraulic cylinder and to the second chamber to retract the hydraulic cylinder, the hydraulic cylinder extending against a weight, the hydraulic cylinder retracting under the weight; an accumulator in flow communication with the first chamber, the accumulator storing fluid from the first chamber during a retraction of the hydraulic cylinder under the weight and releasing the fluid as a supply to the bidirectional variable displacement hydraulic pump during an extension of the hydraulic cylinder; and at least one flow control valve for relieving hydraulic pressure between the bidirectional variable displacement hydraulic pump and the hydraulic cylinder, wherein the bidirectional variable displacement hydraulic pump is in direct communication with the first chamber and with the second chamber, the bidirectional variable displacement hydraulic pump is in direct communication with the first chamber and with the second chamber and the pressure relief valve includes an electro-hydraulic override.