Patent ID: 7444808

Claim:
Hydraulic system, comprising at least one hydraulic drive means ( 1 ) structured and arranged to be coupled to a load ( 6 ) to move the same, a conduit system ( 10 ) connected to the hydraulic drive means ( 1 ) for conveying hydraulic liquid to and from the hydraulic drive means ( 1 ), the conduit system comprising a single pump ( 12 ) having a first outlet connected to a first port of said hydraulic drive means ( 1 ) by a first passage and a second outlet connected to a second port of said hydraulic drive means ( 1 ) by a second passage, and structured and arranged for generating a flow of hydraulic fluid in the conduit system ( 10 ), and a motor ( 13 ) structured and arranged to power the pump ( 12 ), wherein the pump ( 12 ) is structured and arranged to control the flow of hydraulic liquid in said passages, the hydraulic drive means ( 1 ) is structured and arranged to be controllable substantially only by controlling the flow of hydraulic liquid in said passages by the pump ( 12 ), a single valve ( 15 ) is positioned in only one of said first and second passages and structured and arranged to fix the hydraulic drive means ( 1 ) in position when closed, with the other of said first and second passages being devoid of a valve, said single valve ( 15 ) being positioned in only said first or second passage without intervening conduit lines being joined to said first or second passage between said single valve ( 15 ) and hydraulic means ( 1 ), and said single pump ( 12 ) has only two outlets and is structured and arranged to (i) pump fluid in one direction to the hydraulic means ( 1 ) through said single valve ( 15 ) to move the load ( 6 ) coupled to the hydraulic means ( 1 ), and (ii) receive energy from the load ( 6 ) through the hydraulic means ( 1 ) causing fluid to flow in an opposite direction through said single pump ( 12 ) and transfer this energy to said motor ( 13 ).