Patent ID: 7703616
Filing Date: 2010-04-27
Classification: B66C,E02F,F15B

Abstract:
1. A telescopable sliding beam comprising: a sliding beam box; at least one first sliding beam and one second sliding beam, where one of the first sliding beam and the second sliding beam telescopes into the other of the first sliding beam and the second sliding beam, the first sliding beam being mounted in the sliding beam box such that it can be telescoped out, the beams adapted to telescope out by first telescoping out the first sliding beam, and when the first beam has telescoped out to a desired point, telescoping out the second sliding beam, the beams being further adapted to retract backward by first retracting the second sliding beam to a desired point, and then subsequently retracting the first sliding beam; a first hydraulic cylinder connecting the first sliding beam to the sliding beam box, the first hydraulic cylinder having a barrel with a cap-ended extension chamber on a first side of a piston and a rod-ended retraction chamber on a second opposing side of the piston; a second hydraulic cylinder connecting the second sliding beam to the first sliding beam, the second sliding beam mounted in the first sliding beam, the second hydraulic cylinder having a barrel with an cap-ended extension chamber on a first side of a piston and a rod-ended retraction chamber on a second opposing side of the piston; and a pressure sequence control system where the first sliding beam and the second sliding beam telescope out in sequence upon reaching a pressure preset, wherein the pressure sequence control is implemented by hydraulic valves, and wherein one of the hydraulic valves will open when a limit pressure preset at said one of the hydraulic valves is reached, the pressure sequence control system including: a first oil supply conduit coupled to the extension chamber of the first hydraulic cylinder, an extension conduit coupling the extension chamber of the first hydraulic cylinder with the extension chamber of the second hydraulic cylinder, a first hydraulic valve being a sequence valve arranged between the extension chamber of the first hydraulic cylinder and the extension chamber of the second hydraulic cylinder, disposed within the extension conduit, a second oil supply conduit coupled to the retraction chamber of the second hydraulic cylinder, a retraction conduit, coupling the retraction chamber of the second hydraulic cylinder with the extension chamber of the first hydraulic cylinder, and a second hydraulic valve being a sequence valve arranged between the retraction chamber of the second hydraulic cylinder and the retraction chamber of the first hydraulic cylinder, disposed within the retraction conduit.