Multistage telescope boom
AssigneePalfinger AG
InventorEckhard Wimmer
Life of this patent
Estimating the term…
Abstract
A multistage telescopic boom or jib, in particular for a loading crane on a truck, has hydraulic units each including a piston and a cylinder arranged between the successive, telescopically nested arms. A pipe projects axially from the bottom of the cylinder into the chamber of the cylinder, sealingly extending into the hollow piston rod when the piston is retracted and sealing the chamber of the cylinder from an inner chamber of the hollow piston rod. In order to ensure an automatic extension sequence of the telescopic arms, the inner chamber of each hollow piston rod is linked to the cylinder chamber of the next outer hydraulic unit by a preferably rigid line, and the inner chamber of each hollow piston rod communicates with the cylinder chamber of the same hydraulic unit when the piston is fully extended.
Claims20
A multistage telescopic boom comprising:
- a plurality of arms including a non-telescoping longitudinally innermost arm and plural, successively longitudinally outer arms each telescopingly nested within a respective precedingly inner arm and successively movable longitudinally thereof;
- plural hydraulic units connecting respective pairs of adjacent said arms, each said hydraulic unit achieving telescopic movement of an outer said arm of the respective pair of arms relative to an inner said arm thereof;
- each said hydraulic unit comprising a cylinder rigidly mounted on said inner arm of the respective said pair of arms, a piston slidable within an interior of said cylinder and dividing said interior into extension and retraction chambers receiving hydraulic fluid, and a piston rod fixed to said piston and fixed to said outer arm of said respective pair of arms, such that said piston rod and said outer arm are movable with said piston relative to said cylinder and said inner arm;
- said piston and piston rod of at least an innermost said hydraulic unit being hollow and having an inner chamber, and said cylinder of said at least said innermost hydraulic unit having mounted on a bottom wall thereof a pipe extending into said extension chamber thereof, said pipe sealingly fitting within said inner chamber and preventing communication between said extension chamber and said inner chamber when said piston and piston rod are only partially extended relative to said cylinder, and said extension chamber and said inner chamber being in communication when said piston and piston rod are fully extended relative to said cylinder, thereby enabling hydraulic fluid to pass from said extension chamber to said inner chamber;
- and
- a fluid line connecting said inner chamber of said piston and piston rod of said at least said innermost hydraulic unit to said extension chamber of said cylinder of the next outer said hydraulic unit;
- whereby hydraulic fluid can be passed to said extension chamber of said next outer hydraulic unit only after said piston and piston rod of said innermost hydraulic unit have fully extended the next outer said arm relative to said innermost arm.
Dependencies are inferred from the claim text.