Hydraulic Activation for a Sliding Carriage

Abstract

A hydraulic system for moving a carriage guided for movement along a linear path by a support frame, such as a backhoe or an excavator. The system comprises two hydraulic jacks, each having a cylinder body and a piston rod. The cylinder bodies of the two jacks are joined to one another, the end of the piston rod of one jack is connected to the support frame and the end of the piston rod of the other jack is connected to the carriage. In the invention, the two piston rods project from the same side of the joined cylinder bodies and in each end position of the carriage, the piston rod of a respective one of the jacks is extended while that of the other jack is retracted.

1 . A hydraulic system for moving a carriage along a linear path by a support frame, the system comprising
 two hydraulic jacks, each having a cylinder body and a piston rod, wherein the cylinder bodies of the two jacks are joined to one another,   the end of the piston rod of one jack is connected to the support frame and the end of the piston rod of the other jack is connected to the carriage; and   the two piston rods project from the same side of the joined cylinder bodies and in each end position of the carriage, the piston rod of a respective one of the jacks is extended while that of the other jack is retracted.   
     
     
         2 . A hydraulic system as claimed in  claim 1 , wherein the joined cylinders are provided with a projecting pin engaged in a slot in a guide movable with the carriage to prevent misalignment between the axes of the piston rods and the cylinders when under load. 
     
     
         3 . A hydraulic system as claimed in  claim 1 , wherein the two jacks have strokes of unequal length and the second piston rod is connected to the side of the carriage that is nearer to the side of the frame to which the first piston rod is connected. 
     
     
         4 . A hydraulic system as claimed in  claim 3 , wherein a fixed shield is mounted on the frame to protect the piston rod of the longer hydraulic jack when it is extended. 
     
     
         5 . A hydraulic system as claimed in  claim 3 , wherein a shield is fixed to the part of the longer hydraulic cylinder that projects beyond the shorter cylinder to protect the piston rod of the short cylinder when extended. 
     
     
         6 . A kingpost assembly comprising
 a carriage and guiding support frame   a hydraulic system arranged for moving the carriage along a linear path by the support frame, the system comprising two hydraulic jacks, each having a cylinder body and a piston rod,   wherein the cylinder bodies of the two jacks are joined to one another, and