Patent ID: 6050430
Filing Date: 2000-04-18
Classification: B66C,F15B

Abstract:
A system for raising and lowering a counterweight, comprising:at least a primary and secondary cylinder connected in series hydraulic communication;said primary cylinder including a first rod connected to a first piston, said first rod for being attached to one end of a counterweight; andsaid secondary cylinder including a second rod connected to a second piston, said second rod for being attached to another end of said counterweight, a surface area of a bottom of said second piston equal to a surface area of a top of said first piston;fluid carrying lines for supplying and exhausting hydraulic fluid from said primary and second cylinders and for providing fluid communication between said primary and second cylinders;regulating valves disposed in said fluid carrying lines for regulating a flow of said hydraulic fluid; andleveling valves, disposed in said fluid carrying lines, permitting said second rod to fully extend if said first rod fully extends prior to said second rod, permitting said first rod to fully extend if said second rod fully extends prior to said first rod, permitting said second rod to fully retract if said first rod fully retracts prior to said second rod, and permitting said first rod to fully retract if said second rod fully retracts prior to said first rod.