Patent ID: 7448310
Filing Date: 2008-11-11
Classification: F15B

Abstract:
1. A hydraulic cylinder comprising: a sleeve cylinder, stationary between extended and retracted positions, for substantially defining a second hydraulic fluid chamber; an internal cylinder, substantially retained within the sleeve cylinder, for substantially defining a first hydraulic fluid chamber; a piston having a piston rod, substantially retained within the sleeve cylinder, and a piston cap, substantially retained within the internal cylinder; an inner portion, substantially defined between the piston cap and an internal cylinder piston rod gland, and adapted to displace the sleeve and internal cylinder to the retracted position upon being filled with hydraulic fluid, to thereby deliver a second power stroke; a first fluid connection for hydraulically connecting to the first and second chambers; a second fluid connection for hydraulically connecting to the inner portion; and a hydraulic system for alternately pressurizing one of the first and second fluid connections while venting the respective other of the first and second fluid connections, so as to effect displacement of the internal cylinder between the extended portion and the retracted position; wherein the internal cylinder is adapted to be displaced to the extended position to deliver a power stroke upon filling either the first or second hydraulic chambers with hydraulic fluid, and wherein the first fluid connection comprises a sequence valve including an operative state for detecting a predetermined pressure in the first chamber and, upon detecting the predetermined pressure, opening the valve to pressurize the second chamber.