Patent ID: 6094910
Filing Date: 2000-08-01
Classification: E21B,F15B

Abstract:
An apparatus for a derrick, comprising:at least one hydraulic piston/cylinder arrangement, the hydraulic piston/cylinder arrangement including a cylinder and a piston, said cylinder including a lower cylinder chamber and an upper cylinder chamber, said lower and upper chambers being separated by said piston, said piston including a piston rod, said piston including a lower surface facing said lower chamber and an upper surface facing said upper chamber, said lower surface including an area being different from an area of said upper surface,a yoke coupled to said piston rod of the hydraulic piston/cylinder arrangement adapted for being raised and lowered upon actuation of the hydraulic piston/cylinder arrangements,guide rails connected to the derrick, said yoke being adapted to travel on said guide rails,a hydraulic system for operating said piston/cylinder arrangement, said hydraulic system including:a reservoir,at least one main pump, said pump including inlet and outlet ports for supplying a hydraulic fluid pressure to said piston/cylinder arrangement,a valve system for control of said hydraulic pressure to said lower cylinder chamber and said upper cylinder chamber, respectively, including at least one cylinder control valve having a plurality of ports, said cylinder control valve having various modes of operation, said cylinder control valve opening and closing communication between said ports in said various modes of operation to selectively establish connection between:(1) said lower chamber of said cylinder and said outlet port of said main pump and between said upper chamber of said cylinder and said inlet port of said main pump for normal raising of said yoke; and between said lower chamber of said cylinder and said inlet port of said main pump and between said upper chamber of said cylinder and said outlet port of said main pump for normal lowering of said yoke;(2) said lower and upper chambers of said cylinder, and between said chambers and said inlet port of said main pump, for rapid lowering of the yoke; and(3) said lower and upper chambers of said cylinder, and between said chambers and said outlet port of said main pump for rapid raising of the yoke;said cylinder control valve including a first port, said hydraulic system including a first line for connecting said first port with one of said inlet port and said outlet port of said pump;said cylinder control valve including a second port, said hydraulic system including a second line for connecting said second port with one of said inlet port and said outlet port of said pump;said cylinder control valve including a third port, said hydraulic system including a third line for connecting said third port with said upper chamber;said cylinder control valve including a fourth port, said hydraulic system including a fourth line for connecting said fourth port with said lower chamber;said cylinder control valve adapted for selectively connecting said first port with said third port and said second port with said fourth port for the normal raising and lowering of said yoke;said cylinder control valve adapted for selectively connecting said second port, said third port and said fourth port with each other for the rapid raising of said yoke; andsaid cylinder control valve adapted for selectively connecting said first port, said third port and said fourth port with each other for the rapid lowering of said yoke.