Patent GB-815340-A (GB)
Title: Spudding mechanism
IPC: E21B1/02
Filed: 1957-01-07
Abstract: 815,340. Fluid-pressure engines. RUSTONBUCYRUS Ltd. Jan. 7, 1957 [March 28, 1956], No. 568/57. Classes 122 (2) and 122 (3). [Also in Groups XXI and XXIX] A reciprocating drill comprises a fluid-pressure actuated reciprocating motor 48 connected to a drill tool 56, a fluid conduit 65 connecting a source 32 of fluid to a valve 60 having an exhaust port 69 and actuated by fluid pressure to connect the motor to the source or to the exhaust port, fluid conduits 119, 122, 123 connecting a pilot valve 101 to the valve 60, means responsive to movement of the tool to move the valve 101, and a throttle valve 129 in an exhaust conduit 128 leading from the valve 101, the valve 101 directing exhaust from the valve 60 through the throttle valve during tool raising so that the setting of the throttle valve determines the rate of movement of the valve 60 and the length of the stroke of the drill tool. A frame 18 carries a telescopic derrick 22, and a pump 29 driven by belt and pulley 27, 26. The shaft driving the pump drives through gearing and clutches a sand reel (not shown) and a winch drum 28. A cable 49 fixed to the winch drum extends around pulleys 50, 52 and over the crown pulley 54 to the drill tool 56. The pump is interposed in the conduit 65 and an outlet conduit 68 leads from the port 69 to the source. The motor 48 is fixed to the frame and comprises a piston 62 working in a cylinder 61 connected to the valve 60. The pulley 50 is fixed to the frame and the pulley 52 is carried by a crosshead 71 reciprocated by the piston and guided by the conduits 65, 68. A cam 118 on the crosshead moves the spool 103 of the valve 101 against a spring 107, the cam being rendered inoperative by raising a lever 114. When the piston is in its uppermost position the drill tool is in its lowermost position. With the piston in its uppermost position and the lever raised, fluid from the source passes from conduit 65 through port 66 and passage 91 in valve 60 then, since cylinder below the piston is filled with fluid, through passage 93 and port 69 and conduits 68 back to the source. A valve 94 within the valve 60 is moved by the fluid and causes a back pressure to be set up in the conduit 119. In view of the setting of the spool 103 the back pressure acting through conduit 123 tends to keep the spool 88 of the valve 60 in the position shown. When the lever is lowered the cam moves the spool 103 downwardly so that the back pressure is applied through the conduit 122 to move the spool 88 to the right, the fluid from the right of the spool passing through conduit 123 to discharge back to the source through conduit 126. Fluid from the source then enters port 66, flows into the cylinder to move the piston downwardly to raise the drill tool, fluid from below the piston exhausting through the conduit 77, port 92, passage 93, port 69 and conduit 68. After a short movement of the piston, the cam 118 disengages and spool 103 returns to the position shown so that fluid from the conduit 119 passes through the conduit 123 to move the spool 88 towards the position shown. Fluid from the left of the spool 88 passes through conduit 122 and valve 101 to exhaust through conduits 128. Adjustment of the throttle valve 129 in the conduit 128 determines the rate of movement of the spool 88 to the left and the stroke of the drill tool, greater valve resistance resulting in a longer tool stroke during a longer time. As the land 88c blocks the passage 86 the movement of the tool is spent and the tool commences its down stroke. When the position of the spool. 88 shown is reached the tool lowers under gravity, the piston and its associated elements being supported by the pressure of the fluid below the piston and this pressure being dependent on the setting of the valve 94. As the piston moves to the top of its stroke the cam 118 moves the spool 103 downwardly so that the back pressure in conduit 119 causes the spool 88 to move rapidly to the right since fluid from port 90 is discharged through conduit 126 without restriction. The resultant quick diversion of flow into the upper part of the cylinder results in quick removal of tool from the bottom of the hole. When the length of cable becomes excessive due to fouling of the tool in the hole the cable tension is zero and the pressure of fluid is insufficient to raise the piston due to the setting of the valve 94 so that drilling stops. An. adjustable relief valve 136 placed between the conduit 65 and the source may be used to stop and start the drill as a supplement or in place of the lever. In a modification in which the piston and drill reach the top of their strokes together, the crown pulley is reciprocated by an inverted motor and the cable passes directly from the winch over the crown pulley to the drill.