GB733759A - Breakout table for use with a portable drilling rig - Google Patents

Abstract

733,759. Rotary earth-boring apparatus. FAILING CO., G. E. Oct. 20, 1953, No. 28945/53. Class 85. In a portable drilling rig comprising a frame, 2 mounted on a motor vehicle chassis and having spaced guide rails 3, 4 on which a drill head 5 can slide forwardly into the drilling position or be retracted to allow the drill pipe 15 to be lifted from the bore hole, the drill head incorporates a pipe rotating mechanism 6 positioned between hydraulic cylinders 9, 10 the piston rods 11, 12 of which are connected by a crosshead 13 which bears on the top end of a drive rod 14 passing through and rotated by the mechanism 6, the rod 14 carrying a removable chuck at its lower end which grips the drill pipe to rotate the latter whilst it is under downward pressure from the crosshead. To uncouple the stands of drill pipe when the pipe is pulled from the hole a breakout table 17 is provided which utilises the drive from mechanism 6. The table consists of a hollow T-shaped body 18 which is hingedly connected to frame 2 by links 37 so that it can be lifted from the horizontal drilling position shown to an upper position for stowage during transport or lowered to a position clear of the borehole to allow casing to be run, the body housing a rotary element 21 having an axial bore 51 through which the drill pipe extends when drilling and into which roller-type pipe slips 53 can be inserted when the pipe is to be held for uncoupling. A chain 63 connects member 21 to a driving member 33 consisting of a sleeve 66 having upstanding lugs 76 which are engaged by similar lugs on a fitting attached to the drive rod 14 after the drill pipe chuck has been removed therefrom. During drilling, the drive rod 14 is positioned axially over the drill pipe 15 which extends through member 21. When the pipe is to be lifted, the rod 14 is uncoupled by reversal of the drive mechanism after a pawl 85<SP>1</SP> has been engaged with ratchet lugs 86 formed on member 21 to prevent backward rotation of the latter. The drill head is then retracted and the drive rod connected to member 33. The pipe 15 is lifted by a derrick and tackle, the slips 53 being engaged at the first joint 16 which is then unthreaded by rotating the drive rod 14 and members 33 and 21, suitable tongs being applied to the stand of drill pipe to prevent rotation. The lifting tackle is then coupled to the next stand and the operation repeated until the last stand has been removed.