GB727780A - Improvements in or relating to a portable well drilling structure - Google Patents

Abstract

727,780. Raising portable derrick masts. MOORE CORPORATION, L. C. July 9, 1953 (Oct. 18, 1952], No. 19062/53. Class 78 (4). The mast 10, 11 of a portable well drilling structure is raised about its foot 7 by a raising line 27 which first draws a pulley 32 on the mast level with a pulley 30 on the base 1 of the structure and then straightens a toggle brace 15 between the mast and the base. In the arrangement illustrated the pulleys 30, 32 are duplicated on opposite sides of the mast and the links 16, 17 of the toggle brace 15 each comprise a lattice frame, the link 16 being pivoted at 19 on the outsides of the legs 11 of the mast. The raising line 27 comprises a length of cable doubled over the hook 26 of the travelling block 21, each half of the doubled cable passing around a pulley 28 on the corresponding side of the mast, over the fixed pulley 30 and under the pulley 32 on the mast, to be secured to a bracket near the corresponding end of the hinge 18 of the toggle brace 15. The hinge 18 of the toggle brace 15 is disposed at the side of the brace adjacent the mast when erected so that the toggle links pass dead-centre immediately before the mast is erect and the weight of the mast then presses into engagement plates 34 secured to the ends of the links and locked together by bolts 35. When the mast is to be lowered the toggle brace is first broken by a line 37 as shown in Fig. 3 or by a line connected to a truck winch. An engine, draw works, and a rotary table 2 are carried on the base 1, which may form part of a vehicle. The feet of the mast and the toggle brace are pivoted on structures 6, 14 so that when the mast rests, in its reclining position, on a support 8 it clears the engine and draw-works.