GB738198A - Improvements in or relating to a well drilling structure - Google Patents

Abstract

738,198. Raising derrick masts. MOORE CORPORATION, L. C. March 30, 1953 [Sept. 5, 1952], No. 8693/53. Class 78 (4). A gin pole 16, Fig. 1, and welldrilling mast 10, 11, raised in succession by traction on a cable system joining them, carry co-operating rollers 30 and guides 31 (see also Fig. 4) so arranged that, during erection, the mast swings past its upright position to which it then returns under the action of gravity; the free return moment renders less critical the moment at which the traction must be removed. In the construction 'illustrated the mast .and gin pole are mounted on a base 1 in the manner described in Specification No. 738,195, to which the Specification refers, but the sling 21 for raising them passes directly from the travelling block 17 over pulleys 22 at the top of the gin pole to anchorages on brackets 24 carried by the mast. Operation of the draw works 3 first raises the gin pole to the position shown in broken lines in Fig. 1 in which guys 26 are taut, and then raises the mast until guides 31, Fig. 4, on the insides of the legs of the mast engage rollers 30 at the top of the gin pole. Continued tension on the sling 21 raises the mast to a position beyond its upright position so that the rollers 30 are at the lowest points of the guides 31. The mast then falls back to its upright position while the rollers 30 move up the portion of the guides 31 at the left in Fig. 4 during which motion the sling 21 is slackened so indicating to the draw works operator that the winding drum should be declutched. The mast and gin pole are secured together when erected by hinged bolts 33 carried on the mast and engaging slotted brackets 35 on the gin pole. When the mast is to be lowered a line is first attached to it so that it may be drawn beyond its upright position until the rollers 30 are in engagement with the longer portion of the guides 31 and the mast and pole are then lowered under the control of the draw works.