GB1409888A - Temporary mast structure - Google Patents

Abstract

1409888 Erecting masts D S D DILLINGER STAHLBAU GmbH 20 Dec 1972 [30 Dec 1971] 58720/72 Heading B8B [Also in Division E1] A temporary readily dismantlable mast structure comprising a mast composed of individual sections 1 connected end-to-end and steadied by guy ropes 5 has a mast base acting as a guide frame 4 for a mast section lifting and lowering carriage 24 permitting vertical movement of an amplitude greater than the length of any individual mast section, the lifting carriage being adapted for attachment around each mast section near its lower end and the mast base or guide frame having at the top a guide 50 through which they pass and by which they are guided as they are raised or lowered. As shown the lifting carriage is tubular and is guided by flanged wheels 27 running on rails 21 welded to three uprights 20 of the guide frame 4. The uprights 20 are joined by a base-plate 16, two spaced top plates 22 and by transverse struts 23 arranged on only two of the three sides of the base, so enabling the insertion of mast sections 1 into the frame 4. The top plates 22 support the mast section guide 50 which is formed with an internal throat and the whole lifting carriage guide frame which is held upright by guys 8 is mounted (see Figs. 3, 4, not shown) by a spherical knuckle (14) on the baseplate 16 engaging a seat (13) on a ground plate 3, mast rotation being prevented by a pair of screws (17) passing through the base-plate 16 to engage the ground plate. To extend the mast, the bottom mast section 1 is connected at its bottom end by a removable bolt 36 to the lifting carriage 24 which is then raised by a cable 29 connected to opposite sides of the carriage and passing over a pair of pulleys 30 on the top plate assembly round a movable pulley 31 secured to a cable 32 wound on a winch 34. A further mast section is then placed within the lifting carriage guide frame and its reduced section connecting piece 40 is inserted into the bottom of the preceding section so that a pivoted latch 44 within the lower section engages over the bolt 36, the mast sections seating one upon another. The mast is then lowered by a small downward movement of the carriage on to a centring piece 19 and the bolt 36 is then withdrawn, freeing the carriage for return to its lowest position so that the operation can be repeated. To support the extended mast, clamping rings 6 (see also Fig. 7, not shown) and supporting guys 5, which can be adjusted by winches 7 during the raising of the mast, are added at intervals. To lower the mast a bolt 36 is inserted into bores in the carriage 24 and in the bottom but one mast section at a point above the latch 44 of the bottom section 1, so that by raising the carriage the bottom section remains on the centring piece 19 whilst the rest of the mast is raised. The mast which may be of aluminium is also provided with a top section 48, which is independently attached to the first mast section from above the guide frame 4 through the guide 50, and may include a ladder 10 and a crows nest 11.