GB578029A - Improvements in masts - Google Patents

Abstract

578,029. Aerial masts. MARCONI'S WIRELESS TELEGRAPH CO., Ltd., and AINSLEY, F. J. June 9, 1944, No. 11084. [Class 40 (v)] [Also in Groups I and X] A mast assembly includes the mast 1 itself, provided with a foot member 2 (Fig. 1), and a base-plate 6, a spigot 5 centrally supported on the base-plate against lateral movement disposed between the foot member 2 and the baseplate 6 and at least one centrally apertured washer 4 of wedge - shaped cross - section mounted on the spigot, the arrangement being such that by rotation of the washer or washers 4, the angle which the mast makes with the base-plate may be adjusted. In the example described there are two washers 4, 4<1>, relative rotation of which enables the mast to be adjusted into a vertical position when being erected upon uneven ground. The base-plate 6 rests upon a tubular cross-piece 7 which receives base-tubes 10 and rests upon a locating plate 28. The foot member 2 whose top surface is sloped outwards to run off rain water, is of insulating material and is spaced from the wedge-shaped washers 4, 4<1> by a plate washer 23 and a lead washer 24. A bolt ring 12 is spaced from the foot member 2 by a lead washer 25 and is tightened down on the latter by the nuts of four bolts 8. The lowest of the four sections of the mast is received in an insulator bush 3 and the joints between sections are of tapered socket form with collars 29, 30 slightly spaced away from the joint to co-operate with a parting tool when taking down the mast. The stay pegs 11 which according to the Provisional Specification also form the earth connection are electrically bonded at 17 to the tubes 10 and the mast sections are bonded to each other at 14. In carrying out the levelling adjustment, keying marks k (Fig. 10), situated at the thickest and thinnest portion of each of the washers 4, 4<1> are brought together, thus making the outer horizontal surfaces of the pair of washers parallel. The washers are then rotated together in the same direction, keeping the marks k coincident until the horizontal projection of the inclined mast is at right angles to the line joining the two pairs of marks k. The washers are then rotated by equal amounts in opposite directions until the mast is truly vertical. Rotation of the washers 4, 4<1> is effected by means of towing bars engaging the recesses rc, rd. The mast may be one of four forming a directional wireless aerial system (Fig. 9) having stay wires 15 and a vertical sense aerial 16. When erecting the system, the four corners of the square locating the positions of the masts are set out by means of a triangular chain arrangement. The masts are then erected by hand using the tubes 10 as levers, the stay wires 15 and sense aerial 16 being secured previously to the masts.