Big Constructional Strength in
Page 29
If you've noticed an error in this article please click here to report it so we can fix it.
Exceptionalload Trailer
(\NE of the largest trailers to be built the works of Carrimore SixWheelers', Ltd.. North Finchley, London, N.12, has just been completed. It is a 30-tanner designed for a concentrated load of 25 tons, and has a fiatplatform no less than 30-ft. long and 10-ft. wide, the, wheelbase being 22 ft. and the loading height 3 ft. 3 ins.
It has been designed and constructed in fulfilment of an order received from W. H. Reay and Co., Ltd., Belfast, and it will be operated in the service of Harland and Wolff, Ltd.
There are eight wheels, those at the rear being arranged in tandem on two full-width axles, and those at the front being transversely positioned and mounted on two short rocking axles. Each carries twin solid tyres measuring 26 ins. by 6 ins.
The front axles support, through the medium of Woodhead trunnion-ended springs, a fore-carriage carrying a standard Carrimore turntable. Each rear axle has a pair of semi-elliptic springs-, the adjacent ends of those on each side, respectively, being shackled to a short rocking beam.
There are numerous points of interest in the construction of the vehicle. In studying these one must remember the big concentrated load and the considerable length of the trailer. Forming the main girders of the frame are six 10-in. by 3i-in. channels. Two of these run the full length at the extreme sides and the other four are arranged in two pairs, one over each spring line.
Considering one of these double longitudinals, we find that the two channels are placed back to back and spaced apart by 6 ins. Underneath, from the back of the turntable to the foremost rear-spring bracket, runs a 15-ft. truss. This is made from 6-in. by 3-in, channel, open side downwards, and is bent in three places. Connecting the truss with the longitudinal are five vertical struts of the same cross-section as the truss.
Strength, neatness and symmetry are permitted by this constructional scheme, for the struts and the ends of the truss fit between the two channels forming the main longitudinal. The struts serve the further purpose of carrying five of the main crossmembers. These are 'mounted under the longitudinals, and each is secured to the appropriate pair of struts.
There are actually 14 cross-members in all; in addition to the five mentioned already, there are at the ends two, of similar cross-section to the side members; above the bogie and above. the tarntable (two each) a further four, of the -same size as those under the main girders; and three small ones of which the positions are of lade note.
These last serve, together with a number of timbers, the latter including wooden runners placed along the tops of the low cross-channels; to support the 11-in. oak floor boards.
A similar principle is employed in the construction of the fore-carriage. There are twin channels forming each of the two longitudinals, and crossmembers of the same section (5 ins. by ,2 ins.). Snugly fixed between the two channels 61 each girder are the brackets for the Woodhead flat-camber springs, whilst the front ends are extended to carry the draw-bar; here again advantage is taken of the duplicated construction, which permits the hinged attachment to be effected with simplicity and strength, the two drawbar ends fitting between the channels.
Both rear-spring brackets, on each side, are accommodated and secured in the same manner, whilst each rockingbeam carrier is bolted symmetrically to the under sides of the two channels forming each main girder. The ends of the beams actually rise and fall between the channels, during part of their travel, and stops are provided to limit the angle of rock permitted. Incidentally, they are mbunted on Hyatt roller bearings, products of Delco-Remy and Hyatt, Ltd. The spring brackets are braced by two tubular ties running across the frame above the spring pins.
• Two Means for brake application are provided—a hand-wheel and screw gear on the side of the trailer and a molt'sstroke lever on the tractor. The lastnamed, we are informed,' will be a Scammell. From this a flexible encased cable runs through the hollow turntable }Aster block, to an idler lever giving a 2-to-I advantage. Thence rods convey the pull to a compensator, from which further encased cables transmit it to the centres of the second and third axles. Here are Bendix transverse compensating double-ended bell-cranks which constitute the final links in the hook-up.