Sixty Tons on Pneumatics
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THE highest-capacity load-carrying trailer so far constructed on pneumatic tyres by The Eagle Engineering Co., Ltd., Warwick, has just been completed to the order of ,Messrs, Sir Robert MacAlpine and Sons. Of the 16-wheeled drop-frame type, it has been designed for the transport of heavy machinery, power-station plant, excavators, and similar loads up to a maximum of 60 tons, which, with its own weight of approximately 161 tons, gives a total maximum of about 761 tons.
The frame consists of three main longitudinal members of twin I5-in. by 4-in, rolled-steel channel, plated top and bottom; these longitudinals are well braced by cross-members. The whole structure is electrically welded throughout and the longitudinals extend to provide a sliding housing for the detachable rear bogies. At the front, the outside frame members are built up in crank form. The forecarriage is also built up from rolled-steel channel members electrically welded to cross-members.
For steering purposes, the forward eight wheels turn as a unit, the turntable being arranged to provide a 90degree lock in either direction. The drawbar is built up of rolled-steel channels.
As will be seen from the illustrations, the 16 detachable steel disc wheels, which have 13.50-in. by 20-in. low-pres surepneumatics, are disposed in two lines of four at front and rear. In each case four-wheeled bogies are employed in tandem form. Each bogie is carried on a transverse tubular shaft, which allows the forward pair of wheels to rise and fall in relation to the rear pair, and vice versa; in addition, the axle carrying each pair of wheels is pivotally mounted on a balancer, so that each pair is also free to rock.
For loading purposes, the rear bogies are readily detachable the ends of the transverse tubular shafts which carry them being built up to fit into sockets formed by the extended longitudinals. Twenty-ton manual jacks are provided to take the weight of the rear end of the frame when the bogies are withdrawn and to allow the rear of the trailer to be lowered to the ground for loading, In addition, two 6-ft. loading ramps are permanently mounted at the rear of the loading platform, for relatively light loads.
Girling brakes with 16-in.-diameter drums are fitted to all eight rear wheels and to the forward row of the front wheels. They are operated by a pres
sure system working at 80 lb, per sq. in, with a separate pressure cylinder for each axle. The system is of Clayton Dewandre design and fneorporates airpressure couplings of the Westinghouse type, the whole system tieing coupled by a convenient pipeline to the towing vehicles.
The overall length, including drawbar, is 47 ft. 81 ins., with a mean wheelbase of 32 ft., whiht the wheelbase of each bogie is 3 ft. 2 ins, The front deck above the forecarriage measures 12 ft by 9 ft., and the loading deck 19 ft, 6 ins by 9 ft.
The latter is boarded with 3-in.-thick oak planks laid longitudinally and flush with the main frame members, this loading deck being 2 ft. 3 ins, from the ground at the front and 2 ft. 1 in. at the rear. Above the forecarriage, the platform is boarded with 11-in.-thick oak boards