New semi-trailers from Boden
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ANEW range of semi-trailers—Boden Mk.III—will be shown by Boden Trailers Ltd. at Earls Court this year. Although there will not be very much difference in the overall appearance of the units, the design has several interesting features.
The most noticeable of these is the redesigned rear end. This has the rear crossmember swept inwards and from the lower run of the main frame members there are two very substantial, tapered, channel-section bumper-bar supports. These are swept back so that the tubular bumper, which is 3.5 in. diameter, ranges level with the rear crossmember of the body.
Much of the redesigning of the new Boden is the result of experience gained from the failures that have been apparent when units produced by the company in the past have returned to the Baden repair shops. This is certain to help in producing an extremely reliable job, and when I visited the Royton, Lanes, works recently to see the new units, several points stood out as being worthy of mention.
Probably one of the most important sec tions of the new production system that is in the process of being developed is the manufacture of the fabricated main beams. These are machine-welded units made up from standard pressed-out web-plates and rolled high-tensile steel flanges. In this manner it is possible for the design of the beam to be altered according to the individual requirements of each semi-trailer made, within certain laid down standards.
Production of beams is carried out at the main factory. and because of a unique position that the Boden company finds itself in with regard to the steel supply, it is unlikely that the units will be left lying about in storage for long periods. Consequently, the paint finish on the trailers is of an extremely high quality, gained without the need for expensive de-rusting and scaling operations.
The main cross-members have been redesigned and they are of tubular section. Where they are joined to the main framewebs there are substantial secondary stiffen ings tied between top and bottom flanges. This, it is claimed, prevents fatigue fractures occurring in the main web adjacent to shackle brackets and also assists in preventing excessive twisting of the main frame assembly when the unit is cornering. To assist further in this direction, triangular webs are welded to the cross-bearers in the region of the neck of the trailer.
Stress diffusers are welded to the bottom flange of the frames at the location of the running-gear brackets in order to disperse fatigue stresses at these points.
Rubery-Owen running-gears are used on both the singleand tandem-axle units. In the case of the single-axle semi-trailers the braking equipment is 16.5 in. by 8.625 in. S cam-units, whereas on the tandem-axles 16.5 in. by 7 in. units are standard. All semitrailers in the range are fitted with threeline air-pressure systems. Tyre equipment is l0-20, 16 ply, on the single axles and 9.00-20, 14 ply, on the tandems.
Cross-members in the frame are of ro I-section and are pierced through the IT frames at 24 in. centres, welded only on vertical run. Cold-rolled rave-members new Roden design are welded to the en bearers, and as this is of a very narrow fla width a clear floor width of 7.75 ft achieved.
Roden two-speed, inverted-screw lanc gear is fitted and the semi-trailers carry completely separate wiring circuits to gu against lighting failure.
Boden states that new production meth have enabled considerable savings in ma facturing costs to be made—enough, in f to permit existing prices to be continued w out increase and in some cases even f( reduction in present prices.