TRAILER MERITS from the
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'With its Low-loading Line and Absence of Obstructions, the Trailer Offers Extensive Scope for the Design of Efficient and Attractive Bodywork
THERE appears to be no limit to the uses to which the trailer may be put. It is made in all load capacities, is designed as an independent or articulated unit and is fitted with all varieties of bodywork.
The four-wheeled trailer may be regarded as the original pattern, from which all modern types have been evolved. Definite progress in design became possible when the trailer body was mounted in a similar manner to that of the motor body, that is, on a steel chassis with pneumatic tyres.
• With the trailer, the axles may be placed so that the load is evenly distributed over both of them. When they are close to the ends of the vehicle, there is plenty of space between the axles for a side doorway.
The height of the floor in front is determined by the diameter of the from wheels and wing clearance, as represented by the tUrntable. Behind this point the height of the floor may be reduced by cranking the side members of the chassis. If an extralow loading line be desired, the rear axle may also be cranked.
A low floor line with a large side opening is a desirable combination for a horsebox. The horges may face the rear, where the grooms' compartment is situated, with the wheelarches concealed under seats or lockers, Aids to Unloading.
This kind of doorway has not the same advantages in the case of a double-deck livestock vehicle, unless the rear portion of the lower deck be narrower than the front and built between the wheels. For a large boxvan, however, a low and wide side doorway often facilitates unloading.
The opening may have a drop side, which forms a ramp, with hinged or
sliding doors or a roller shutter above it. Sliding doors may run either inside or outside the body. The inside door requires a casing for its' reception, so that it does not obstruct the load. On the other hand, the outside door, although saving an inch or two of overall.. width, is more liable to damage unless the panels be recessed for it.
Small two wheeled trailers serve a wide range of purposes, functioning, for example, as a goods-carrying tender to a car taxed according to its horse-power rating. These trailers are used for market work of all descriptions, including the conveyance of livestock. The body is built between the wheels and there are no wheel-arches.
Although there is a good demand for a stock size of trailer chassis, no difficulty is experienced in obtaining a chassis which is specially designed for a special body. Main and subframes are made to the dimensions specified, and simplify the construction of the lower part. of the body and its mounting.
The construction of motor vehicles with body and chassis combined (instead of as separate superimposed units) has often been advocated as a means for increasing strength and saving weight. This idea has been put into practice in a few instances, but further development in this direction is hampered, because this form of construction tends to restrict the variety of bodywork which may be built on a standardized foundation.
There should, however, be greater scope with the trailer for this method of integral construction, owing to the fact that there is more opportunity for designing it throughout to individual requirements, also less financial outlay is involved.
The reasons advocated for streamlining the motor vehicle also apply , to the trailer. It may be pointed out that wind resistance is less important because the trailer is shielded by the tractor, but, in many instances, the trailer is much higher and a sloping or curved front introduced into the upper part of the body reduces windage.
For some time the fronts of semitrailers have been semi-circular in plan. The centre of this semi-circle is approximately that of the turntable. This design has the practical advantage that, apart from lessening wind resistance, the front of the liody conforms with the turning radius and reduces the amount of clearance necessary between the tractor and trailer.
Much development has taken place during the past few years in twowheeled trailer design, owing to the increasing demand for caravans. The ingenuity displayed in the details of their appointments should suggest ideas for improving the equipment and fittings of the goods trailer.
Like the caravan, the travelling shop, also the mobile showroom and other vehicles designed for the commercial representative, require bodywork with compactly arranged fitments.
Good Headroom, Low Height.
The trailer, with its low-loading line, allows the body to have standing headroom without uridue overall height. If the two-wheeled type be utilized, there may be a central gangway at a low level throughout.
This arrangement is an advantage in a mobile shop. By its use, there is as little difference as possible between the height of the floor of the shop and that of the ground, with the result that the counter is at a convenient level for the customer standing outside. The panels of the near or off side are hinged, so that the upper portion is raised to form a canopy and the lower part hinges down to become a counter. The whole of the side of the body opens in this manner, or a portion of it is set apart for a showcase.
The surface of the outside counter is flush with the top of an inside counter, under which there are shelves and drawers, with similar fittings at the ends and on the other side of the body. The entrance is at the rear.
For the commercial traveller, a box-type body about 3 ft. 6 ins, wide may be built between the wheels. Access to it is provided from each side. A wider body built over the wheels has a similar means for access.