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THE LOW LOADING-LIN 'OR GOODS TRANSPORT.

28th December 1926
Page 50
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Page 50, 28th December 1926 — THE LOW LOADING-LIN 'OR GOODS TRANSPORT.
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Reasons Why the Low-built Chassis, a Will Soon be Popular for Other PI Avoiding the Use of Whzel-arc

ent Used Mainly for Passenger Vehicles, i. The Influence of the Loading Bay.

• Reducino, Obstruction by Them.

THE use of a low loading-line for passenger vehicles has grown in favour rapidly during the last year or two. By reducing the height of the floor, entry and exit are rendered easier and safer, the centre of gravity is brought closer to the ground, the overall height is lessened and the general appearance is improved. Any one of these advantages is of sufficient Importance to justify the preference shown for the low chassis; taken collectively, they form an irresistible Floor Height Related to Wheel Diameter.

The low loading-line, however, is not a feature which is of value only in connection with buses and coaches, because its superiority becomes at once evident when adopted for most classes of goods transport. With the passenger vehicle it is customary for the height of the chassis to determine the height of the floor, but, with a van or lorry, the position of the floor is often controlled by the diameter of the hind wheel, because the wheel-arch must be eliminated. If the hind wheel is 3 ft. nigh, the clearance above it 8 ins, and the thickness of the bottom frame 2 ins., the floor is 3 ft. 10 ins. off the ground. Many commercial vehicles have a floor height exceeding 4 ft. Not only is the floor relatively high, but it has to be supported on deep cross-bearers, which add considerably to the weight of the bodywork.

Advantages and Disadvantages of the Wheel-arch.

It is thought, however, that when commercial vehicles are built with an uninterrupted floor space it is often an instance of following a conventional style rather than a necessity arising from the class of goods carried. It is, of course, more convenient when made in this way, especially when the van is loaded and unloaded from the back, but it is a question whether this simplicity is not bought too dearly. The floor of the body mounted on the conventional-type chassis could often be six, eight or even twelve inches lower if the body were mounted directly on top of the chassis. Every package has to be lifted to and from the floor level, and this operation is repeated a hundred times during the working week.

Loading Bays and Floor Height.

Loading bays may facilitate these operations, but usually this only reduces the labour expended at the warehouse, and not when the goods are being delivered. The presence of these loading bays, no doubt, has an influence on the floor height of railway and general delivery vans, milk vans, coal lorries and so on, but it is a factor which should not be allowed to control unduly the design of the commercial-vehicle body. The work at the loading bay is seldom confined to the serving of a fleet of standardized vehicles, so that if floors be made lower it should not entail any great incon

53? venience. The ideal loading bay is one which has a series of adjustable ramps, each, say, 5 ft. or 6 ft. wide, representing the width of a van for dealing with all goods which are not handled by a crane or other special loading gear. Another reason why the elimination of the wheel-arch may be considered a matter of convention, rather than necessity, is that one may see in the same thoroughfare two delivery vans of similar capacity carrying the same class of goods—one with and the other without a wheel-arch.

The rounded top of the wheelarch is more detrimental to quick and easy loading than the actual size of the obstruction formed by it. It is, therefore, an advantage if the wheel-arch be surrounded by a rectangular casing, but the amount of wheel-arch recess cannot be disregarded, and probably this is the most important factor which militates against its use in vans which are from 5 ft. to 6 ft. wide.

Low Floors Without Wheel-arches.

There are three methods whereby the height of the floor may be reduced without the necessity for a wheel-arch :— 1. The body is designed so that the width is about 4 ins. le,-e than the distance between the inner faces of the hind wheels. This arrangement may be satisfactory for a light delivery van, but would unduly curtail the loading capacity of a larger body. A compromise is effected if only the lower part of the body sides be built between the wheels and the upper part built over them, 2. The track of the rear wheels is made to suit the width of body required so long as the legal limit Is not exceeded. This arrangement has the disadvantage that it Increases the difficulty of driving in crowded traffic and through narrow gangways, as the driver is not able to judge easily the space required for manceuvring his vehicle. This design is more suitable for a front-wheel-driven chassis, or when the body is mounted as the trailer of a tractor-;trailer vehicle.

g. This (the best) way is to reduce the height of the hind wheels. This method is already adopted for horse-drawn vehicles designed for carrying machinery, boilers, stone blocks and heavy and concentrated loads, and has been successfully applied to motor transport, as, for example, the S.D.-Freighter of Shelvoke and Drewry, Ltd. The new Low-Deck vehicle of Corber and Heath, Ltd., is designed on similar lines. The Guy chassis is also mounted on small wheels, and although this particular chassis has generally been supplied for passenger service, it is doubtless quite suitable for goods transport.

Small Wheels.

A chassis which is designed to give a fiat mounting or floor level of just over 2 ft. gives practically the same scope for special bodywork as a two or four wheeled trailer. It is often assumed that small road wheels set up excessive vibration and reduce the life of the tyres considerably, but if the design be such tha,the load is evenly distributed over both the front and rear axles, and long, flexible springs are used, fragile material, such as glass, may be carried safely, and even after mileages of 10,000 and more the tyres will be found in goad condition.

The Scope of the Lowloading Chassis.

For house-refuse collection the low loading-line is ideal, because no ladders are required. The labour is halved in handling such heavy and cumbrous items as milk churns anti baulks of timber, eases of mineral waters, barrels of beer and so on. There is also a decided advantage when the bodywork must take the form of a tall superstructure such as is necessary for carrying large sheets of plateglass. If a standard lorry be used, a considerable detour may often have to be made in order to avoid roads where there are low bridges, but when the overall height has been reduced some 20 ins. to 24 ins, by the use of a low chassis there is little fear of time being wasted in this way.

For the transport of live stock the low floor level is particularly suitable, because the loading ramp can he short and light in weight and of easy incline. This type of chassis should also make a special appeal to those who run any kind of travelling shop or stall, as a serving counter of easy reach can be designed, while still retaining a proper depth of body side below it. The introduction of the low loading-line gives scope for improved design in such vehicles as pantechnicons, where a hind loading well is often used. The body may then be built throughout as a plain box-van without wheel-arch or well. The nurseryman finds a well floor an advantage, so that a palm, complete in its tub or pot, can be carried without unduly increasing the overall height of the load. Here, again, a similar form of body construction becomes possible. If easy riding qualities can be assured, and an average speed of not

more than 15 m.p.h. is required, then the chassis with small wheels should be ideal for mounting ambulance bodies, giving scope for either side or rear loading of the stretcher, whilst the caravan body so mounted is without wheel-arches and has, therefore, extra space for lockers, a consideration of importance when so much has to be arranged in a confined space.

In the designing of chassis of the low-frame-level pattern, the question of clearance up to the back axle is not of such great importance as is the case with the passenger vehicle, as the regulations which are enforced in connection with public-service buses do not then apply. This renders the task of the designer far easier when he is dealing with chassis for goods transport. It will not do, however, to take undue advantage of this particular point, for our builders must always consider the possibilities of further developing our overseas trade, and chassis with excessively low clearance could certainly not be satisfactorily employed over bad roads or tracks.

Nothing has yet been written as regards the question of how such chassis as we have referred to could be driven. There would appear to be ample opportunity for thought in this direction; for instance, frontwheel drive might prove advantageous.

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