PARCELCARS FOR LIGHT LOADS.
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Existing Types Critically Examined and a Suggestion Advanced For An Entirely New Design.
. D 1CENTLY PUBLISHED figures 1.A. relating to the munber of light. parcel carriers on the market would lead one to believe that very little attention is being given to the construction of what should be a useful type, the sales of which, providing that, a. thoroughly satisfactory model could be evolved, should be enormous. This is a market, which has been, to a large extent, overlooked, and what, attempts have been made to capture it have not been persisted in sufficiently to evolve the model which will commend itself to the tradesman or the manufacturer whose loads are not heavy enough to warrant his employing a full-sized motorvan. It is true that some of the cheap American vans set up a strong opposition to the parcel carrier, but that a light carrier could be constructed to withstand the rough usage to which one may expect such a vehicle to be subjected, without an unduly high cost for upkeep, is certain, and its running cost, should be only a. fraction of that of even the cheapest, van on the market. Providing that the right model were developed, it should score over the van, where loads are light, in the following respects even if the first cost were not so very far below that of the cheapest van.
A youth or girl could be employed to drive, who, with a very liftle instruction, should be able to manage the machinery and who would not be so costly as the more eX111elleed man necessary for driving a van.
Owing to the lighter weight, the tyre bill should be very appreciably less than that of the lightest van. The consumption of petrol in such vehicles is so low that it becomes almost a negligible item.
The Storage Question.
A well-designed carrier could, in many cases, be stored in an outhouse attached to an ordinary shop, whereas even the lightest van generally requires the maintaming of a separate garage.
In the past such vehicles !nice not cmpared ,favourably with the van in the matter a repairs. Most of the vehiclas offered to the public for this purpose have originally been designed for carrying passengers ,f or pleasure and, with only a few minor alterations, have been converted to the carrying of goods.,
Although it may be Said that there are many light parcel carriers,. it might be well to consider 'bow many of 'these are primarily designed for goods, and are
not, merely converted passenger carriers. Leaving out those intended for use as taxis,–there are no fewer than 20 models in manufacture, but of these very few could be considered goods carriers, pure and sirriple.
Before the war there were, perhaps, more of this class of vehicle being manufacture than at present. Some of the firms who were engaged in this class of trade seem to have drifted away to some other class of manufacture. It is only reasonable to imagine that they followed the line of least resistance, and either found this class of vehicle difficult to sell, or that they could command better prices and more profits in other fields. It is not reasonable to think that any firm would voluntarily abandon a type unless there were some powerful reason for doing so.
Which is the Right Model ?
The question may be asked : " Has the right model been found yet!" Our own opinion is that the model which will . eommend itself to the shopkeeper and other business men for the carrying of lighter loads than those which make a van profitable; has not yet been evolved. Unless we give more serious attention to the matter, we shall awake one day to the fact, that some enterprising foreigner has done the trick and that we are shut out. This has happened before, in another model, and it may happen again in this case.
In reviewing the subject and trying to devise some means to obtain a satisfactory model, which will meet the requirements of the majority of probable users, it, is necessary first to decide on the load which such a vehicle is to carry. In some cases the type has been made to carry as much as 8 cwt. and, ;n others, as little as 4 cwt. This is a point on which it would be well to collect, as much information as possible, as so much depends upon it, as regards both first cost and upkeep. General experience would go to show that from 4 cwt. to 5 cwt. is about what is required.
What Type of Vehicle is Required ?
Having obtained a general consensus of opinion RS to the weight to be carried, and supposing that, for the purpose, we take the loads as between 4 cwt. and 5 cwt., the next thing to consider is what. advantages are offered by the different types available and what are their disadvantages.
No absolutely perfect model is ever likely to be produced, so all that, can be done will be to select the type which has the greatest, number of good points and the fewest bid points,lmth of which should be studied with a thorongh knowledge-of what such cars are expected to do and the handling they are likely to receive.It must not be thought for a minute that these vehicles are going to receive the same careful attention and handling as the ordinary car gets from its owner-driver.
Roughly speaking, there seem to be three types which have been tried in various fornis for use as paroelcars, apart from the four-wheeled ordinary type, which may be called the van type. These we will refer to as Types 1, 2, and 3, and we show them in diagrammatic sketches.
Fig. 1 shows the type which has two stoering wheels and one rear driving wheel. ii has Ackerman steering, with it accompanying multiplicity, of joints and connections. A chain is generally used for the transmission of driving power, and the driving wheel is usually enclosed on each side by the supporting members.
Fig. 2 shows the type which is a little more than a bicycle with a side box. Its driving is usually by means of chain. It has one driving wheel, one steering wheel and one support. wheel. Fig. 3 shows the type which has two rear driving wheels and one front steering wheel.
The Good and Bad Points of Each Type.
To balance the good and bad points of Type 1 is not very difficult. It may be said that. one driving wheel is much simpler than two; and that no differential is necessary. Against UM must be taken the points on the other side. These
appear to be as follow we have the bulk of the weight carried on the steering wheels. These have all the joints necessary for this class of steering, which may work fairly well on a car, where they can be made in a more costly style, but which rattle loose on a vehicle of this class very soon and render, steer ing difficult. The driving being done by one wheel
imposesextra strain on the tyre, and there isalso some difficulty in selecting a tyre which will adhere to the ground under all conditions.. The members which support the .rear axlo and the chain transmission of power to the rear wheel both impede the changing a tyres.
There is difficulty in desighing any
thoroughly satisfactory drive to the rear wheel, as chains do not fit in with modern ideas, on account of the difficulty of enclosing them, and either bevel or worm drive is not easy to apply in the case of a single rear driving wheel. Brakes can easily be applied to the back wheel,but that is hardly goad enough for modern ideas. When it oomes to applying brakes. to the steering wheels, the number of entail parts is increased.
Mudguards on this type present some difficulty, as, in the case of the rear guard, it is difficult to attach it to any but an unsprung part, with the result that renewals --are frequently required. Taken on the whole, this type of vehicle is far better suited to passenger carrying than for goods, as it must be remembered that even a parcel carrier must be able to work in all weathers, and theeprotectitan of the driver in this type is ao easy matter.
Fig. 2 shows Type 2 to be practically a bicycle and side box. Most of the difficulties. mentioned as being inseparable from Type 1 are present in this form of carrier. The steering is simpler, but the wear on the tyre is worse. There is less likelihood to side-slip on greasy roads, because of the steadying effect of the idle or support wheel. Two of the wheels are difficult to get at in the case of tyre trouble. The problem of protecting the driver from weather is even greater, whilst the difficulty of providing a dueI able method of transmitting the power to the rear wheel is the same as in Type 1. The trouble with mudguards and other small fitments is also the same.
A Suggested New Type.
Fig. 3 shows a type which is likely to fit in with all the requirements of such work better than any other. It is, however, not perfect, but its bad points are few, whilst its good points are many. It has been made from time to time in several forms, but does not seem to have been Laken very seriously as regards details of design. We have endeavoured to collect all the details which have been embodied in the various designs of this type which have been produced, and have introduced some from other designs, and feel sure that a vehicle constructed on the lines indicated would come nearer to filling the requirements than any other type.
It must not be thought that we have any axe to grind or that we are recommending any particular make. So far as we are aware, nothing ot the exact type is being made or is even contemplated by any firm. It would be impossible here to give an accurate specification of such a. design, so we will conteut ourselves with outlining the essential fea.tiiree of the plan.
Fig. 3 shows a general assembly, from which it will be seen that the steering is by one wheel mounted in a fork provided with quarter-elliptical springs and having a. vertical fork to prevent side roll of the wheel. This reduces the number of working and wearing joints to a minimum. The front hub should be of the detachable type witha central removable bolt. The mudguard should be attache-d to the sprung part of the frame, and would be better not to steer with the wheel, as guards which fill the latter condition are a perpetual source of trouble. Some simple strut could be arranged to rest on the ground while the front wheel is being removed. The light weight on such front wheels renders tyre trouble very alight. As shown, the driver can be fairly well protected from weather.
The Position of the Engine.
In this type the position of the engine is not all that could be desired, so far as cooling is concerned. We take it that. air cooling is the only system worth considering, on account of its simplicity. Although sheltered by the driver and not in an ideal position, such engines can be kept, cool by well-designed air scoops, which are known to work satisfactorily on small cars. The engine can be either of the V or opposed-cylinder type.
The most suitable clutch, and one B29 which deserves more popularity on other types is the internal leather cone working in a bath of oil. This clutch is particularly suitable for use by inexperienced drivers, as it takes up without shock and cannot be damaged by being allowed to slip.
Nothing has yet been found so durable and lasting as the ordinary gearbox and straight shaft to a worm or bevel gear on the back axle. On the type suggested we have found this class of transmission even more durable than on an -ordinary car. This is probably due to the small power and the light load. If well proportioned, such a transmission, being entirely enclosed, will last long enough to satisfy the most exacting user.
It has been suggested that the differential might be omitted from the rear axle so as to reduce cost. Experience of this type has shown that one of its features
its extreme handiness in turning about in small spaces, and to dispense with the differential would be to rob it of this handiness or put a strain on the tyres.
Type of Wheels an Open Question.
Although wire wheels are the lightest and strongest for such a design, they undoubtedly offer some difficulty as regards cleaning. On the question of which class of wheel is the most suitable for this machine, there may be differences of opinion, as both wire and light pressedsteel have their good points. In the way of rear springing nothing simpler than the ordinary half-elliptical can be imagined, and nothing is better for the purpose. There is no particular reason for the use of tube or pressed steel in the frame of such a vehicle, as the light channels and angles which can be procured form ideal frames for such con struction, -especially if care be taken to arrange the lines so that a trussed structure is formed ana transverse strains are avoided wherever possible. Bolts are preferable to rivets in such parts, on account of the ease of repairs in case Of accident. The rear mudguards can easily be fixed to the spring frame, and will be less affected by vibration than in most types of parcelceue.
On no account should any brake be fitted to the front wheel of this type, as it would only put unnecessary strains on parts which are not suited to bear them. The back wheels can have one brake at, each end of the axle and one tiansmission brake This forms the cheapest and simplest arrangement.
If properly designed, the body should chow a very considerable saving when compared with the cheapest van.
The Advantages of the Type.
Taking this type us a whole, it offers great advantages over all others, as, owing to the parts being enclosed, there is not the continual wearing out of small details, which is always going on when such parts are exposed. The continual irritation caused by parts breaking and coming loose through being attached to unsprung portions of the structure is avoided.
Objections have been raised to the steering of one wheel in front, on the ground that the driver is not able to judge the distance from kerbs and other obstructions. In actual use this does not occur. All three hubs can easily be trade interchangeable, so as to enable a spare wheel to be used.
The placing of the driver in front has been found in other cases to rechice the number of " buffs" very considerably.