Another New All-British Chassis.
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Chassis Design—and Particularly that of the Wells 212-tonner, Considered from the Point of View of the User.
When considering the design of a. chassis kr, any particular description of work or for a certain load, the following are amongst the principal problems which present themselves and which must be solved in a manner entirely favourable to the user.
Strength.
The strength of the framework and the details of the transmission must be such as to enable the vehicle to carry the load at a reasonable speed and operating over give-and-take roads, and the number of hours per day should not, in the ideal chassis, need to be taken into account, providing that the periods at which the mechanism receives attention occur at intervals which are not too remote, one from another.
Power.
The engine power must be ample. One of the advantages of the use of motor transport is that its speed enables it to compete with rail and horse combined; it would, therefore, be folly to purchase a machine which, even if capable of running at the legal limit of speed on the level, had not sufficient engine power to maintain a high average speed in hilly districts.
Wear-resisting Qualities.
Next in point of importance comes the question of its wear-resisting capabilities. Bearing surfaces should be ample, not only so that renewal of bushes and pins does not become necessary at too early a' date in the life of the vehicle, but also in order to prevent the development of rattle and noise while the machine is, to all intents and purposes, almost new Accessibility for Adjustment.
Ease of access when minor adjustments become necessary, as of corn-se they must from time to tune, and also for the renewal of small wearing parts is of paramount importance. This same feature also must be considered in connection with the larger parts, so that time is not wasted when repairs and overhauls become due and also in case of unavoida Me accident involving breakage of some important detail, and the consequent need for it replacement.
Springing.
Adequate springing is the next point for consideration. In a commercial vehicle, where axle-loads may vary, in
the case of two-ton machine, from one ton to three tons, this department of design is one which calls forth an exercise of considerable ingenuity. It. is advisable for the sake of long life both of chassis mechanism and bodywork, that the springs most be sufficiently flexible to carry the weight of the bodywork only without the whole machine being subject to excessive vibration. Yet at the same time strength must be available in order that the fully loaded vehicle may travel rough roads without risk of spring breakage, besides the need, of course, for correst suspension in these circumstances.
432.8 Driver's Comfort.
Ease of operation and the comfort of the driver must also be considered. We must also keep in view the advisibility of a good steering lock, in order that the chassis may be manipulated with ease in narrow roads and awkward turnings. Facile steering:, handiness of side-levers, and ease of clutch withdrawal count in this respect, Next in order of importance comes the question of suitability in point of di mensions for carrying various types of bodywork, varying from the plain flat lorry to the large covered van for light bulky goods ; and from the staked lorry suitable for conveying barrels to the modern and expensive type of touring char-i-bancs body. Number of Parts a Minimum.
Another item which receives, we aro afraid, less consideration than it ought, -even in these days of advanced knowledge in the design of commercial vehicles, is the question of spares. It is very often possible by means of .a little -ingenuity to make the same sized bush perform several functions. This feature perhaps affects more particularly Colonial users, who have not the ready access to the manufacturers' workshops to which users in this country are accustomed. At the same time, it must not be forgotten that economy both of production and operation is dependent on the limitation of the number of different small parts employed.
The consideration of these matters was occupying our thoughts as we journeyed to the Church Wharf works of Wells Motors Ltd. on a recent occasion, and we were struck by the idea of applying the above principles in the form of a test to the next new chassis that we had the pleasure of examining. Briefly, the following few notes state the case for the Wells 2-tonner.
How the Wells Chassis Stands.
Firstly, as regards strength, the frame is a pressed-steel one, of good depth, and, being made of high-tension-steel, should be well able to stand any amount of hard work with the rated load superimposed on it. We noticed particularly in regard to the engine underframe that this important part of the structure had re
ceived special attention. At the rear
Another All-British Chassis--con.
end of the frame also consideration of its possible use for towing purposes from time to time had been made, and tie-rods riveted in place. Cross members had been placed wherever they were likely to be needed, and we were struck by the design of these for the engine underframe, both from the point of view of simplicity and of strength. Other parts of the chassis also, examined from this point of view appeared to be all that is desir
able. The road wheels are of pressed steel made in halves and welded together, and the various shafts and gearwheels are all made of materials chosen as being particularly suitable for the duty which each one has to perform, besides being robust in respect. of their actual dimensions.
A Dorman Engine.
A6 for engine power, it is almost sufficient, if we point out that the power unit employed is the Dorman type j.J., which has been passed by the War Office as being suitable for use on subsidy vehicles for loads of anything up to 4 tons gross. The dimensions are 110 mm. bore and 140 mm. stroke, which give 28 h.p. by the I.A.C. rating, and it is aLso probable that this figure will be considerably exceeded at the normal engine speed. In applying the principles enumerated above, it may be advisable to take the engine as a separate entity, including also the fan and clutch. If we then remember that the War Office specification partieularly calls for such features as accessiiiility, and if we recall also that before this type of power unit. received subsidy certificate it had to undergo a most rigorous test, it may almost be taken for granted that this section of the chassis would pass easily under our examination. There are one or two features of engine construction which must be touched upon before we leave this important unit. One of these is the !nevi sum of large water spaces and of adequate ducts for the cooling water. In the case of the model under review the cylinders are east in pairs with a generous space between barrels and water jackets for carrying an ample supply of water. The piping, moreover, is of such a size as to render possible the use of the thermo-syphon means of circulating the cooling water in the event of failure of the pump. A suitable lubrication system is also necessary, and this must be considered particularly in relation to the lack of any great need for supervision on the part of the driver. In the Dorman
engine this is accomplished by means of an automatic pump in a reservoir below the engine which forces the oil under pressure to the main bearings and bigends, the lubricant passing on its way through a tell-tale, which is easily visible and is placed on the dashboard.
Good-sized Bearings the Rule.
With regard to wear-resisting, the designer of the Wells chassis seems to have paid particular attention to this point. Not, only are the main bearings throngh• out the machine of ample size—as an 'example of this we may point to the. wheel bushes, which have been made to subsidy specification and are, therefore, capable of taking almost a hundred per cent. greater load than that for which the chassis is designed—but this feature of ample bearing surface has been carried almost to excess, if that were possible. We observed it in such small things as the bearings for the engine control rods; it is evident in the brackets which carry the brake shafts as well as in the shackles for the road springs. Wherever ball bearings are used they are of such a size that there is very little likelihood indeed of their giving way with fair usage. As stated above, attention to this bearing question in the matter of small details is necessary in order to obviate early development of undue rattle, the most obvieus sign of wear.
Brake Adjustment Easy.
Accessibility for minor adjustment and replacement of small parts is visible in the arrangement of the brake gear. It was, in fact, this particular portion of the mechanism which we had in mind when stating this to be a matter worthy of consideration. Facilities for rapid and easy adjustment of brakes tend to encourage the driver to keep these always up to their work. The brake shoes are accessible for relining, by taking oft the rear wheels, when the shoes can be re!moved at once by hand, no tools being necessary. It would be well to state here
that both foot and hand brakes take effect on drums bolted to the rear wheels, Another point not quite in this cornicetion, perhaps, but having a bearing LW it, is the matter of accessibility of grease cups. Wherever possible on the Wells chassis these are placed where it is possible for the driver to get at them for replenishment without having to get underneath the framework. Take one, as an example. The foremost universal joint on the propeller shaft is lubricated by means of a grease cup situated outside the frame, and lubricant is carried through a long copper pipe.
Accessibility of Large Units.
The feature of accessibility for repair end removal of large units is perhaps illustrated to some extent by the photo graphs which are reproduced on these pages. The rear axle parts can be dismantled completely without the need for a screw jack. Removal of the hub caps renders the withdrawal of the axle shafts an easy matter. By uncoupling the torque tube and sliding the small coupling at the rear end of the propeller shaft forward, it is possible to remove the casing carrying the worm and worm wheel, and the whole of the driving mechanism is then available for inspection and repair. Similar attention has been paid to the gearbox. This important unit, which provides four speeds and reverse, although a three-speed box may also be specified if desired, is three-point suspended in an admirable manner. The front end is carried in a single bearing bolted to a cross-member of the frame ; the rear end is bolted to a steel casting, which has journals turned on its extremity. The latter hear in suitably disposed brackets on the main frame. By uncoupling the leather joint on the front of the gearbox and taking out the bolts holding the brackets at the front end of this unit, it is possible to swing it round the rear end and any of the shafts or gears may then be removed. The same ease of access is noticeable in the design of the radiator. This is made to li%ar Office specifications, and provides ample cooling area. It is also, as the W.D. insists, carried in trunnion bearings entirely above the frame. It can, therefore, be removed with a minimum of trouble, and since the tubes are of large diameter, terminating in removable headers of cast alurninenn, the overhaul of this' unit is simplified.
" B " Type Springing.
Now, with regard to the springing, particular attention has been paid to this on the chassis we are considering. One of our illustrations depicts the arrangement of the rear erid, where long semi elliptic springs are provided which take the weight of the chassis and bodywork and a, small portion of the load. After these have deflected a certain amount, however, rubber buffers on the top of the rear sprite's make contact with the lower ends of volute springs carried in brackets on the frame. Those of our readers who are familiar with the construction of the L.G.O.C. type buses will recognize this as a standard feature of those well-known chassis. At the time we examined this machine, the same principle had not been applied to the front springs, but we were informed that this was to be done.
Effective Locking Gear in Gearbox.
The other points mentioned in the brief outline specification with 'which we commenced . the article, have also received consideration to the. same extent as the with which we have already dealt. The comfort of the driver has been considered in that the position of the steering wheel, pedals and side levers, has been carefully thought out. The operation of the clutch does not .call for any excessive exertion, and the steering wheel is large in diameter. The change-speed mechanism, too, is facile in operation, and a very effective locking device is included in the box, so as to relieve the mind of the driver from any fear of engaging more than one of the different gears at the same time. We had not the pleasure of a run on the chassis, so that we were not able to see very much more under this head.
Spare Parts. Dimensions. Price.
Mr. Wells has also paid attention to the question of getting the number of spare parts to a minimum, and where it has been possible to use the same size bush for two or three different purposes he has taken advantage of that possibility and reduced the number of component parts of fhe chassis accordingly. As regards dimensions, the overall length is 19 ft., the width being 6 ft. 6 iris., with a wheelbase of 11 ft. 6 ins., and a track of 5 ft. What may be termed the useful length of frame, that is to say, the distance from immediately behind the driver's seat to the end of the franne, is 11 ft. The height from the floor to the top of the frame when the chassis is loaded is 2 ft. 7 ins., and the weight of the stripped chassis 2 ton 7 cwt. It is worthy of note that every detail of this high-grade machine is made to jig and to Newall standard gauges, consequently strict interchangeability is ensured. A feature has been made of the supply of indexed numbered diagrams with each chassis, so that in the event of spare parts being needed it would be a simple matter to order them, and, at the same time, to be sure that the right item would be delivered.
The chassis price complete with tires, delivered in London, is £700.