REPLACING PNEUMATICS BY SOLIDS.
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Why the Tyre Equipment as Planned by the Vehicle Manufacturer Should Rarely be Altered.
ADviCE IS OFTEN solicited by users of light .delivery vans, mostly of the converted pleasure-car type, as to the advisability of replacing the pneumatic tyres, with which these are provided, by solid tyres.
This practice is unhesitatingly to be condemned, as the solid tyros will certainly exercise a most deleterious effect on the life of a. light vehicle as whole, and on the units of which it is comprised. Rear axles, especially, though they may be quite satisfactory when employed; with pneumatica, fail very rapidly when the latter are replaced by solids. The .wonderful cushioning effect of pneumatics absoabs the major portion Of the vibration, and, to a large extent, eliminates the greater shocks. • A mean between the two, which can sometimes be employed with advantage, is to have the pneumatic tyres filled with some cellular composition, such as Rubberine. The tyres then, though-not so resilient az those filled with air, are certainly a gaeat improvement on solids, arid have frequently been employed with considerable success. In connection with pneumatics, it may also be mentioned that fitting dual tyrea to the rear wheel's is usually found less satisfactory than replacing the existing pneumatic tyres by others of larger dimensions. Twin tyres considerably increase the braking stresses., and in many instances have thereby caused. fractures of the driving shafts; also the outer tyres exercise considerable levikage on the wheel bearin s, and this leverage-, in cases where non-floating es are fitted, causes frequent breakages at the point where it is greatest, i.e., where the axle shafts protrude from their end bearings. Y.Z.
. REPLACING SOLIDS BY PNEUMATICS.
Even a Change that Appears Beneficial Introduces New and Destructive Factors. _ QUITE A CONSIDERABLE number of users of heavy commercial motor vehicles are considering the employment of giant pneumatic
tyres in lieu of the solid tyres at present fitted to their machines. It must be remembered by these users that the question of cost is not the only one which arises. The fitting of pneumatics means that the speed of the vehicle will certainly be increased considerably unless the engine is fitted with an efficient fool-proof governor. This increased speed is an advantage in many ways, but a great disadvantage in others, particularly in the case of vehicles constructed to run at normal speeds. The heavy, comparatively low-speed engine, fitted to most heavy torarnercial vehicles, is not intended to run for any considerable time above its normal. speed, and if it does so its wear will be abnormal, and its life consequently diminished.
The increased speed will also necessitate, in some cases, a more efficient cooling system, either a larger radiator or a larger pump, which, when the. vehicle is run at lower speeds, may cause the -engine to
. maintain a temperature which is so low as to decrease its efficiency, Another important consideration is that of the power of the brakes. Brakes intended to arrest the vehicle in a reasonably short distance when it is travelling at, say 12 to 15 m.p.h., may be totally inadequate when its speed is increased to an appreciable extent.
In many cases the use of large pneumatics may prove, and ha-s proved, of the greatest benefit, but their use, to any great extent, will call for vehicles designed expressly for the purpose with higher gear ratios and lighter construction throughout.
Y.Z.
CONGESTION ON BUS ROUTES.
. An Ill-devised Mode of Taxation that has Undoubted Evil Effects. .
IN MANY PARTS ,.of th,e country considerable congestion of motor traffic is prevalent over certain routes. Several different services of passenger omnibuses and chars-k-bancs are sometimes run over exactly the game routes, thus tending to cause rapid wear of the roads and multiplication of services which would probably be far better employed on other routes. The cause of this congestion is that the County Councils were authorized, as a wax measure, As, impose a mileage charge for road upkeep on passenger motor vehicles running on new routes; hut, if these routes were being used before 1917, no charges can be made for other services running over the same reads, even if -these services be instituted after that date ; thus all services, whether rival or friendly, have to keep to the same routes, or else be mulcted a considerable sum by . the County Councils. Those services which do use new routes are, therefore, in a very unfavourable position compared with those running on the old routes.
The result of this measure is that the spirit of enterprise is discouraged, and districts which would otherwise be opened up arid improved by passenger vehicle services are being left to stagnate, whilst the needs of others are more than met.
It would seem far more equitable if the charges were either removed altogether—imposed, as they were, as a war measure only—or else to distribute them evenly between the various road users. It is , palpably unjust for certain, users ,af motor vehicles to pay, unless they use certain routes, whilst others escape. The trials and tribulations of those chars-habancs proprietors who run tours, and whose vehigles, consequently, often pass through several counties, the mileage charges of which probably vary considerably, have' I note, already been dealt with in the
columns of this journal. J.J.
THE AGRIMOTOR UNDER THE BUDGET.
An Anomaly in the Classification which Penalizes the Small Tractor.
IT CERTAINLY seems to me that the committee which drafted the scheme of motor taxation for the Chancellor of the Exchequer was not in possession of complete facts concerning agricultural tractors, because it woald seem that the ,smaller classes of vehicles are either to be allowed to go tax free (which would not be reasonable to expect) or will be charged, at the very highest rate. As the scale of taxation is set out in the Budget, tractors the unladen weight of which is over 2,1. tons, but not over 5 tons, will bear a tax of £6; those that exceed 5 tens will be charged £10. "All other motor tractors will be charged £21." Obviously there must be trouble in differentiating between he agricultural tractor and the motor tractor, because each is "a mechanically propelled engine which draws but does not itself carry any load —." The agricultural tractor which is referred to in the same paragraph as the locomotive ploughing engine and which has only limited use on the road is to pay 5s. duty per annum. But, taking the Budget phrasing literally, tractors below 2i. tons in weight, instead of being charged less than the 26 charged to those of that weight and just over, will be charged the 221 duty. There are many tractors which are under 2i tons in weight, so that the matter is one of importance and should be taken up not only by the Farmers' Union (which has already been approached by some of its branches and proposes to act) but by
all who are interested. A.G.T.