TYRE PROGRESS: HOW MAKERS VIEW IT.
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Prominent Tyre Manufacturers ExpressTheir Opinions on Past and Future Developments in Effecting Greater Insulation between Road and Vehicle.
THERE are 19 exhibitors in the Tyre Section of the Commercial Vehicle Exhibition at Olympia, and the range of equipment which is shown by the various manufacturers is most representative. TLere is little purpose to be served by referring to the exhibits of individual makers, for practically all of them ace in a Position to meet the requirements of users in all channels of goods and passenger transport activity. The prominence which is being given on most of the stands to giant pneumatics and to cushions is indicative of the trend of tyre development and of the efforts which are being made to increase riding comfort on buses and coaches and to ensure safe transport of fragile commodities by goods vehicles.
The rubber tyre, whether it be pneumatic, cushion or solid, is the first line of defence between road and vehicle, and, whatever it fails to absorb in the matter of vibration has to be damped out, so far as possible, by the ordinary suspension system, and, although auxiliary springing devices have been introduced to assist in this direction, it is the tyre which has to bear the brunt of road shock.s. Upon its cushioning properties depends, to a large extent, the ultimate degree of shock communicated to the load.
Tyre makers as a whole recognize this fundamental fact, as is reflected in their successful endeavours to popularize pneumatic and cushion equipment for vehicles carrying heavy loads and travelling at high average speeds.
But our intention is not to dogmatize, for we have been successful in obtaining for the benefit of our readers the experienced views of a number of prominent tyre makers on present developments and future progress. Although exigencies of space, preclude the reproduction in extenso of these opinions, the excerpts which we publish will serve to stimulate interest in the communications we have received, and which we hope to publish at full-length in following issues.
Before we proceed, however, we will give the names of the exhibitors in the Tyre Section, together with the numbers of their stands, these being given in parentheses in the following list:—Avon India Rubber Co., Ltd. (246) ;13ergougnan Tyre Co. (236) ; J. W. and T. Connolly, Ltd.' (242); Ducasble Tyre Co., Ltd. (235) ; Dunlop Rubber Co., Ltd. (227) ; Englebert Tyres, Ltd. (231)); Goodyear .Tyre and Rubber Co. (Great Britain), Ltd. (229) • Harboro' Rubber Co. (230) ; Henley's Tyre and Rubber Co., Ltd. (240) ; Hutchinson, Etabs. (233) ; Leyland and Brimingham Rubber Co., Ltd. (228); • Chas. Macintosh and Co., Ltd. (237) ; Michelin Tyre Co., Ltd. (231) ; North 'British .Rubber Co., Ltd. (244); Parker Tyre Co., Ltd. (234) ; Pirelli, Ltd. (241) ; St. Helens Cable and Rubber Co,, Ltd. (288) ; Shrewsbury and Milliner Tyre Co., Ltd. (245) ; G. Spencer Moulton and Co., Ltd. (232).
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What the Dunlop Company Thinks.
The opinions of the Dunlop Rubber' Co, Ltd., must inevitably command the utmost respect, for their name is a household ward in the industry. After dealing with the three main classes of equipment (solid, pneumatic and cushion) the company offer the view that "the order of cushioning which these three tyre arrangements are able to give is at a maximum for a properly constructed and correct size of pneumatic tyre, and at a minimum for a solid tyre. The so-called cushion tyres occupy a place in reference to cushioning about midway between the two, although fairly wide differences of cushioning are possible as between different types or designs of cushion tyre.
"The question as to the form of tyre which shall be adopted depends almost solely upon conditions outside the tyres themselves, because, as a rule, all three kinds can be provided for any given vehicle. In cases where cushioning capacity is of great relative importance, such as on passenger vehicles, there is no question whatever that it is upon the development of the purely pneumatic form of tyre filet the future of Such transport will deprnd. "The type of pneumatic equipment which has amply proved itself as advantageous is the straight-side type, which, as is 'will-known, does not rely upon the inflation pressure to maintain it upon the rim." It is the Dunlop Co.'s opinion that goods-carrying vehicles up to a 50-cwt rating will, in a very short time, be almost exclusively shod with pneumatic tyres. "The cushion tyre," they add, "does not yet indicate an immediate field of development as original equipment of new vehicles, unless the circumstances are quite special. It has, however, a value in existing vehicles, especially in those which at one period of the, year are used for goods and at another period for passengers."
An Established French Company's Opinion.
Dealing with the merits of the pneumatic tyre and the advance which it has made in the eyes of chassis makers, a famous French company—the Michelin Tyre Co., Ltd.— offer the enlightening fact that "whereas three years ago approximately .5 pr cent, of the output of such manufacturers in passenger vehicles was fitted with pneumatics, the proportion now has increased to 70 per cent."
• Furthermore, it i. their opinion that in a year or so 100 per cent of such vehicles will be so equipped. The future holds secure the confirmation or disapproval of this belief. It must be remembered, however, that all the figures quoted by the Michelin Tyre Co. concern vehicles operating on Continental roads, which are not so good as poat-war British roads.
This company offer some interesting comparative figures relating to average running costs of 24 to 33-seater coaches and buses equipped with solid and pneumatic tyres, the data having been obtained from users running vehicles on each class of equipMent under identical conditions. We will now let them speak for themselves " The average reduction in petrol consumption .due to the uSe of pneumatics is 13.58 per cent—in several important Cases theactual figure is 20 per cent. The average reduction in the maintenance cost of vehicles including general overhauls, is 37.5 per cent. The estimated increase in the life of the vehicle is, on an average, 26.5 per cent., to which must be added the general efficiency of the vehicles, and th3 possibility of increased speed enabling them to do more work in a given time.
"In fact, the smaller length of time required for a given journey, and the greater time for which the vehicles are actually available for work, owing to the reduction in repairs, results in a reduction of the overhead charges per mile run, since wages, interest on capital outlay and depreciation are spread over a greater mileage. "All the foregoing advantages are obtained for the average increase in running cost of .65d. per mile for pneumatics as compared with solids."
• The Observations • of the North British Rubber Co.
Let us now see what tkr North British Rubber Co., Ltd., have to say upon the subject. It is this company's view that "the present trend of development in the tyring of commercial vehicles, both–goods and passenger, is' decidedly towards greater z!osofort and resilienee. This is aceomplished by fitting pneumatic tyres of sufficient size to carry the load and replacing the existing solid tyrea,:while givina' more comfort to the passengers ; it also extends the life of the chassis and reduces repair bills, while, in some cases, the petrol consumption is also reduced.
"Meat of the new chassis nowadays are built to take pneumatic tyres. On passenger vehicles it is advisable to have deflation alarms, say, of the detonator type, so as to give the driver due warning should the tyres become deflated."
The Opinion of the Avon Company.
With many years of experience upon which to draw—they were founded in 1885—one must acknowledge the claims of the Avon India Rubber Co., Ltd., to speak with authority. This company "think there is no question as to the general trend of development in the tyring of commercial vehicles. More and more giant pneumatics have been seen during the past year and, in our opinion, more and more will be seen in the future. The use of 'compromise' tyre § (generally known as air cushion) is also increasing, and solid tyres look like being confined eventually to only the heaviest types of vehicle, such as steamers."
To support their contention of the increasing popularity of pneumatic and cushion tyres they instance the advantages of such equipment pointing to "increased mobility, added comfort for passenger S or protection for fragile goods, reduction of chassis and body wear, and less damage to roads."
A Summary of• the Goodyear Company's Views.
Another company who have played a worthy part in extending the use of cushion tyres and pneumatics are the Goodyear Tyre and Hubber Co (Great Britain), Ltd. They have for many years past been definitely of the opinion that the use of smooth tread, comparatively hard, solid tyres must eientually be discontinued lot all commercial vehicles—except perhaps of tiro very heaviest, slowest and most cumbersome types.'
It is somewhat difficult to generalize as to the class of service for which different types of tyre are best suited, but this company roughly divide them as follows :— "Heavy-duta Cushion Tyres.—For lorries that carry heavy loads at slow speeds and do general heavy haulage work. For lorries that carry their own loads and pull trailers, and work off the "al ir gravel pits on construction jobs, etc.
"Pneumatic Cushion Tyres.—For light and medium-weight lorries, and for front wheels of heavy ones that carry fragile loads on town deliveries. For those vehicles constantly working over bad roads or Cobble-stone streets, where their radius of operation is limited. Also wherever extra cushioning is required and, for some reason, giant pneumatics are not suitable.
"Giant Pneumatic Tyres.—For all: passenger-carrying vehicles and all lorries carrying fragile loads. For lorries making suburban town deliveries, or wherever speed is essential. For lorries making long rims" to scheduled tithe. For lorries engaged on work over soft, unmade roads, in fields or on farms, and wherever the maximum speed, cushioning and comfort are required."
Henley's Tyre Company Give Their Impressions.
The Crbservations which are made by Henley's Tyre and Rubber Co., Ltd., are founded on experience in all parts of the conatry with different elasm-s of vehicle, and in offering them the company stress the point that it is difficult to lay down hard-and-fast rules for users in all parts of the country -anent the use of varying tyre equipment. Conditions of operation and types of vehicle employed, they say, must be the guiding factors.
They add, however, that "the pneumatic tyre, particularly the straight-side type, has made wonderful stride-s of recent months, and for vehicles carrying 18 to 20 passengers, or 30 cwt. to 2 tons, it is in most cases the ideal tyre equipment, provided the owner of the vehicle is in a position to stand the extra cost per mile ot the tyres.
"For Vehicles over this capacity, the pneumatic tyre may be suitable and satisfactory equipment, but, in a large number of cases, it will be found that the semi-pneumatic or air
• cushion tyre will be most suitable, offering as it does a large degree of the comfort of pneumatic tyres, without risks of punctures and bursts, and at much lower cost per tyre-mile."
Turning to the use of solids on very heavy vehicles, Messrs.. Henley's express the opinion "that the use of solid tyres should be cat down so far as possible by all vehicle otyners with a view to affording-additional comfort to passengers, additional protection to goods, and less wear and tear of the roads."