" K.T." Tire Developments.
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Most of our readers will be quite familiar with the unique form of tire which is known as the " K.T." Some six months ago, a small selling company, with the title of The Commercial Tyre Co., Ltd., was formed to operate as sole licensee for the United Kingdom in the matter of the sales and manufacture of this special tire. This organization has its headquarters at. 534, Old Kent Road, S.E., and a photograph of a part of the front of the new premises is reproduced on this page. It will be noticed that a small motorvan, shod with " KT." tires, and belonging to Messrs. Mc4'itie and Price, is included in the picture. One of the first strokes of business policy to be initiated by this company was to effect arrangements by which the price of " KAP:a " could be reduced to that of solid-rubber tires of a similar weight-carrying capacity. This move, of course, yielded to the sales organization of the new company a considerable advantage, which could not be offered previously to possible users.
Quite in the early days of the development of the motorbus industry in the Metropolis, operating engineers were keenly interested in the various possibilities of the first pattern of 'K.T." tire, which was then brought to their notice. Tho unusual form of construction of this speciality yielded certain advantages which were unique, so far as tires for heavy commercial-motor vehicles were concerned. The earliest patterns of
K.T." tires undoubtedly possessed very remarkable possibilities in the matter of sideslip prevention. The semi-pneumatic form of construction of the separate cushions, even in the earliest designs, also yielded a resiliency that was only slightly inferior to a very highly-inflated pneumatic tire. On snow or ice-bound roads, the "KT." may be said almost to have had matters its own way, as, within the writer's experience, most exhaustive tests, with a view to ascertaining the adhesion which could be obtained by the use of these tires, proved that a hold
could be maintained on road surfaces even under such trying conditions as those indicated In the early clays of the commercial exploitation of this special tire, it is undoubted that the company which was then doing the business found that the cost of production seriously militated against the more-extended adoption of the tire, and that the cost of manufacture would have to be very materially reduced, in order to allow the .tire to become a really-marketable commodity. It may be now recorded that both the design and the methods of manufacture have been so much improved as to place the present factors in a most-favourable position for obtaining business even of a highly-competitive nature. It may not be out of place once again to write a few notes with regard to the constructional features of the tire, although our readers may remember that we have not neglected to keep them apprised of the constructional developments which have taken place during the past few years. The tire proper consiats of a band of rubber without any fabric of embedded metal, and this is moulded in such a way as to form a double or a single row of studs or round projections; each of these studs is hollow, and forms the special pneumatic tread which ia the particular characteristic of " K.T." tires. To hold this special form of rubber band, the projections are forced through a perforated, endless, steel hand, and this combined arrangement is then forced on to the [dive of the wheel. It will, therefore, be seen that, when a fully-tired wheel is ready for the road, whilst only the tops of the rubber studs come into contact with the road surface, an ample base of rubber is interposed between the perforated rim and the steel feline band. The air beneath each of the studs becomes hermetically sealed, and so forms a series of separate air cushions or springs. Although the constructional features of the tire may, at first sight, appear to the user to be not of the simplest description, it is obvious that the pneumatic characteristics are obtained with the maximum of simplicity.
What evidently proved to be the mostdifficult task of the designers of the "XL," tire was the careful ascertainment of the size of the individual staid which can he embodied in each grade of tire. The particular quality of the rubber mixture which was necessary to obtain the best results with each size of stud, the weight-carrying possibilities of various stud forms, and the final contour of the stud which should give the hest results were all problems which engaged the inventors and their advisers strenuously during a period of several years. Another difficulty which was encountered was in connection with the perforated steel rims. These, in the first place, were made much in the same way as the ordinary steel bands that are used in connection with the endless type of band tire, viz., by means of welding. In
order to secure the necessary strength in a welded rim, like that necessitated by the " K.T." form of construction, it was eventually found that this could only be obtained satisfactorily by the use of very heavy section bands, and this naturally reacted prejudicially on the tires. After welding these rims, they had to be turned internally and externally, in order to secure accuracy, and this, of course, was a slow and costly process. This matter of the rims was a serious deterrent to the original company's interests in the early days, and unremitting attention to the improvement of this detail was necessitated. Now, a special patented process has been evolved, and the double-flanged rims are now actually made without welding of any kind out of a flat sheet of metal. The minimum weight of metal is now employed, and, of course, production is greatly simplified and much cheaper. A flat sheet of metal is first of all converted into a form like that of the lid of a pillbox, and it is then turned inwards and a sheet of metal is cut out to correspond with the top of the lid. A ring of metal is then left with a flange on each side, which is bent in wards. This process leaves the rims finished exactly to the required diameter ; further machining is unnecessary. Another interesting process has had to be evolved in order cheaply and effectively to bevel the perforations in these rims. The difficulty of doing this by machine satisfactorily will be realized if it be borne in mind that each of the holes is perforated on the arc of a circle. So difficult a feat was the effective machining of this bevel, that, we are informed, one large steel concern in the Midlands actually offered a prize of 100 guineas to any member of its staff who could devise a suitable tool, but the premium went. unclaimed. Undismayed by such nonsuccess„ however, the " K.T." pioneers went ahead with what must be considered extraordinary persistence, and eventu. ally devised a tool which now does the work satisfactorily both in the matter of time and cost.
We have dealt with the evolution of the processes by which the " K.T." tire is manufactured and assembled at some length, in order to emphasize the point of view Chat some of those who were responsible in the first place for the " K. T." proposition realized that, although their early methods of produc
tion handicapped them so very severely, there was sufficient basic good in the design to warrant the expenditure of a great amount of energy in the overcoming of those early difficulties.
The advent of the " K. T." tire on the market as a commercial proposition is a distinct advantage to all users of commercial-motor vehicles. The claims of its makers on the scores of resilience and non-skidding have been well known for several years, and that such tires can now compete satisfactorily on the score of price will be welcome news to a large number of our readers.
Mr. L. Fenner is the manager of the Commercial Tyro Co., Ltd., and we arehappy to hear from him that the first six months of the operation of the new organization has yielded wholly-good results. It will be remembered that Mr. Fenner, who had extensive experience with the old Vanguard Co. and with the London General Omnibus Co., relinquished his position with the latter concern in order to take control of the destinies of the " K.T." tire. He is just back from a business trip in Scotland, where• he has arranged to open a depot under the company's name in Glasgow.