The Progress of the Cushion Tyre.
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IN CONSIDERING the battle which is now progressing between the solid tyre and the giant pneumatic, one is inclined to pay too little attention to the claims of the cushion tyre. This, however, is of undoubted importance, for steady progress is being made with this type, as it forms a most useful mean between the solid and the pneumatic, whilst the experience of thousands of users has shown, and is showing, that, while having the reliability, freedom from puncture and good mileage of the solid, it gives a remarkable extra degree of resilience and absorbs road shocks to such an extent that axles, chassis and body, and the contents of the vehicle, whether it be human or other freight, are isolated to a considerable degree from the vibration which appears when solid tyres are employed. There is now a number of successful tyres of the cushion type on the market, and some of these have been described in the columns of this journal.
Recently, however, we have received interesting particulars regarding. the running of the cushion tyres made by Henley's Tyre and Rubber Co., Ltd., 20-22, Christopher Street, Finsbury Square. London, E.C.2. These tyres, for instance, are employed by the \Greyhound Motors, Ltd., of Bristol, on their Dennis saloon buses running on the London-Bristol service.
Many of the vehicles comprising the Greyhound fleet have been running on these tyres for over a year, the mileages amounting in several cases to over 25,000. The company have found that they form excellent non-skids and have considerably reduced the maintenance costs •Ni rough routes.
In a test recently conducted by the makers before representatives of Scotland Yard, a Tillings bus wag driven at 20 m.p.h. on to a concrete surface covered with a thick mixture of lubricating oil and wet clay, .and no sideways skid could be obtained, in spite of applytng the brake with force and carrying out the test on a cambered
surface. .
Vehicles with -these Henley tyres have climbed snow-covered hills where solid-tyred vehicles, even with chains fitted, failed, and they have a great advantage in that there is no danger whatever of a wheel being lowered considerably through the bursting of a tyre, as might happen in the case of a large pneumatic, which might be serious, especially in the case of a double-decker bus.
The design of the Henley cushion tyre is quite simple: it has deep slots extending from the centre line to the sides and staggered as regard spacing. There is also a pear-shaped cavity in the centre of the tyre extending to the base, and, purely for the sake of facilitating manufacture, two steel bands are employed, these being held together by specially shaped keys.
When making the central cavity, core nieces in 20 sections have to be employed; the air in 'the centre is at atmospheric pressure, and the chief purpose of the cavity is to permit spewing of the rubber. This also applies to the side grooves, but they have the extra advantage that they assist greatly in the prevention of skidding.
It is considered by the makers that a fair average mileage for a tyre of this type is 30,000, and mileages of over 50,000 have actually been obtained. The company have taken over contracts which will necessitate an average considerably exceeding 30,000 miles if they are to have a return for their money.
As regards the effects on a chassis, in both Aberdeen and Dundee many spring breakages were occurring on the buses running there when solids were used, and these have been practically obviated by fitting Henley's cushion tyres. No alteration is required to the wheels, and it is claimed that these tyres can be run at half the cost of pneumatics, for the initial cost is but little higher than that of the ordinary solid tyre.
For Ford one-tonners, the new Henley tyre is fitted on a Hayes rim, thus obviating the need for altering existing wheels.