Value of Rubber in Chassis Construction
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Mof interest is contained in the paper, 'Rubber Min Automobiles," read by Mr. Colin Macbeth, M.I.A.E., M.S.A.E., on Tuesday evening before the Rubber Growers' Association, the Institution of Automobile Engineers, and other Institutions. In his introduction the author said that he felt that the suspension of all types of wheeled traffic will provide a greater effective use of rubber. Rubber is employed not only for absorbing shocks, but increasingly as a packing material to mask any irregularities in chassis construction. The few ounces built into ingenious engine mountings are the outcome of the demand for quick assembly -with satisfactory performance. Summing up the modern employment of the, material. it may be said that tyres are larger in section softer and MOTO durable. Rubber upholstery is being increasingly n37
employed, whilst many other applications, some small, are steadily increasing, not only in number but in the weight utilized.
Dealing with tyres and as a contribution towards the reduction of tread wear, the author suggests that the tread should be considered in its cross-sectional design As a solid tyre mounted on a yielding base. So constructed it would be found that private-car treads, which wear out more rapidly, are so wide at the contact face that they should be considered as twin treads. There are sound arguments for the employment of twin treads for counteracting wear in cornering. Two-band or two-ribbed designs are not advocated. The portions should not be plain flat surfaces, but " cut " to suit the experience of the designer.
Rubber is being used increasingly between springs and axles as plain or moulded strips or moulded bushings. They reduce noise and wear. Rubber is used in connection with bumpers, and the latest running boards have rubber -vulcaniaed to the steel, so that the wide hollow and flexible edges yield to posts, etc_ instead of being torn off. Wings of this material are being applied successfully to many public-service Vehicles. Flexible • clutch centres have been made in great quantities, using rubber as a major flexing
member. They have often proved unsuitable because of indifferent Methods Of incorporating the unit.
Scaminell vehicles' have a special coupling between . engine and gearbox, the resilient components being fairly hard rubber with canvas reinforcement vulcanized to the bearing faces. Angular deflection under full torque is from 2-3 degrees.
The author recommends also flexible connection between the live axles and driving wheels. This should reduce maintenance costs and prevent breakages. From steering wheel to steering-point connections it has re.praced's other materials on many of the cheapest and I** ,. 'expensive
chassis. . . .
To allow for a flexible connection betwe.en the over-• hanging front ends of buses and the chassis. frame sirl members, the Leyland company arranges a flexible support at the forWard bulkhead.
Rubber uplicilstery is being increasingly employed in the inflated, cellular, sponge or Latex-treated hair designs, whilst movable rubber floors are being extensively employed on commercial vehicles.
The'author then described a number of methods of-using rubber' in suspension systems, and gives much useful data-.