MOTOR NOTES

Opotiki News, Volume II, Issue 182, 15 May 1939, Page 4

MOTOR NOTES

RUBBER USED IN NEW SPRINGING SYSTEM FOR CARS Home time ago, there was described a motor car suspensory, system by inflated rubber bags, which has been developed by ai • prominent American tyre At the time, it was mentioned that engineers throughout the' world were paying far moire attention to springing than to any other part of the car, and that the arrangement described was entirely in accord with the present trend, which was to get away from leaf springs is possible. Details of another new springing system which also uses rubber, although not in the shape of inflated bags, have been received 1 from England. This lias been designed for independent .springing front and rear, and is exceedingly simple in its de- v tails. How it- will behave in practice remains to he seen. Each wheel is carried by a longitudinal radius arm attached to the chassis on a fulcrum point a short distance from one. end, while the other extremity is attached to the wheel hub. Surrounding the fulcrum is a large disc of rubber compressed to give a frictional gripi between two metal discs.-.with lips turned in, one disc being attached to the radius arm and the other to the chassis frame. The whole assembly is held together by a lateral holt, whose nut can he turned down or slackened in order to vary the grip of the rubber between the discs. As the road wheel moves up and down, the radius arm creates a torsional resistance in the rubber disc. Additional Aid. The whole task of providing a soft spring action, however, is not left to the rubber disc in torsion, but,rubber iu compression is used as well. At some other point oil the radius arm,

either in front of the fulcrum or behind it, is placed a cylindrical rubber pad contained in telescopic metal sheaths. As the road wheel moves upward, this rubber pad is compressed. Because the pad is anchored to both the raditts arm and! the chassis frame, movement of the read wheel downward places it in tension. The metal-sheathing surrounding this pad is so arranged that compression of the rubber up to a certain point is unrestricted, but beyond that point the rubber pad expands sufficiently tot iill the diameter of the sheathing so that further compression is impossible. This pad, therefore, tends to act as a check on excessive spring movement in just the same manner as the ordinary hydraulic shock absorber applied to leaf springs. In support of the idea of using rubber in this fashion for suspension can he cited the manner in which rubber is largely used in cars for absorbing shocks and vibration in other directions—in flexible engine supports, for instance. Pros and Cons. The new scheme has some favourable features of which the absence of noise and the elimination of oiling . points, save possibly one on each of the fulerums, are obvious. . On the other hand, some trouble may be experienced in using longitudinal radius arms as the twisting forces imposed on them by the tendency of a car to roll on corners are great. Radius arms used in this fashion on other springing systems . have hot proved too successful for this reason. Nevei theless, the invention is ah interesting one, showing the tendency of the present day. Rubber, properly. applied, should be a splendid medium for springing, because it can be manufactured in. almost any degree of “sponginess,” and thus the designer lias at his hand a far wider latitude in the control of his springing medium than he lias with leaf springs.