A Promising Rubber
Page 25
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Suspension System
Introduction of Metalastik "Spring Aid,Which Saves Weight and Affords Improved Suspension ONE hesitates, when one considers allow firmly established is the steel spring and how long the suspension system it represents has endured, even to entertain the possibility of its
being supplanted. Whilst aware of its shortcomings, on the one hand, and of the attractions of rubber as a substitute, on the other,one still recalls the attempts that have been made in the past to break away from convention, and finds little, of recent times, to show for them. The Scammell system is, however, one case we can call to mind where rubber is wholly relied upon for vehicle suspension.
Enough, however, has been done to prove that, despite one's hesitation, there are real possibilities, and those who have had experience of operating vehicles in which rubber suspension is incorporated are warm in its praises.
Now a new application of rubber, as an elastic medium for vehicle suspension has made its appearance. It comes, moreover, from an important concern with wide experience of rubber, which has carried out exhaustive research], experimenting and testing before going ahead with the scheme.
Metalastik, Ltd., Evington Valley Road, Leicester. a company which is well known in connection with devices for vibration insulation, etc., in which rubber is bonded to metal, has developed an apparatus named the Metalastik Spring Aid. As can be seen from the accompanying pictures it is supple mentary to the steel spring. In its present form it shares the w ork of the la tter, thus permitting weaker and, therefore, lighter springs.
The Spring Aid comprises a cylindrical block of rubber, with a hole in the middle, bonded to a plate at the top and to another at the bottom. These plates are bolted to a frame bracket and to the spring fixing, respectively. They are shaped to accommodate and support the block when it is deformed by the load, so that, under this condition, it assumes a shape of a horizontal ellipse. . Not only does the rubber share the load, but also it takes the recoil. Being bonded to the plates it is put in a state of tension when the distance between frame and axle increases. Thus, it takes the place of a spring damper, as well as performieg its primary function.
The characteristics of the Spring Aid can be varied in two ways--by changing the size of the hole and by altering the quality of the rubber to make it harder 'DI softer. We are informed that in the ease of a 10-12-ton chassis a saving in weight of 86 lb. was effected by fitting the Metalastik device to the rear axle.
In the accompanying graph, the respective characteristics of a Spring Aid, a steel spring and the two together, are shown. In the arse of the rubber, the spring rate builds up as the load comes on, affording a
progressive action. Thus, a definite improvement is effected by its employment, besides the gains in respect of lightness and recoil control.
We understand that a prominent vehicle builder in this country has subjected the Spring Aid to a 20,000-mile test and that the results were entirely satisfactory.