RO-11/GIVI composite link
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• A General Motors-developed composite leaf spring could soon become an option on Rubery Owen-Rockwell trailer suspension.
Rubery Owen-Rockwell has signed a letter of intent with GM's component-manufacturing Inland Division, whereby RO-R has the sole right to use the spring on trailers and semi-trailers.
The spring is an uprated version of the component used by GM on its Corvette cars since 1981. RO-R has tested it extensively at its Darlaston laboratory in the Midlands, and a British tri-axle semi-trailer fitted with the springs has been undergoing test at GM's proving ground in Michigan, USA.
Neither RO-R nor GM will say precisely what the spring is made of except that it is not carbon fibre but "a mixture of polymers, resins and other fibres."
The composite spring's principal advantages over steel leaf springs are its low weight and excellent durability — but it will be costly.
Rubery Owen-Rockwell's technical director, Jack Diggs says it is too early in the programme to fix its price, but he expects the composite spring to be "about twice the cost of a standard, monoleaf steel spring but with a service life three times as long."
Compared with a typical steel monoleaf spring, the GM composite one is about 8kg less, but its spring rate and deflection characteristics are more like those of a three-leaf spring, which is much heavier.
Rubery Owen-Rockwell had been developing its own carbon fibre/epoxy trailer spring. but CM understands that delamination proved to be an in
surmountable problem. RO-R says its partnership with GM could lead to the development of other new composite trailer suspension components.
The next stage in the de
velopment of the GM/RO-R spring will be fleet trials on about 30 semi-trailers. An example of the spring will be on display at next month's Motor Show.