Leaf springs fabricated from cfrp weigh only 20% as compared to one made of steel and yet have the same spring rate and load carrying capacity. Leaf springs are essentially beams in bending, with minor torsional loads and localized edge loads, hence most of the fiber can be oriented along the length of the leaf.
A hybrid of glass and carbon bumper has been designed for heavy trucks and buses, giving a corrosion resistant product some 30kg less in weight, with superior vibration resistance.
Drive shafts: Carbon fiber has been used for fabricating drive shafts for many years and initially, cost was a serious drawback, but with lower costs and development of fibers with improved mechanical properties, it is estimated that over 12,000 composite shafts are now in service in the industry today. Carbon fiber produces lightweight shafts with good corrosion resistance and excellent torsional strength and fatigue resistance; reduced need for balance weights; better damping characteristics and torsional compliance, which reduces shock loads on gears and universal joints. The mechanical properties enable single span shafts up to 6m in length and not requiring a center bearing reduce vibration. The fiber is filament wound in a helix to provide optimum properties.
Strengtwell manufactures driveshafts for Spicer, who has replaced an Al tube with an overwrap of glass and carbon fiber construction by using a combination of filament winding and pultrusion. Starting with a filament wound glass tube, the carbon fiber is pultruded over it, with the axial presentation of the carbon fiber providing optimum properties for bending stiffness. This construction is used for Class 8 heavy trucks with a span of 3.3 m and is likely to be extended to nearly twice the length for other heavy trucks. The Nissan 350Z has a carbon fiber drive shaft.
Buses: North American Bus industries are using composite bus structures fabricated in Hungary and assembled in the US, made from multiaxial knitted E-glass, but employing some triaxial woven carbon fiber to reinforce areas around windows and roof, permitting standard bus windows to be used.