A common application is in vehicle suspension systems, where abushing made of rubber (or, more often, syntheticrubber or polyurethane)separates the faces of two metal objects while allowing a certain amount ofmovement. This movement allows the suspension parts to move freely, forexample, when traveling over a large bump, while minimizing transmission ofnoise and small vibrations through to the chassis of the vehicle. A rubber bushingmay also be described as a flexible mounting or antivibrationmounting.Based on different embeded material,bushing could be divided intoSteel bushing,Cpper bushing,Aluminium Bushing,and Rubber Bushing.
These bushings often take the form of anannular cylinder of flexible material inside a metallic casing or outer tube.They might also feature an internal crush tube which protects thebushing from being crushed by the fixings which hold it onto a threaded spigot.Many different types of bushing designs exist. An important difference comparedwith plain bearings is that the relative motionbetween the two connected parts is accommodated by strain in the rubber, ratherthan by shear or friction at the interface. Some rubber bushings, such as the Dblock for a sway bar, do allow sliding at the interface between one partand the rubber.
(2)Flexibility of rubber also introduces anelement of play in the suspension system. This may result in camber, caster, ortoe changes in the wheels of the vehicle during high-load conditions (corneringand braking), adversely affecting the vehicle's handling.For this reason, a popular aftermarket performance upgrade is the replacementof rubber suspension bushings with bushings made of more rigid materials, suchas polyurethane. Polyurethane bushings are also available for many vehicleswith approximately the same characteristics as the manufacturersoriginal bushings, but with greatly increased durability.This is useful onvehicles that have a reputation for wearing out standard rubber bushings, butfor which harder bushings with increased harshness of ride are not wanted.
· Anti-roll bar (US Sway bar)links and mountings
· Shockabsorber mountings
· Double wishbone suspension assemblies
· Most high-speed inline internalcombustion engines are prone to torsional vibration of their crankshafts; thestraight six and straight eight engines being particularly prone to thisproblem due to their long crankshaft length. Although straight eight enginesfaded from the marketplace in the 1950s, many straight six engines have andstill do feature crankshaft vibration damping utilizing rubber bushes. The3,442 cc Jaguar XK 6-cylinder engine of 1948 andmost subsequent versions of the ubiquitous Jaguar XK engine used a proprietaryMetalastik vibration damper to protect their crankshafts from potentiallydamaging torsional vibrations. To quote William Heynes, "TheMetalastik damper consists of a steel plate to which is bonded, through a thickrubber disk, a malleable iron floating weight. Variations of the weight, rubbervolume and mix, give these dampers a very wide field over which they canoperate."
In fastening, bushings are alsoused to transfer loads from a fastening to a much larger area in the underlyingstructure, the object being to reduce the strain on individual fibers withinthe underlying structure.