INDEPENDENT SUSPENSION

WHAT IS INDEPENDENT SUSPENSIONIt is a type of suspension in which all the four wheels of a vehicle can sprung independently.Depending upon roads, wheels moves different in vertical plane keeping the main body unaffected by road surface.

NEED OF INDEPENDENT SUSPENSIONWith obvious rigid suspension the vehicle tilts on one side.Vehicle body tilt is avoided by independent suspension.Generally coil spring is used instead of leaf spring as it has more elastic strain energy. It takes less space and is lighter too.

SUSPENSION POSITION IN VEHICLE

TYPES OF INDEPENDENT SUSPENSIONSwinging half axle suspensionDouble wishbone type suspensionMac Pherson strut type suspensionTrailing link type suspensionMulti link type suspension

SWINGING HALF AXLE SUSPENSIONWheels mounted rigidly on half axles which in turn are pivoted to frame.Depending upon surface, whole half axle jumps up and down.

ADVANTAGES:Independent ride

DISADVANTAGES:Camber varies.Very bad handling

WHO USE IT:Mercedes 300SL (1954)

DOUBLE WISHBONE TYPEBasic unit consists of two arms (V-arms) called upper and lower wishbones.Spring is provided in between two arms for damping provision with shock absorber inside. Basic Unit

BASIC UNIT ATTACHED TO AXLEBoth wishbones remain attached with frame.Vehicle weight is transmitted to lower wishbone by body and then through coil spring.Depending upon bump, wheels moves up and down oscillating both wishbones.

ADVANTAGES:Controlled camberGood handlingUnsprung wt. is reduced

DISADVANTAGES:Camber presentCostly and complex

WHO USE IT:European sports cars like Ferrari, lotus and some sedans.Camber present

Mac PHERSON STRUT TYPESame as double wishbone; but top wishbone is removed and coil attached to a strut.

BASIC UNITBlue Lower wishbonePurple Coil springLight yellow StrutGreen - frame

BASIC UNIT ATTACHED TO AXLEInvented in 1940 by Earl S. Mac Pherson of Ford.Lower wishbone is pivoted and free to oscillate up and down.This oscillation is damped by coil spring and shock absorber.

ADVANTAGES:Compact and cheap; thats why used for front axle the most.Lighter than double wishbone, therefore less Unsprung mass and less shocks.

DISADVANTAGES:Average handling.

WHO USE IT:Most front wheel drive compact cars.

TRAILING LINK SUSPENSIONBasic unit consists of a coil spring and trailing arm.Trailing arm remains parallel to road while coil spring remains perpendicular.

BASIC UNIT ATTACHED TO AXLECoil spring is attached to trailing arm which in turn is attached to frame.Another end of trailing arm is coupled with wheel hub.Road bumps winds and unwinds the coil spring and oscillate the trailing arm simultaneously.Semi trailing link arrangement is used when frame back is angular.

ADVANTAGES:Camber and wheel track almost constant.Only allows up and down motion of wheel.

DISADVANTAGES:Less refined than multi link suspension.

WHO USE IT:Many mid price to high price sedans and coupes, mostly before 1990. After that multi link suspension came in existence. Used for rear axle suspension where more space is present in horizontal plane.

MULTI LINK SUSPENSIONA number of links are attached rigidly to wheel to take various forces.Different no. of arms can be used depending upon the requirement.

BASIC UNIT ATTACHED TO AXLECame in existence after 1990.It is the extension of Mac Pherson type suspension.

ADVANTAGES:Most useful to avoid camber during up and down motion of wheel and during wheel rolling during steering.Wheel track remains constant.

DISADVANTAGES:Its a compromise between efficiency and space.Not as cheap as Mac Pherson type suspension.

WHO USE IT:Luxurious sedans like BMW 3 series, Mercedes S class.

WHEEL MOTION WITH MULTI LINK SUSPENSION

UP AND DOWN MOTION

MOTION IN ROLLING

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