MOTORSPORT SUSPENSION SYSTEM

MOTORSPORT SUSPENSION SYSTEMBY ANIZ ALIRoll.No-227th SemesterAutomobile Engineering

INTRODUCTIONSuspensionis the term given to the system ofsprings,shock absorbersandlinkagesthat connects avehicleto itswheelsand allows relative motion between the two.dual purpose contributing to the vehicle's road holding/handlingandbrakingfor good active safety and driving pleasure, and keeping vehicle occupants comfortable and reasonably well isolated from road noise, bumps, and vibrations, etc.keep the road wheel in contact with the road surface as much as possible, because all the road or ground forces acting on the vehicle do so through the contact patches of the tires. In supercars and sports oriented vehicles the suspension plays a vital role in maintaining traction under conditions of acceleration, braking and hard cornering.Thus in motorsports, suspension systems are critical to driver safety and performance optimization.

SUSPENSION GEOMETRYSuspension system can be classified into the following ways:-

-Dependent suspension

-Independent suspension

-Semi independent suspensionDEPENDENT SUSPENSIONAdependent suspensionnormally has abeam(a simple 'cart' axle) or (driven)live axlethat holds wheels parallel to each other and perpendicular to the axle. When thecamberof one wheel changes, the camber of the opposite wheel changes in the same way (by convention on one side this is a positive change in camber and on the other side this a negative change).De Dionsuspensions are also in this category as they rigidly connect the wheels together.

SEMI INDEPENDENT SUSPENSIONIn this case, the motion of one wheel does affect the position of the other but they are not rigidly attached to each other. Atwist-beam rear suspensionis such a system.

INDEPENDENT SUSPENSIONAnindependent suspensionallows wheels to rise and fall on their own without affecting the opposite wheel. Suspensions with other devices, such as way barsthat link the wheels in some way are still classed as independent.The variety of independent systems is greater and includes:-Macpherson strut-Upper and lowerA-arm(double wishbone)-Multi-link suspension

DOUBLE WISHBONE SUSPENSIONThe double wishbone suspension was first used in the 1930s in Europe and then in 1935 in Detroit. Many vehicles used it until front wheel drive cars came into being starting in the 1970s when a form of the double wishbone suspension called the Macpherson strut came to be heavily used. The double wishbone is classified as an independent suspension system that has been used to replace the beam type dependent suspension systems previously discussed. DOUBLE WISHBONE SUSPENSION

The double wishbone suspension system consists of two equalsized short wishbone shaped members (arms) positioned one over the other. The closed ends of the two wishbone arms are hinge mounted to the top and bottom of the vehicle knuckle to provide vehicle steering. The vehicle knuckle supports the spindle or hub to which the wheel is mounted. The two open ends of each wishbone member are hingemounted to the vehicle frame.DOUBLE WISHBONE SUSPENSIONIn the event that the double wishbone suspension is used for a drivewheel application, a coil spring is seated on the central portion of the upper arm and extends upward where it is supported by a body member. In this case, the upper arm supports most of the vertical load and there is space for the vehicle drive shaft below. When the double wishbone suspension is used on a nondrive wheel application, the coil spring is seated in the central portion of the lower arm and again extends upward to a body support member, with the lower arm supporting most of the vehicle load.

DOUBLE WISHBONE SUSPENSIONADVANTAGES- - Versatile (placement of shock absorbers) - Because of the length of the upper and lower arms, vertical suspension movement results in an increase in negative camber. This means that the tires on the outside of a turn stay in better contact with the road DISADVANTAGES- - May take more space - Slightly more complex than other systems like a Macpherson strut. - Due to the increased number of components within the suspension setup it takes much longer to service and is heavierSHORT ARM/ LONG ARM SUSPENSION

The short/long arm suspension is a modification of the double wishbone. In a short/long arm (SLA) suspension, the two arms are of unequal length with the upper arm being shorter than the lower arm. The short/long arm suspension is considered to be an independent suspension since the two wheels are not directly connected as they are on the solid beam type.

PUSH ROD/PULL ROD SUSPENSIONPushrod pull rod, the difference as the name suggests is the whether the rod pushed up to the rocker or pull down to the rocker. Pull rod was first brought to F1 by Gordon Murray as Brabham in the 70s, the Pull rod set up has a strut from the outer end of the upper wishbones that runs diagonally to the lower edge of the chassis and "pulls" a rocker to operate the spring\damper. A pushrod is the opposite; the strut runs from the lower wish bone to the upper edge of the chassis.

PUSH ROD/PULL ROD SUSPENSION

Black - PushrodYellow - RockerDark Yellow - Rocker splined to Torsion barLight grey- torsion barRed - DamperBlue - antiroll bar linkages.PUSH ROD/PULL ROD SUSPENSION

The torsion bar passes through the centre of the rockers and fix to the front of the chassis. The Rocker pivots on the torsion bar. The push rod pushed the rocker and twists the torsion bar to provide the spring in the suspension, the rocker then compresses /extends the damper and operates the antiroll bar if the car is in roll.PUSH ROD SUSPENSION

PULL ROD SUSPENSION

Which is better Push or Pull rod systemIn terms of their effectiveness as controlling the wheels, both are equal. In terms of effect on aerodynamics each has its merits depending on the prevailing rules and trends. Pull-rod clearly provides a lowerC.O.G, although access can be an issue.

One difference is in the load passed through the wishbones. As per Newtons third law, the rod has to react to the force of the springs. This passes back from the rocker to the mount on the wishbone. In push-rods case, this reaction force is in the opposite direction to the force fed from the wheel into the chassis, the two offset each other. With Pull-rod the force from the rod and the wheel act in the same direction, this doubles the load in the upper wishbone and resultantly in the mounting the on the gearbox. This can be accounted for design and weight of the final wishbone design.

Which is better Push or Pull rod systemHowever, push rod also has its structural problem. The push rod when the suspension in bump (wheel rising) the rod is in compression and would tend to bow outwards. The push rod was the first suspension component to have carbon fibre cladding for reinforcement, again design and weight is needed to offset this load. Suspension experts point out that pull-rod suffers similar compression bending when the suspension is in droop (wheels falling), but droop is considered less critical in wheel control, than bump. Theres no one answer to which is best, you look at your design requirements and pick which solution works, best. Next year the best car is not necessarily going to be the one with Pull-rod rear suspension.MULTI LINK SUSPENSION SYSTEM

The multi-link suspension uses three or more lateral arms and one or one or more longitudinal arms, which don't have to be of equal length and can be angled away from their natural direction. Each of the arms has a spherical joint or rubber bushing at each end, causing them to work in tension and compression and not in bending.

MULTI LINK SUSPENSION SYSTEM

The arms are joined at the top and bottom of the spindle. When this spindle turns for steering, it actually alters suspension's geometry by torquing all suspension arms. The suspension's pivot systems are designed to allow this. Multi-link arrangements are used on both the front and the rear suspensions, but the former replaces a lateral arm with a tie-rod that connects the rack or steering box to the wheel hub

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