DOI 10.4010/2016.558 ISSN 2321 3361 © 2016 IJESC

Research Article

Volume 6 Issue No. 3

Indian automobile Suspension System Assessment Chaudhari Mahendra M Assistant Professor VN College of Engineering, Bota, Maharashtra, India Abstract: A vehicle suspension has a great impact on ride produced. Suspension system suspends the body on the shock absorbing system and the same time maintains contact patches of four tires in effective contact with the road surface. There are few major functions of vehicle suspension system. It separates the chassis from the road by allowing vertical compliance for the wheel to follow uneven road. It can maintain proper steer and chamber angles to road, it reacts to all forces produced by the tires resist roll of the chassis and keep the vehicle tires in contact with the road. Suspension can be classified in to two types: active and passive suspension system. These systems can compromise the ride comfort for vehicle load carrying, and vice versa. Passive suspension consists of elements that can only store energy in their spring and dissipate energy through shock absorber. There is no external energy supplied to a passive suspension system. Active suspension however adds energy to the suspension using actuator to produce desired force in the suspension system. Keywords: Suspension system, Components of suspension system, Conventional suspension system, Development of suspension systems, Dampers used in suspension system I. Introduction: The term suspension suggest supporting from above, as in suspension bridge or suspender seems the earliest form of suspension used on the roads did literally suspend the body of the horse-drawl carriage at the four corner by every flexible leaf spring with outer end that curved over and upward to join the shackle pins in the carriage frame. In the modern automobile suspension plays a dual role. It suspends the body on the shock absorbing system and the same time maintains contact patches of four tires in effective contact with the road surface. One cannot overemphasize the importance of the second role. If we fell in this the driver cannot control the vehicle. Rally drivers are well aware that effective road contact is sometime lost. They were safety harnesses and crash the helmets reduce danger form the eventuality and the backup crew carry host of spares to repair the damage. Even so good suspension system under normal condition keeps all four wheels in contact with road surface and makes it possible for a driver of avg. ability to keep the vehicle under satisfactory directional control. A bad suspension systems fells to do under identical road conditions. It is perfectly logical therefore to begun our analysis of suspension systems from the bottom since the cars four areas of contact with the road surface made by the tires are so vital to behavior of vehicle in motion.

severe stress on engine and transmission system as well as the body of work. The vehicle component or axle should be properly suspended. Moreover if the front and rear wheel axle are allowed turn in the bearing rigidly attached to frame, extremely uncomfortable ride would be resulted. To avoid the transmission of road effects to the passengers while traveling in the vehicle on uneven ground, it is therefore necessary that the wheel and axle should be insulated from the frame. For this purpose suspension systems are used. Good suspension systems have springiness and damping. Springiness is an elastic resistance to a load while damping is ability of absorbing energy of compressed spring. A spring liable to overshoot its original position and starts damping up and down if this energy is not absorbed. For smooth traveling of the wheels, their size is an important factor. Although a large wheel rides on most of road irregularities yet all types of road wheel are not available to iron out the effects. i) Objectives of suspension system: The main objectives of suspension system are as under.  

II. Suspension system: The occupants of motor vehicle would suffer severely as well as its structures would be subjected to excessive fatigue loading if the chassis is provided with direct transmission of the load carried by the rolling wheels of vehicle. To safeguard the working parts of the motor vehicle against fracture or breakdown due to continued and

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



To minimize the effects of stresses due to road shocks on mechanism of the motor vehicle and provide a cushioning effects for both. To safeguard the occupants against road shocks and provide riding comfort. To keep the body of motor vehicle on wheel keel while traveling over rough ground or when turning in order to minimized the rolling, pitching or vertical movement tendency. To provide the requisite height to body structures as well as to bear the torque and braking reactions.

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 

To isolate the structural of vehicle from shock loading and vibration due to irregularities of the road surface without impairing its stability To keep the body perfectly in level while traveling vehicle over rough and even ground.

ii) Principles Of Suspension System: There are three principles of suspension system underlying the satisfactory springing of motor vehicles are:  Reduction of weights of the wheel and other components receiving the road shocks to minimum or reduction of upspring weight.  Reduction of rolling or pitching of body to a minimum with suitable design and attachment of spring.  To absorb satisfactorily the as well as smaller road impacts with the help of single springing device. iii) Components Of Suspension System: . The components used in suspension system are as follows: a) Leaf Springs: The leaf springs are of various types they are as follows:  Full elliptic.  Three quarter and Quarter elliptic.  Transverse elliptic. b) Spring Shackles:  U-type.  Y-Type (rear suspension).  Link Type. c) Axles:  Live axle.  Dead axle/front axle.  Stub axel. d) Wheels:  Artillery wheels.  Wired spoke wheels.  Steel disk wheels.  Solid type wheels.  Pneumatic tyre wheels. e) Shock Absorber  Single and Double Acting, Mechanical. f) Stabilizers: iv) Different Types Of Suspension Systems: Suspension system of an automobile system is designed considering various parameters like load, sprung and up sprung weight, engine HP type size, load distribution, types of transmission system. 1) Conventional suspension system. 2) Independent suspension system. a) Independent front-end suspension. (i) Wishbone type. (ii) Mac parson strut type. (iii) Vertical guide type. (iv) Trailing link type. b) Independent rear suspension. 3) Air and Hydro elastic suspension.

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III. Conventional Suspension System: In conventional system the chassis frame is supported on the axle through springs. The spring is used may be leaf spring or coil spring. When one wheel encounters a bump or pothole on road, the other wheel also moves by same amount as first. This gives gyroscopic effect and wheel wobble. i) Classification of Suspension Spring: The conventional system generally uses different type of springs they are classified as follows. 1) Steel spring:(a) Leaf spring (b) Coil spring (c) Torsion bar 2) Rubber spring. (a) Compression and Disc type rubber spring (b) Compression share spring.(c) Steel reinforced rubber 3) Plastic spring 4) Air spring.5) Hydraulic spring The construction of leaf spring is as shown in figure.

The longest or main or master leaf of a spring is coiled around the ends to form eyes. These eyes embrace the shackle pins and also bushed with bronze bushes sometimes the second leaf partly embrace the eye of the main leaf as safe guard. To prevent the longitudinal displacement the leaves are bolted by center bolt as shown in figure. Similarly another method to prevent the displacement of leaves is that the leaves are sometimes made with projection at the bottom and races at the top surface. These leaves are also assembled that the projection of upper spring should mesh in the recess of lower spring. The bolt or I bolt the spring as the unit to the axle at the spring seat to adjust the variation in length of master leaf due to passing the vehicle across a projection on the road surface. The one end of leaf is directly mounted on frame with a pin and other end is connected through the shackle. If the both ends of spring are connected to shackle then the spring will not be able to accommodate the change in length. Therefore through shackle flexible connection is optioned. IV.

Development Of Suspension Systems: Previously the vehicle use conventional suspension systems. They use different springs. But there are fundamental limitations of suspension systems. The basic limitation is that the static deflection varies as the inverse square of natural frequency of the spring. Attempt have

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been made to overcome this problem by using rising rate spring, but this is only palliative and many research workers in the field have been studying the application of closedloop control systems to automotive suspensions and there have already been several experimental application. The suspension researchers develop some new suspension system. Out of that some are as follows: i) Independent Suspension System: The term suspension suggest supporting from above, as in suspension bridge or suspender seems the earliest form of suspension used on the roads did literally suspend the body of the horse-drawl carriage at the four corner by every flexible leaf spring with outer end that curved over and upward to join the shackle pins in the carriage frame. Conventional system provides greater simplicity. They contain systems like rigid axle suspension. They are widely used in heavy carriers. Suspension is directly using leaf spring hence they have less complexity. In this system both the wheels of the vehicle are suspended in combination as directly axle is suspended. Simplicity is the only advantage they do not provide effective suspension.

In the modern automobile, suspension plays a dual role. It suspends the body on the shock absorbing system and the same time maintains contact patches of four tires in effective contact if the road surface one can not overemphasize the importance of the second role if we fell in this driver cannot control the vehicle rally drivers are well aware that effective road contact is sometime lost. They were safety harnesses and crash the helmets reduce danger form the this eventuality and the backup crew carry host of Spares to repair the damage even so good suspension system under normal condition keeps all four wheel in contact with road surface and makes it possible for a driver of avg. ability to keep the vehicle under satisfactory directional control bad suspension systems fells to do under identical road conditions.

International Journal of Engineering Science and Computing, March 2016

It is perfectly logical therefore to begun our analysis of suspension systems from the bottom since the cars four areas of contact with the road surface made by the tires are so vital to behavior of vehicle in motion. To prevent the system form entry of dust or foreign particles the flexible cover is provided at the lower end of container. This cover seals the units. A passive suspension system is one in which the characteristics of the components (springs and dampers) are fixed. The designer of the suspension determines these characteristics, According to the design goals and the intended application. Passive suspension design is a Semi active suspension system uses a damper in which the level of damping force can be adjusted. Dampers in which the damping force can be externally adjusted are called controllable dampers. Controllable damper has a range over which the level of damping can be varied. This is shown in Figure. A heavily damped suspension will yield good vehicle handling, but also transfers much of the road input to the vehicle body. When the vehicle is traveling at low speed on a rough road or at high speed in a straight line, this will be perceived as a harsh ride. The vehicle operators may find the harsh ride objectionable, or it may damage cargo. A lightly damped suspension will yield a more comfortable ride, but can significantly reduce the stability of the vehicle in turns, lane change maneuvers, or in negotiating an exit ramp. Good design of a passive suspension can to some extent optimize ride and stability, but cannot eliminate this compromise. The suspension system connecting a vehicle body to the wheels and its type allows the wheel to move in an essentially vertical direction in response to good surface irregularities, a spring element temporarily stores and releases energy thus insulating the vehicle body from acceleration peaks. A shock absorber or ‘damper’ insures that oscillation induced by road unevenness or aerodynamic forces (or by accelerating braking), which would impair ride comfort and road holding die away quickly. With development of technology a new concept called independent wheel suspension has emerged. In this system both the wheels are suspended independently as every wheel has its independent suspension system. This provides suspension for actual road conditions. This system is very complex but have advantages like low weight, plenty of scope for achieving favorable “elasto – kinematics effects”, no coupling of masses, no suspension parts that run right across the vehicle. Hence nowadays in most of the passenger cars this system is used and preferred over conventional system, providing thermal sooth drive. 

Independent Front End Suspension System: The arrangement of road wheel connected to the frame and not effecting the movement of the other wheels is called as independent suspension system. This system generally adopts in front wheels due its several advantages as follows. The trouble of front brakes and low pressure tyres due to wheel wobble are eliminated in this suspension

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system. In this system the wider spacing of the front springs improves the steering conditions and qualities. In this suspension the up sprung parts are less heavy than in axle suspensions. This allows the use of low rate springs so that riding qualities are improved. The common types of front suspension systems are as follows: 1) Wishbone suspension system: In Wishbone suspension system basically used a helical springs on both side of wheel inner end. Lower control arm and upper control arm nothing but the wishbone frame. In this arm i.e. upper arm mount the helical compression coil spring both side of steering wheel for suspension purpose. Steer a wheel with the help of stabilizer bar which connected strut rod to lower arm. One helical spring is being used between two wishbones with support of the frame member. The upper wishbone is provided at the inner end on hydraulic damper while the outer end is provided a stub axle carrier. The lower wishbone has sufficient length thus it gives more constant track when the wheels are lifted.

force for stabilize the control the arm gives the steering inclination.

A strut contains shock absorber and spring and carries stub axle on which vehicle is mounted. 3) Vertical guide type: In this system the stub axles can slide up and down and also allow turning of wheels when steered. The lower end of swivel pins are fixed with the cross member of chassis while the ends are supported with spacing rod. Helical springs are used between spacing rod and sliding member of the axle and are arranged in such a way that swivel pins may pass through them. In this system the caster angle, chamber angle or track of wheel is not altered as the wheels rise or fall. The main difficulty in this system is that to keep the sliding member free from the shake and slackness.

The arms of the lower wishbone are so designed that they may resist the breaking torque. This type of arrangement is provided in most of the cars. 2) McPherson strut type: In this system only lower wishbone is used which is hinged to the cross member. A simple Macpherson Strut suspension on the right front wheel of a rear-wheel drive vehicle.in this components of suspension system are shock absorber, coil spring, strut rod, control arm, ball joint as well as stabilizer rod shown in figure. The McPherson strut is a type of car suspension system which is uses the top of a telescopic damper as the upper steering pivot.it widely used in the front suspension of modern vehicle and is named for American Automotive engineer Earle S. .It’s a well-known as “double wishbone” or “multi-link” suspension. The wishbone positions the wheel and resist, baking and side

International Journal of Engineering Science and Computing, March 2016

 Independent Rear Suspension System: The rear wheel of general vehicle power driven therefore considerable difficulties are there to provide independent suspensions. Figure shows one of the methods of rear wheel suspension.

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and Toyota to name but three. Formula one cars represent the extreme of active suspension implementation, being fully active systems using high bandwidth aerospace specification components. For wide spread commercial use much cheaper actuators and control valves must be used, and so semi-active or low bandwidth systems are the norm here. The oleo-pneumatic actuator is a popular choice, giving both a low frequency active element and a high frequency passive element in one unit.

Universal coupling keep the wheel vertical while the sliding coupling is required to keep the track constant. Apart from some advantages some disadvantages are there for independent rear suspension system. Higher initial cost and complex in design. More maintenance is required with increased number of bearing. Steering system requires more frequent attention. More rigid stub frame is required. ii) Active Suspension System: Traditionally automotive suspension designs have been a compromise between the three conflicting criteria of road holding, load carrying and passenger comfort. The suspension system must support the vehicle, provide directional control during handling and provide effective isolation of passengers/payload from road disturbances. Good ride comfort requires a soft suspension, whereas insensitivity to applied loads requires stiff suspension. Good handling requires a suspension setting somewhere between the two. Due to these conflicting demands, suspension design has had to be something of a compromise, largely determined by the type of use for which the vehicle was designed. Active suspensions are considered to be a way of increasing the freedom one has to specify independently the characteristics of load carrying, handling and ride quality. A passive suspension system has the ability to store energy via a spring and to dissipate it via a damper. Its parameters are generally fixed, being chosen to achieve a certain level of compromise between road holding, load carrying and comfort. An active suspension system has the ability to store, dissipate and to introduce energy to the system. It may vary its parameters depending upon operating conditions and can have knowledge other than the strut deflection the passive system is limited to. Active suspension systems that have been successfully implemented include the high profile examples found on Formula One racing cars. Most major motor manufacturers are researching their own systems and some are near to fruition. These include Jaguar, Mercedes Benz

International Journal of Engineering Science and Computing, March 2016

iii) Adjustable Suspension System: This system has the advantage of allowing to operator to occasionally adjust the dampers according to the road characteristics.

It is however, unrealistic to expect the operator to adjust the suspension system to respond to time inputs such as potholes, turns, or other common road inputs. iv) Semi Active Suspensions: Semi active suspension systems were first proposed in the early 1970’s. In this type of system, the conventional spring element is retained, but the damper is replaced with a controllable damper as shown in fig.

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Whereas an active suspension system requires an external energy source to power an actuator that controls the vehicle, a semi active system uses external power only to adjust the damping Levels, and operate an embedded controller and a set of sensors. The controller determines the level of damping based on a control strategy, and automatically adjusts the damper to achieve that damping. One of the most common semi active control policy is skyhook control which adjusts the damping level to emulate the effect of a damper connected from the vehicle to a stationary ground, as shown in Figure.

Dampers used in suspension system: A damper is a device that dissipates energy in the form of heat. Energy is changed to heat by forcing a viscous fluid through an orifice. In a vehicle, energy from the road, rather than being transmitted to the vehicle, is changed into a temperature rise of the fluid inside of the damper. Two types of dampers are commonly used in vehicular applications, twin-tube and monotone dampers. Both twin-tube and monotone dampers typically have bilinear damping characteristics. This means that the slope of the damper force vs. relative velocity is greater at low than it is at high velocities, as shown in figure. Twin and monotone dampers have the same outward appearance and the same general structure, as shown in Figure. In both cases, the shock absorber has a piston that traverses back and forth inside a cylinder. In a monotone damper, the piston travels in a single cylinder that contains a fluid chamber and the fluid and air chambers. Velocities pressurized air chamber. A floating piston is used to separate. The air chamber is used to accommodate the change in the fluid chamber volume, due to the volume of the piston rod. As the piston rod pushes in, it reduces the fluid chamber volume, which is gained back by the floating piston moving down against the compressible air chamber. Conversely, when the rod is pushed out, the fluid chamber volume increases and the floating piston moves unto fill the excess volume, in order to avoid the creation of a vacuum in the fluid chamber. If vacuum is created in the fluid chamber, then the fluid will cavities as it passes through the damper

piston and the damping effect will be significantly diminished. In the twin-tube configuration, there is air in part of the outer tube. The compressible air is in direct contact with the incompressible fluid. As the piston rod enters the damper, the air compresses to compensate for the change in volume available to the fluid. Likewise, when the piston rod is withdrawn from the damper, the air expands in order to avoid the creation of a vacuum.

V.

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In the twin-tube damper configuration, it is necessary for the air to remain at the top of the outer cylinder. If the air didn’t remain at the top of the damper and were to pass through the damper valuing, the damping effect will be significantly diminished, as in the case where the fluid cavities. Since there is note barrier at the fluid-air interface, the air will only remain at the top of the outer cylinder if the Damper is operated in its upright position. In either style of damper, the damping force is the result of viscous friction arising from the passage of the working fluid through an orifice. The level of the damping force that results is function of properties of both the orifice and the fluid. The size and shape of the orifice as well as the viscosity of the fluid determine how easy it is for the fluid to pass through the orifice. VI. CONCLUSION: Recent suspension developments scenario in Indian suspension system are very, useful in all passenger vehicles as well as number of suspension system are utilized to variety of vehicle structure and application base. This

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suspension system provides high degree of comfort and it reduces the shocks and vibrations coming to the vehicle body. Due to reduced vibration the maintenance of the vehicle is decreases, hence reduces the operating cost. Due to the self-adjusting technique, increases the flexibility of any kind of roads. It also reduces the breakdowns. The dampers used in this system increase the comfort ness, which is not possible in conventional system. VII. REFERENCES [1] Colin Campbell. “Automobile suspensions” 1981 paperback ISBN: 0412158205 chapman and Hall publication. Chapter-2nd pages 22-40, 41-53, 77-104,120128 [2] Dr.Kirpal Singh, “Automobile engineering” Vol-1, 12th edition. Standard Publication Distributors. Module 3 [3] Gavale S.L , “Automobile manufacturing” 1st edition chapter -3 [4] G. B. S. Narang, “Automobile Engineering”, 5th Edition 1989, Khanna. [5] David Landau, “Laminated spring” Patent citation international paper publishing (Sep 19, 1916) patent No.US1199038 [6] North American, “Leaf spring element having high fatigue and wear resistance and method of producing same” Patent citation (June 15, 1971) patent No.US3585086 [7] Ressort Du Nord S.A, “Vehicle suspension spring” Patent & International paper published (Aug 17, 1976) patent No.US39795005 [8] Toledo Woodhead spring Ltd, “Multi leaf Laminated spring” Patent and patent citation paper publish (Dec 25, 1962) patent No.CA654806A [9] Dana Corporation, “Trailer spring assembly”, international patented research paper publishing since March 24, 1998. Patent No. US5730427. [10] Paul F.White, “Suspension Apparatus & method for contact wire at trough & crest of a track vertical curve” Patent citation (Sep 25, 2014 & Oct 2, 2014) paper No. US10140291

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