Understand Suspension Systems: Types, Working, & Benefits

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Need of Suspension

  • The absorbing shocks and vibration caused due to the road irregularities.
  • For the transmitting vehicle load to the wheels supporting the weight.
  • The maintaining stability of the vehicle contact of wheels to the ground.
  • The providing cushioning and ride comfort to the passengers
  • The preventing body squat and the body dive.


  • To safe guard passengers and goods against road shocks.
  • The preserve stability of vehicles while in motion Pitching or the Rolling.
  • To provide the wheels always in contact with road while driving cornering and the braking.
  •  The maintain proper steering the geometry.
  • To the provide suitable riding and the cushioning properties.
  • The allow rapid cornering without extreme body the roll.
  • The prevent excessive body squat or the body dive.
Vehicle Squat And Dive


  • There should be minimum deflection.
  • It is should be of low initial the cost.
  • It is the should be of minimum weight.
  • It should have low maintenance and low operating the cost.
  • It should have minimum tire wear.

Road irregularities

  • The daily use of the road infrastructure, continuous changes of weather conditions, and vehicle’s overweight will produce different road surface wearing pattern.
  • In addition the deficient road construction process will be the eventually lead to road surface the irregularities.
  •   Nearly 20% accidents are triggered by infrastructure’s condition.
  •   Potholes, road cracks, unevenness and different friction levels can promote accidents due to emergency maneuvers.

Vehicle Axis System


  • A roll rotation the about x-axis.
  • A pitch the rotation about y-axis.
  • A yaw rotation about the z-axis.

Basic suspension movements

  • The Bouncing: The vertical movement of complete the body.
  • The Pitching: The rotating movement of the parts between spring road and a portion of the spring weight the itself.
  • The Rolling: The movement about longitudinal axis the produced by centrifugal force the during cornering.

Sprung and Un-sprung Masses

Sprung Mass:-

  • The vehicle with a suspension such as and the  automobile motorcycle or a tank sprung mass or sprung weight is the portion of a vehicle’s total mass that is supported above the suspension.
  • The sprung weight typically includes the body frame the internal components passengers and the cargo but does not include the mass of components suspended below the suspension components including the wheels wheel bearings brake rotors the calipers.

Un-sprung Mass:-

  • The ground vehicle with a suspension the un-sprung weight or the Unsprings mass is the mass of the suspension wheels or the tracks as applicable and the other components directly connected in to them rather than supported by the suspension.
  • The Un-sprung weight includes the mass of components such as the wheel axle’s wheel bearings wheel hubs tires and a portion of the weight of drive shafts springs shock absorbers and the suspension links.
Sprung and Unsprang Masses

Types of Suspension

  • Non-independent the Rigid suspension has both right and the left wheel attached to the same solid axle. When one wheel the it’s a bump in the road upward movement causes a slight tilt of the other wheel.
  • Independent suspension allows one wheel to move up and the down with minimal effect to the other.

Components of Suspension System

  • The springs which neutralize the shocks from road surface Energy the storage.
  • The Dampers which act to the improve comfort by limiting the free oscillation of the springs. Energy the Dissipation.
  • The Stabilizer sway bar or anti-roll bar which the prevents lateral swaying of the car.
  • The linkage system which acts to hold the above components in place and the control the longitudinal and lateral movements of the wheels.

Coil spring : is the most common type of spring found on the modern vehicles.

Leaf springs : are now limited to the rear of some the cars.

Components of Suspension System

Leaf Springs

Forces and Moments acting on Leaf Spring:

  • The Vertical force caused by the vehicle laden weight.
  • The Longitudinal forces caused by tractive and the braking effort.
  • Transverse forces caused by the centrifugal force side slopes the lateral winds.
  • Rotational torque reaction caused by driving and the braking efforts.

Leaf Spring

  • The Leaf spring (LS) was invented by the Obadiah Elliot of London in 18th century. He simply piled one steel plate on top of the another pinned them together and the shackled each end to a carriage it was the first ever leaf spring used and the vehicle.
  • It is the originally called as a laminated or carriage spring and the sometimes referred to as a semi-elliptical spring or cart the spring.

Leaf Springs

  • The Leaf springs are formed by the bending.
  • They are made of long strips of the steel.
  • The Each strip is named as the Leaf.
  • The long leaf is called Master Leaf and it is the consists of eyes at its both ends.
  • One end is fixed to the chassis frame the other end is fixed to the shackle spring.
  • The spring will get elongated during expansion and the shortened during compression.
  • This is change in the length of spring is compensated by the shackle.
  • The U-bolt and clamps are the located at a intermediate position of the spring.
  • The bronze or rubber bushes are the provided on both eyes on the master leaf.

Types of Leaf Spring

There are six types of the leaf springs

  • Full – elliptic type
  • Semi – elliptic type
  • Quarter – elliptic type
  • Three Quarter – elliptic type
  • Transverse Spring type
  • Helper Spring type

 1. Full elliptic

  • The advantage of this type is the elimination of shackle and the spring.
  • The lubrication and wear frequently which are one of the main drawback of this type of the springs.

  2 .Semi elliptic

  • The Mostly used in Trucks buses for rear and the front Suspension in some cars for the real    suspension 

3. Quarter elliptic

  • This type is rarely used in to the now-a-days.
  • The gives very less resistance in the road shocks.

  4. Three Quarter elliptic

  • This type is rarely used in to the now-a-days.
  • The gives good resistance to the shocks but occupies more space than other the types.

  5.Transverse Spring

  • The type of spring is arranged transversely across the vehicle instead of longitudinal the direction.
  • The transverse spring for the front axle which is bolted rigidly to frame at the centre and attached to the axle by means of shackle at both the ends.
  • The Disadvantage of this spring is the vehicle body in this case is attached to the springs at only two places which imparts the vehicle a tendency to roll easily when it is the runs fast on sharp corners.

   6. Helper Spring

  • The Helper spring (HS) are the provided on many commercial vehicles in addition to the main leaf springs.
  • They allow wide range of the loading. When the vehicle is lightly loaded these helper springs do not come into the operation.
  • But as load is increased they take their share of the load.
  • The generally helper springs are used on rear the suspension.
Helper Spring

Manufacturing Process

  • Shearing of flat the bar
  • The Canter whole punching the Drilling
  • End heating process forming the Eye Forming  Wrapper Forming  Diamond cutting  end the trimming width cutting the  tapering  punching  is  grooving end bending forging /the eye grinding  Canter hole punching  Drilling the nabbing
  • The Heat Treatment heating and Chamber forming Hardening Quenching the Tempering
  • The Surface preparation Shot peening and the Stress peening Primary painting
  • The Eye bush preparation process   reaming and boring Bush insertion the reaming
  • Assemble Presenting & the load testing Finish painting marking & the packing

Characteristics of Leaf Spring

  • The Leaf spring (LS) acts as a linkage for holding the axle in position and the thus separate linkage are not a necessary. It makes the construction of the suspension simple and the strong.
  • The positioning of the axle is carried out by the leaf springs so it makes  disadvantageous to use the soft springs i.e. a spring with low spring the constant.
  • Therefore this type of the suspension does not provide good riding the comfort.
  • The inter leaf friction between leaf springs affects riding the comfort.
  • Acceleration and the braking torque cause wind-up and vibration. Also wind-up causes rear-end squat and the nose-diving.

Coil Springs

  • The Coil springs (CS) are made of the special round spring steel wrapped in the helix shape.
  • The strength and handling characteristics of the coil spring depend on the following.
  • The Coil diameter
  • Number of the coils
  • Height of the spring
  • Diameter of the steel coil that forms spring
  • The larger diameter of a steel stiffer the spring.
  • The shorter height of the spring stiffer the spring.
  • The fewer coils stiffer the spring.
  • The coil springs are used mainly with the independent suspension though they have also been used in the conventional rigid axle suspension as the can be well accommodated in the restricted spaces.
  • The energy stored per unit the volume is almost double in case of the coil springs (CS) the leaf springs.
  • The Coil springs (CS) do not have noise problems nor do they have static the friction
  • Coil springs can be take the shear as well as bending the stresses.
  • The coil springs (CS) however cannot to be the take torque reaction and the side thrust for which the alternative arrangements have to be the provided.
  • The helper coil spring (CS) is also sometimes used to the provide progressive stiffness against increasing the load.
  • The springs are designed to the provide desired ride and handling come in a variety of the spring ends.

Spring Rate

  • The spring rate (SR) also called deflection rate is the value that reflects how much weight it takes to the compress a spring certain amount.
  • The spring rate (SR) or stiffness the spring constant is defined as the load required per unit deflection of the spring.
  • The constant rate spring continues to compress at the same rate throughout its complete range of the deflection.
  • The variable rate spring may compress one the inch under a 100-pound load but only compress and additional half an inch under a 200pound the load.
  • Before a spring is installed on a vehicle or any load is the placed on it is at uncompressed length or the free length. Once installed the weight of the corner of vehicle resting on the spring is called its static the load.

Coil Spring Mounting

The Coil springs (CS) are usually installed in the spring pocket or spring seat. Hard rubber or plastic cushions insulators are the usually mounted between the coil spring and the spring seat.

Spring Coatings

All springs are painted or the coated with epoxy to help prevent breakage. A scratch nick or pit caused by the corrosion can cause a stress riser that can lead to the spring failure.

Rubber Springs

  • The rubber springs (RS) can be the store more energy per unit mass than any other type of the spring material considerable weight can be saved with the rubber suspension.
  • It is the more compact than other the springs.
  • It has also the excellent vibration damping the property.
  • One more advantage of the using rubber is that it not suddenly fail like steel so there is the less risk.
  • The First introduced in the 1958 by Eric Multan.


  •  The represents a rubber suspension system in the simplified form that is similar to the one used on a popular the small car.
  • The spring is installed the between frame and top link of the suspension system.
  •  The spring is connected to be the point near link pivot deflection of the spring reduces to the minimum without affecting total wheel the movement.
  • The arrangement of a spring provides rising rate characteristic which is the soft for a small wheel movements but becomes harder as the spring deflects.
  • The energy released from the rubber spring after deflection is considerably less than that imparted to the it.
  • The internal loss of the energy is called hysteresis which is and the advantage because lower duty dampers to be the used.
  • The Someone rubber suspension systems have a tendency to the settle down or creep during the initial stages of the service therefore allowance for this is must to be the provided.

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