Types of Suspension System used in automobiles

By: Prayag nao

Suspension is the system of springs, shock absorbers and linkages that connects a vehicle to its wheels and allows relative motion between the two.^[1] Suspension systems serve a dual purpose — contributing to the vehicle's roadholding/handling and braking for good active safety and driving pleasure, and keeping vehicle occupants comfortable and reasonably well isolated from road noise, bumps, and vibrations,etc.

 Suspension Springs:

Suspension spring are sandwitched b/w the vehical body and wheels.It stores energy when the vehical come across bumps,bcz spring rise and compressed.

Commanly used springs are:

• Laminated or leaf spring.
• Torsion spring.
• Coil spring.
• Hydroelastic spring.
• Air spring.
• rubber spring.

Laminated Spring: 

 Leaf spring consist of number of steel strips or blades which are placed over one another.Length of these blade vary in length which is clearly shown in fig.

Center bolt used to hold these leaves.Master leaf is the one which is longest of all the leaves.To keep the blade aling,straps and clips are used.

This is Stress distribution analysis across a leaf spring

Coil spring:

Coil springs can be used where space is restricted.They are generally used with independent suspension.Energy stored per unit volume in Coil spring is twice of leaf spring.

Static friction in case of coil spring is less,they do not have any noise problem.

 

 Torsion bars:

It consist a rod which is in torsion and takes only shear stress.Torsion bar always stores energy more than leaf and coil spring.It is lighter in weight and can be accomodated easily.

                                                                                                                               It's lower end is fixed to lower wish bone and rear end is fixed to frame.When the wheel ancounter the bumps,lower wishbone moves up and down,which exerts torque on torsion bar.Thus torsion bar acts as a spring.

 

Air Suspension:

Air Suspension uses air spring.Air spring is filled with air or cylinder piston enclosing air.When wheel encounters to a bump then piston moves up and down,causes compresses air to provide springing action. 

Advantages:

• Provide smooth ride,as it is a low natural frequency spring.
• Air spring rate can be manipulated.
• maintains constant fream height under all conditions of loading.  

Disadvabtages:

• High cost.
• Additional linkage is required to stabilize it.
• Shock absorber is necessary if using air suspension.

 

  

Rubber Spring:

 Rubber spring are used bcz it has excellent damping properties, it is more reliable.

 

Hydroelastic Suspension:

 It Comprises of a hermetically sealed hydraulic system.It makes use of rubber cone spring which are used as independent suspesion for all wheels.hoses are used to connect the front and rear units to carry alcohol/water mixture.

When a car passes over a bump,the tapered piston forces the liquid to move to rear unit .Due to this force the car's rear part rise to same level as front part.In this way the bounce is eliminated.