Semi elliptical leaf spring | Leaf spring diagram | Nipping of leaf spring

Leaf spring is one of the suspension systems which consists of a number of curved shape plates (known as leafs) that are held with each other with the help of a central bolt.

As per the shape and number of plates used there are Different types of Leaf springs as follows:- 

i) As per a number of plates:- 

a) Mono leaf spring

b) Multi-leaf spring

ii) As per shape:-

a) Elliptical leaf spring

b) Semi-elliptical leaf spring

c) Quarter elliptical leaf spring

d) Full elliptical leaf spring

e) Transverse leaf spring

f) Platform leaf spring

What is semi elliptical leaf spring?

1) Semi elliptical leaf spring is one of the types of leaf spring which is widely used in heavy vehicles for rear suspension.

2) As per the name it consists of a number of semi-elliptical flat plates of rectangular cross-section.

3) The leaf springs vary in length which is arrange lower to each other having reducing the length.

4) Upper leaf is known as the Master Leaf & other leafs under Master Leaf are known as Graduated leafs.

5) U-shape bolt is used to hold the rear axle to leafs.

6) One end (Left eye) of the Master leaf is fixed to the frame & Another end (Right eye) of the Master leaf is connected to the shackle.

7) The shackle is used to compensate for the deflection of leaf spring.

8) When leaf spring moves upward due to bumping, The shackle rotates about the fulcrum to compensate for horizontal deflection.

9) The Rebound Clips are used which holds the Master Leaf & Graduated Leafs together. Hence the stresses are distributed over the complete length of each leaf.

10) In Leaf Spring, Stresses due to bear the load are distributes over the complete length of each leaf. Hence it has the ability to withstand the higher working load

Semi elliptical leaf spring diagram:

Semi elliptical leaf spring

Nipping of leaf spring:

  • Nipping is method to apply pre-stress on graduated leafs for sharing of load equally.
  • Generally, the maximum load comes on the Master leaf, Hence Due to Nipping, Stress on Main leaf is reduced by sharing.
  • This method increases the Efficiency of the leaf Spring. Due to Nipping, Life of the leaf spring gets increased.
Nipping of leaf spring

How nipping is done?

  • For Nip generation, Radius of curvature in Next Adjacent leafs are Reduced. Due to this the gap is Present between two adjacent leafs this is known as Nip. 
  • In same manner, Radius of curvature for every next leaf is Reduces for provision of nip.
  • Then by using U-Bolt all the leafs are tight together to Remove the gap between the leafs.
  • Due to that, The pre-stress is generated in each leaf, which tries to regain it’s original shape & pushes it’s upper leaf in upward direction This method is known as Nipping of leaf spring.
  • Nipping helps to distribute load on Master leaf to Each graduated leaf.
  • Therefore, Due to this method, Efficiency & Life of the leaf spring Increases.

Advantages of Semi elliptical leaf spring:

Semi elliptical leaf spring has the following advantages:-

  1. It can works for Heavy load.
  2. It Absorbs vibration due to irregular road surfaces and provides the comfort ride.
  3. It keeps the vehicle tyres in contact with road on the irregular road surface.  

Applications of Semi elliptical leaf spring:

Semi elliptical leaf springs are mainly used in heavy vehicles such as:-

  1. Truck
  2. Buses
  3. Train

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Pratik is a Graduated Mechanical engineer. He enjoys sharing the engineering knowledge learned by him with people.

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