What is Spring ?

INTRODUCTION OF MACHINE

● Generally an elastic deformation of a mechanical element is undesirable.  However, when the flexibility of deflection in mechanical system is specifically desired, springs are used.  

● A spring is defined as an elastic or resilient body, whose function is to deflect or deform when load is applied and recover its original shape when load is removed 

● Applications of Springs: 

   The important applications of the springs are:

1.  To apply a force, e.g.  springs in clutches, brakes, spring loaded valves, etc. 

2. To measure a force, c.g.  spring balance 

3.  To store an energy, e.g.  springs in clocks, toys etc.  

4.  To absorb shocks and vibrations, e.g.  springs in vehicle suspension systems.  

TYPES OF SPRING

Though there are many types of springs, the following are most commonly used types of springs in engineering applications. 

1. Helical compression and tension springs 2. Conical and Volute Springs 

3. Torsion Springs

4. Disc or Belleville Springs 

5. Leaf or Laminated Springs 

1.  Helical compression and tension springs:

● Helical springs are made of wire wound in the form of helix.  The cross - section of wire will be circular, square, or rectangular depending upon the type of load and deflection requirement.  

● Based on the type of axial force the spring is expected to take, the helical springs are further classified as: 

    (i) Helical compression springs

    (ii) Helical tension spring

(i) Helical compression springs: 

Helical compression springs are used for taking compressive forces, as shown in Figure.

Helical compression spring

(ii) Helical tension springs: 

Helical tension springs are used for taking tensile forces, as shown in Figure.  

Helical tension spring

     ● Based on the helix angle, the helical springs can be classified as: 

          (a) Close coiled helical springs 

          (b) Open coiled helical springs

(a) Close coiled helical springs:

      In closed coiled helical springs, the helix angle is very small, usually less than 30 °.  The coils are so close that there is a very small gap between the two consecutive coils.  

(b) Open coiled helical springs: 

      In open coiled helical springs, the helix angle is large, usually more than 10 °.  The wire is coiled so that there is large gap between the two consecutive coils. 

2.  Conical and Volute Springs: 

● Conical and volute springs, shown in Figure are used in special applications where a telescopic spring action is required or a spring with spring stiffness that increases with load is desired 

● In such springs, as the load increases the number of active coils gradually decreases.  The decreasing number of coils results in an increasing spring stiffness.

3.  Torsion Springs: 

● Torsion springs are of helical or spiral type, as shown in Figure. These springs are used to apply the small torque.

● The helical torsion springs are used in door - hinges and automobile starters.  The spiral springs are used in mechanical watches and clocks.

4.  Disc or Belleville Springs: 

● Disc or belleville springs, shown in Figure, are used where high spring stiffness is required.  

● These springs are made up of number of conical discs held together by a central bolt or a pipe passing through disc hole.

Belleville Spring

5.  Leaf or Laminated Springs: 

● Leaf spring consists of a number of leaves held together by means of clamps and bolts, as shown in Figure.

● It is commonly used in automobile suspension system.

Lead Spring