Explain the principle of operation and working of Shock Absorber.

Construction:

• A telescopic shock absorber derives its name from tubular shape of early telescopes used in ancient times.
• They are 2 types viz. mono tube and twin tube type. The twin type shock absorber is as shown in the figure.
• Rod G is attached to a 2 way valve A; while another similar 2 way valve B is attached at the lower end of cylinder C.
• There is a fluid (oil) in the space between the valve A and B and also in the annular area between cylinder C and tube D.
• H is a gland in the head J. The eye E is connected to axle and eye F is connected to the chassis frame.

Working:

• Consider that the vehicle has come across a bump.
• Then the eye E would move up and thereby the fluid will pass from the lower side of valve assembly A to the upper side. But since the volume of the space above A is less by the volume of rod G, the fluid will also exert its pressure on valve assembly B and go to the underside of valve B.
• This passage of the fluid through valve opening provides the damping.
• A similar process takes place in opposite direction for rebound.