Shock absorbermono shock absorbers Suppliers and suspension spring has different roles in the suspension system of a vehicle.
When a pothole or bump comes under the wheel, suspension spring allows the vertical movement of the wheel and to adjust accordingly so that the passenger floor will remain at level.

But when bump/pothole pasess as a result of springing action it causes to continue the up and down movement of the wheel. To prevent this shock absorber is used to dampen the springing action.
Basically, spring provides the necessary movement of wheels while the shock absorber act as vibration damper for the spring.