shock absorber 
noun
A device for absorbing jolts and vibrations, especially on a vehicle: figurative small firms function as a shock absorber for underemployed workers in a recession...
- The supporters of a flexible Canadian dollar exchange rate suggest it is an adjustment mechanism - a shock absorber needed to cushion us from the blows of commodity price volatility.
- It functions both as a shock absorber, cushioning the blow when the bones in the shoulder collide, and as part of the joint's connective structure.
- The meniscus functions as a shock absorber and weight distributor in the knee joint.