The volvo bounce badly on rough roads and the shock absorbers cushion the impact. The volvo v50 rear shock absorber has two cylinders inside and outside and the piston moves in the cylinder. As the piston rod enters and extracts the volume of oil in the cylinder increases and shrinks accordingly so it is necessary to maintain the balance of oil in the inner cylinder by exchanging with the outer cylinder. So there should be four valves in the double cylinder shock absorber that is in addition to the two throttle valves on the piston mentioned above there are installed between the inside and outside the cylinder to complete the exchange of circulation valves and compensation valves.