ST Suspensions - Spring Strut Construction:
• Excellent all-around performance, providing a balance between performance and comfort for everyday use
• High-quality components for long durability
• Use of twin-tube technology, independent reactions from damping inputs minimized chassis vibrations and increase driving dynamics
• Come with all necessary components, vehicle-specific certificate and insallation inscructions
Functional principle of twin tube shock absorbers
With a Twin-Tube shock absorber, the piston works inside of an inner tube. The space between the inner tube and the casing is used as an equalization chamber. Changes in volume caused by position of the piston rod change the oil level in the equalization chamber between the outer casing and inner tube.
When the car swings downwards in the direction to the road, the piston rod moves downwards too. Oil displaced by the piston rod is pressed into the equalization chamber between the tubes through the specially designed orifices in the compression valve at the lower end of the inner tube. Pressure that is created through this valve creates the actual compression forces. Oil underneath the piston also flows upwards through the piston check valve with low pressure which influences the damper characteristics.
When the car swings upwards, away from the road, the shock absorber is extended. The piston rod is extending outward from the housing. The rebound phase valve at the lower tube presses oil that flows downwards through the holes above the tube. The upward motion is slowed down. When the piston rod is pulled out of the case, its volume is balanced out by the oil that flows from the equalization chamber back into the inner tube through the compression valve.
Functional principle of monotube shock absorbers
With a one-piston shock absorber, the piston works in the damping case. Both, traction and compression valves are integrated into the piston at the end of the piston rod. Depending on the speed the shock absorber is compressed or extended with, the forces rise. The separating piston separates oil from the gas space which is under strong pressure. The gas space balances the oil expansion with temperature differences and volume changes while the piston rod retracts. That's how the separating piston moves upwards and downwards. The gas pressure of 25-30 bar in the separating space is necessary in order to support the damping forces in the direction of the pressure.
When the car swings downwards in the direction to the road, the piston rod is moved downwards. The compression phase valve on the top of the valve presses oil that streams upwards through the holes. Therefore, the downward movement is slowed down. The separating piston is lowered to the same degree as the piston retreats downwards. The gas pressure underneath the separating piston prevents the oil from foaming above the piston.
When the car swings upwards, away from the road, the shock absorber is extended. Thereby, the piston rod is moving out of the damping case. The rebound phase valve at the lower piston presses the oil that flows downwards through the holes in the space above the piston. Therefore the upward motion is slowed down. The separating piston is lifted upwards to the same degree as the piston extends.