Twin-Tube Shock Working Principle: Compression vs Rebound Damping

What Shocks Do

Shocks do not hold the car (springs do). They dissipate spring oscillation, converting vibration energy to heat.

Twin-Tube Structure

• Working cylinder: Piston moves in oil
• Reservoir tube: Outer, oil compensation
• Piston valving: Controls oil flow resistance
• Base valve: Between reservoir and working tube

Two Strokes

• Compression: Wheel up, piston down, oil flows to reservoir - lower damping for comfort
• Rebound: Wheel down, piston up, oil through piston valve - higher damping to stop body motion

Characteristics

Rebound damping is typically 2-3x compression. Failure is usually seal leaks reducing damping - the car keeps bouncing.