Linear, Digressive, and Progressive Damping
Linear, digressive, and progressive damping describe how damper force changes as shaft velocity increases.
Main curve shapes
- Linear damping: force rises approximately in proportion to shaft velocity over the region being described.
- Digressive damping: force builds relatively quickly at low velocity, then rises more slowly after a valve or shim circuit opens. This can provide body support while limiting the force increase over sharper inputs.
- Progressive damping: force rises at an increasing rate as shaft velocity increases. It can add stronger control as movement becomes faster.
How the terms differ
These labels describe the slope of part of a force–velocity curve, not the quality of the complete suspension. One damper can contain different shapes in different velocity regions, and compression and rebound need not use the same shape. The transition point, force level, hysteresis, temperature stability, and smoothness of valve operation matter as much as the category name.
The terms also do not describe position-sensitive end stops or spring progression. Those depend on suspension travel rather than only shaft velocity. A useful comparison therefore needs the full dynamometer conditions and both compression and rebound traces. For the underlying damper mechanics and vehicle trade-offs, see Suspension dampers.