Regressive valve assembly (Source: RE Suspension, Penske Racing Shocks)
The objective of the regressive valve is to produce a compression damping characteristic that allows increased low or mid-speed damping force or driver feel, while providing more suitable lower levels of high speed compression damping for bump absorption.
Spring washers can deflect in a linear, progressive, or regressive means and these devices show a symmetrical deflection around the washer's axis. Spring washers can be stacked to create spring sets or series where deflection and load capacity can vary without materially affecting the forces involved.
More linear damper characteristics imply that a vehicle responds in a more consistent way to road inputsspring progressivity affects vehicle roll and pitch angles during maneuvers and can change the lateral balance of the vehicle along the corner.