The Tractive dampers are equipped with the Tractive DDA Valve (Dynamic Damping Adjustment ). The DDA valve is typically mounted on the piston rod below the main damping piston and controls a bypass flow.

The damping characteristics of shock absorbers with DDA technology are determined by the main shim stack on a piston with same tuning possibilities as known from high end aftermarket / racing shock absorbers. The DDA valve is based on a dynamically balanced solenoid valve. When the valve is not energised, all flow goes over the main piston and the FIRM curve is the same curve as a non-electronic shock absorber with the same shimstack and piston. When the valve is energized, the bypass opens proportionally to applied current. At full current of 2 Amps the SOFT curve is achieved, the shape of the damping curve and the level of damping is determined by the DDA valve orifice size and main shim stack.