The RTD shock absorbers are pressurized gas (nitrogen) type which provide damping by forcing hydraulic fluid through internal orifices to resist suspension movement. The RTD shock absorber has the capability of providing multiple modes or values of damping forces, in both compression and rebound direction. The damping forces are achieved by redirecting the flow of hydraulic fluid by using a solenoid valve. The solenoid valve varies the amount of fluid allowed to bypass by pulse width modulating the solenoid. The solenoid valve is an integral part of the shock absorber and is not serviceable separately.

The softer modes are accomplished by pulse width modulating the solenoid valve OFF more than ON causing hydraulic oil to by-pass the main shock absorber valving. A more firm ride is accomplished by pulse width modulating the solenoid valve ON more than OFF causing the hydraulic oil to flow through the main shock absorber valving. The RTD solenoid valve is a normally open design and when OFF will be in the full soft position.