[5.] Haas, M., "UniAir - The first fully-variable, electro-hydraulic valve control system", Schaeffler Publication, 2010
et al., "Design and Control of a Two-stage Electro-hydraulic Valve Actuation System," SAE Technical Paper 2004-01-1265, 2004, doi:10.4271/2004-01-1265.
* degree of damping of the shock absorbers automatically progressively increases while the piston is approaching to extreme positions, regardless of the magnitude of the control parameter, namely, value of "control current" on the coil of the electro-hydraulic valve;
In the Fig.2 the electro-hydraulic valve is not shown.
Another thing to point out is that proportional valve in opposite to electro-hydraulic valve
require higher level of fluid cleanness.
The power train features Fiat's electro-hydraulic valve
management MultiAir system.
The MultiAir offers new electro-hydraulic valve
control system which makes it possible to reduce consumption levels and polluting emissions.
Using electro-hydraulic valves
, the computer controls the flow of hydraulic fluid to rotate the casters to match that of the front tractor tires.
The inclusion of analog electro-hydraulic valves
requires closed-loop, current-controlled pulse width modulation (PWM) outputs from the ECU.