Hydraulic Proportional Solenoid Valve

solenoid valve
A valve that uses an electromagnetic coil for actuation.
A solenoid valve is an electromechanical valve for use with liquid or gas. The valve is controlled by an electric current through a solenoid coil.
Valve that is actuated with a electromagnetic solenoid magnet. 2 possible variations, NC (naturally closed) which is closed when there is no current applied and NO (naturally open) which is open when no current is applied

proportional
Corresponding in size or amount to something else
one of the quantities in a mathematical proportion
having a constant ratio
properly related in size or degree or other measurable characteristics; usually followed by `to'; "the punishment ought to be proportional to the crime"; "earnings relative to production"
(of a variable quantity) Having a constant ratio to another quantity

hydraulic
Denoting, relating to, or operated by a liquid moving in a confined space under pressure
(of cement) Hardening under water
moved or operated or effected by liquid (water or oil); "hydraulic erosion"; "hydraulic brakes"
Of or relating to the science of hydraulics
of or relating to the study of hydraulics; "hydraulic engineer"
(hydraulically) in a hydraulic manner; "the block is then tested hydraulically to its full design test pressure on each stream separately"