Edwards Vacuum boosters are unique in utilizing a hydrokinetic fluid coupling to connect the electric motor shaft to the lobe rotor. When the gas load is high the rotational speed of the rotor is reduced. As the gas load decreases, the rotor accelerates to full speed. The blower can operate continuously over a wide vacuum range without the risk of overloading the motor and without the need for a gas bypass or pressure sensor switch.
The motor shaft drives one of the rotors through the fluid coupling. The 1:1 gears inside the coupling cover drive the second rotor in the opposite direction inside the stator housing.