vacuum boosters are positive displacement pumps with two figure eight shaped impellers rotating in opposite directions inside the casing.
As each lobe of an impeller passes the blower inlet, it traps a quantity of air equal to exactly one fourth the displacement of the blower.
The entrapment occurs four times per revolution. The entrained air is forced around the case to the blower outlet. Timing gears accurately position the impellers in relation to each other to maintain the minute clearances
so vital to the high volumetric efficiency of the pump.
As each lobe of an impeller passes the blower inlet, it traps a quantity of air equal to exactly one fourth the displacement of the blower.
The entrapment occurs four times per revolution. The entrained air is forced around the case to the blower outlet. Timing gears accurately position the impellers in relation to each other to maintain the minute clearances
so vital to the high volumetric efficiency of the pump.