The cast iron, dynamically balanced tri lobe blower is a positive displacement unit with a pumping capacity determined by size, operating speed and pressure conditions. It operates with two tri-lobe impellers mounted on parallel shafts, rotating in opposite directions within a casing closed at the ends by side plates. As the impellers rotate, air is drawn into one side of the casing and forced out of the opposite side against the existing pressures. The discharge pressure depends upon the system resistance or back pressure. A pair of accurately machined alloy steel, hardened and ground timing gears maintain clearances between the impellers during rotation, resulting in 100% oil free air. 

Lobe compressor blowers are constant volume machines and as such, deliver a fixed discharge against the system back pressure. It is important to have adequate size piping and large radius bends to maintain high working efficiency and low power consumption. Recirculating air from the discharge to suction may result in over heating. Using throttle valves in the intake or discharge piping to increase capacity, increases the power load on the motor which may seriously damage the compressor. 

Robuschi Pressure Vacuum Model bearings have a lifespan of 20,000 hours, even under the most severe operating conditions. The rotors ensure reduced clearances, which increases volumetric efficiency. The gas seal on the rotor shafts is an exemplary feature. It ensures the flow of oil-free gas by a labyrinth seal coupled to oil splash discs.