Roots pumps – operating mode

The rotary piston vacuum pumps or also Roots pump consist of two counter-rotating 8 shaped pistons which  90 ° arranged in an offset pattern to each other. These pistons rotate without touch with each other and to the body housing, on account of a compulsive coupling about a gearwheel pair.

For a simple explanation of the functionality we look only at the right side of the Roots pump:

On the inlet side is the neutral suction chamber to be seen which grows by the rotation of the pistons. The gas to be sucked off from the recipient is sucked off by the volume enlargement.

After the maximum suction chamber volume is reached, the piston closes the inlet of the suction chamber, there originates a sickle-shaped space. If the piston turns further, the side opens to the outlet and the gas under pre-vacuum is condensed by the streaming gas. The whole gas volume from the suction chamber is expelled by the rotation of the piston.

A new working cycle begins.