US Patent 7546778 Flow meter

An axial flow meter includes a housing including a generally elongated body with a continuous internal bore. Two spindles are mounted parallel to one another in the housing. Each spindle has a blade on the exterior surface of the spindle. Blades on each of the two spindles engage with each other. Bearings at each end of both spindles engage the spindles. At least one of the bearings engaging each one of the spindles is fixed in a position relative to the elongated body thereby preventing axial movement of the two spindles while allowing rotational movement of the two spindles.