Screw 1, having a two-start helical groove d, rotates about fixed axis D and is the element driven by external power. At its left end screw 1 has gear 3 which meshes with internal gear 4 having twice as many teeth as external gear 3 and is rigidly attached to internal link 2, rotating about fixed axis C. Link 2 has a single-start internal helical projection (thread) a fitting into groove d of screw 1. The inside diameter of link 2 (disregarding the projection) is twice the outside diameter of screw 1. When screw 1 rotates, it rotates link 2 and fluid is delivered in the direction of the arrows.
$4009$THP,GP$