Patent ID: 9464632
Filing Date: 2016-10-11
CPC Classification: F04C

Claim Text:
1. A double-helical gear rotary positive displacement pump comprising a main pump housing rotatably supporting at least a driving shaft and at least a driven rotary element, the driving shaft being associated to at least a first double-helical toothing and the driven rotary element being associated to at least a second double-helical toothing meshing the first double-helical toothing which together constitutes four helical toothing portions, wherein only one of the four helical toothing portions is idle with respect to an axially adjacent one of the helical toothing portions, the idle helical toothing portion being constrained from moving axially, but allowed to rotate, by at least one axial constraining element acting between the idle helical toothing portion and the driven rotary element to which the idle helical toothing portion is mounted.