Importance

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Abstract

A labyrinth shaft seal for preventing the migration of gear lubricant from a mixer drive assembly into a batch of process materials being mixed. In the preferred embodiment, a portion of the gearcase outboard of the upper quill bearing, preferably the actual bearing mount, is provided with an axially-directed circular face, the mount being formed of relatively soft material such as ductile cast iron. A disc-shaped seal element having a central aperture and supporting an axially-directed peripheral cylindrical flange is sealingly mounted on the quill above the quill bearing and extends radially from the quill and generally parallel to the circular face. The flange is formed of material substantially harder than the circular face. The axial positions of the outer bearing race mount on the housing and the disc-shaped seal element on the quill are selected so that, upon assembly of the bearings and seal, the lower edge of the flange interferes with the circular surface causing the disc-shaped seal element to be elastically deformed to define a dish-shaped spring having a depth of 0.010 inch. Upon rotation of the quill, the flange is urged by the pre-load of the spring to incise and then occupy an interference-fit groove in the circular surface, thereby forming an inexpensive, and effective labyrinth seal against leakage of gear lubricant through the quill bearing.

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First Claim