Apparatus for adjusting the gap of a size reduction machine

Claim 1

A size reduction machine for use in process industries to continuously and precisely reduce the size of particles, while controlling fines, said machine comprising an impeller mounted on a rotatable shaft, a motor operably connected to said shaft for effecting rotation of said shaft, said shaft and impeller being mounted within a channel having an input and an output, a screen having a tapered apertured wall formed in a frusto-conical shape, with a wide end of said screen being open, a circular flange surrounding and extending outwardly of said wide end, said screen rigidly mounted within said channel so that any particles passing from said input to said output pass through said screen, said impeller being shaped and mounted so that a gap between an edge of said impeller and an interior of said screen remains substantially constant as said impeller rotates relative to the screen, said shaft having an impeller receiving end, said receiving end having a diameter for receiving said impeller terminating at a machined shoulder, said receiving end having an axially extending threaded bore and a bolt for releasably fastening said impeller to said shaft, wherein the improvement comprises an extensible spacer means for positioning the impeller along said receiving end for determining said gap, said spacer means mounted on said end shaft portion between said shoulder and said impeller, said spacer means comprising a first collar having an external thread threadably engaging a second collar having an internal thread whereby an axial length of said spacer means is varied as said first collar is rotated relative to said second collar, said first collar having one end machined for sealing abutting with said shoulder and a shroud extending opposite said one end, said second collar having a base portion and a barrel portion extending therefrom, said barrel portion having said external thread, said shroud extending over said external thread to said base portion, said spacer means having a sealing means for sealing said shroud with said base portion whereby said internal thread and external thread are enclosed as said axial length is varied, substantially preventing particles from intruding into said spacer means as particles pass from the input to the output, and said bolt engaging said threaded bore releasably fastening said spacer means between said impeller and said shoulder locking said first collar relative to said second collar.