This invention relates to holding arrangements for cutting picks, particularly but not necessarily exclusively point attack picks, which are intended to be free to rotate in use. It relates to rotatable cutter picks themselves and to assemblies of other picks with their holding arrangements.
To provide for rotatability it is known to provide a pick with a cylindrical shank fitting freely in a cylindrical bore of a pick box, which may be sleeved to make rotation easier. These picks are usually employed in the severe conditions of mining and it is found that the freedom of a pick to rotate in the bore is impaired by build-up of foreign matter in the bore. As a result the working life of the pick will be considerably reduced because wear is concentrated on only a portion of the cutting tip.
According to one aspect of the invention there is provided an arrangement for holding a cutter pick comprising a pick box having a bore and sleeve receiving a shank of the pick lining at least a part of the length of said bore, the sleeve being rotatable in the bore to permit rotation of the pick about a longitudinal axis, a thrust ring at the front end of the bore being arranged to fit closely to the tool and the bore so as to impede the passage of foreign matter into the bore, said ring having an end face to support the pick against rearward axial forces.
According to another aspect of the invention, there is provided a cutter pick assembly comprising a point attack cutter pick rotatably mounted in a sleeved bore of a pick box, the forward end of said bore being substantially closed against the ingress of foreign matter by a metal thrust and seal ring closely fitting the pick and the pick box and having a forward annular face for supporting the pick against rearwardly directed cutting forces.
According to a further aspect of the invention, there is provided a point attack cutter pick comprising a cylindrical shank having an annular recess receiving a spring clip for retaining the pick shank axially in a bore of a sleeve and having a radially extending skirt at the forward end of the shank with a rearwardly directed recess for engagement by a thrust and seal ring supporting the pick against rearwardly directed cutting forces.