GB862104A - Lubricant seal - Google Patents

Abstract

862,104. Boring earth. HUGHES TOOL CO. May 27, 1958, No. 16866/58. Class 85. [Also in Groups XXVI and XXXIV] A lubricant seal for an earth boring drill comprises an annular ring 21 which is axially resilient and is interposed between opposing surfaces 22, 28 respectively on a leg 3 of a bit head 2 and the base of a corresponding cutter 7, the ring 21 having limited radial movement on the shaft 4 of the cutter to allow for rapid axial and wobbling movements between the confronting faces 22, 28. The ring 21, which is preferably dished, consists of a radially-slotted core 30 which is made e.g. of steel and is encased in material 36 having inner and outer oppositely axially-extending annular ridges 34, 35 which are urged info engagement respectively with the faces 22, 28. The material 36 is made e.g. of a chemically inert oil resistant synthetic rubber or plastic. The core 30 may be circumferentially corrugated instead of being radially slotted. In a modification an inner deformable beading along the inner periphery of the ring extends axially inwardly to contact the surface 21 of the leg 3. The head 2 has an internal chamber 5 from which flushing fluid is conducted downwardly through a passageway 6 to the cutters 7. Radial loads on the cutter are taken by roller and ball bearings 8, 9, the latter also receiving loads axially of the shaft. A pilot pin 11 on the end of the shaft 4 fits within a bushing 12 pressed into the bore 13 of the cutter, a thrust button 14 carried by the cutter at its closed end assuming a portion of the outward thrust. The cutter is first mounted on the shaft with the bearings 8 in place, the balls then being introduced through a bore 15 until the ball bearing is complete whereupon a pin 16 is welded in the bore 15. Lubricant for the bearings is supplied from a chamber 17 in the head 2 the lower end of the chamber communicating with the bore 15 and cut-away portions of the pin 16, so that lubricant may run freely to the bearings. The upper end of the chamber 17, closed by a plug 10 having a breather 20, accommodates a slidable member 19.