Abstract: A rotary drilling head wherein rotary friction between the rotary spindle assembly and the spindle housing is limited by improvements in bearing and seal lubrication and by seal structure such that the gripping action of a resiliently flexible packer on a drill string provides a rotary drive connection sufficient to impart rotation to the spindle assembly through rotation of the drill string.

Abstract: A stripper packer having a mounting collar to which a stripper rubber is releasably secured by compressive clamping means in a manner such that the compressively deformed stripper rubber is maintained in releasable fluid pressure-tight face sealing engagement with the mounting collar.

Abstract: In a drilling head assembly for rotary well drilling a tubular member has an external screw thread near its lower end, with the outer surface of the member below the thread tapering downwardly to its lower end to form a sealing surface. Screwed onto the thread is a metal ring that extends down past the sealing surface and is provided with an annular recess encircling and facing the sealing surface, from which it is spaced. A resilient sealing member encircles the ring and is secured to it, with the portion of the ring beside the sealing surface and below it embedded in the sealing member which also fills the annular recess in the ring. The sealing member converges downwardly below the ring to a neck portion, and the inner surface of the sealing member converges from above the annular recess downwardly to the neck portion so that the sealing member between the tapered sealing surface and the encircling portion of the ring is compressed by them to form a seal.