Abstract: A new and improved dead man safety assembly having an activator lever mounted for movement from an operable position to an inactive position and a safety trigger mechanism coacting with the activator lever for preventing unintentional movement of the activator lever to the operable position. The control mechanism activated by the activator lever may be fluidic or electrical. The instant special application of the dead man safety assembly is related to control of hand-held abrasive hose and nozzle structures.

Abstract: A control valve assembly for regulating the mixing of abrasive from a pressurized tank with high pressure fluid during abrasive blasting operations having a tubular abrasive flow pipe and an abrasive control nozzle within a control valve housing, with provisions for moving the abrasive control nozzle and the tubular abrasive flow pipe relative to each other to and from an abrasive fluid mixing position from and to a sealed, closed position, respectively.

Abstract: Specially designed stress relief grooves for threaded end portions of tools and for collars on reciprocating or rotating drill string mounted tools.

Abstract: An improved seal assembly for sealing between relatively movable members in an oil tool or the like including a split protective ring held in position by a seal ring having a circumferential locking shoulder.

Abstract: An improved hydromechanical drilling jar for applying upward and downward jarring blows to an object stuck in a well wherein the jar comprises a mechanically operated jar section which is connected with a hydraulically operated jar section by flexible tubular connector means for providing flexibility therebetween for relieving bending moments on the jar sections during use. The jar sections are separable for ease in storage and transportation and may be relatively positioned in a drill string as desired.

Abstract: A hydraulic jar for applying a jarring blow to an object stuck in a well wherein two separate annular fluid chambers are provided in the jar, with one of the chambers confining a body of operating hydraulic fluid and means for restraining relative longitudinal movement of the jar for developing tension and stretch in the drill string so as to produce the jarring blow, and with the second annular fluid chamber confining a body of heavy lubricating fluid and splined portions and jarring surfaces to isolate foreign particles from the operating fluid chamber to prevent or inhibit internal jamming or sticking during actuation. Because the means disposed in the operating fluid chamber are subjected only to forces developed during the pulling stroke, the operating fluid chamber may have a greater area for the development of greater pull loads at lower hydraulic pressures than prior hydraulic jar.