Abstract: A drill pipe transfer arm supports the bottom portion of a drill pipe and positions it in relationship to the drill string to permit angle drilling with a tilted drill tower. The transfer arm is uniquely suited to circular carousels and features a drill pipe conforming saddle which permits close-quarter operation with a packed carousel.

Abstract: Central to the invention is a universal, center case sub-assembly from which, by adding components thereto, one may fabricate a rim style center case assembly, or a concealed-vertical style center case assembly, or a surface-vertical style center case assembly, or a combination rim and vertical style center case assembly, for a panic-type exit device. Besides minimizing the number of diverse components and parts required for the fabrication of the aforesaid center case assembly styles, the universal sub-assembly comprises an improved design which offers a marked mechanical/leverage advantage to the trim linkage.

Abstract: Disclosed herein is an erosion resistant down hole rock drill bit which utilizes a radial distribution of carbide cutter bits or buttons about the exhaust hole. This minimizes carbide wash or removal of base metal which retains the carbide and thereby extends bit life.

Abstract: Disclosed is a new method of construction for multiple or gang down hole rock drills. A rigid mounting cylinder with alignment and securing means for the individual drills is provided. The cylinder further serves to attach the multiple drills to a single drill string which supplies air to the individual drills. The cylinder further facilitates rock chip removal by filling all but the peripheral annulus which forms the exit channel for exhaust air.

Abstract: A fluid impact tool of the type known as a percussion or rock drill characterized by a percussion mechanism which provides alternative reverse percussion to assist in drill string removal or recovery.

Abstract: The lock mechanism has a spring and cam assembly provided for returning the lock plunger assembly of the mechanism from a locked to an unlocked position thereof. In addition, however, the spring and cam assembly carries an enlongated limb. When the lock plunger assembly is translated to a locked position, it forces the limb to extend from the spring and cam assembly to a disposition in which it blocks a knob catch which is carried in the outside spindle of the mechanism. Accordingly, for being blocked by the limb, the knob catch cannot be depressed and, consequently, the knob which is latchingly engaged by the catch, cannot be removed from the outside spindle whenever the mechanism is in its locked disposition. The spring and cam assembly comprises a compact unit which is slidably received in the outside spindle and confiningly supports the limb therewithin for extension therefrom into obstruction of the knob catch.

Abstract: An operating scheme for electronic locks wherein both the key and the lock have a first and second combination. The lock will open when the first key combination equals the first lock combination and the second key combination equals the second lock combination. The lock recombinates to the first key combination and the second key combination when the first key combination equals the second lock combination.