Abstract: A drilling system for a mining machine, the mining machine including a frame and a boom moveable coupled to the frame and a drill string positioned in a blast hole. The system includes an air compressor, a drill bit connected to the air compressor configured to receive low pressure air. The drill bit has a nozzle free drilling body, three sealed rotating cones, each cone with a plurality of cutting elements. Each cone having a sealed bit bearing assembly with diaphragm free lubricant spaces. A single central air conduit in the drilling body providing continuous high flow rate low pressure air from the drill string configured to strike the plurality of outer surfaces of the sealed rotating cones upon exit of the high flow rate low pressurize air from the single central air conduit cooling the sealed bit bearing assemblies. A relief conduit is used.

Abstract: In a drill bit which has a reservoir for storing a supply of lubricant, generally grease, a lubricant passage is formed for flow of lubricant from the reservoir to the bearing. A relief port is formed in the drill bit body to connect at least one of the reservoir and the lubricant passage with an outside surface of the drill bit body. A normally-closed relief valve is mounted in the relief port to selectively permit fluid flow through the relief port and protect the lubrication system against changes in pressure, especially increases in pressure on the grease side, such as might be caused by thermal expansion of the grease or the production of off-gases by the grease. The valve is provided in the form of a small screw-in unit capable of separate manufacture and testing and comprises a valve body carrying a flexible diaphragm element. Venting is provided via a puncture in the diaphragm element.

Abstract: An earth boring bit has thrust surfaces with enhanced cooling features. The bit has a body with three depending bearing pins. A cutter having an axial cavity is mounted on each bearing pin. The bearing pin and the cavity have one or more mating thrust surfaces that are perpendicular to the axis of the bearing pin. These thrust surfaces absorb outward forces that the cutter imposes on the bearing pin. At least one of the thrust surfaces consists of a series of tungsten carbide buttons spaced in a circular array. These buttons have flat ends for engaging the opposite thrust surfaces. The buttons protrude from the supporting metal, allowing cooling fluid to be circulated past to cool the thrust surfaces.

Abstract: A hydraulic mast digger has a kelly head with improved retaining and sealing features. The digger is of the type having a kelly with a bearing assembly mounted between the kelly and a bearing sleeve. The bearing sleeve is reciprocally carried in the hydraulic cylinder and moves in response to hydraulic fluid pressure. The bearing assembly allows rotation of the kelly with respect to the bearing sleeve. A cap is secured by threads to the bearing sleeve above the top of the kelly to define a piston. The cap has an upwardly facing shoulder located below the upper edge of the bearing sleeve. A retainer is rigidly secured to the cap and extends down into the space between the cap and bearing sleeve. A locking device locks the retainer to the bearing sleeve. Preferably the locking device includes a key that fits within slots formed on the retainer and bearing sleeve. A primary seal encircles the retainer.

Abstract: A device for applying an additional downward force to the rotating cutting tool of an earth boring machine. The machine has a mast and a rotating drive member suspended by the mast for vertical movement and for rotating the cutting tool. A rotatable drum is carried by hydraulic cylinders adjacent and below the top of the drive member. The drum has a brake and is connected by a downcrowding cable to the top of the drive member. Downward movement of the hydraulic cylinders while the drum brake is locked creates tension in the cable, applying downward force to the drive member. A take-up cable is wrapped around the drum in the opposite direction. It is reeved over the mast and connected to the top of the drive member by a spring. The spring takes up slack in the cable when the hydraulic cylinder returns for a new stroke and allows the kelly to move downward as the drum is pulled down by the cylinder.