Abstract: A cutter bit assembly having an elongated cutter bit and a bit holder engaged with a bit block. The bit holder and the bit block have an elongated opening for receiving the elongated cutter bit.

Abstract: A rock drill feed system moves a drill toward and away from a wall with a reciprocating hydraulic motor powered by pressurized fluid. The pressurized fluid is controlled by a movable control valve that has a first position obtained manually to move the drill inwardly to drill, a second position obtained automatically when the drill has completed drilling, and a third position obtained automatically when the drill has been completely withdrawn. The sensing of the location of the drill to position the control valve is accomplished by measuring the pressure and flow rate of the hydraulic fluid delivered to the motor with pressure responsive switches. When the pressure exceeds a preselected level and the flow rate drops below a preselected level, the two pressure switches close to produce a signal that moves the valve to another position.

Abstract: A material for use in making electrical contacts is produced in a powder form suitable for later processing into electrical contacts by standard metallurgical techniques generally involving compacting, sintering, and forming or cutting to make the desired contact size and shape. The material, and in most general applications the contact made from the material, essentially consists of silver, approximately 15% cadmium oxide by weight, and lithium oxide at a proportion of about .005 weight percent of lithium, which is approximately equal to .04 molecular percent of lithium oxide. The lithium oxide is added and uniformly distributed on the surfaces of the powder particles by precipitation.

Abstract: A computer based control system having a protection circuit including a bistable circuit arranged to disable the outputs of the control system at the end of a scan period of the system. The bistable circuit is operated through logic gates arranged to monitor fault in the control system.

Abstract: A material for use in making electrical contacts is produced in a powder form suitable for later processing into electrical contacts by standard metallurgical techniques. The material consists of a first metal, such as silver, and the oxide of a second metal, such as cadmium, added to the first metal in a proportion up to the limits of solubility of the second metal in the first metal. An oxide of a third metal having a low electronic work function level, such as lithium oxide, is added and uniformly distributed on the surfaces of the powder particles by precipitation. A fourth metal, such as tellurium, that is insoluble in the first metal is also added to provide selected characteristics.

Abstract: A material for use in making electrical contacts is produced in a powder form suitable for later processing into electrical contacts by standard metallurgical techniques. The material consists of a first metal, such as silver, and the oxide of a second metal, such as cadmium, added to the first metal in a proportion up to the limits of solubility of the second metal in the first metal. An oxide of a third metal having a low electronic work function level, such as lithium oxide, is added and uniformly distributed on the surfaces of the powder particles by precipitation. A fourth metal, such as tellurium, that is insoluble in the first metal is also added to provide selected characteristics.

Abstract: The contact materials comprise silver with additions of mercury or mercury and tellurium and silver-cadmium oxide compositions with additions of mercury and tellurium. The methods of making the materials include the steps of adding a silver-mercury alloy to molten silver and to a molten silver-tellurium powder mixture. The materials including cadmium oxide are produced by heating a mixture of powders of silver, a cadmium-tellurium compound, cadmium oxide, and mercuric oxide powders in a reducing atmosphere and then reoxidizing.