Abstract: A pressurized medium actuated gripping device which is included in a rock or earth drilling machine for rotary drilling, and is adapted for gripping a drill rod for transmitting rotation and/or axial movement to a string of drill rods, said gripping device including a rotatable housing in which gripping jaws arranged around the drill rod are movable substantially radially relative said rod, and also a sleeve-shaped piston element of elastomeric material, which is sealingly arranged in the housing for separating a pressure chamber, arranged for the supply of pressurized medium and between the housing and the piston element, from a central space, wherein the gripping jaws are arranged, and which is adapted for actuating the gripping jaws into engagement with the drill rod when the pressure chamber is supplied with pressurized medium.

Abstract: A device in rock drilling machines with a gripping device (24) which is rotatably mounted in a non-rotating drilling head (14) and intended to grip a drill string (21) for transferring rotational and axial movements to it. The gripping device is hydrostatically mounted (42, 43, 45-49) in the drilling head, whereby the pressure in a pressurized fluid between their coacting bearing surfaces (42, 43) automatically increases for increased loading pressure between these surfaces.

Abstract: A feed beam for a rock drill comprises a box girder (13), a saddle (10) slidable along the box girder, and two power units (20,20a) inserted into the ends of the box girder.Each power unit comprises a pair of fixed pulleys (22,24) located outside the end of the box girder, an hydraulic jack (26) carrying a pair of movable pulleys (28,30) within the box girder, and a cable coupled between the power unit and the saddle and passing over the four pulleys.

Abstract: An improved relocatable wiring system for supplying lighting and power to a floor area in a building is disclosed. A plurality of lighting fixtures installed in a ceiling structure for lighting the floor area are connected in one or more branch circuits. Each branch circuit is defined by a plurality of plural conductor branch circuit cables which distribute power to the fixtures. Connectors are permanently attached to the opposite ends of each branch circuit cable. A connector at one end of a cable is joined to a connector on the next cable in the branch circuit by a circuit connector module having two receptacles keyed to receive and interconnect the two connectors. The circuit connector module also has a connector which mates with a receptacle permanently attached to a lighting fixture, which connector is in turn connected to a lighting circuit in the fixture.