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: A reciprocating sanding and rubbing machine has a shoe portion to which the sanding or rubbing member is attached, this shoe portion being connected through a rack and pinion drive gear assembly to a symmetrically balanced piston assembly which is reciprocally driven by a pneumatic drive. The piston assembly is greater in length than half the total length of the tool, and moves in a carriage block reciprocally relative to the shoe. Two pistons and two associated pairs of compression chambers are employed, one of these pairs of chambers being used for drive in one direction, and the other pair being used for drive in an opposite direction. The pistons are supported on sleeve bearings which align them within the cylinder chamber, thereby minimizing wear on the pistons and the cylinder walls. Reciprocating motion of the piston is achieved by means of pneumatic valving arrangement employing a rotatable valving member which is driven by a rack and pinion gear assembly in response to motion of the shoe.

Abstract: A system for porting of hydraulic fluid in a hydraulically driven seismic energy vibrator of the reciprocating mass type. A mass is reciprocated relative to an earth contacting frame which includes at least two hydraulic piston rods coacting with internal cylinders within the mass. The piston rods, of the type having double rod ends, each include a single axial bore therethrough in communication with respective opposite sides of the piston ring assemblies, and cross porting is effected between opposite ends of the mass cylinders.

Abstract: A pressure fluid operated feed drive system for a movable member, and particularly for a slide of a machine tool, the system having a source of fluid pressure feeding a pair of interconnected piston and cylinder units connected between the member and a fixed support. The piston rod side areas of the pistons are arranged in effective opposition and valve means are provided to permit pressure fluid to be supplied selectively to the units to enable the member to be moved alternatively by a force derived from differing piston areas.