Abstract: A ripping tool positioned below the earth's surface is driven by the output of a vibrating, preferably, resonant, force transmitting beam which has lateral dimensions smaller than those of the ripping tool and is positioned below the earth's surface. The beam is configured to have a single resonant node when restrained from vibrating at such node and is supported so that the single node is above the earth's surface and restrained from vibrating. The output of the beam is enlarged in thickness to form a hammer.

Abstract: A pavement chipping tool uses a sonic oscillator which includes a housing integral with a resonant beam. The oscillator includes a rotating shaft journaled in two sets of bearings with an eccentric weight attached to the shaft between the two sets of bearings and a pair of weights on either end of the shaft beyond the bearings. The eccentric mass of the center weight is equal to the sum of the two outer weights. The bearings have inner races keyed to the shaft.

Abstract: A force transmitting, preferably resonant, beam having a pair of straight divergent legs meeting at a juncture. A work tool is located adjacent to the end of one leg, which is the beam output. A sonic oscillator is coupled to the end of the other leg, which is the beam input. The beam is supported so as to restrain the juncture from vibrating. In one embodiment, the legs form an angle of approximately 90 degrees and the beam is driven at or near its resonant frequency by the oscillator. An integral ear extends from the juncture along a plane that bisects the angle between the legs. The beam is pivotably supported at its juncture and a stop abuts the ear to position the beam output.

Abstract: Asphalt or concrete pavement is removed from a road bed by an elongated cutter blade that extends in a downward and forward direction along a cutting plane to a cutting edge. The cutting plane forms an acute angle of between 45.degree. and 55.degree. with the surface of the pavement. The cutter blade is intermittently driven with a force parallel to the cutting plane in the forward direction while the cutting edge penetrates the pavement to drive the cutter blade incrementally in a forward direction and plane off the pavement in a chisel-like manner. A source of vibrations is connected to one end of plural spaced apart resonant beams. At the other end, the beams drive the cutter blade.

Abstract: A sonic generator produces a reciprocating force that is transmitted to a tool by a resonant or nonresonant force transmitting member having an output that reciprocates about a neutral position responsive to the force of the sonic generator. A continuous unidirectional force is applied to the sonic generator by a tool carrier. The tool advances intermittently along a work path through a medium responsive to the continuous unidirectional force and the reciprocating force. A gap is held between the neutral output position of the transmitting member and the tool when the tool is unable to advance through the medium responsive to the continuous unidirectional force and the reciprocating force. Specifically, the force of the sonic generator is sufficiently large relative to the unidirectional force to overcome the latter, and to drive the tool holder back away from the tool when the tool is unable to advance along the work path, thereby establishing a protective gap.

Abstract: A sonic generator produces a reciprocating force that is transmitted to a tool by a resonant or nonresonant force transmitting member having an output that reciprocates in forward and backward directions about a neutral position responsive to the force of the sonic generator. The tool is located forward of the output of the force transmitting member, and is movable in backward and forward directions along the work path. A changing gap is formed between the tool and the output as the output reciprocates, the gap tending to close and strike the tool as the output reciprocates in a forward direction and tending to open as the output reciprocates in a backward direction. A continuous unidirectional force is applied to the force transmitting member. The tool advances intermittently along the work path through the material being processed responsive to the continuous unidirectional force and the reciprocating force.

Abstract: A control valve for hydraulic systems including a sleeve and a spool supported for slidable motion therein, the sleeve and spool having control lands supported in slightly spaced relation to avoid chipping or abrasive contact and resultant imprecision in valve accuracy.