Abstract: A wrench assembly is mounted on a drill rig so as to have some freedom of movement in three axes. The wrench assembly includes a wrench subassembly having an upper wrench and a lower wrench. Both the upper wrench and the lower wrench are provided with jaw assemblies that are adapted to grip a pipe section or to release it. One of the upper wrench and lower wrench is pivotally moveable with respect to the other to apply a twisting force to a pipe section gripped by one of the upper and lower wrenches with respect to an adjacent pipe section gripped by the other of the upper and lower wrenches. The wrench assembly also includes a generally planar support table. The wrench subassembly is attached to the support table in such a manner as to allow the wrench subassembly to pivot about an axis that is perpendicular to the plane of the support table, and in such a manner as to allow the wrench subassembly to tilt with respect to the plane of the support table.

Abstract: A wrench assembly is mounted on a drill rig so as to have some freedom of movement in three axes. The wrench assembly includes a wrench subassembly having an upper wrench and a lower wrench. Both the upper wrench and the lower wrench are provided with jaw assemblies that are adapted to grip a pipe section or to release it. One of the upper wrench and lower wrench is pivotally moveable with respect to the other to apply a twisting force to a pipe section gripped by one of the upper and lower wrenches with respect to an adjacent pipe section gripped by the other of the upper and lower wrenches. The wrench assembly also includes a generally planar support table. The wrench subassembly is attached to the support table in such a manner as to allow the wrench subassembly to pivot about an axis that is perpendicular to the plane of the support table, and in such a manner as to allow the wrench subassembly to tilt with respect to the plane of the support table.

Abstract: A wood chipper includes a cutting assembly and a feed wheel for feeding material through an adjustable throat opening adjacent the feed wheel and toward the cutting assembly. A throat sensor measures the size of the throat opening and an electronic control unit (ECU) controls operation of the wood chipper in accordance with the size of the throat opening. The ECU controls forward, reverse and non-rotation of the feed wheel as well as down pressure applied by the feed wheel on feed material moving through the throat opening. The feed wheel down pressure may be constant or vary in any number of ways. One option includes applying down pressure in a pulsating manner.

Abstract: A wood chipper includes an engine and a cutting assembly. A rotatable feed wheel and a gap-bounding member define therebetween an adjustable gap through which feed material moves toward the cutting assembly. An electronic control unit (ECU) controls force applied to the feed wheel or gap-bounding member toward the feed material in response to an operational condition of the wood chipper. The ECU can maintain or vary the force in any desired manner. One option is to apply the force with a pulsating mechanism in a pulsating manner to enhance the feeding procedure. The pulsating mechanism is in communication with a sensor from which the ECU receives signals typically indicating an operational speed of the cutting assembly or the engine. An ECU logic circuit permits the pulsating force only if the operational speed exceeds a predetermined threshold.