Abstract: A crusher for reducing the size of pieces of rock, concrete and the like is disclosed. A pair of resonant beams are suspended at their upper nodes from the upper end of a frame. The beams are driven by an oscillatory driver which engages the beams near their anti-nodes. A pair of opposed jaws are mounted at the lower ends of the beams and their mutual, reciprocal action applies compressive forces to material fed therebetween which causes the material to break apart. The jaws may be moved apart by a pair of hydraulic cylinders to allow adjustment of the material size discharged from the crusher. The hydraulic system actuating the cylinders is especially adapted to absorb shock imparted by the reactive forces of the jaws against the material being crushed.

Abstract: A press for applying impact forces to a work object includes a horizontal resonant beam having an output end for applying the impact forces. The beam is secured to a frame at two nodal points, one of which may be moved up and down by a hydraulic cylinder. The beam is excited by an eccentric weight oscillator and the output end of the beam is urged against the work object by the cylinder. In operation, the force applied by the cylinder to the beam should be maintained less than the oscillator force so that the output end of the beam does not freeze against the work object, causing the beam to enter a forced resonant mode.

Abstract: A resonant work performing apparatus is disclosed which includes a resonant system which is vibratory in resonance at an unloaded resonant frequency. The resonant system has a vibratory input at a frequency near the resonant frequency, and a vibratory output responsive to vibrations at the input. The resonant system has at least one intermediate node, and the apparatus includes a frame attached to the resonant system substantially at the node. A vibrational force is applied to the input of the resonant system at a given frequency near the unloaded resonant frequency to excite the resonant system to at least near resonance. A sensor is used to determine the frequency of the resonant system. Application of the vibrational force is controlled responsively to the sensor to hold the applied vibrational force at the given frequency.