Abstract: An electrical property sensor is presented that includes a printed circuit board with a first face separated from a second face by a thickness, the first face having a length and a width. The sensor also includes an aperture extending from a first face of the printed circuit board to a second face of the printed circuit board. The aperture includes a receiving electrode and a transmitting electrode. When a fluid flows through the aperture and a voltage is provided at the transmitting electrode, a cunent flow is measured at the receiving electrode.

Abstract: A vibratory hammer for use in driving a work piece such as a pile, pipe, caisson or plate into the earth includes a support frame 10 adapted to be suspended from a crane or the like, and a vibrator assembly 12 that is suspended from the frame. The vibrator assembly includes at least one pair of laterally spaced, parallel rotary shafts 40 that are rotatable in opposite directions to one another, and a weight 46 is supported on each shaft. Each weight is shiftable radially relative to the corresponding shaft between a balanced position in which the center of mass of the weight is collinear with the longitudinal axis of the shaft, and an eccentric position in which the center of mass of the weight is offset radially from the longitudinal axis of the shaft. Preferably, a fluid-actuated piston-and-cylinder assembly 54 is supported between each weight and the corresponding shaft for selectively carrying out the shifting movement of the weights. However, other types of shifting mechanisms could also be employed.