Abstract: The hydraulic system for actuation of the mud valve of a measurement-while-drilling tool is characterized by a hydraulic actuator having a piston operatively connected to the mud valve of a measurement-while-drilling tool, which hydraulic actuator incorporates an internal by-pass which, cooperatively with movement of the piston, opens to unload hydraulic pressure from the system at either end of stroke of the piston. Return from the by-pass to the pump may be restricted so as to maintain some hydraulic pressure on the piston at end of stoke so as to prevent movement therefrom by external forces. The hydraulic system may include high pressure means, strainer means and means to equalize pressure between hydraulic system pressure and pressure external of the system.

Abstract: A hydraulic system for supplying hydraulic fluid for operating a mud pulse generator includes an accumulator that has a reservoir. The accumulator is arranged to maintain the fluid pressure in the reservoir. The system also has a pressure operated, one way inlet valve that is arranged to allow hydraulic fluid to be added, under pressure, to the reservoir. The one way inlet valve also includes a valve core.

Abstract: An assembly is used in a subterranean well. The assembly includes a first collar that has a support for supporting an oil tool at a first location and a second collar that is connected to the first collar for retaining the tool at a second location downhole of the first location.

Abstract: A mounting assembly is used to mount a printed circuit board on an oil tool. The assembly includes a flat surface on the oil tool. The flat surface is arranged to receive the printed circuit board. The assembly includes a clamp that is adapted to engage with peripheral edges of the printed board substantially around the periphery of the printed circuit board and to clamp the printed circuit board on the flat surface of the oil tool.

Abstract: An ultrasonic probe utilized in an ultrasonic ranging system for determining fluid volume and/or fluid leakage in an underground storage tank, as well as monitoring fluid inventory, is provided which is characterized by (i) having its calibration reflectors positioned whereby each of the secondary echo packets formed by the calibration reflectors of the ultrasonic probe becomes imbedded into the trailing edge of a primary echo packet of another calibration reflector or to cause its secondary echo packet to be detected by the transducer after the transducer has detected a primary echo packet associated with the fluid surface, (ii) each of the calibration reflectors being positioned perpendicular to and offset from the longitudinal axis of the probe body, (iii) an ultrasonic sound wave dampening member fixedly positioned in the probe body between the transducer assembly and the tank bottom, the wave dampening member having a surface facing toward the transducer assembly wherein the surface is configured to damp