Abstract: A rack and pinion power steering system 10 is provided and includes a variable orifice valve 22 which controls the flow of fluid in and out of a hydraulic cylinder 20. Variable orifice valve 22 is communicatively coupled to a source of pressurized fluid 30 by use of a conduit 42 and an electronically controlled valve assembly 38. The pressurized fluid received through conduit 42 controls the operation of valve 22. Based upon the pressure of the received fluid, valve 22 selectively increases and decreases the volume of fluid flow in and out of cylinder 20, thereby causing cylinder 20 to have enhanced damping characteristics during certain vehicle operating conditions (e.g., during relatively high vehicle speed operating conditions).

Abstract: A boring bit for drilling is provided comprising one set of rotatable toothed wheels secured thereon as well as one set of tubular nozzles and one central nozzle for injecting drilling fluid from a chamber in bit body toward the bottom of a borehole. The boring bit comprises the inlet end of said tubular nozzle being secured on the bit body and connected with said chamber while its outlet end is quite close during operation to the lowest point of toothed wheels and the bottom of a borehole, and the fluid passage of said tubular nozzle from the inlet end to the outlet end is straight and cylindrical. Branch fluid passages are provided on the main fluid passage of said central nozzle for washing and cooling toothed wheels.