Abstract: In a method for making hydraulic tubing a low carbon steel tube suitable for use as hydraulic tubing is coated on its inside surface with zinc phosphate and the outside surface is electroplated. The resulting hydraulic tubing will resist rust on the inside and on the outside during storage.

Abstract: In a method for making hydraulic tubing a low carbon steel tube suitable for use as hydraulic tubing is coated on its inside surface with zinc phosphate and the outside surface is electroplated. The resulting hydraulic tubing will resist rust on the inside and on the outside during storage.

Abstract: A wind turbine has a rotor; a hydraulic pump coupled to the rotor, two or more variable displacement hydraulic motors which are driven by fluid flow from the hydraulic pump, at least one generator coupled to the variable displacement hydraulic motors and a closed loop hydraulic oil circuit for carrying pressurized oil from the hydraulic pump to the motors and to return oil to the pump from the motors. A controller in the closed loop hydraulic oil circuit controls the flow of oil in the closed loop circuit and displacement in each of the variable displacement hydraulic motors. Control of flow in and out of the motor for each revolution of that motor controls the flow to the hydraulic pump which has a fixed displacement, thereby controlling its rpm, thereby controlling the rotor rpm. A hydraulic accumulator can be provided in the closed loop.

Abstract: A wind turbine has a rotor; a hydraulic pump coupled to the rotor, two or more variable displacement hydraulic motors which are driven by fluid flow from the hydraulic pump, at least one generator coupled to the variable displacement hydraulic motors and a closed loop hydraulic oil circuit for carrying pressurized oil from the hydraulic pump to the motors and to return oil to the pump from the motors. A controller in the closed loop hydraulic oil circuit controls the flow of oil in the closed loop circuit and displacement in each of the variable displacement hydraulic motors. Control of flow in and out of the motor for each revolution of that motor controls the flow to the hydraulic pump which has a fixed displacement, thereby controlling its rpm, thereby controlling the rotor rpm. A hydraulic accumulator can be provided in the closed loop.

Abstract: A pipe flaring die has a central opening with a profile configured to reduce stress concentrations at the base of the flared portion of the pipe. The profile includes an annular relief area intermediate an annular gripping surface and an annular beveled portion which defines the angle of the flared portion. The relief area provides a longer transition distance for the formation of the flared portion which results in a reduced residual stress concentration created at the base of the flared portion during the forming process.

Abstract: A pipe coupling device for holding a metal pipe having a selected diameter within a range of a nominal diameter plus or minus a specified tolerance is also useful for easily determining if any pipe is within specifications. A split metal ring having a diameter equal to the nominal diameter for the metal pipe and a transverse split having a width equal to the specified tolerance is placed around the pipe. A nut having a tapered cylindrical bore having diameter such that the diameter plus twice the thickness of the split metal ring equals the nominal diameter of the metal pipe plus the specified tolerance is fitted over the split metal ring. If the pipe is undersized it will slip through the split metal ring. If the pipe is oversized the nut will not fit completely over the metal ring surrounding the pipe.

Abstract: A pipe coupling device for holding a metal pipe having a selected diameter within a range of a nominal diameter plus or minus a specified tolerance is also useful for easily determining if any pipe is within specifications. A split metal ring having a diameter equal to the nominal diameter for the metal pipe and a transverse split having a width equal to the specified tolerance is placed around the pipe. A flange having a tapered cylindrical bore having diameter such that the diameter plus twice the thickness of the split metal ring equals the nominal diameter of the metal pipe plus the specified tolerance is fitted over the split metal ring. If the pipe is undersized it will slip through the split metal ring. If the pipe is oversized the flange will not fit completely over the metal ring surrounding the pipe.