Abstract: A method of treating a surface of a machine element to permit the outer layers thereof to freely expand when repeatedly subjected to sudden temperature variations without thermal stressing the inner layers thereof.

Abstract: A method of treating a surface of a machine element to permit the outer layers thereof to freely expand when repeatedly subjected to sudden temperature variations without thermal stressing the inner layers thereof.

Abstract: A low volume submersible pump assembly has features to stabilize the operation. The pump assembly includes a centrifugal pump driven by a submerged electrical motor. The centrifugal pump has an impeller configuration that is designed for high specific head, but potentially unstable operation. At the design speed, the pump potentially could deliver an indeterminate flow rate for a given head. Also, at the design speed, the design flow rate will yield a design head that is very close to the maximum head at zero flow. The pump has the characteristic of requiring a significant increase in torque to produce higher flow rates. To stabilize the potentially unstable pump, a variable speed drive varies the speed of the motor to maintain constant torque. Maintaining a constant torque allows a considerable variance in head with only a small variance in flow rate resulting.

Abstract: A thrust reducing apparatus for a progressing cavity pump used in a well and driven by a submersible pump motor. A piston is mounted to the top of the rotor and located in a bore between the stator and the tubing which extends to the surface. A bypass passage enables fluid discharged from the pump to flow past the bore and the piston. An annulus passage extends into the bore above the piston for communicating fluid pressure in the annulus to the top of the piston. The lower side of the piston is exposed to discharge fluid pressure from the pump, resulting in a net upward force on the piston. The piston pulls upwardly on the rotor to reduce the downward thrust on the rotor.