Abstract: Low profile valves are described. In an embodiment, a tubular member for fluid transport has a valve constructed within a wall of the tubular member for controlling a radial flow of fluid, such as water, oil, or gas, through the wall without impeding the flow of fluid or tools through the tubular member or near the exterior of the tubular member. The low profile valve may be used, for example, in the oil and gas industries as a pressure relief valve or check valve. When used as a pressure relief valve, a load member such as a spring, strap, or rocker arm maintains a backpressure on the valve. Example low profile valves can provide flow control from within a very thin annulus between other components.

Abstract: A two-step hydraulic valve is described. In an implementation, a two-step hydraulic valve with retrograde spool action has a pilot spool that controls hydraulic force applied to a main spool to switch a rod of a hydraulic actuator back-and-forth between extension and retraction. The main spool is hydraulically driven in retrograde motion to the pilot spool, providing improved reliability and switching action for the valve. The pilot spool also has an overtravel feature that can be used to hyperextend the rod for various purposes. In an example system, the two-step hydraulic valve controls a hydraulic actuator connected to drive a submersible reciprocating pump, such as a diaphragm pump.

Abstract: A two-step hydraulic valve is described. In an implementation, a two-step hydraulic valve with retrograde spool action has a pilot spool that controls hydraulic force applied to a main spool to switch a rod of a hydraulic actuator back-and-forth between extension and retraction. The main spool is hydraulically driven in retrograde motion to the pilot spool, providing improved reliability and switching action for the valve. The pilot spool also has an overtravel feature that can be used to hyperextend the rod for various purposes. In an example system, the two-step hydraulic valve controls a hydraulic actuator connected to drive a submersible reciprocating pump, such as a diaphragm pump.

Abstract: Low profile valves are described. In an embodiment, a tubular member for fluid transport has a valve constructed within a wall of the tubular member for controlling a radial flow of fluid, such as water, oil, or gas, through the wall without impeding the flow of fluid or tools through the tubular member or near the exterior of the tubular member. The low profile valve may be used, for example, in the oil and gas industries as a pressure relief valve or check valve. When used as a pressure relief valve, a load member such as a spring, strap, or rocker arm maintains a backpressure on the valve. Example low profile valves can provide flow control from within a very thin annulus between other components.

Abstract: A submersible pump includes a pump valve configured to switch the pump between first and second states in which a piston is respectively extended and retracted. The pump valve includes first and second components that reciprocate between corresponding first and second positions. The pump is in the first state when both components are in their corresponding first position. The pump is in the second state when both components are in their corresponding second position. Neither the valve nor the pump is hydraulically locked at any time during normal operation.

Abstract: A submersible pump includes a pump valve configured to switch the pump between first and second states in which a piston is respectively extended and retracted. The pump valve includes first and second components that reciprocate between corresponding first and second positions. The pump is in the first state when both components are in their corresponding first position. The pump is in the second state when both components are in their corresponding second position. Neither the valve nor the pump is hydraulically locked at any time during normal operation.

Abstract: Passenger boarding bridge extendable sections are provided with roller assemblies supporting one extendable bridge section relative to a second extendable bridge section wherein the roller assemblies assist in reducing the downward load in the overlapping area of the bridge sections.