Abstract: A downhole coupling has a first part with a sleeve end and a first connector end, and a second part with a pin end and a second connector end. The sleeve end and pin end are secured together via an interference fit. A second downhole coupling has a first part with a sleeve end and a first connector end, and a second part with a pin end and a second connector end. One or more shear pins may be present, each shear pin positioned within a shear pin bore that extends through the sleeve end and partially into the pin end. Related methods and combinations are disclosed.

Abstract: A downhole coupling has a first part with a sleeve end and a first connector end, and a second part with a pin end and a second connector end. The sleeve end and pin end are secured together via an interference fit. A second downhole coupling has a first part with a sleeve end and a first connector end, and a second part with a pin end and a second connector end. One or more shear pins may be present, each shear pin positioned within a shear pin bore that extends through the sleeve end and partially into the pin end. Related methods and combinations are disclosed.

Abstract: Sealing systems and level monitors for a tank are disclosed. A housing defines a bore and has exterior dimensions suitable for fitting in a port through the tank. An elongate member or cable passes through the bore of the housing. First and second seal assemblies are set within the bore against first and second stops, respectively, in the housing. The first and second seal assemblies are spaced from one another to form a fluid reservoir and are both sealed to the housing and to the elongate member or cable. The fluid reservoir may be pressured by a bias device. The elongate member or cable may be connected to a float.

Abstract: Sealing systems and level monitors for a tank are disclosed. A housing defines a bore and has exterior dimensions suitable for fitting in a port through the tank. An elongate member or cable passes through the bore of the housing. First and second seal assemblies are set within the bore against first and second stops, respectively, in the housing. The first and second seal assemblies are spaced from one another to form a fluid reservoir and are both sealed to the housing and to the elongate member or cable. The fluid reservoir may be pressured by a bias device. The elongate member or cable may be connected to a float.

Abstract: A fluid pressure powered apparatus comprises a double-acting member, a first pilot valve, a second pilot valve, and a switchable valve is disclosed. The double-acting member is operable between a first stroke end and a second stroke end by fluid pressure from the switchable valve. The first and second pilot valves are configured to establish a biasing fluid pressure to first and second bias surfaces, respectively, of the switchable valve. The first and second pilot valves are actuatable by the double-acting member when at the first and second stroke ends, respectively, to reduce the biasing fluid pressure on the first bias surface. In operation, the reduction of biasing fluid pressure on either the first bias surface or the second bias surface, respectively, triggers the switchable valve to switch between a first stroke position and a second stroke position, respectively. A method of reciprocating a fluid pressure powered apparatus is also disclosed.

Abstract: A rod coupling formed of a tubular housing having a first box end and a second box end. The tubular housing has an interior surface defining a bore extending along the tubular housing from the first box end to the second box end, and has an exterior surface. Plural openings extending transversely through the housing from the interior surface to the exterior surface. A coating on the exterior surface of the tubular housing covers the plural openings, and may fill the openings or extend through the openings to form knobs inside the tubular housing. The coatings may taper from the exterior surface towards the interior surface. The openings are preferably distributed uniformly around the tubular housing. The openings are preferably distributed in plural rows. A rod string may be made up of plural such rod couplings and connecting rods.

Abstract: A rod coupling formed of a tubular housing having a first box end and a second box end. The tubular housing has an interior surface defining a bore extending along the tubular housing from the first box end to the second box end, and has an exterior surface. Plural openings extending transversely through the housing from the interior surface to the exterior surface. A coating on the exterior surface of the tubular housing covers the plural openings, and may fill the openings or extend through the openings to form knobs inside the tubular housing. The coatings may taper from the exterior surface towards the interior surface. The openings are preferably distributed uniformly around the tubular housing. The openings are preferably distributed in plural rows. A rod string may be made up of plural such rod couplings and connecting rods.

Abstract: A control system for a reciprocating device. The control system includes a switching valve having a fluid supply inlet, an exhaust outlet, a restrictor on the exhaust outlet, a drive line, a valve operable to connect one of the exhaust outlet and the fluid supply inlet to the drive line and a toggle for operating the valve, the toggle being movable by motive force through an arc between a first position in which fluid flow is from the fluid supply inlet to the drive line and a second position in which fluid flow is from the drive line to the exhaust outlet, the toggle passing through a middle position where fluid flow may flow from the drive line to the exhaust outlet and from the fluid supply inlet to the drive line. A reciprocating device is provided that is operable to move in a first direction due to fluid pressure in the drive line and a second, opposed, direction due to a motive force activator when pressure in the drive line is reduced (exhausted).