Pump drive head pump assembly with a hydraulic pump circuit for preventing back-spin when the drive head has been shut off

A pump drive head comprising:

• a housing;
• upper and lower bearings disposed in the housing;
• a main shaft operatively connected to a driving apparatus and received in the upper and lower bearings, the main shaft including an outer tube and a liner tube, wherein the outer and liner tubes abut along a first portion of their length and are separated along a second portion of their length thereby forming an elongate tubular space;
• and
• a standpipe coupled at one end to the housing, below the lower bearing, and received within the elongate tubular space between the outer and liner tubes of the main shaft.

A pump drive head comprising:

• a housing;
• upper and lower bearings disposed in the housing;
• a main shaft operatively connected to a driver apparatus and received in the upper and lower bearings, the main shaft including an outer tube and a liner tube, wherein the outer and liner tubes abut along a first portion of their length and are separated along a second portion of their length thereby forming an elongate tubular space;
• a backspin preventer coupled to the main shaft;
• and
• a standpipe coupled at one end to the housing, below the lower bearing, and received within the elongated tubular space between the outer and liner tubes of the main shaft.

A pump drive head comprising:

• a housing;
• upper and lower bearings disposed in the housing;
• a main shaft operatively connected to a driving apparatus received in the upper and lower bearings, the main shaft including an outer tube and a liner tube, wherein the outer and liner tubes abut along a first portion of their length and are separated along a second portion of their length thereby forming an elongate tubular space;
• a standpipe coupled at one end to the housing, below the lower bearing, and received within the elongate tubular space between the outer and liner tubes of the main shaft;
• a hydraulic pump including
• a hydraulic pump chamber disposed in the housing and communicating with the main shaft,
• a first gear disposed in the hydraulic pump chamber and coupled to the main shaft,
• a second gear disposed in the hydraulic pump chamber and intermeshing the first gear, and
• a suction port located between the first and second gears and operable for one direction of rotation of the main shaft;
• and
• a hydraulic circuit coupled to the suction port for resisting said one direction of rotation of the main shaft.

A pump drive head comprising:

• a housing;
• upper and lower bearings disposed in the housing;
• a main shaft comprising an outer tube and an inner tube operatively connected to a driving apparatus and received in the upper and lower bearings, wherein the outer and liner tubes abut along a portion of their length are separated along another portion of their length thereby forming an elongate tubular space;
• a hydraulic pump including
• a hydraulic pump chamber disposed in the housing and communicating with the main shaft,
• a first gear disposed in the hydraulic pump chamber and coupled to the main shaft,
• a second gear disposed in the hydraulic pump chamber and intermeshing the first gear, and
• a suction port located between the first and second gears and operable for one direction of rotation of the main shaft;
• a hydraulic circuit coupled to the suction port for resisting said one direction of rotation of the main shaft;
• and
• a standpipe coupled at one end to the housing, below the lower bearing, and received within the elongate tubular space between the outer and liner tubes of the main shaft.

A drive head for use in driving an oil well downhole pump, comprising:

• a housing;
• upper and lower bearings disposed in the housing;
• a shaft for connection to a driving apparatus and received in said upper and lower bearings for rotation therein, said shaft including:
• concentric inner and outer tubular shaft members, said inner and outer shaft members being connected together at upper ends thereof and being spaced apart from said upper ends to lower ends thereof to define an annular chamber with a closed upper end, said outer tubular member being mounted in said upper and lower bearings, and
• a non-rotatable standpipe coupled at a lower end thereof to said housing below said lower bearing and received within said annular chamber between said inner and outer tubular members.

A drive head for driving a downhole pump in an oil well, comprising:

• a housing having a fluid reservoir therein;
• upper and lower bearing assemblies disposed in upper and lower ends, respectively, of said housing;
• a shaft for connection to a drive motor, said shaft being mounted in said upper and lower bearings for rotation therein and extending through said reservoir, said shaft including concentric inner and outer tubular members;
• said inner and outer members being spaced apart and connected together at upper ends thereof to define an annular chamber with a closed upper end, said closed upper end being the upper end of said reservoir, said outer tubular member being mounted in said bearings;
• a non-rotatable standpipe coupled at one end to said housing below said lower bearing and received within said annular chamber between said inner and outer members, said standpipe including an annular plate removably connected to said housing and having a concentric bore for receiving a shaft therethrough and a pipe member having a bottom end secured to said annular plate, said pipe member being sized to be inserted into said annular chamber with an upper end thereof positioned above the upper end of said reservoir;
• a first seal disposed between an outer surface of said pipe and said outer tubular member, a second seal disposed between an inner surface of said outer member and a bottom surface of said upper bearing;
• a backspin retarder mounted in said reservoir and coupled to said shaft for controlling reverse rotation of said shaft, said backspin retarder including a hydraulic pump having:
• a hydraulic pump chamber in said housing, said shaft extending into said pump chamber;
• a first gear in the hydraulic pump chamber and connected to said shaft for rotation therewith;
• a second gear in the hydraulic pump chamber for meshing engagement with said first gear;
• a suction port in said pump chamber between said first and second gears and operable for one direction of rotation of said shaft and inoperable in the other direction of rotation of said shaft;
• and
• a hydraulic circuit coupled to the suction port for resisting said one direction of rotation of the main shaft.