Abstract: A dual well pumping unit (12) has two hydraulic ram units (26), one for each well, which are connected together for regenerative assist. Synchronized variable stroke and variable speed pump down control is provided, such that should pump down be encountered in one of the wells, programmable controllers (46) reduce the speed and the stroke of a ram unit (26) for a pumped-down well by the same percentage, to maintain a constant cycle time between upstrokes and down strokes such that the ram unit (26) of the pumped down well will remain synchronized with a ram unit (26) of the other well. Preferably the speed and the stroke of the ram unit (26) of the pumped down well will be decreased by 1.5% per stroke when pump down is detected, and will be increased by 3% per stroke until a constant fluid level is reached.

Abstract: A dual well pumping unit (12) has two hydraulic ram units (26), one for each well, which are connected together for regenerative assist. Synchronized variable stroke and variable speed pump down control is provided, such that should pump down be encountered in one of the wells, programmable controllers (46) reduce the speed and the stroke of a ram unit (26) for a pumped-down well by the same percentage, to maintain a constant cycle time between upstrokes and down strokes such that the ram unit (26) of the pumped down well will remain synchronized with a ram unit (26) of the other well. Preferably the speed and the stroke of the ram unit (26) of the pumped down well will be decreased by 1.5% per stroke when pump down is detected, and will be increased by 3% per stroke until a constant fluid level is reached.

Abstract: A dual well pumping unit (12) has two hydraulic ram units (26), one for each well (preferably with each ram unit (26) having three hydraulic rams). Each hydraulic ram units is connected to first ram pump (18) and a second ram pump (20). The drive shaft (40) of the first ram pump (18) is coupled to the drive shaft (38) of the second ram pump (20) and to a rotor of a drive motor (16). The ram pump (18) and the ram pump (20) are preferably variable displacement piston pumps which are controlled by a microprocessor based controller (44), such that during the downstroke of the hydraulic ram (26) the ram pump (18) operates as an hydraulic motor powering the ram pump (20) and during the up stroke of the hydraulic ram (26) the ram pump (20) operates as a hydraulic motor to provide assist to the ram pump (18).

Abstract: A dual well pumping unit (12) has two hydraulic ram units (26), one for each well (preferably with each ram unit (26) having three hydraulic rams). Each hydraulic ram units is connected to first ram pump (18) and a second ram pump (20). The drive shaft (40) of the first ram pump (18) is coupled to the drive shaft (38) of the second ram pump (20) and to a rotor of a drive motor (16). The ram pump (18) and the ram pump (20) are preferably variable displacement piston pumps which are controlled by a microprocessor based controller (44), such that during the downstroke of the hydraulic ram (26) the ram pump (18) operates as an hydraulic motor powering the ram pump (20) and during the up stroke of the hydraulic ram (26) the ram pump (20) operates as a hydraulic motor to provide assist to the ram pump (18).

Abstract: A dual well pumping unit (12) has two hydraulic ram units (26), one for each well (preferably with each ram unit (26) having three hydraulic rams). Each hydraulic ram units is connected to first ram pump (18) and a second ram pump (20). The drive shaft (40) of the first ram pump (18) is coupled to the drive shaft (38) of the second ram pump (20) and to a rotor of a drive motor (16). The ram pump (18) and the ram pump (20) are preferably variable displacement piston pumps which are controlled by a microprocessor based controller (44), such that during the downstroke of the hydraulic ram (26) the ram pump (18) operates as an hydraulic motor powering the ram pump (20) and during the up stroke of the hydraulic ram (26) the ram pump (20) operates as a hydraulic motor to provide assist to the ram pump (18).

Abstract: A hydraulic rod pumping unit (12) has a constant horsepower regenerative assist featuring downstroke energy recovery. The pumping unit (12) has a hydraulic ram (26) connected to a ram pump (18). The drive shaft (40) of the ram pump (18) is coupled to the drive shaft (38) of an accumulator pump (20) and to a rotor of a drive motor (16). A hydraulic accumulator (24) is connected to the output of the accumulator pump (20). The ram pump (18) and the accumulator pump (20) are preferably variable displacement piston pumps which are controlled by a microprocessor based controller (44), such that during the downstroke of the hydraulic ram (26) the ram pump (18) operates as an hydraulic motor powering the accumulator pump (20) and during the up stroke of the hydraulic ram (26) the accumulator pump (20) operates as a hydraulic motor to provide assist to the ram pump (18).

Abstract: A hybrid hydraulic-electric pumping unit (12) with downstroke energy recovery is disclosed which is operated in a conventional flow mode to supply hydraulic fluid to a hydraulic ram (26), and then is operated in a reverse flow mode to receive the hydraulic fluid from the hydraulic ram (26) and turn an electric motor (16) to generate electric power. A single hydraulic hose (48) connects the pump (18) to the hydraulic ram (26), and is used for both passing the hydraulic fluid from the pump (18) to the hydraulic ram (26) and from the ram (26) to the pump (18). The potential energy of the weight of sucker rods (10) lifted in operating the pumping unit (12) is recovered by operating the pump (18) and motor (16) with return of the hydraulic fluid from the hydraulic ram (26) through the pump (18), which turns the motor (16) to generate electric power.

Abstract: A hybrid hydraulic-electric pumping unit (12) with downstroke energy recovery is disclosed which is operated in a conventional flow mode to supply hydraulic fluid to a hydraulic ram (26), and then is operated in a reverse flow mode to receive the hydraulic fluid from the hydraulic ram (26) and turn an electric motor (16) to generate electric power. A single hydraulic hose (48) connects the pump (18) to the hydraulic ram (26), and is used for both passing the hydraulic fluid from the pump (18) to the hydraulic ram (26) and from the ram (26) to the pump (18). The potential energy of the weight of sucker rods (10) lifted in operating the pumping unit (12) is recovered by operating the pump (18) and motor (16) with return of the hydraulic fluid from the hydraulic ram (26) through the pump (18), which turns the motor (16) to generate electric power.

Abstract: An electric variable speed drive includes a hub member, a driven member, a magnetic coupler, and a rotary electrical connector. The hub member is mounted for rotating with the shaft of a prime mover. The driven member is rotatably supported on the hub member by bearings, and includes a mechanical output portion such as a pulley. The magnetic coupler includes an electric coil and magnetic poles which are mounted for rotating with one of the hub and the driven members. An armature is mounted to the other of the hub and driven members. An electric current is passed through the electric coil to magnetically couple the hub member to the driven member. The extent of the magnetic coupling between the hub and driven members is determined by the electric current passing through the electric coil.

Abstract: A method and apparatus for Varying the speed of operations of an oil well pumping unit powered by a motor wherein variations in oil viscosity may be efficiently accommodated. An oil well pumping unit which includes a submersible pump actuated by means of a reciprocating string of sucker rods is monitored for both rod position and load present on the sucker rods. The oil well pumping unit is driven by an electric or gas motor through a controllable coupling and the speed of the oil well pumping unit is then varied, utilizing the controllable coupling, in response to variations in sucker rod load. As the lowering of the sucker rod is impeded by high viscosity oil, the load on the sucker rod decreases. This decrease in sucker rod load is utilized to decrease the speed of the oil well pumping unit by means of the controllable coupling to ensure that bridle separation does not occur.