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).