Abstract: Regenerative hydraulic power transmission for subsurface pumps, including a power source, a variable flow rate hydraulic pump, means to reverse flow through the hydraulic pump responsive to change in direction of the subsurface pump stroke, and an inertial assist for the power source which gathers energy from the downstroke of the subsurface pump and utilizes the gathered energy to power the upstroke of the subsurface pump. The transmission can vary upstroke speed apart from downstroke speed, pump stroke length and dwell time of change in stroke direction.

Abstract: A reversible flow variable rate hydraulic swashplate pump furnishes hydraulic fluid to stroke a piston supporting a subsurface pump. The controller determines reversal of pump flow and timing and speed of upstroke and downstroke of the subsurface pump. No valving restricts hydraulic fluid flow, and energy from the falling mass of the beam and sucker rods is accumulated during downstroke to be utilized during upstroke. The invention also includes the method steps of pumping hydraulic fluid to a cylinder containing a piston supporting the subsurface pump piston at a constant increasing rate until a maximum preset flow is reached, decreasing the flow to zero at a rate different than the increasing rate, reversing the hydraulic fluid flow to flow from the cylinder to the hydraulic pump at a constant increasing rate until maximum preset reverse flow is reached, and reducing reversed flow to zero at a rate different than the increasing flow rate.