of its operating range in the first position when the spool as shown in fig1 is up liquid is drawn into the input of the pump 56 which is driven by motor 58 from the space a in the closed end of the large diameter cylinder through the conduit 68 through the valve 44 in accordance with arrows 45 through the pipe 71 into the pump 56 and out of the pump through pipe 72 through the valve 44 and through the pipe 70 into the accumulator 48 when the reciprocating piston system comprising the large diameter piston 18 piston rod 22 and the small diameter piston 20 is moving down the liquid inside of the tubing is substantially at rest and the only movement of liquid is from the well through the check valve 34 into the space b of the small cylinder in this operation there is a minimum of power required and the excess power of the motor and pump 58 56 serves to force liquid at high pressures into the accumulator 48 to increase the volume of the liquid 49 and decrease the volume of the gas 51 in order to store liquid at an increasingly higher pressure when the pressure in the accumulator 48 gets to a sufficiently high value the pressure sensitive second valve 52 connected to the accumulator by pipe 73 bypasses some of the high pressure liquids through pipe 74 and causes the valve 44 to move downward into its second position in the second position the motor driven pump 56 draws liquid from the high pressure accumulator adds its own energy to the liquid and forces.