An air driven hydraulic pump includes two opposed cylinders to either side of a center section. Two pneumatic pistons are slidable in the opposed cylinders and are coupled with one another by a common shaft extending through the center section. The pneumatic pistons ride in the opposed pneumatic cylinders and include hydraulic plungers extending therefrom. Cylinder heads integral with the cylinders provide hydraulic cylinders aligned with the hydraulic plungers. An air valve delivers pneumatic pressure to alternate sides of both pneumatic pistons such that the forces on the pistons are additive alternately in each direction.