A pallet truck hydraulic jack has a base plate mounting a lift cylinder with a reciprocal piston or lift rod and a pump cylinder with a reciprocal pump piston. A frame mounts a pair of forks having retractable rollers at their ends and is pivotally mounted upon the base plate and operatively engaged by the lift rod for raising the frame and lowering the rollers. A hydraulic reservoir is mounted upon the base plate. A hydraulic control system includes a pivot axle depending from the base plate having a bore coaxial of the lift cylinder. A plunger piston within the axle shaft bore is connected to the lift cylinder piston rod. There are a plurality of manifold passages formed in the base plate, adapted for supplying pressurized hydraulic fluid from the pump to the plunger piston and to the lift rod, which interconnects the reservoir and the pump and interconnects the reservoir and the lift cylinder. A cartridge type directional control valve assembly within the base plate controls the flow of pressurized hydraulic fluid in the respective manifold passages so that manual actuation of the pump effects a quick lift of the frame when it is unloaded, effects an additional application of lifting force through the lift cylinder when the frame is loaded, bypasses pressurized hydraulic fluid to the reservoir when the frame is overloaded, and provides a release of pressurized hydraulic fluid from the pump cylinder and the lift plunger and returns it to the reservoir for lowering the frame and forks. The cartridge type directional control valve may be conveniently removed and replaced in the hydraulic control circuit when required in minimum time.