Abstract: An automatic dump trailer leveler provides for the lateral leveling of the dump box of a semi trailer dump body vehicle during dumping operations. The present leveling system may also be adapted for other vehicles having tilting bodies or body components, for precluding their lateral tipping when dumping operations are undertaken on laterally sloping terrain. The present system includes low and high pressure hydraulic pumps, with the low pressure pump providing hydraulic fluid for taking up slack in the leveling struts or jacks and the high pressure pump providing pressure for leveling the dump box of the trailer or dump vehicle. The present system is operable simultaneously with operation of the dump box lift strut, and may include delay switches for precluding secondary extension of struts immediately after they have extended to adjust for settling to one side.