Embodiments disclosed herein provide a modular apparatus and system for automatically raising and lowering the deck height of a towed trailer. The embodiment is comprised of a trailer frame to which a drop axle is attached via a dynamic height adjustable means, such as electrically operated air springs. The drop axle may have two or more wheels mounted to opposite ends of the drop axle and attached to the trailer frame via the dynamic height adjustable means. Thus allowing the dynamic height adjustable means to raise and lower the trailer frame above and below the centerline of the wheels, which aids loading and unloading of cargo onto the trailer.