Abstract: A trailer dolly includes an internal combustion engine, a transmission providing both forward and reverse drives, and a centralized lifting handle. The internal combustion engine provides much better power and much less weight than electric counterparts. The forward/reverse transmission includes a sliding shaft which engages a select one of two bevel gears with a larger bevel gear to select forward or reverse drive. The sliding shaft slides along with an elongated clutch cylinder of a centrifugal clutch. An alternative transmission uses sprockets and chains to obviate a case to enclose lubricant. Counter-rotating sprockets alternatively engage a dog-tooth gear to select either forward or reverse drive. The lifting handle mounted generally at the center of gravity (with the trailer dolly in a substantially horizontal position) makes single-handed lifting and carrying of the trailer dolly quite easy.