Abstract: A trailer assembly including a cab, a first trailer hitched to the cab, a second trailer having a dolly hitched to the first trailer, and a third trailer having a dolly hitched to the second trailer. Each dolly has a framework with a front hitch and has a wheel assembly fixedly connected to the framework. The wheel assembly has an axle and four wheels and leaf springs. The dolly has a thrust bearing unit with a bearing axis. The thrust bearing unit has a bottom race fixedly connected to the framework and has a top race angularly displacable relative to the bottom race about the bearing axis. The top race has a pivot plate with a horizontal pivot axis. The pivot plate has trunnions with pivot pins for pivoting of the pivot plate about the horizontal pivot axis relative to the top race. The pivot plate has a hinge groove for connecting to a hinge pin under the overlapping trailer. The thrust bearing unit has brake means, operated by a driver in the cab by controlling a fluid meter.