A wheel hub for attaching to a vehicle includes a hydraulic engine received in a hub shell and attached or secured to the vehicle, for allowing the hub shell to be rotated relative to the hydraulic engine and the vehicle. The hydraulic engine includes a rotatable spindle, and a coupling device coupled between the spindle of the hydraulic engine and the hub shell, to allow the hub shell to be driven or rotated by the hydraulic engine. A plate and a casing are rotatably received in the hub shell, to rotatably support the hydraulic engine in the hub shell with the plate and the casing. A directional control device may be used to control rotational movements between the spindle of the hydraulic engine and the hub shell.