A chassis or framework-like structure underneath a railroad car to which wheel axles (and, hence, wheels) are attached through bearings. (Not to be confused with railway truck or railtruck, which are British English synonyms of railroad car)
A small, one-wheeled (or rarely, two-wheeled) cart with handles at one end for transporting small loads.
To convey in a wheelbarrow.
To cause the weight of an aeroplane to become concentrated around the nosewheel.