Bogie
A bogie (called a truck in North American English) is a chassis, with wheels, attached to a rail vehicle, such as a boxcar. A bogie usually has four or six wheels. Each rail vehicle has a pair of bogies. The bogies can turn slightly to allow the rail vehicle to pass easily around curves in the railway track.
Bogie Media
Experiment, the first successful American locomotive with a bogie, built in 1831 to a design by civil engineer John B. Jervis
Bogies allow the wheelsets to more closely follow the direction of the rails when travelling around a curve in the railroad.
A diagram of an American-style truck showing the names of its parts and showing the journal boxes to be integral parts of the side frame. The journal boxes house plain bearings.
Side view of a SEPTA K-Car bogie
Mockup of the pneumatic bogie system of an MP 89 carriage used on the Meteor metro, showing the two special wheelsets
Articulated bogie on an NCTD Sprinter Siemens Desiro VT642
Japanese archbar bogie with axleboxes
Diamond frame bogie, elliptical springs and American style journal boxes