A bogie or railroad truck holds the wheel sets of a rail vehicle.

An axlebox, also known as a journal box in North America, is the mechanical subassembly on each end of the axles under a railway wagon, coach or locomotive; it contains bearings and thus transfers the wagon, coach or locomotive weight to the wheels and rails; the bearing design is typically oil-bathed plain bearings on older rolling stock, or roller bearings on newer rolling stock.^[1]

Plain bearings are now illegal for interchange service in North America.^[2][3][4] As early as 1908 axle boxes contained a set of long cylindrical rollers allowing the axle to rotate.^[5][6] It was also used on steam locomotives such as the Victorian Railways A2 class, the LMS Garratt, the LSWR 415 class, and the GCR Class 1.^{[5][dubious – discuss]}

A large steel pin—or rod—which passes through the center plates on the body bolster and truck bolster.^[7] The truck turns about the pin, and stress is taken by the center plates.^[7]

One of a pair of plates which fit one into the other and support the car body on the trucks allowing them to turn freely under the car.^[7] The one on the truck may also be called center bowl.^[8]

The frame at either side of the truck.^[3][4]

Each truck has a bolster—a transverse floating beam—between the side frames.^[9] It is the central part of every truck on which the underframe of the railcar or railroad car is pivoted through the center pivot pin.^[7][9]

There is one side bearing located on each side of the centerplate on the truck bolster. In case of a shared bogie on an articulated car, there are two on each side.

The brake rigging includes the brake lever, the brake hanger, the brake pin, the brake beam and the brake shoes.

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• Journal boxes and axle boxes
• An American journal box showing a plain bearing^[10]
• This Bettendorf-style freight car truck uses journal bearings in journal boxes that are integral parts of the side frames. The center pin can be seen pointing up from the bolster. It has coil springs.
• Railroad car wheels are affixed to a straight axle, such that both wheels rotate in unison. This is called a wheelset.
• An archbar-type truck with American style journal boxes that are bolted to ends of the side frame
• A Bettendorf-style truck with axle boxes, which are not part of the side frames, at the wheels
• A Swiss axlebox
• Japanese archbar truck with axleboxes at the wheels
• Diamond frame bogie, elliptical springs and American style journal boxes
• Closeup of a shared bogie with 4 specially adapted side bearings and an articulated connector between two sections of an articulated well car. The roller bearings are not enclosed by an axle box.