Undercarriage is the part of a moving vehicle that is underneath the main body of the vehicle. The term originally applied to this part of a horse-drawn carriage, and usage has since broadened to include:

• The landing gear of an aircraft.
• The chassis of an automobile.
• The tractor treads of a tractor or tank.
• The underframe of a locomotive
• The undercarriage assembly of a train car or locomotive, known as a bogie, incorporating the train wheel sets, suspension, brakes and, in powered units, the traction motors

• Bicycle frame
• Container chassis
• Locomotive bed
• Locomotive frame
• Motorcycle frame