Welcome back to our Word of the Week!

What do aircraft and horse-drawn carriage have in common? Let’s take a look:

undercarriage (noun, countable)

UK /ˈʌn.dəˌkær.ɪdʒ/ US /ˈʌn.dɚˌker.ɪdʒ/

That part of a moving vehicle that is underneath the main body of the vehicle.

Originally, the term applied to the wooden frame supporting structure of a horse-drawn carriage and was the main element connecting the wheels, the cabin, the coachman station and the horse harnesses.

Since then, however, the usage of the term has broadened quite significantly and is nowadays used for a whole variety of vehicles, such as the chassis of an automobile, the tractor treads of a tractor or tank, the bogie of a train carriage or locomotive, that is to say the mechanical assembly including the wheel sets, suspension, brakes and, in powered units, the traction motors.

Of course, when talking about aviation, the word undercarriage designates the fixed or retractable set of wheels and other parts that support a plane when it is on the ground and make it possible to take off and land, otherwise known as landing gear.

Undercarriages come in a great variety of configurations, from the simplest systems such as a single steel tube to retractable arrays of strut-mounted wheels on larger aircraft.

Main landing gear on a Cessna 210
Main landing gear leg with trailing link and an oleo strut on a Cessna 404
20-wheel undercarriage on an Airbus A380-800