Underframes in a frame form are connected to the front and rear positions of a carrying truck. 搬送台車の前後位置にフレーム構成した台枠を連結する。 - 特許庁
In those days, wagons and underframes of the passenger carriages were made of iron, and main bodies including walls and roofs were made of wood.
当時の客車は台車や台枠は鉄製だが壁や屋根を含む本体は木造であった。 - Wikipedia日英京都関連文書対訳コーパス
To prevent a vehicle outside plate being damaged at car collision and reduce damage to a car body by surely making underframes collide with each other if by any chance a collision accident should occur to make height difference between underframes of vehicles. 万一、車両の台枠間に高低差が生じる衝突事故が起きた場合に、台枠同士を確実に衝突させて衝突時における車両外板の破損を防止して車体損傷の低減を図る。 - 特許庁