the lower frame on which a vehicular structure rests: the underframe of a bus.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
How to use underframe in a sentence
On this underframe the superstructure or frame is erected to form the body of the car.The Story of the Pullman Car | Joseph Husband
M, is of the internal pole type, and is supported on the underframe of the wagon.
The underframe is provided with spring axle boxes, and also with spring buffers and drawbars.