Trapezoidal frame
It is composed of two longitudinal beams and several beams. The cross-sectional shape of the longitudinal beam is trough, zigzag, box, etc. The longitudinal beams can be made into curved, constant-section or variable-section in the horizontal or longitudinal plane.
The trapezoidal frame is widely used on commercial trucks and some passenger cars because of its high bending strength and fast and convenient parts installation. It is rarely used in passenger cars.