Before revision: Vertical and torsional twisting transmitted by going over uneven surfaces Transverse lateral forces caused by road conditions, side wind, and steering of the vehicle Torque from the engine and transmission Longitudinal tensile forces from starting and acceleration, as well as compression from braking Sudden impacts from collisions Frame rails A vehicle's bare ladder frame Pickup truck frame, with heavy c-shaped longitudinal rails (slightly arced over the rear axle), a similarly sized c-shaped crossmember just forward of the axle, and a tophat-shaped smaller gauge crossmember towards the rear Typically the material used to construct vehicle chassis and frames include carbon steel for strength or aluminum alloys to achieve a more lightweight construction.
After revision: Vertical and torsional twisting transmitted by going over uneven surfaces Transverse lateral forces caused by road conditions, side wind, and steering of the vehicle Torque from the engine and transmission Longitudinal tensile forces from starting and acceleration, as well as compression from braking Sudden impacts from collisions Frame rails A ladder frame, named for its shape Pickup truck frame, with heavy c-shaped longitudinal rails (slightly arced over the rear axle), a similarly sized c-shaped crossmember just forward of the axle, and a tophat-shaped smaller gauge crossmember towards the rear Typically the material used to construct vehicle chassis and frames include carbon steel for strength or aluminum alloys to achieve a more lightweight construction.