Frame rails Vehicle frame

pickup truck frame. notice hat-shaped crossmember in background, c-shape rails , cross member in center, , slight arc on axle.

typically material used construct vehicle chassis , frames carbon steel; or aluminum alloys achieve more light-weight construction. in case of separate chassis, frame made of structural elements called rails or beams. these ordinarily made of steel channel sections, made folding, rolling or pressing steel plate.

there 3 main designs these. if material folded twice, open-ended cross-section, either c-shaped or hat-shaped (u-shaped) results. boxed frames contain chassis rails closed, either somehow welding them up, or using premanufactured metal tubing.

c-shape

by far common, c-channel rail has been used on every type of vehicle @ 1 time or another. made taking flat piece of steel (usually ranging in thickness 1/8 3/16 ) , rolling both sides on form c-shaped beam running length of vehicle.

hat

hat frames resemble u , may either right-side-up or inverted open area facing down. not commonly used due weakness , propensity rust, can found on 1936–1954 chevrolet cars , studebakers.

high performance custom frame, using boxed rails , tube sections

abandoned while, hat frame gained popularity again when companies started welding bottom of unibody cars, in effect creating boxed frame.

boxed

originally, boxed frames made welding 2 matching c-rails form rectangular tube. modern techniques, however, use process similar making c-rails in piece of steel bent 4 sides , welded both ends meet.

in 1960s, boxed frames of conventional american cars spot-welded here , there down seam; when turned nascar stock car racers, box continuously welded end end strength.

design features

pickup truck chassis holding vehicle s engine, drivetrain, suspension, , wheels

while appearing @ first glance simple form made of metal, frames encounter great amounts of stress , built accordingly. first issue addressed beam height, or height of vertical side of frame. taller frame, better able resist vertical flex when force applied top of frame. reason semi-trucks have taller frame rails other vehicles instead of being thicker.

as looks, ride quality, , handling became more important consumers, new shapes incorporated frames. visible of these arches , kick-ups. instead of running straight on both axles, arched frames sit lower—roughly level axles—and curve on axles , down on other side bumper placement. kick-ups same thing, don t curve down on other side, , more common on front ends.

another feature seen tapered rails narrow vertically and/or horizontally in front of vehicle s cabin. done on trucks save weight , increase room engine since front of vehicle not bear of load back. design developments include frames use more 1 shape in same frame rail. example, pickup trucks have boxed frame in front of cab, shorter, narrower rails underneath cab, , regular c-rails under bed.

on perimeter frames, areas rails connect front center , center rear weak compared regular frames, section boxed in, creating known torque boxes.