TRUCK BODY MOUNTS
Truck users have been questioning the mounting of bodies on heavy trucks. The following body mounting guidance is
Truck frames are built to be both stiff, in that they resist bending, twisting, parallelogramming, and flexible, in that they
allow bending and twisting as the wheels and axles follow the road and terrain. Although this stiffness and flexibility may
seem to be a contradiction, the metal suppliers and truck manufacturers work together on the users problem to get the
most flexibility (within the limits the metal allows) to carry the truck and its loads without damage for the life of the truck. A
truck frame that is too stiff, without flexibility, will crack. A truck frame that is too flexible will be overstressed, become
bent out of shape, and finally crack.
Bodies, to be mounted on heavy trucks, are normally rigid or very stiff and mounted on sub-frames for support.
This leads us to the task of mating a relatively flexible member, the truck frame behind the cab, to a relatively rigid
member, the truck body.
Since a truck frame that is too stiff will crack, means must be provided between the body and the frame to allow the
frame to flex as it is supposed to do, while carrying and securing the rigid body on the truck.
Components used in mounting a body on a truck frame include the following:
a. Breaker strips between the tops of the truck frame and the bottom of the body for flexing.
b. Shear bolts with brackets provided on each side of the truck to prevent shifting.
c. Twin studs or U-bolts provided along each side from rear to near the front of the body to provide clamping.
d. The plates bridging the U-bolts or twin studs to spread the loadings.
e. Internal braces installed in the truck frame channels to prevent crushing of the frame rails.