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INTRODUCTION
PRELIMINAR STUDIES AND CONSIDERATIONS
MOUNTING AND CONSTRUCTION
5.3.3
These connections do not allow movement between the chassis frame and the sub-
frame. Therefore, the subframe will follow all movements of the chassis frame. If
the connection is perfectly rigid, the chassis frame and the subframe could, at cal-
culation level, be considered as if they were a single profile in the vicinity of the
connection.
When using these connections, the chassis frame displacements will be followed by
the subframe (torsion, flexion), which will collaborate to absorb the stresses occur-
ring during the performance of the equipment installed in the vehicle or during driv-
ing. In cases where high stress resistance and rigidity are required, for example for
a crane in the rear overhang, for special service vehicles, or a semi-trailer, etc., the
use of connections resistant to shear forces is recommended. These are generally
placed in the area of the rear overhang.
In these cases, HMC recommends using type R_1 connections.
Fig. 5-116 SPBGC53_005 R_1-type subframe connection
5.3.4
While driving, both the chassis frame and body are subjected to static and dynamic
stresses. Static forces are generated by the mass (the weight) of the vehicle and its
load. They are the only forces acting when the vehicle is stationary.
Dynamic forces arise when the vehicle is being driven, and are largely the result of
the shocks produced by the road surface. They used to produce torsion in the ve-
hicle. Other dynamic forces are those that arise when different equipment installed
on the body, such as a tipper or a crane, is working. These operations cause some
torsional and bending forces that should be considered.
Additionally, lateral forces sometimes occur in very long vehicles or vehicles with a
trailer, when they are making turns. It is therefore important to fix the upper body
to the chassis frame correctly, since an incorrect setting can damage the body itself,
the connections and the chassis frame. It could also cause instability in the vehicle,
and loss of control when driving.
To achieve the best possible assembly between chassis frame and body, it is nor-
mally necessary to combine rigid and flexible connections in the vehicle, in order to
obtain the appropriate rigidity and the resistance to absorb any kind of stress
caused by the different forces.
V1.0, February 2015
POWER TAKE-OFF
Rigid connection
Combining flexible and rigid connections
Body Builder Manual Part II, Specific Book LCV
MAINTENANCE AND DAMAGE PREVENTION
ELECTRIC AND ELECTRONIC SYSTEMS
WORK ON BASIC VEHICLE
APPENDIX
159
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