Peterbilt Model 320 Operator's Manual after 8-07 - Peterbilt Motors ...

PART 5: SEAT AND RESTRAINT SYSTEMS
Inspection of the Restraint System
WARNING! Failure to properly inspect and
maintain restraint systems can lead to serious
injury or loss of life. Without periodic
inspection and maintenance to detect unsafe
conditions, seat restraint components can wear
out or not protect you in an accident.
The typical three-point seat systems in passenger cars may
seem very similar to the three-point seat belt system in
heavy duty vehicles, but there are some key differences
that all users of this system should be aware of:
• In typical passenger vehicle automotive seat belt applications,
the normal life of the vehicles is usually 8
to 10 years and the total mileage frequently does not
exceed 125,000 miles (200,000 km). Heavy duty vehicles
often see this type of mileage in a very short
period of time, and accumulation of mileage in excess
of 500,000 miles (800,000 km) during the vehicle lifetime
is not unusual.
• A significant difference in the two systems is the
amount of movement of webbing in the system. In
an automotive application, there is little movement of
the seat belt system, except when the user puts on or
Inspection of the Restraint System
takes off the belt. In trucks, however, there is almost
constant movement of the belt through hardware due
to ride characteristics and seats which are designed
to move, in order to enhance driver comfort. There
can even be movement of the webbing in the seat
belt system when the belt in not being used. Relative
movement between the seat and the cab, which normally
occurs whenever the truck is in operation, can
cause wear of the seat belt webbing.
• Environmental conditions represent another major difference
in the systems in automobiles and heavy duty
and specialty vehicles. Unlike the automotive environment,
heavy duty and specialty vehicles may be very
dirty, and have more exposure to the sun’s damaging
ultraviolet rays, thus resulting in a reduction of the life
of the seat belt system.
The high mileage associated with heavy duty vehicles and
possible wear of the 3-point seat belt system, the continual
relative movement of the system, the possible contact with
the vehicle seat or other parts of the cab structure, and the
potential exposure of this system to severe environmental
conditions make it crucial to inspect the three-point seat
belt systems regularly. It is recommended that the seat
belt system in a vehicle be inspected every 20,000 miles
(32,000 km) or more often if the vehicle is exposed to severe
environmental conditions. Any seat belt system that
R(08/07) Y53-6015 – 65 –