User's Manual

Date of Origin – 02/01/08

1. You, the operator, have control of the most important factors that affect safe trailer opera-

tion and vehicle stability. Trailers are a tool and, like any tool, are safe only when properly

used by a conscientious, trained and qualified operator.

2. The fifth wheel should be securely mounted to the tractor frame and proper connection

between the tractor and trailer verified.

3. The driver should be familiar with the characteristics of the particular trailer and of the

load to be transported.

4. The driver should be familiar with the nature of the roads and traffic which may be en-

countered during the trip.

5. Stability – Caution - like any other vehicle, semi-trailers can tip or slide out of

control if turns are negotiated at too high a speed or when making violent ma-

neuvers such as abrupt lane changes or other evasive actions to avoid ob-

stacles.

6. Within the relatively narrow confines of road laws limiting vehicle size and weight, to-

gether with the characteristics of available tires, suspensions, and other components,

there is little that a manufacturer can do to affect the inherent stability of a trailer other

than keeping the load as low as feasible, considering the requirements for loading space

and adequate tire clearance. This means that the major factors affecting operational

stability are the knowledge and skill of the driver. The predominant causes of rollover

accidents are:

a. Excessive speed

b. Violent swerving or turning

c. Application of brakes or tractor power while turning.

d. Entering curves at too high a speed

7. Tire Characteristics: High pressure truck/trailer tires have different characteristics under

high speed cornering conditions than do passenger car tires. Truck/trailer tires are

designed for carrying high loads over long distances. Their lateral stability becomes

unpredictable when lateral forces approach .04g. This means that commercial vehicles

must be operated in a conservative manner when cornering.

8. Braking and Acceleration: Either braking or accelerating while cornering can significantly

reduce the stability of the vehicle and should be avoided. The best driving practice is to

decelerate to a safe conservative speed before entering a corner or approaching con-

gested traffic, and then to apply only moderate power until a straight path has been re-

established.

You, the operator, have the Greatest Control

over Safe Operation.