Copyright © 2001 FleetWatch magazine and FleetWatch On-Line.

No part of this publication may be reproduced without the prior written permission from the publishers. Views published are not necessarily those of the publishers.

Considering that the fifth wheel and kingpin is the only link keeping truck tractor and semitrailer/ s secured as a combination, the crucial role these components play in the safe handling of the combination cannot be understated. Both fifth wheel and kingpin are required to conform to various safety standards, both nationally and internationally, says Manie Roux, Technical and Product Support Manager, JOST Transport Equipment.
 

eeing that these components are classified as safety critical components, it is beyond comprehension that they are allowed to deteriorate to the extent that can be seen in the pictures to the right. It is clearly evident from pictures 1 and 2 that the fifth wheel was used in this extremely dangerous condition for a prolonged period of time. Now consider that the fifth wheel (a JOST JSK36C) from which these components were removed was fitted to a truck tractor hauling fully laden fuel tankers!

The condition of these components borders on gross neglect and could have resulted in a serious road accident and possibly the loss of human lives.

A few precautions are all that is required to ensure the safe operation of the kingpin and fifth wheel: -

1. Correct selection criteria

The correct fifth wheel must be selected to suit the operation, road conditions, the imposed load and the D-value. The kingpin selected must suit the thickness of the rubbing (skid) plate. Other selection criteria are: -

• Ease of replacement and/or serviceability

• Availability of replacement parts on a national basis and the product know-how and support you receive from your suppliers

• Shock loadings transmitted to truck tractor and semi-trailer chassis

• Influence on driver fatigue

2. Correct fitment procedures

The correct number, diameter and strength of mounting bolts must be used. The bolts must be torqued to the correct torque specification for the type of bolt used. All installation dimensions must conform to the tolerances set for each specific dimension.

3. Correct maintenance procedures

Don’t be fooled by claims of "maintenance free" products.

Maintenance of the fifth wheel and kingpin must be included in a formal and routine maintenance program. The fifth wheel and kingpin must be cleaned, inspected and wear parts replaced on regular pre-set intervals (depending on the type of application). Specific procedures are to be followed when cleaning and maintaining fifth wheels and kingpins.

Dangerous maintenance practices include: -

• Relying upon a "fix it when it breaks" maintenance programme

• Straightening of bent fifth wheel top plates in a bending press

• Welding up the top plate of the fifth wheel and re-machining

• Replacing wear parts with nongenuine parts

• Rotating worn kingpins through 90º

• Ignoring bent rubbing (skid) plates

4. Correct coupling and uncoupling procedures

Very specific coupling and uncoupling procedures must be followed when coupling a semitrailer to a truck tractor. These procedures also vary for different types of fifth wheels and if not strictly adhered to could result in mis-couplings with disastrous consequences for the driver of the combination and other road users.

Coupling and un-coupling procedures must incorporate routine safety checks that are to be conducted with each and every coupling and un-coupling of a semi trailer. These safety checks requires only a few seconds to conduct, but could result in huge savings in down-time and damage to capital equipment and could quite possibly save human lives.

5. Traceability

Traceability of components is of utmost importance and reputable manufacturers do not hesitate to clearly mark their products and/or replacement parts.

Components and replacement parts should be clearly marked with identification plates, stating load ratings, manufacturer’s name and product name and description. Top right is an example of a "no-name brand" of kingpin sold to a major transport operator, bearing no identification marks or specification data:

The quality of the kingpin shown is clearly inferior and poses a real risk to safety. Another concern is the absence of any identification markings on the kingpin. Should the kingpin be the cause of a serious accident (which is likely in this instance), the transport operator will find it impossible to prove the origin of purchase and/or the identity of the manufacturer.

The precautions mentioned here will not only ensure that the maximum life span is obtained from the equipment mentioned, thus contributing towards lower CPK values, it will also greatly contribute towards road safety and reduced down-time.

Considering that a fifth wheel and flanged type kingpin only contributes approximately 0,35% towards the total price of a truck tractor and tri-axle semi-trailer (excluding payload), is it worth it to compromise safety and human life by ignoring these components?

Don’t be fooled by claims of "maintenance free" products. Maintenance of the fifth wheel and kingpin must be included in a formal and routine maintenance programme.