Issue link: http://read.dmtmag.com/i/34501
5TH WHEEL MAINTENANCE AND PLACEMENT Placement of the 5th wheel can be determined by the need to properly distribute the load over the drive tandems and the steer axle for legal loads. It can also be placed to lengthen or shorten the overall length of the tractor-trailer unit. However, with sliding 5th wheels, many drivers place the 5th wheel to give the smoothest ride and easiest steering. The placement and movement of the 5th wheel can change the tire loading substantially, causing tire overload or tire underload conditions. Insufficient lubrication of the 5th wheel is a major cause of poor vehicle handling. Distortion of the 5th wheel plate will cause a similar condition to lack of lubrication and dog tracking of the trailer. A 5th wheel in the most rearward position, combined with stiff front axle springs, can cause the front tire to periodically unload, leading to vehicle shimmy and irregular tire wear. Vehicle manufacturers usually recommend a 5th wheel placement that results in payload transfer to the front axle. Improper front axle load distribution can adversely affect braking and handling, which can result in excessive tire wear. Distortion of the 5th Wheel Proper Amount of Lubrication Insufficient Lubrication Section Three: Extending Tire Life 59