Pivoting Fifth Wheels on Frameless End Dumps

While operating a Frameless End Dump, it is necessary to prevent the fifth wheel, on the truck tractor, from pivoting. This needs to be done due to the fact that the Frameless End Dump has a King Pin mount that pivots. If the fifth wheel plate is not fixed to prevent pivoting you end up with a double pivot which would cause a whip like action when taking off or stopping the rig. Manufacturers of this style of End Dumps, and manufacturers of fifth wheel plates have developed a locking fifth wheel plate. This is accomplished either with pins that lock the fifth wheel plate either on the horns of the plate or at the front of the plate, or with one long bar that does the same thing. However not all companies or operators of these trailers are aware of this or opt to include this option, especially if they buy a used trailer.

Members of industry have come up with different ways of coping with this situation. One company installed wood blocks under the fore and aft edges of the fifth wheel plate. This has met some resistance because of the blocks being wood. However, these blocks do support the entire edge of the front and rear of the plate. A company in Arizona welded metal support blocks under the fifth wheel the plate. These blocks are approximately 1+ inch square, minimizing the over all contact on the plate. This minimized contacted will, over time, adversely affect the integrity of the fifth wheel plate, due to localized wear. Another company actually designed their own locking system similar to the ones manufactured. Photographs were taken of these three examples.

After searching the WEB for any applicable information and not being able find any, Manufactures and members of the Enforcement/Safety community were contacted. £ Mr. Jeff Simms-Truck Tractor Manufactures Association-contacted by Tom Shonk, Durango Mobile Port supervisor£ Mr. Bill Coply-FMCSA£ Mr. Randy Hurley-Colorado State Patrol Motor Carrier Division£ MR. Jeff Byers-Port of Entry and National Training CenterMr. Byers stated as long as everything was in a workman like manner and did not cause a safety violation, any form of locking/fixing the fifth wheel plate from pivoting was acceptable.It is necessary for the committee in conjunction with industry partners to develop a minimum standard for immoblization of the fifth wheel plate and what type of material is acceptable to accomplish this. This standard is necessary in order to prevent a fatal or injury accident caused by material and/or design failure.