Fifth wheel reliability/durability/maintenance

Considering that fifthwheels have been the same design since the 1940’s and kingpins have been the same size since the longest trailer was only 20 ft and gross weights were 1/3 what they are now I’d say they were designed overkill since the beginning.

They never needed to be redesigned or replaced by a different system for safety issues in all that time.

 

Holland has been building the FW 35 since 1950. That should say something.

Got original 1951 on my Diamond T. Plate surface is still thick and good. Rebuilt it a few years ago with the new kit. Fit right in.

 

Maybe replace the springs. I had one (there are 2) that pulls the jaw around the kingpin break. Some greases can get real sticky in cold temperatures, making it hard for the jaw to close. I use Schaeffer's spray 1/5th wheel grease, and it gets veyl "tacky" in the winter. I'll use plain bearing grease then.

 

the holland 3500 is simple solid and easy to rebuild imo,once locked it cant come unlocked without pulling release, on mine my pivot pins for the jaws have grease fittings on them real hard to get at, i ran lines to them and put remote fittings where its easy to grease, iv seen some places not grease them mabe not knowing they are there wich cause it to sieze over time, other than that bullet proof

 

Always visually check that the jaws are closed around the kingpin. A couple years ago there was a story on here of a truck that lost a trailer going down interstate. Killed the driver following him. He had no time to do anything. It must not have fully latched or something.

 

When it comes to 5th wheel maintenance, grease is your friend. Some of the newer model have auto-adjusting jaws, but if you pull for a company that has a wide variety of trailers that vary across a lot of years, sometimes the new auto adjust 5th wheel will adjust itself to a more worn pin, then the next pin won't be as worn and it might have trouble locking.

 

Check the bolts on the frame. They'll corrode over time. When I was stripping down my W900 for restoration, every bolt in the frame was corroded down to about half its original diameter. Last thing you want is the entire 5th wheel and slide assembly to peace out from the rest of the truck.

 

In my younger days i drove a hd wrecker. Helped work an accident where the truck was hung in the guardrail and loaded trailer was hanging by the kingpin off the side of the bridge probably 200 ft in the air. It took wreckers and a crane on the upper bridge to lift the trailer back onto the bridge. Those kingpins are stronger than you think if latched properly!