Fifth wheel rating(s)

[cranetruck]

How is a 5th wheel rated, vertical loading and horizontal (pull)? What does, say a 45,000 lb rating actually refer to? How does the rear bogie capacity fit into the equation? Same 5th wheel assy is used on deuces and 5-tonners, for example.

Thanks.

 

[dm22630]

Well here is 60,000lbs being pulled by an 818.......

M872 trailer & M818s weigh 20k each....

 

[scooter01922]

Those JUST fit huh. Sweet looking recovery.

 

[cranetruck]

It's kind of a blanket term. Basically it means the max. weight to be coupled to the fifth wheel. Knowing that it will be a trailer of one form or another it will not have a complete load placed vertically upon it. Long and short of it is.........whatever the weight is that you are hooking to the fifth wheel should not exceed its rating. Key term there is "should not", not that we all go by that.

Thanks!
Sounds reasonable. There is a decal on the frame near the 5th wheel on my 757 marked "Max Load 45,000lb", so it must be the trailer then and not the 5th wheel itself, since the same part is used for other trucks. Couldn't find the rating in any of the TMs I looked in...

 

[LanceRobson]

My notes show a minimum of 17% of the total trailer weight on the fifth wheel with a target of 20% and a max of 25% total weight on the fifth wheel.

That said, I got my Class A license in '77 so there may have been an change in industry standards.

Lance

 

[cranetruck]

It's beginning to make sense now, 20% of 45,000 lb is 9,000 lb just like shown on the tag on the door.
Thanks again, fellows!

 

[Wolf.Dose]

The fifth wheels can hold a much bigger load than the truck is designed for. Commonly the maker is Holland Hitches. If you find any kind of makers label on it, you can contact them. Normaly they give you the informations about the fifth wheel.
However, the trucks are not made for these weights. Check for tire load capacyty. You will be shocked!
First the horse powers are to low for something more than 28 to 30 tons gross combination weight (five ton class). Also the power trains are not made for more.
Second the fifth wheel load maximum is the difference between the curb weight (the real one, not the theoretical Army weight) and the declared gross weight of the tractor. But only, if the fifth wheel is at the theoretically best location. Normally the location is in a position that overloads the front axle. Only calculation can help you to find out the real maximum load.
If you overload your truck one or two times by one or two tons, it will not really suffer from that. But every overload shortens the livetime by several 1000 miles, depending on the roads you use. Mountains kill, plains not so much!
If you have a truck desinged to hawl tanks even with low hose powers the truck will serve you very long, for it is almost impossible for you to overload it with your loads.
The relatively new Freightliners are trucks, line pull 120000 lbs, which means a gross rig weight below the legal 40 metric tons in Europe, for the semis awailable at the US Army in Europe do not cover the neccessary gross weight. Theoretically they are good for 54 metric tons. This will not help with semis with 20 to 25 tons permissable weight. And their power train is not really the state of the art, even 10 or 15 years ago. OK, it is automatic, but not enough ratio steps.
Wolf