dump truck with fifth wheel?

[Robo McDuff]

There is a line of material about a cm thick between the main frame and the dump sub-frame. I thought it was metal, but today I took of a piece sticking out and found that it is wood?? It that normal?

 

[hndrsonj]

There is a line of material about a cm thick between the main frame and the dump sub-frame. I thought it was metal, but today I took of a piece sticking out and found that it is wood?? It that normal?

Yes, they all have that.

 

[Robo McDuff]

Thanks. I was worried it would be metal and the parts rusted together. Hope it comes off in one piece and can be re-used. Iff all goes as planned, the dump unit will get off on Monday.

 

[Robo McDuff]

Thinks are looking up, even though the weather is still lousy. We took off the dump bed today.

I thought the 8 bolds at the back would be a problem. No Sir. 37 years after manifacturing, only one bold initially put up a bit of a fight but with a lot of WD 40 all of them came of easily. The 4 spring-laoded ones I estimated to be a piece of cake, well, they quickly became a major PITA.

Whatever. In the end, a guy parking his much newer huge dump truck with crane next to the farm got interested, and came by this morning to take the bed off. Had a bit of a scare at the first jolt, but the PTO slipped out easily and the rest also went without a hitch.

 

[Robo McDuff]

Been driving around with that in the back of the car for far too long. Dutch farmers have an amazing viarity of equipment. The neighbor was, it think, actually disappointed that the truck guy beat him to taking the bed off, but he was a sport taking the fifth wheel out of my private car and, after flipping it upside down, put it on the truck.

 

[Robo McDuff]

The flipping upside down was on my request. I need to drill holes in the base plate and the bolts connecting the fifth wheel proper to the base plate are immovable (that is, without heavy power tools).

I now also really know why the spacer wood is there: to provide room for the rivets sticking out on top of the chassis. When I saw that and it dawned, I though "o sh.........." That looked like the next #$%^^%$ major problem. The I started measuring and praying and lo and behold! .. maybe it will all fit after all.

The base plate is 96 cm (37.8") wide, the M51A2 frame 86 cm (33.9"). The holes in the base plate connecting the 5th wheel to the DAF are exactly outisde the farme of the M51A2. Which means I have to drill 12 holes in the base plate and 12 holes in the chassis.

Oops, the bloody rivets mess up everything. Maybe not. See the last two pictures. The last but one shows that the base plate is not a flat plate but what the Dutch call a damwand profile. The last picture shows the rivets and a piece of cardboard showing where the profile is raised and where it fits onto the chassis. You are looking down on the three most forward rivets from the X cross-member with the left chassis rails, above the tandem.

Hard to see, but the profile just misses all the rivets, with exception of the fourth rivet just outside the left of the picture. That means I have to cut a whee little hole in the bend of the profile, and it will fit perfectly. That will bring the 5th wheel center at 128 cm (50.4") from the end of the chassis. This is a bit before the middle of the tandem.

The first two pictures show the 5th wheel on the orignal truck and is ID tag. This Jost fifht wheel came off a Czech DAF truck, is suitable for over 50 tons, and has EU and Dutch recognition.

 

[jesusgatos]

How did this project turn out?

 

[quickfarms]

How did this project turn out?

You should look at the patent linked in post number 9 for your project

The quick attachment of the dump body is interesting. A friend of mine used to own a dump truck that could be converted to a tractor in a weekend. They would use it as a tractor when there was not a lot of dump work.

 

[jesusgatos]

I did, thank you, and am planning on building something like that for our trucks. Just doing my homework, trying to figure out the best way to tackle this because it's not just a one-off project and I don't want to make the same mistake/s 4-5 times.

 

[Robo McDuff]

A longer description of what I did was done in a dump conversion thread

In short, remove 12 bolts and disengage the links and drive shaft to the hydraulics and get the dump assembly off. Place the 5th wheel and tighten 10 bolts and you are ready to go. With a crane next to it, I can do it within 30 minutes.



I was thinking to make the 5th wheel somehow permanent and change the dump sub-frame to fit around it. Problem with that idea is that the whole dump hydraulics are fitted within the sub-frame and would not fit above the 5th wheel. That idea has been dumped permanently.

Another plan is to add hydraulic legs to the dump assembly so that you can raise the assembly including hydraulics and sub-frame and drive the truck from underneath it. Problem there is that the hydraulic pump sticks 10" below the sub-frame, so you would have to raise the dump assembly rather high. And you would have to disconnect the drive shaft and links to the hydraulic pump each time.

I am thinking about fixing the hydraulic pump and reservoir to the main frame, with quick-release couplings. That way, if the dump is removed, the truck still has functional hydraulics, maybe for a small crane or whatever. In that case, fixing hydraulic legs to the dump assembly and driving the truck from underneath it really becomes a piece of cake.

The truck became street legal in July 2011 with the following data:
The max allowable weight for the vehicle itself (as dump truck) is 42,472 Lbs
The max allowable pulling weight for semi is 68,460 Lbs
The max allowable pulling weight for trailer is 68,460 Lbs
The max allowable gross train weight in either configuration is 90,462 Lbs

 

[jesusgatos]

Whoa, are those metric lbs? haha. Thanks for sharing. All very helpful.

 

[Robo McDuff]

The metric data as on the registration state following:

The empty weight of the vehicle is 9,980 kg.
The max allowable weight for the vehicle itself (as dump truck) is 19,265 kg
The max allowable pulling weight for semi is 31,053 kg
The max allowable pulling weight for trailer is 31,053 kg
The max allowable gross train weight in either configuration is 41,033 kg

This registration counts also as an EU type-approval, meaning all EU countries HAVE to accept this car as legitimate 1973 built. The standard document is nine pages long, although a lot of the detail-entries are empty in my case.

When I saw the final conclusion that I can go to 41 ton GVW I had to swallow, it was more than I expected.

 

[quickfarms]

Nice work.

At first I questioned drilling the top of the frame rail. Here in the US you are not allowed to drill the top of bottom flange and the top or bottom 2" of the web, the side of the frame. You are also not allowed to weld on the frame, with a few specific exceptions.

I like that you consulted an engineer that specializes in vehicle modifications and had the DOT sign off on it.

 

[jesusgatos]

Have been looking into that and haven't found anything definitive yet regarding holes in the sides of the framerails. Only this. When I was making new body mounts for an M1031 I referred to GM's upfitter guide and think they recommended staying something like 1" away from the top/bottom flanges. If you have any better sources, please share.

 

[Robo McDuff]

Drilling in frames is regulated similar in Europe: you are not allowed to do ANY drilling or welding to the frame unless specifically allowed beforehand by the manufacturer and/or the DoT. Rule of thumb is that maybe you can get permission for drilling into the center line of the side of the frame rails. Drilling in the flanges or welding anywhere are considered an absolute no-no.

I got permission beforehand after discussion with the DoT and local IVECO truck service that does body modification work as well and is known by the DoT. My trifold luck: the age of the truck, the fact that this truck did never had any previous road registration, and the fact that Kaiser Jeep does not exist anymore. Otherwise I would have to ask for the manufacturers permission as well. If I would have come to the DoT after the fact without asking them, the truck would have been rejected and never be allowed on the road anymore and I would have had 10 tons of scrap. I was not going to risk that, in the worst case I would have left that project alone.

Nice catch in the law: once you drill or weld the frame, it officially becomes a different vehicle unless the DoT agrees that the modification is minimal enough. So before and after any frame modification, you have to go for inspection to the DoT and if they see a problem, they can directly reject you or force you through a new type approval checking.

This is what I do not understand with bobbing trucks and the US laws. All these bobbed trucks, in Europe you would have a big problem getting them legal. Its an interesting point, just started a thread on this to find out more about it.