Tri-axle Bogie

[Nige]

See attached photo. How much weight does anyone estimate this bogie will carry supported from a point directly above the centre axle and to move at no more than say 5mph..? Tyres are currently 11R22.5 radials. If the tyres were changed to 12R22.5 would that significantly increase the load that the bogie could carry..?

 

[willd8r]

I guess it would depend on axle, suspension,and chassis rating.Tyres would be the strong part.
I may be wrong. Cheers Will

 

[truckdoctor]

It should support quite a bit. How many times is the trailer going to be loaded like that? If it is once or twice things should go well but if it is continuous you might want to go bigger. I know that when I worked at the drill rig moving company we would winch up 80 or 90k over the tail of trucks with 44 to 65k rears on them. I had to move a 90k mud pump with a bed truck that had a 20k front and 65k rears. I didn't have to go far but it was not something I would want to repeat too many times. The bed trucks had 11-24.5 rear tires and 425/65/22.5 fronts if I remember correctly. The tires were normaly highway tires, we only had one truck with 12-24 tires with 70k rears on it.

 

[Scrub Puller]

Yair . . . Nige As willd8r says I would have thought the tyres if they are good would have been the least of your worrys.

My experience (long ago) was oil-field work like truckdoctor's when it was commonplace to winch thirty or forty tons off the ground and over the back roller.

The trucks were bogie Macks and Peterbuilts and could occasionaly hit 30 mph. You have an extra axle under the load, will be travelling slow, most likely over a prepared surface, hopefully not too many tight turns and the loading would have been nice and gentle with a crane . . . my WAG guess would be around eighty tons.

Cheers.

 

[Nige]

I'm thinking of turning that bogie into a suspended towing appliance to sit the front end of this on .............. the load on the front wheels of the haul truck when empty is about 60-70 tons. Note what I said in the OP that the speed would be low and it would all be on well-graded hard dirt roads.



We would use it at maximum maybe a couple of times a year (None at all if we were really lucky) to get dead trucks back to the shop

 

[tireman]

315/80R22.5 is the biggest non super single you can get in 22.5, and they'll carry 8270 per tire(dual) x 12=99240. That's as close to your target as you'll get, and if the suspension and axles will hold it, I'm confident what you're wanting to do the tires will hold. 70 ton would put you at 11,667 per tire. Going slow on dirt, there will be minimal if any heat build up, and I'm sure you know Nige that heat is a tires worst enemy. 11R22.5 load cap. is 6005 dual, 12R22.5 is 6780, 445/65R22.5 is only 12,xxx. So dual 315's is your max load capacity. Shouldn't be an issue.

 

[tireman]

If you had two and could rig them together(one under each side), they would work as they sit. I'm sure you already knew that though.

 

[06Pete]

How much further forward could you move the load to load your tractor because you realy have 5 axles to load with a tandem tractor or if you could use a triaxle tractor 70 ton would be about 23300# per axle plus empty weight. Those are 6 lug hubs so they should be atleast 22000# axles and that is highway speed so at 5mph I would think you would be fine.

 

[Nige]

Putting the load over the centre axle is pretty much as far forward as I can go. Any further and I would start to run into clearance issues with the horse collar behind the engine on the haul truck chassis.

 

[JDOFMEMI]

Nige

I think it would do what you want to just fine, in the controlled situation you are describing. Tires will handle serious overloading if they are in good condition and the speed is slow. I can't remember where I read it, but it seems like I read that you could double the rated capacity at a 5 mile per hour pace.
The frame looks strong enough, and the sa,e thing can be said of wheel bearings as tires. Overloading at low speed can be done without problem. I would say if the load does not bend the axle housings, it would haul it for short slow trips.
The dolly frame would be built to hold around a 50 ton load at highway speed, and typical design for such is a minimum of 5G loading for impact, so the design should hold 250 ton static, give or take. Your slow speed will reduce any impact loading to no more than 2G, and that is not likely. With that figure in mind, you would not seem to be in danger structurally either. Sounds like a good idea to me.

 

[Nige]

Thanks Jerry, and all who contributed. I was reasonably confident that the bogie will carry the weight. Now I have to find (and maybe modify) a 5th wheel that pivots on 2 axes to serve as the hookup point. After that it's a case of making and installing the king pins on the front of each truck.

Digressing - I remember many years ago working for an outfit in Africa that had a bunch of Goldhofer ex-tank transporter trailers pulled by Oskhosh 6x6 oilfield tractors. The trailers were rated as 100 tons payload according to "those who knew". So our guys would happily load 2 x fully-equipped D9G's on them beacuse there was plenty of space on the deck and send them off from one site to another along dirt roads and wonder why they were blowing trailer tyres like it was going out of fashion - this was before the days of tubeless BTW. When I looked at the data plate on one of the trailers it was clear that it was rated 100 tons @ 5mph, but only 50 tons @ 30mph. Clearly the salesman who sold them had not mentioned the speed restriction when he sold them as "100 ton trailers" .................

 

[Dualie]

well in normal service at highway speeds the axles are probably rated for 20,000lbs a piece. At 5mph you could probably double that.

 

[CM1995]

well in normal service at highway speeds the axles are probably rated for 20,000lbs a piece. At 5mph you could probably double that.

That would be my suggestion as well. Being in a mine application, you can regulate your speed and somewhat the route, to make it work.