Building roll cage

[bdog]

I have a machine like this. It has an enclosed cab but other than that the same. It has a flat bed that does not tilt. It weighs roughly 19,000 lbs.

I almost rolled it today and it scared the crap out of me. I doubt the cab could withstand a roll over.

I want to build a roll cage. I plan to redo the front grill guard (which is currently exactly like in the picture) and extend that up over the cab and tie it in to the flat bed. Basically I will have four vertical posts - two coming up from the grill guard and two coming up from the flat bed. All four tied together over the top of the cab.

The big question is what size material to use? Overkill is not a problem. Added weight is no issue. I was kind of thinking 4" x1/4" wall square tubing? Let me know you thoughts. I plan to gusset all joints and make it stout but I want to make sure the material is adequate.

As to what happened I was going down a steep hill, dropped over 100' in 200' and it started to slide. It turned sideways and slid about 50' to a stop and rocked sideways almost going over. Quite frankly it was one of the most scariest things I have ever had happen to me. All I could think about was the cab wasn't going to hold if it rolled and I was going to be crushed.

 

[RNeumann]

The quality of the steel will be a huge factor. Wall thickness too. As for the type and or size- I have no idea but I’ll give this a bump.

 

[Thomas]

Nice rugged built. :thumbsup:

 

[oosik]

A thought. Go to your local Caterpillar tractor dealer. See what they put on a crawler dozer of similar size & weight. It would have similar stresses in a roll over situation.

 

[aczlan]

View attachment 587467
I have a machine like this. It has an enclosed cab but other than that the same. It has a flat bed that does not tilt. It weighs roughly 19,000 lbs.
I almost rolled it today and it scared the crap out of me. I doubt the cab could withstand a roll over.

I would look and see if there is a dataplate in the cab saying that it is a certified ROPS/FOPS, something like this:

Source

Aaron Z

 

[ovrszd]

I agree with Aaron. I'm guessing the cab is certified.

My Sons and I build tube buggy rockcrawlers. Triangles are how you get strength. They are more important than material specs.

With ROPS that ability is sometimes restricted. If so then material dimensions are increased to overcome it.

Just understand if you go that route the mounting points become crucial. An intact square box is worthless laying on the ground beside the rolled vehicle.

 

[ArlyA]

The other fellows have it right on several points. Go look at ones that's made for a similar machine and mimic it. Whenever I'd building something, I always look at other engineered and successful designs and mimic them as much as possible and practical. Saves you time, money and maybe your life. But same as the other fellow state "Why wouldn't your cab be roll certified?"

View attachment 587467

I have a machine like this. It has an enclosed cab but other than that the same. It has a flat bed that does not tilt. It weighs roughly 19,000 lbs.

I almost rolled it today and it scared the crap out of me. I doubt the cab could withstand a roll over.

I want to build a roll cage. I plan to redo the front grill guard (which is currently exactly like in the picture) and extend that up over the cab and tie it in to the flat bed. Basically I will have four vertical posts - two coming up from the grill guard and two coming up from the flat bed. All four tied together over the top of the cab.

The big question is what size material to use? Overkill is not a problem. Added weight is no issue. I was kind of thinking 4" x1/4" wall square tubing? Let me know you thoughts. I plan to gusset all joints and make it stout but I want to make sure the material is adequate.

As to what happened I was going down a steep hill, dropped over 100' in 200' and it started to slide. It turned sideways and slid about 50' to a stop and rocked sideways almost going over. Quite frankly it was one of the most scariest things I have ever had happen to me. All I could think about was the cab wasn't going to hold if it rolled and I was going to be crushed.

 

[bdog]

I would look and see if there is a dataplate in the cab saying that it is a certified ROPS/FOPS, something like this:
View attachment 587491
Source

Aaron Z

I can find no tag on the cab. I was in the machine 9 hours today and looked and saw nothing. I can't imagine it is certified. The uprights are at most 11 GA and maybe 2"x3" material. Also the machine from the factory had a dump bed. I would guess the payload weight would not be factored into the ROPS rating since if it rolled the dump bbed would spill out. Now it doesn't have a dumbed it has a flatbed with about 7,000lb of stuff on it. I doubt the ROPS could handle that even if it was meant to handle the original machine.

 

[Industrial Toys]

Nice Machine. That's no Toy, Boy!

Back in the 80s, a friend and I went halves on a VW dunebuggy. Some guy would build them in his garage with a Canadian Tire Buzz Box. Long story short. My friend Rolled it, nearly killing him and a passenger. He was just scraped up and the passenger got a concusion. EVERY weld on that roll cage broke! I guess the guy couldn't even weld one new piece of tube to another but welding to an old Bug would be even harder.

My point is, the welding is more critical than the material it's made out of. If the material is not up to the task, it may bend or crumple somewhat, but if the welds fail, you have nothing.

 

[sandfs]

Some kind of pipe line rig? Crawler carrier? I'd bet the ROPS specs are listed with the manufacturer model. Sure they tend to minimize just for cost savings but it still has to meet a certain level of specs. The height ratio looks like it was designed more to stop a roll over rather than endure a roll over. If I didn't feel all warm and fuzzy about it I would lean toward full width gussets, added cross tubes, re-enforcement vs total replacement. Keep the weight down. The heavier the top gets the higher the likely hood of a roll over.