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Roll cage design recommendations with pictures
- Thread starter bp71k5
- Start date
Cool, but ya lost me with "tertiary"I don't know that fancy word.
tertiary = secondary
GEORGIA GABE
1/2 ton status
bp71k5
3/4 ton status
Thanks for all the feedback on this. It helps.
I did attempt to add some bracing to the B pillar in that first picture, but it only triangulates the midpoint of the vertical portion.
Is something like this (B-Pillar addition) what you guys are suggesting? To me, this appears to make much more sense in a side flop situation. I also may be able to change it a bit to make getting in the back easier.
I did attempt to add some bracing to the B pillar in that first picture, but it only triangulates the midpoint of the vertical portion.
Is something like this (B-Pillar addition) what you guys are suggesting? To me, this appears to make much more sense in a side flop situation. I also may be able to change it a bit to make getting in the back easier.
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That is the best way to strengthen the B pillar and keep a decent pass thru. Seat belt harness will still be an issue. You will have to add something for a mount point to a tube like that. I did this, which is a similar design but I use a straight across tube for the belt to wrap around, then gusseted it with another tube. I though about doing it just like your design but I didn't like how the tube cut across the center of the seat back interfearing with the seat belt slots in my Mastercraft seats. It does not leave a good mount point for the harness mount. You can see the seat bent slots are just above the tube, Thats how it should be.
That makes the B pillar very stout. The a and c pillars could still use gussets or more tube.
A pillar loop flanged to floor-under floor flanged to chasis. B Pillar loop. Tops of A and B connected, one diagonal from top of Driver A to Passenger B. Diagonal across B loop. C loop connected to B like B to A. Diagonals from top of B to bottom of C. I think that would be minimum. Should have an X or Diagonal in the A loop, but that would be to invasive for your application. You can flange to the floor with back plates, or flange to the floor then to the chasis, or cut a hole through the floor to the chasis.
That's nice and clean. Instead of two B Diagonals you can do one top to opposite bottom corner. The rearward bend in the C loop is a failure point. I would make that straight. The top of the C loop could be just behind the rear seat if you wanted. And that would help with penatration if you don't want to run a top B-C Diagonal.
Take a look at this photo album
http://smg.photobucket.com/albums/v227/Hurc/Moab EJS Roll in Jeepster/
Look at every picture closely and study it.
I watched this roll in person. This was the hardest and longest rollover I have witnessed to date. I think it was 4 or 5 times that he rolled. BTW it's Potato Salad hill from top right to the Ravine on the left as you are driving up.
This cage had NO side to side triangulation in it with the exception of the roof. The roof was very well designed and thought out. IMO this saved this guys life at the time. Yes the cage displaced at least 2' to the side but the guy walked away with only his pride hurt. Build your roof to match this roof at a minimum.
I think you can get away with less side to side bracing that would intrude on the passenger space but you MUST make up for that with a well triangulated roof.
In the case above the entire roof acted in one large assembly that was very hard to deform. In order for the cage to layover it had to take and bend every vertical support tube in the cage.
Granted this was a one time use cage but it did its' job.
This is a good real world example of a cage doing it's job and failing but still managing to stay together enough to protect the lone occupant.
Just a little actual real world stuff for you to look at
http://smg.photobucket.com/albums/v227/Hurc/Moab EJS Roll in Jeepster/
Look at every picture closely and study it.
I watched this roll in person. This was the hardest and longest rollover I have witnessed to date. I think it was 4 or 5 times that he rolled. BTW it's Potato Salad hill from top right to the Ravine on the left as you are driving up.
This cage had NO side to side triangulation in it with the exception of the roof. The roof was very well designed and thought out. IMO this saved this guys life at the time. Yes the cage displaced at least 2' to the side but the guy walked away with only his pride hurt. Build your roof to match this roof at a minimum.
I think you can get away with less side to side bracing that would intrude on the passenger space but you MUST make up for that with a well triangulated roof.
In the case above the entire roof acted in one large assembly that was very hard to deform. In order for the cage to layover it had to take and bend every vertical support tube in the cage.
Granted this was a one time use cage but it did its' job.
This is a good real world example of a cage doing it's job and failing but still managing to stay together enough to protect the lone occupant.
Just a little actual real world stuff for you to look at
I remember that one but didn't see it in person.
I would say that cage did a marginal job and that guy is very lucky.
The pictures there really prove my point about how important a and b pillar supports are. Even simple tubing gussets would have made that cage deform a few inches rather than a foot.
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bp71k5
3/4 ton status
That's a great idea. I never thought to look for roll cage pictures -after-they have been rolled.
Am I right in the pics near the end that the cage was built from HREW and not DOM?
That's a great idea. I never thought to look for roll cage pictures -after-they have been rolled.
Am I right in the pics near the end that the cage was built from HREW and not DOM?
Yes thats HREW.
That's a great idea. I never thought to look for roll cage pictures -after-they have been rolled.
Am I right in the pics near the end that the cage was built from HREW and not DOM?
What makes you think you can tell the difference from the pictures?
Regardless, good cage design is much more important than material.
Oops, you can see the seam in one of the pictures. What I said above still applies though.
Trust me. That cage did one hell of a good job at holding up. I thought for sure the guy was going to be really badly hurt. He did somethings that saved that from happening like laying over to the inside but still the cage left plenty of survivable space inside.
It does prove your point however that A and B pillar supports are needed. However it also shows that in a single to double roll something simple will hold up (somewhat).
That's a great idea. I never thought to look for roll cage pictures -after-they have been rolled.
Am I right in the pics near the end that the cage was built from HREW and not DOM?
Failed cage analysis is the best way to learn what to do and what not to do.
I don't know about the DOM vs. HREW in this case.
I think that all things should be made from DOM.
What does the seam have to do with anything? DOM comes both seamed and seamless. DOM just means it is Drawn Over Mandrel which gives a much more precise sizing on the OD as well as the ID while smoothing the seam inside the tube.
Run the Top of the C loop as wide as the rear seat, slightly rearward of the rear seat. bottom of C loop go to top of frame in front of tailgate. Diagonal from top of C to bottom of B both sides.
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bp71k5
3/4 ton status
The DOM seam is usually much less obvious (I couldn't find it on the sample tube I've looked at.) The pictures don't show where that piece came from so maybe it was just a weld failure example.
