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Author Topic: Structural engineering anyone??  (Read 3346 times)
paulcjhastings
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« on: January 25, 2008, 01:48:01 PM »

I'm deciding whether to put a slide out room in my Setra. If there are any engineers that belong to the board, and are interested in consulting please contact me.
« Last Edit: January 25, 2008, 02:11:02 PM by paulcjhastings » Logged

Paul Hastings
1993 Setra 215 w/ Detroit Series 60 & Allison HT748
Belle Plaine, MN
612-987-6021cel
Ray D
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« Reply #1 on: January 25, 2008, 04:30:59 PM »

Talk to Dave Galley, he has articles in the magazine.  I don't know if he still takes on these projects, but he is very knowledgeable and has done a few.

Ray D
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Songman
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« Reply #2 on: January 25, 2008, 05:20:25 PM »

Lord, don't get an engineer involved! haha...

Lots of the best projects I have seen were deemed impossible by engineers and then done successfully by normal folks.
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paulcjhastings
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« Reply #3 on: January 25, 2008, 05:36:43 PM »

Talk to Dave Galley, he has articles in the magazine.  I don't know if he still takes on these projects, but he is very knowledgeable and has done a few.

Ray D

I tried calling the numbers listed in his book, he must have moved or changed them. If anyone has an updated number I'd be happy to here from him.

Songman, for non critical applications you are correct, but I'm making a major modification to the structure and I only want to do this project once. I mainly need a guy to help me "run the numbers" and see if my eyeball engineering is accounting for all the variables.
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Paul Hastings
1993 Setra 215 w/ Detroit Series 60 & Allison HT748
Belle Plaine, MN
612-987-6021cel
Songman
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« Reply #4 on: January 25, 2008, 05:48:20 PM »

I know... You're talking about safety and that is important. I was only teasing... mostly.  Wink
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makemineatwostroke
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« Reply #5 on: January 25, 2008, 06:10:09 PM »

Paul, the Eagle and the Setra have the same frame set up so try Gary Bennett at B&B Coach or some of the people here on the board that are installing slides on the Eagle.
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Ray D
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« Reply #6 on: January 25, 2008, 08:14:56 PM »

You might leave him a message on his website

http://www.winlockgaley.com/
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dkhersh
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« Reply #7 on: January 25, 2008, 08:58:54 PM »

Also you may be able to get your local college engineering class involved.  This also is suggested by Dave in his book of slideout additions.
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rv_safetyman
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« Reply #8 on: January 26, 2008, 06:22:18 AM »

I am an engineer and I take offense at the comment by Songman Grin Grin

Lots of folks have put in slides and have had no problems.  I would suspect that many did it without the benefit of an engineering analysis.  They just built it "hell for stout".

If you find an engineer to work with you, make sure they consider the dynamic loads.  Doing a static analysis is quite straightforward with today's software.  However, that is much less than half the story.  The flexing and twisting that our coaches undergo while going down the road are the real issues.  That kind of analysis is much more difficult.  Next, any analysis should consider the fact that the reinforcing of the opening will change the dynamics characteristics of the original structure.

If I were doing a slide, I would design it so that the slideout structure tied into the frame structure with pins so the it became a part of total structure. when closed. 

After you read the above comments you will see why lots of folks have the  "shoot the engineer and get on with the project" attitude Wink.  I would suspect that most engineers would shy away from the project because they would not have enough information to do the proper dynamic analysis and because of the liability issues.

Jim
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Jim Shepherd
Evergreen, CO
’85 Eagle 10/Series 60/Eaton AutoShift 10 speed transmission
Somewhere between a tin tent and a finished product
Bus Project details: http://beltguy.com/Bus_Project/busproject.htm
Blog:  http://rvsafetyman.blogspot.com/
paulcjhastings
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« Reply #9 on: January 26, 2008, 06:57:51 AM »

Thanks everyone for the replies.

Point 1)I don't have the time to wait for a class of students to take this on as a project and have them spend a semester or two figuring out what to do. Also student engineers have no fabrication experience.

Point 2) I have spoken to Gary Bennet on the phone, he asked me to email him some pictures. I did that and haven't heard anything back. So I'm looking for other input, he has a business that installs slide out rooms and would probably rather concentrate on that, rather than helping someone diy a slideout and have to provide that person tech support for the life of the slide.

(Jim Wrote)
"If I were doing a slide, I would design it so that the slideout structure tied into the frame structure with pins so the it became a part of total structure. when closed."

Jim, does this mean you have an interest?? Wink

It is my intention to do this, based on the generic drawings in Galey's book he doesn't use that as a factor in load bearing. However he does discuss using a camlock or pinning the top. I was intending to use a piloted hitch pin in each corner, this should carry vertical and horizontal loads and contribute in some measure to the diagonal loading of the slide in the opening. The reason for the need for the engineering consult: I don't want to over build and add unnecessary weight. As is said in experimental aviation "Keep watch over the oz's and the lbs. will take care of themselves" 

Thanks again.
 
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Paul Hastings
1993 Setra 215 w/ Detroit Series 60 & Allison HT748
Belle Plaine, MN
612-987-6021cel
jjrbus
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« Reply #10 on: January 26, 2008, 07:24:19 AM »

 I'm a retired engineer and I take no offense.
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Remember, even at a Mensa convention someone is the dumbest person in the room!

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Ray D
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« Reply #11 on: January 26, 2008, 09:23:09 AM »

If the eagle and the setra have the same frames, than you have all the numbers in Dave Galleys book, for more strength you could add in the diagonals that he suggests for the type of frame Prevosts have.  I have a friend that is an engineer and he agreed with Dave's numbers. 

Ray D
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Bob Belter
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« Reply #12 on: January 26, 2008, 02:40:34 PM »

                              1/26/08
Ahoy, Bus Folk,

“Shoot the engineer and let’s get on with it” is a very common response to a complex problem.  Yah, I’m an Aero engineer.

The problem is that the engineer will want to design a (slide-out or other) installation which does NOT compromise the original strength.   The big difficulty in creating an original design is “What are the loads?Huh?.  That the bus has been running down the road for a number of years is evidence that what’s there must be OK, so let’s hang onto it.  The brute strength and awkwardness scheme will give you a LOT more weight than you want, may well overload other components, and may still leave you weak.  I’ve not looked closely, but I believe that a lot of the slide-outs being installed seriously compromise the structure.

Jim says it well.  Setra is a great-great-great grandson of my -01 Eagle, and the Eagle structural truss-work is very light and strong.    I’d do a slide-out design which achieves the strength of the original truss-work, and conical pin it when closed.  Done right, you can have the original strength with little more weight.  Wracking loads on uneven ground when open may distort the structure enough to preclude lock-in.  Sidestep the issue:  Do a leveling system which makes the front lift a single point, and two points in back, so there is no distorting torque on the structure.

Enjoy  /s /  Bob
   
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paulcjhastings
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« Reply #13 on: January 26, 2008, 04:00:17 PM »

I see a few engineers responding but no one jumping up and down to help me Wink

Perhaps I can endear myself with an engineer joke.
Question: What does and engineer use for birth control?(scroll down for answer)






























Answer: His personality Roll Eyes

I know this doesn't apply to you guys.
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Paul Hastings
1993 Setra 215 w/ Detroit Series 60 & Allison HT748
Belle Plaine, MN
612-987-6021cel
busguy01
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« Reply #14 on: January 27, 2008, 04:56:28 AM »

I am real sure that the last comment will insure NO One will help out!
I am doing slide outs on a MCI EL3. I gathered all the info and drawings I could and then hired a local structure guy ( also gave him Daves book). For a fee -- NOT FREE - he did a set of drawings for the structural mods needed. There are a lot of mods not directly around the hole in the side. Many mods to the the underside of the bus and other parts of the bus. We used 40 LBS of wire in the wire welder making the mods!
Be safe - not sorry. There is more to it than meets the eye.
JimH
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Started with nothing - still have most of it left!
1963 Eagle 01 with Detroit 60 series done (Gone-sold!)
MCI EL3 in progress. raised roof & Slides
2009 Revolution 42 Sticks and staple
Summer - Yankton, South Dakota
Winter- Port St Lucie, Florida
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