Frames - Fiberglass RV


Reply
 
Thread Tools Search this Thread Display Modes
 
Old 03-15-2013, 05:37 PM   #1
Senior Member
 
cpaharley2008's Avatar
 
Name: jim
Trailer: 2016 2ndGen Escape19 Prairie Schooner pulled by 2014 Dodge Ram Hemi Sport
Pennsylvania
Posts: 6,398
Registry
Frames

I'm aware of at least 3 different brands/shapes of frames on our fiberglass trailers. Some have a "C" channel, some have "I" beam and others have boxed tubular frames, any where from 1" x 2", 1.5" x 3" and 2" x 4". In addition there may be some round tubular frames of various sizes.
I wonder which type would be the best or stronger type frame? Your opinions, please?
__________________

__________________
cpaharley2008 is offline   Reply With Quote
Old 03-15-2013, 05:51 PM   #2
Senior Member
 
Thomas G.'s Avatar
 
Name: Kinga DeRode
Trailer: For Sale Or Rent
Rooms to Let 50 Cents
Posts: 5,103
Quote:
Originally Posted by cpaharley2008 View Post
I'm aware of at least 3 different brands/shapes of frames on our fiberglass trailers. Some have a "C" channel, some have "I" beam and others have boxed tubular frames, any where from 1" x 2", 1.5" x 3" and 2" x 4". In addition there may be some round tubular frames of various sizes.
I wonder which type would be the best or stronger type frame? Your opinions, please?
Part of my job as an auto engineer was to design truck frames. A closed section (round or square tube) is much much stronger in torsion (twisting) than an open section (C, L or I beam). So ideally, the frame should be closed to minimize twisting and have a tall section to minimize vertical bending.
__________________

__________________
UHaul and Burro owners, join the UHaul Campers on Facebook. https://www.facebook.com/groups/529276933859491/
Thomas G. is offline   Reply With Quote
Old 03-15-2013, 05:58 PM   #3
Senior Member
 
Bob Miller's Avatar
 
Name: Bob
Trailer: 1973 Hunter Compact II
California
Posts: 7,912
Yep, just the same way we used to box in Model "A" & Deuce frames.

That said, because torque twist isn't to common an issue on trailers,(lol) I would opt for an aluminum channel frame.

There are lots of trailer frame builders out there ready to bid on your job.
__________________
Bob Miller is offline   Reply With Quote
Old 03-15-2013, 06:41 PM   #4
Senior Member
 
Jared J's Avatar
 
Name: Jared
Trailer: 1984 19' scamp
Kansas
Posts: 1,610
Ideally, boxed. that said, with our requirements, there is no reason it can't be c-channel or I-beam, either.

The main thing I see is that most of these frames are pretty underbuilt, IMHO. I get the theory, but I disagree with it at the same time.
__________________
Jared J is offline   Reply With Quote
Old 03-15-2013, 07:01 PM   #5
Senior Member
 
Name: Randy
Trailer: 1980Trillium 1300
Ontario
Posts: 355
Aluminum cross members added.

...I had a home made utility trailer(DIY) in which I reinforced the frame with 2 aluminum cross members. They were bolted to steel frame rails by steel brackets welded to the rails. Someone said the combination of alum and steel don't do no good. But after a few years of using the trailer, I go under-neath and had visual check on them and found no problem at all. So, please give me some advice or explanation if that combination is bad. I would be really appreciated. Thankyou
__________________
Thinh is offline   Reply With Quote
Old 03-15-2013, 07:27 PM   #6
Senior Member
 
Thomas G.'s Avatar
 
Name: Kinga DeRode
Trailer: For Sale Or Rent
Rooms to Let 50 Cents
Posts: 5,103
Quote:
Originally Posted by Bob Miller View Post
.........That said, because torque twist isn't to common an issue on trailers,(lol) I would opt for an aluminum channel frame...........
You will get twisting (about the longitudinal axis) in the frame anytime one wheel sees a different road input than the other wheel.
__________________
UHaul and Burro owners, join the UHaul Campers on Facebook. https://www.facebook.com/groups/529276933859491/
Thomas G. is offline   Reply With Quote
Old 03-15-2013, 07:49 PM   #7
Senior Member
 
rabbit's Avatar
 
Name: Jack
Trailer: '98 BURRO 17WB
Delaware
Posts: 2,548
Tom, I know you designed or spec'd for trucks but I respectfully disagree. I've seen the comparison tests of full size p'ups to check for degree of torque in the frame. With four points of support and one point (one wheel) off the ground, it's easy put a frame in winding (twisted out of a single horizontal plane). How does that work with two wheels and hitch point (ball joint) which is not rigid but able to pivot laterally (within admittedly constrained limits of motion)? Now with two weight-bearing points (wheels) I know from experience that a trailer frame can be twisted by adding a single jacking point any place on the frame off the longitudinal centerline of frame and also ahead or behind the line of the axle. Going with your statement would mean that simply putting one wheel thru a pothole or over the edge of a bad berm would transfer a twisting action to the frame. I don't see how that can be the case but I'm open to an explanation. Fizzix wasn't my best subject.

Jack
__________________
rabbit is offline   Reply With Quote
Old 03-15-2013, 08:31 PM   #8
Senior Member
 
Thomas G.'s Avatar
 
Name: Kinga DeRode
Trailer: For Sale Or Rent
Rooms to Let 50 Cents
Posts: 5,103
Quote:
Originally Posted by rabbit View Post
.......... Going with your statement would mean that simply putting one wheel thru a pothole or over the edge of a bad berm would transfer a twisting action to the frame. I don't see how that can be the case but I'm open to an explanation. Fizzix wasn't my best subject.

Jack
You are thinking in terms of statics. When you hit a bump on the road the inertia of the trailer mass resists motion (F=MA) . The wheel that hit the bump can either lift or twist the frame, which ever takes less force.
__________________
UHaul and Burro owners, join the UHaul Campers on Facebook. https://www.facebook.com/groups/529276933859491/
Thomas G. is offline   Reply With Quote
Old 03-15-2013, 09:15 PM   #9
Senior Member
 
rabbit's Avatar
 
Name: Jack
Trailer: '98 BURRO 17WB
Delaware
Posts: 2,548
My trailer frame doesn't behave like Newton's. Does it? I'd love to see some sort of wire frame animation in side elevation. Some sort of sensor map. Maybe I'd be convinced. Maybe there's macro twist and micro twist. I don't deal well with the itty bits. I concede (gulp).

jack
__________________
rabbit is offline   Reply With Quote
Old 03-15-2013, 09:30 PM   #10
Senior Member
 
Donna D.'s Avatar
 
Name: Donna D
Trailer: Escape 5.0 TA, 2014
Oregon
Posts: 24,433
Sigh. I've seen truly "boxed" frames that rusted from the inside out. Moisture gets in and was unseen until a failure. So, I can't provide an opinion about what is strongest. There's the thing about "use" that keeps getting in the way...
__________________
Donna D.
Ten Forward - 2014 Escape 5.0 TA
Double Yolk - 1988 16' Scamp Deluxe
Donna D. is offline   Reply With Quote
Old 03-15-2013, 10:42 PM   #11
Senior Member
 
Jared J's Avatar
 
Name: Jared
Trailer: 1984 19' scamp
Kansas
Posts: 1,610
Quote:
Originally Posted by Donna D. View Post
Sigh. I've seen truly "boxed" frames that rusted from the inside out. Moisture gets in and was unseen until a failure. So, I can't provide an opinion about what is strongest. There's the thing about "use" that keeps getting in the way...
I believe salt is a big issue on that one. My '89 nissan is known for it, although not like toyotas. It spent most of it's life in North Dakota. I washed the frame rails out several times a winter, and in summer. Mine are still fine, 24 years later.
__________________
Jared J is offline   Reply With Quote
Old 03-16-2013, 01:42 AM   #12
Senior Member
 
David Tilston's Avatar
 
Name: Dave W
Trailer: Trillium 4500 - 1977, 1978 (2), 1300 - 1977, 1973, and a 1972
Alberta
Posts: 5,315
Registry
Quote:
Originally Posted by rabbit View Post
My trailer frame doesn't behave like Newton's. Does it? I'd love to see some sort of wire frame animation in side elevation. Some sort of sensor map. Maybe I'd be convinced. Maybe there's macro twist and micro twist. I don't deal well with the itty bits. I concede (gulp).

jack
Finite element analysis movies would be nice, but I only have AutoCAD.
Finite element method - Wikipedia, the free encyclopedia
__________________
David Tilston is offline   Reply With Quote
Old 03-16-2013, 07:33 AM   #13
Senior Member
 
rabbit's Avatar
 
Name: Jack
Trailer: '98 BURRO 17WB
Delaware
Posts: 2,548
FEM: a numerical technique derived from variational method for finding approximate solutions to boundary value problems.

HUNCH: a swag without the calculus.

Dave, I made a hard copy of the Wikinition. Highlighted the two or three sentences I understood. Then I highlighted the ones I thought I might understand after fifteen more readings. Then I developed strong feelings of inadequacy and ate the hard copy.

jack
__________________
rabbit is offline   Reply With Quote
Old 03-16-2013, 08:10 AM   #14
Senior Member
 
rabbit's Avatar
 
Name: Jack
Trailer: '98 BURRO 17WB
Delaware
Posts: 2,548
Now I'm gonna just throw this out there as a sort of pathetic attempt at understanding and y'all jump right in and give me clues like say Warm or Warmer! or Cold or Colder until I get more confused than I am.

Could it be that there's twist in a frame (all joints out of whack) such that longitudinal members aren't parallel in side elevation and then there's localized twist in a single frame member, say in the rail near the location of the axle mounting flange in the case of unsprung axles? I'm really trying to home in in this. Please stop spinning me when I'm facing the piñata.

jack
__________________

__________________
rabbit is offline   Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
1977 13' Window Frames 360icon Classified Archives 5 06-14-2011 08:57 PM
boler frames willisworms Classified Archives 2 06-02-2011 09:19 PM
Frames - why black? Andrew GPSMapNut General Chat 19 01-22-2011 12:17 PM
Cleaning Aluminum Window Frames Tara_B Problem Solving | Owners Helping Owners 3 06-21-2009 02:45 PM
SURFSIDE WINDOW FRAMES GHYNES Modifications, Alterations and Updates 8 05-29-2007 09:25 PM

» Upcoming Events
No events scheduled in
the next 465 days.
» Virginia Campgrounds

Reviews provided by


Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 03:38 AM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.