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Old 03-18-2015, 09:26 AM   #11
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I contacted my dealer yesterday to see how things were coming along and this is what I found out. The two minor problems, refrigerator door and rear screen door, were fixed. The new axle has been installed and they are in the process of installing the replacement metal. The service department said that because the metal was very thin and over 30' long that it took 8-12 men to install it. He said one slip and it would end up in the trash. When I asked about the frame camber and the factory rep he said he didn't know anything about that but thought the trailer would be done by the end of the week. I know the service department is big, (supposed to be the largest in Oklahoma) perhaps this explains the breakdown in communication. Hoping all is well.
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Old 03-18-2015, 09:35 AM   #12
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Can someone explain what frame camber is?
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Old 03-18-2015, 09:49 PM   #13
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I have tried to find this out myself, maybe others can help. The best explanation I can understand from reading about it is as follows. If you see a large empty flat bed semi trailer, they often are arched upwards. This is positive camber. When the appropriate load is applied, ( dozer, excavator etc.) the "arch" straightens out.

The problem I have understanding this is how this is different than an arched leaf spring with a load.
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Old 03-18-2015, 09:55 PM   #14
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Originally Posted by comfun1 View Post
I have tried to find this out myself, maybe others can help. The best explanation I can understand from reading about it is as follows. If you see a large empty flat bed semi trailer, they often are arched upwards. This is positive camber. When the appropriate load is applied, ( dozer, excavator etc.) the "arch" straightens out.

The problem I have understanding this is how this is different than an arched leaf spring with a load.
I had never heard it called camber before. Learn something every day.
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Old 03-18-2015, 10:20 PM   #15
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Never seen or heard about camber on an RV before, large trailers that carry thousands of pounds are laid out differently, i.e., the wheels are at the back and the trailer and the bed flattens with the load, not so on a fifth wheel.
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Old 03-18-2015, 10:24 PM   #16
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I missed OC's question earlier... OK cambering a beam is giving it a crown (positive camber) by basically prestressing the beam so that deflection under load basically flattens out the beam versus inducing a sag (negative camber) in it. Camber actually does nothing at all for structural capacity. It's basically an aesthetic consideration that provides engineering efficiency because you can use a smaller cambered member versus using a heavy straight one to achieve the same deflection limit.

Now as a structural engineer, you are taught you don't camber short beams (less than ~25 foot), shallow sections (web less than ~12" depth), beams used in moment frames, and beams that are cantilevered. Mechanical engineers, where crossing the domain of structurals (yeah, I know), challenge these rules somewhat because they depart from AISC standards and are working with fabricated beams (like trailer frames).

As the OP raises concern, and why structurals avoid camber in cantilevers is because of a spring-like effect. It's not at all the action of a leaf spring where spring steel behavior is different (and can take the cyclic deflection), but is the eccentricity once loaded that causes a greater reaction at the rigid support that over-stresses - liken to why the really, really large fellow shouldn't use the diving board at the pool.

With a trailer frame, when hitched, each frame rail can be treated a simply support beam with the pin corresponding to the coupled hitch and the roller corresponding to the axles. The length of span from axle to bumper gets interesting in the case of a toy hauler where the greatest load could actually occur versus in the cabin (and the span between coupler and axle where typically cambered). So, in the case of a toy hauler garage frame, things get interesting if camber is induced, CCC is not stellar and the owner goes for using all of it (and often more) to stuff the garage.

Lippert does camber several of the longer camper frames. They have to because of the shallow beams they are using for frame rails to conserve weight and clearance. However, I wouldn't expect it for a toy hauler frame.
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Old 03-19-2015, 12:11 PM   #17
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I got a call from my dealer today, my camper is done. I was mistaken about Forest River coming to look at it, it was Lippert that came to check the frame camber. Apparently, Lippert furnishes the axles and builds the frames. All I was able to find out about it was that they did some welding on the frame. He did tell me that frame camber problems don't happen very often. Perhaps when I go to pick it up I will be able to find out more. I believe this is the first Grey Wolf Toyhauler with a slide. Perhaps this caused it to be weaker on the slide side. At any rate I am good to go camping again!
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Old 03-19-2015, 12:17 PM   #18
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I missed OC's question earlier... OK cambering a beam is giving it a crown (positive camber) by basically prestressing the beam so that deflection under load basically flattens out the beam versus inducing a sag (negative camber) in it...
Always heard it called "pre-stressing", not camber.
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