[AT] ROPS

[Steve W.]

Dennis Johnson wrote:
> I agree with Dean that the only significant this is the height of the
> center of gravity, and the width of the rear heels. The front only
> comes into play only on a few extreeme circumstances such as dropping
> the rear wheel in a hole or something like that. I have personally
> done rollover testing of big trucks on tilt tables, and have also
> designed rollover bars (Headache racks) for many truck. I have seen
> some of these units tested when the trucks rolled over, and have seen
> some fail, but still took enough energy to prevent killing or severly
> huring the driver. The problem with most rollovers is it is rarely as
> simple at the tilt table testing. Many times there are 2 or 3 factors
> that add up to cause accidents.
> 
> 

Very true. One of the things I like to do at race tracks is ask if the
roll cage was actually engineered OR was it just "well we needed a
couple hoops to pas the rule book" type stuff.

It would be real easy to design a ROPS system if ALL it had to do is
support the weight of a tractor. Now if you want it to support that
tractor after it rolls over while traveling on a downhill slope and
moving at 8mph at the time. That gets interesting.

One of the new requirement for fire equipment starting this year is a
built in roll protection system that is required to support the weight
of the vehicle without failure. BUT the standard is written in a way
that NO motion is included in it. The "test" the maker must pass is to
flip the vehicle with a crane and show that the cab doesn't crush. I
sent in a query about having the test be realistic and have the vehicle
rolling at 45mph and flipping and see what the cabs do. The answer I got
back was that my method was impractical!!!!!
I guess they must see a lot of trucks just flipping over while parked....

-- 
Steve W.
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