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QUESTION:A brief request for comment from the group, yesterday
I was recruited to assist in a small way for a friend,
whos son-in-law was getting a new house.
Actually, he had already received the house, and it
was sitting on a side street at the bottom of the hill.
Three sections to be specific. The goal was to
bring the sections to the foundation site which was
at the end of a good quarter mile dirt driveway,
quite steep, narrow, and winding.
My role there was only as a gofer and spotter.
The house sections were first hitched to a large
truck which could haul them along the paved road
to the bottom of the dirt driveway, where they
had their trailer hitches attached to a tracked
excavator bucket with chains.
My first question is, how much does a prefab
house section weigh?
Next question is, how strong was the chain
used, it had links about 7/16 diameter or
so, and was doubled over a couple of times
between the pintle hitch and the hook on
the bucket.
Given the amount of shock loading involved,
and the considerable grades climbed, I
was pretty worried that the chain would fail
under load and allow the trailers to careen
back down the roadway.
Can anyone do a back of teh envelope
guess as to how close the chain was to
its ultimate limit?
There was no way that a normal haul truck
could have done the transport btw, the
road was so winding that the ability to
swing the arm on the excavator to help
the trailers negotiate the curves was
vital to the operation.
ANSWER: Normally a 'trailer' type manufactured home doesn't weigh all *that*
much... 20 tons would be a big one. However, if this was in three pieces it
might have been something other than a trailer-type. I'd guess 10 tons to
be an unlikely maximum for one third of a manufactured home.
7/16" chain has a rated safe pull strength of around 3500lbs in a vertical
lift, but won't break until it hits 14,000lbs. On a bumpy uphill pull, I'd
expect the conditions to be similar to a vertical pull.
If the excavator could handle the strain, then each piece probably wasn't
more than maybe 7 tons. That would be a dangerous load on a single strand
of 7/16" chain, indeed, but with a few wraps to share the pain a bit, and
maybe a bit of give in the excavator hydraulics softening the blows...
The dipperstick pull on that would be wicked. I wouldn't want to try
that with any excavator that *I* owned (if I owned one 8-).
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