"G.R. Patterson III" wrote in message
...
[...] The ones with which I've dealt are pretty bulletproof. You
might want to change brands the next time yours goes.

The one I had to fix is a Craftsman. I don't know how old it is.

As far as the gearing/load issue goes: a certain amount of work (force over
distance) will be required to raise the door. If the hangar door needs to
be raised more distance than a garage door does, then more work will be
required for the hangar door, all else being equal.

Of course, if the hangar door is carefully counter-balanced and is on
frictionless mounts, then practically no force is required to move it, and
practically no work is required over the entire opening process.

But assuming that past the gear that reduces the force required on the chain
is a door that is similar in nature to a garage door with respect to the end
resultant force required to move it, you don't get something for nothing.
In order to "extend" the range of the garage door opener enough to match the
total range of the hangar door, you'll have to reduce the leverage of the
garage door so much that the force becomes an issue.

Pete