Peter R. wrote in message ...
G.R. Patterson III wrote:

Garage door openers drive a sprocket that operates a circular chain. Some of the
older units had a block on the chain that tripped a switch when the door was raised.
This block could be adjusted to fine-tune the system. My Genie units do not have
this. I assume (but do not know) that they simply pull the chain for a fixed distance
(most doors are 7' tall).

So. Measure the distance you have to pull your chain to open the hangar door. Work
out the ratio between that and 7'. Rig a reduction gear out of two appropriately
sized pulleys and a belt and drive that from a chain driven by a garage door opener.
You can probably use your existing chain pulley as one pulley in the reduction gear
and mount the whole thing high on the wall.

Thanks, George. I might just try this project.

Actually many residential garage doors will open up a 10' high door
when they have the right length rail & chain. So if your door is 10'
tall you do not need to change the reduction at all, but if your door
is taller then 10' you would have to change the reduction. However if
you change the reduction very much (depends on door height) you are
also going to increase the speed that the door opens which may result
in an unsafe operating condition & is also going to put more wear &
tear on the door. Residential garage door openers are not designed for
this type of use & for your own safety is not something I would
personally recommend doing.

Doordoc