On Fri, 05 Feb 2010 09:10:18 -0800, wrote:

On Feb 5, 8:03Â*am, Tim Wescott wrote:
A 120 pound gate, 18 feet long and 3 feet high, hinged at one of the
lower corners and supported by a damper that is pivoted to the top
corner and working at a 45 degree angle, puts a 510 pound load on the
damper _just_ to keep the gate still -- decelerating the gate takes
even more load, to the tune of 1700 pounds if you want to close the
gate in one second (that's assuming constant deceleration over 45
degrees in 1/2 second).

(I decided I didn't want to close it that fast).

Anyone who suggested a fire-door damper -- where can I find one that'll
support a ton?

--www.wescottdesign.com

Tim, there is a place NW of Redmond that has a heavy steel gate with a
similar pivoting scheme. He has a chain drive an an electric motor to
raise and lower the thing. It is not 18 ft long, but is still pretty
heavy.

Could you construct a similar mechanism for your gate?

Yabut. We're far enough out in the boonies that we lose power at least
once every winter, and the power line from the shop to the gate is hosed
and needs to be replaced -- I not only need a round tuit, I need to rent
a @#$% ditch witch _and_ figure out where the old line is.

So whatever else it does, it has to work manually, at least sometimes.

--
www.wescottdesign.com