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Recalculations place it at 0.4999.
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For those who have a driveway with a gate. Powered,
remote control openers are convenient but sometimes
An aluminum 6'x15' gate swinging on ball bearing hinges,
properly installed and leveled moves easily enough for this
This idea is to use the jet of air from
an electric leaf
blower piped from the hinge side to the latch side and
discharged through a slit on the side of a vertical
tube(capped) and aimed opposite from the direction the
gate is to move.(open) This vertical tube is mounted on a
swivel coupler on its bottom and has a tab on its side that
contacts an arm on the stop post which turns the tube 180
degrees while a limit switch at the hinged end stops the
blower and a gravity latch engages the gate.
(close) Said gravity latch has a light weight arm that is
tripped to open by the blast of air starting the gate going
in the opposite direction. Another latch. tab, and tube
rotation setup is on the other end.
If the gate is stopped in mid swing it will stall and not
damage the gate as some commercial electric openers will
Limit switches and blower are housed behind the column
on the hinge side. Blower is connected by flexible tube to
PVC piping fastened to back side of gate or to the tubing
of the gate itself in the case of a new vs. a retrofit
application. This is not solar/battery but supplied with
Various types of propeller/fan arrangements were
considered and rejected due to safety or other snags.
The same action/reaction effect would work as well
using the force of a water stream or the blast from a bank
of shotgun shells but would present other problems.
gravity latch [cudgel, Nov 09 2015]