Brian,

It's a normal door hinge, but has a spring concealed inside an oversized
hinge pin. Ace hardware had a variety of hinges, and these were the
heaviest duty. It was just called a 4" "spring hinge". A very similar one
was called a "self closing" hinge. It has a large( 5/16"?) diameter hinge
pin and the spring is somewhere inside the center section of this. One of
the plates has extensions that wrap around each end of this pin. The other
plate has a wide center section that wraps around the rest of the pin. The
advantage of this hinge is that both plates are very well supported so that
the hinge can take a significant vertical twisting load. The two ends of
the hinge pin are apparently connected by some internal smaller pin, so that
one can rotate independently of the other. There is a small radial slot cut
into the part of the first plate that's wrapped around the hinge pin, and
there are several small radial holes drilled in the hinge pin behind this
slot. This allows the hinge pin at this end to be turned relative to the
wrapped portion of the plate by inserting a supplied small steel pin into
one of the holes. There is a second, very short "lock pin" supplied. By
turning this end of the hinge pin by means of the two small pins you can
wind up the spring inside to the desired tension, and then insert the lock
pin to hold it permanently in that position. That's the best I can do to
describe it. You'll have to go to the hardware store and see if you can
find one. Once you see it, I think you'll understand completely. The other
advantage of this hinge is that the spring is fully contained inside.

--
Bob (Chief Pilot, White Knuckle Airways)

"Brian Lawson" wrote in message
news
Hey Bob,

Thank you. Looks very well made, but I don't understand the term
"spring hinge" I guess, and no spring is visible. Is that the type
of hinge that would go, say on the doors to the kitchen in a
restaurant, which will swing open by pushing from either side ( in and
out ), and then return to "closed" (neutral) when released?

Good pix by the way.

Take care.

Brian Lawson,
Bothwell, Ontario.