Spiral Bearing or similar which will raise a gate when open and cause it to close
I have been commissioned to make two separate, very solid oak gates, each about 1 m square for the entrances to our War Memorial Hall. I have designed some wooden hinges, lined with lignum vitae to fit on to exsisting steel vertical pins. The Hall Committee would like the gates to close automatically after being pushed open. The lignum vitae lining is next to the steel, otherwise in time the steel will cause the oak to stain black. I think by now you will know I am a professional woodworker and not a practicing engineer.
I am seeking advice from engineers about the possibility of fitting what I would call a rise and fall - type bearing that will allow the gate to open about 180 degrees and rise when opeing and subsequently fallback into place once the visitor has passed through the gate. I do not particularly want to introduce external 'closing devices'. I want to fix something under the 4 wooden hinges on the horizonal base of the vertical steel pins. Is this possible? Any advice most welcome.
Ian, Northumberland.