After having read most of the replies. Some longer than others!
For push backs
Ground locks ....NO
Steering bypass pin....YES
The only time I'd tow with ground locks in is from line to the hangar, etc. Especially with APU problems. No hydraulics (although I wouldn't tow without brake accululator pressure just in case).
I know it's theoretically possible, but everthing is working to keep the gear down. It takes a great deal of force to get the nose gear up. You're working against hydraulics (3000 psi on Airbus) and downlock springs which lock the gear down in the event of freefall in flight.
The end
