It could be that in certain emergency situations, say loss of contact with the main computer, all ship's gravity systems automatically revert to a default 1G setting. This gets us turbo-shafts that work the way we'd expect them too most of the time, but a plausible scenario for gravity (and air) in the shaft in Disaster. and any other time we want it.
In Trek V the gravity may have been turned on simply as part of whatever maintenance was being performed at the time.
There would be no gravity in the shafts AT ALL. Why would you even put gravity generators in there? There's no point. It only endangers people.
And STV the whole scene with the turbo lift shaft is just humorous fluff.