I think there is quite a wide tolerance band when it comes to gears in low speed, low pressure applications insofar as sizing of teeth is concerned. Another, possibly important, factor is the material the gears are made of: cast iron for lots of them, not hardened. So any out of ideal issues correct themselves during the run-in period. Things might be a bit noisy, but as parts adjust themselves, they should quiet down.
I am by no means suggesting that gear geometry is not important - it is. One can get away with quite a bit of inaccuracy - just look at the approximation of the tooth shape as produced by involute gear cutters. And that is an accepted way of making gears...
I am by no means suggesting that gear geometry is not important - it is. One can get away with quite a bit of inaccuracy - just look at the approximation of the tooth shape as produced by involute gear cutters. And that is an accepted way of making gears...