2422:43 (is this a planetary gearbox? European manufacturer?) represents a ratio of 56.326:1, and yields these final screw speeds at 60 Hz (actually, a bit lower once slip is factored in).
2 pole, 3600 RPM motor, 63.9 RPM screw
4 pole, 1800 RPM motor, 32.0 RPM screw
6 pole, 1200 RPM motor...