Don't know what everybody else thinks but 3 guys in this forum always seem to talk good sense and I always read their comments with interest, well done guys you make the forum. They are: etharp, liftdoctor, and trainer. I think it has all been said and everyone seems to favour AC drive. In my humble opinion AC is best for Reach, Counterbalance and VNA. And SepEx is best for pallet jacks.
Only problem you will get with AC motors, is Encoder bearing failure. The motors are "Asynchronous" 3-phase motors. Which means the Inverter logic needs the feed back from the encoder in the form of 2 channels 90 deg out of phase to detect direction and speed. This allows the Inverter to synchronise rotor speed and frequency to maintain the motor at its most efficient. Think of it as the timing on an engine, as the RPM increase the vacuum advance moves the firing point more degrees before top dead centre. Ac motors run with a slip value that varies with speed a torque.........................Try disconnecting the encoder and test the result. The motor will not run or run very slowly with a high frequency vibration and the current readings will be through the roof. Don't run 'em for too long it could blow the inverter.
The bearings are tricky little buggers to replace and have to be fitted carefully to avoid damaging the encoder. I usually warm 'em up inside a plastic bag in warm water before fitting. Anybody got another solution? Some of my colleagues emery the seating to make it slip on easy, but I always think this could cause problems in the future!