There seems to be a trend towards using AC motors for MHS (and even forklifts).

I just want to know if AC motors are less susceptible to failure?
I ask because recently we had been experiencing cases of roller decks on my ETVs (elevating transfer vehicles) lowering by itself, sometimes too fast, posing a safety hazard. Apparently the causes were faulty speed drives and severely worn commutators on our hoist motors.

Then we are told that the use of AC motors would eradicate such a problem. Is this true?