Anything can be abused. Looking over a chipper should give some clues. I was thinking a chipper doesn't have a transmission, swing gear or other components that can be abused. Can still be abused but not as many components to abuse. I would think chipper operators would be well trained because it's a dangerous machine. Employer could be in a heap of trouble if someone were injured or worse due to lack of training or not having an experienced supervisor. Anytime I've seen chippers being used the people feeding them looked to be working safely and not just throwing everything in at once. They would wait for one batch to go through before feeding more trees into it. Some chippers have auto feed and most have a safety bar that stops them if a person hits it. I've seen a new large chipper throw a piece of wood back out because it was too big and/or the chipper wasn't running fast enough. It was during a pre delivery inspection and one of the people had never seen a chipper operate. I think it was only about 3/4 throttle at the most. Chippers have a pretty good whine at full RPM!