OK, it's not like they are a recent invention. Been around for some time, in fact. But I have only recently discovered just how useful they can be in the shop.
I have always used carts to move heavy stuff around so it's not like the light did not have many opportunities to go on. But for some reason, I have never considered putting my heavy machines on wheels.
I'm not talking about big CNC stuff here. I don't have that kind of a shop. But I have a lot of shapers and saws and lathes and so forth and for my entire woodworking career, I have tugged and pulled at them trying to "scootch" them over a bit or get them out of the way entirely.
Maybe it's just that I was never aware of some really nice heavy duty casters with solid locking devices that would easily support a 1,200-lb. planer or a heavy shaper. I have seen such casters but they always had wheels so large that they would put the working surfaces too high. But recently, I acquired a beautiful old PM160 planer which is wide enough (54" net!!!) that it simply had to be moveable if I was still going to be able to get stuff in and out of the shop door. I found some really nice heavy duty casters (from Great Lakes Caster) that only raise the machine about three inches but allow it to be easily moved by one person and that also have very stable feet that are lowered by means of a small dial-like adjuster. When they are spun down, the planer stays put under load and it only takes a few seconds to raise or lower them.
So now I'm on a tear. I'm putting these things on everything. No more dragging machines out of the way every time we need a bit more space. No more pulled backs and banged knees and toes and bruises. I don't know why it took me so long to figure this out. Funny how we miss the most obvious things.