I have to source something for a machine I am designing, and I have absolutely no idea of what it is called. Basicaly, a man is rotating a large flywheel by hand. The flywheel is heavy, and so it has a lot of inertia. Consequently, if the man rotates it too fast, it becomes a real pig to slow it down again. I know that in a situation where I am dealing with linear motion, rather than rotary motion, I can tie in whatever is moving in a linear movement to a hydraulic cylinder and put in a "restrictor" (needle valve) so that as oil is moved from one end of the cylinder to the other through a hydraulic hose and through the needle valve, it limits how fast the linear motion can be. Is there a similar hydraulic speed limiter for rotary motion? I have never seen one, but I'm sure that they must exist, and be commercially available.---Brian