I am doing an analysis using mechanism of a some gears. I noticed that when I control the mechanism with an equation and if I accelerate it to high velocities, that the assembly seems to reverse in direction and spin backwards. Doesn't seem right, but at one point it slows down and you could see it going in the opposite direction. I was using a simple ramp equation (y=a+bt) to control the acceleration. Could it be just an illusion due to the speed? Any ideas what could be causing this?