This article was updated May 5, 2023. It was originally published Sept. 24, 2009. Shaft keys—sometimes called sunk keys—transmit torque between shafts and shaft-mounted components such as gears or ...

Tapering is one of the most important parts of any marathon training plan, but in many cases, it’s also one of the hardest to implement. Ever heard of the taper tantrums? They can feel real if you get ...