Small Engines (Lawn Mowers, etc.): John Deere Rx95 Transaxle shaft key, woodruff key, jdparts

Question
Hello,
I have a JD RX95 and I've had to replace the smaller pulley that sits on the transaxle. When I got the transaxle off, and small, half-moon looking object fell off. According to John Deere's jdparts website, it's a shaft key. What exactly does this do, and how/where/do I put it back on when I install the transaxle?

thanks in advance, grass is looking alittle rough..

Answer
It is called a woodruff key.  If you look in the shaft pulley came off of you will see a rectangler shape hole.  The key in round side down.  Sometimes there is a small spring that goes in the hole first to put tension on the key.  If this is the case there'll be a round hole inside the rectangler hole.  The pulley will slide over the key to the attaches the pulley to the shaft so they both turn at the same time.  Hope this helps.