crank shaft gear oil slinger question

on the crank shaft, in front of the timing gear there is a "oil slinger." I was thinking that when I had removed the timing cover, the oil slinger was half way onto the same key as the timing gear. Now that have I the new timing set installed, and I slid the oil slinger over the crank it just free wheels. I reinstalled my old timing set and it does the same thing. Is it just the pressure of the balancer on the face of the oil slinger that holds it stationary?

The purpose of the slinger is to sling oil away from the front main seal so that it isn't over loaded with oil and more prone to leaking. This is what they look like:
http://image.carcraft.com/f/techarticles/9554617+w200/116_0010_eng_14_z.jpg

http://image.mustangmonthly.com/f/i...mp_0905_25_z+289_budget_build+oil_slinger.jpg

Its been quite some time since I have done the one in my truck, but as I recall it just gets squeezed in there.