Ask in the flash forum.
I just signed up for this forum and I browsed the alternatives, but I didnt find a flashforum. How do you find it?
without seeing the "storyboards" for this I'll try to help out.
Essentially you'll need to make the Truck portion its on Movie Clip (MC), next create the plow as a separate MC. you should now have these two MC's in your library. edit the Plow MC so it has its own animation, complete with stops so it doesn't loop continuously. Now open up the Truck MC and give it it's own animation as needed.
Make a new layer within this Truck MC and place the Plow MC into it. This way you can make the Plow move independent of the Truck MC animation.
From hear its a matter of syncing the two MC to make it appear as though they are working together.
If you have an .Fla started, feel free to send it over and I'll take alook to see if I can be of help.
To get to the Flash forums you will need to use the pulldown on the Forums home page.
If you are just starting in Flash then you should go through the tutorials that are listed on the splash page when you open Flash.
If you have one movieClip that is your snow plow, and you want to animate a plow blade, then open the snow plow movieClip and then draw or paste in your blade movieclip. Your blade movieclip will now be part of the plow movieclip.