Ratchet Lock Animation Problems

Greetings Cadtutor forums,

I am currently working on designing and animating a clock for my Engineering Course. I have finished part one and am now working on the animation aspect of the assignment. The problem i seem to be having is getting the ratchet wheel and ratchet lock constrained properly. I have extruded a rounded profile of the ratchet as a surface and constrained the edge of the lock to it, but the tangent constraint only allows me to select portions of the total surface profile. How do I constrain the lock to the entire profile?

Also, congratulations to anyone who managed to complete my novel of a question. You deserve a cupcake.