how do I make the gear spin?

I've Tried to figure out how to make gear spin by motor.
Hooking it directly doesn't work to spin it.
So I've to hook nail it first to hookable to motor object like wooden plank. Then the plank is connected to the motor.
Well, it works.
Thanks "Try" for revealing us these sets of the objects.
Also, Golden found that the gear doesn't work yet. Mine said it's just link weakly at a momment.