Shunting Problem

From Read Before Posting: Show your beginning work, or ask a specific question about the exercise, or explain why you're stuck.
Oh ok so far I got this much as the solution
1.Locomotive pulls B up
2. Locomotive pulls A to the right
3. Locomotive pushes B pack and brings it to A's position

but I am stuck now because locomotive does not enter the tunnel
 
Oh ok so far I got this much as the solution
1.Locomotive pulls B up
2. Locomotive pulls A to the right
3. Locomotive pushes B pack and brings it to A's position

but I am stuck now because locomotive does not enter the tunnel
What keeps the locomotive from entering the tunnel? You might consider drawing diagrams for each step.
 
Oh ok so far I got this much as the solution
1.Locomotive pulls B up
2. Locomotive pulls A to the right
3. Locomotive pushes B pack and brings it to A's position

but I am stuck now because locomotive does not enter the tunnel
They emphasized that, though the locomotive can't fit into the tunnel (too tall?), it can push either car far enough through the tunnel that it can be reached from the other side. That will be a key step, don't you think?

If that alone doesn't help you, I would try thinking about what the last steps of the process might look like, in order to know what you have to accomplish in the first steps.

As has been suggested, you'll want to sketch the process, which will both help you keep track of what is happening, and make it easier to tell us what you mean -- "pulls B up" doesn't tell me as much as a picture could!
 
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