You can tell how to make animations of a 2-axis streetcar without a wrist. And also how to make animations of opening the door.

even for 2 axle tram you have to define a bogie. Please have a look at the lexicon article.

For making a door animation, there is a lexicon article in german language here, at the very far bottom you could find Point 9.1.

There is the information of how to animate a sliding door and even a small script to have a look at.

which one, the first one for the bogie or the second one for the sliding door?

For the doors: You know how animations work (everything is written in the lexicon), now you just need to use your knowlegde and create an animation for your doors. There is nothing different to it than create e.g. a button. If you show me what type of door you need, I can explain the way I would do it in detail.