How do I tween (or something like it) a model while its already getting tweened?

I am making a train, and on that train i have a lot of switches. While the train is getting tweened, I want the switches to be able to tween (Flip up and down) while the train is still moving. How would I go on about this?

I have already experimented a little with motor6d, welds, and weldcontrains, but nothing is working.