Uhhh, its very hard to see it if you can. The computer I'm using here at work has a hard time with video, so the picture is kind of grainy. I think you can see them in the first shot of the engine room in the movie when Bell gives the order for "all ahead full", then turns around.

Take a look at this picture. The turning engine is on the lower left side of the base. The little horizontal wheel you see by the big vertical wheel) You can also see the little pistons right above the horizontal wheel. Anyway, when they want to use it, they can tilt that little corkscrew looking thing under neath the horizontal wheel so it can connect onto the big wheels gears and turn it.