The rotarys are steam powered, and if you ever get a chance to see one in operation you'll never forget it. Video is probably the next best thing.
The D&RGW identified all major narrow gauge non-revenue equipment with the letter "O" followed by a second letter. Rotarys included ON, OM, OO, and OY. The Derrick was OP. the Pile Driver OB. The Jordan Spreader was OU. Flangers were numerous, including OK, OD, etc.
Someone will have a roster of all this equipment. Those are the only ones I recall off the top of my head.