That one's controls are kind of weird, it will only allow one "valve" to be open at a time, so you have to track one way, then turn, then continue, stop, raise your boom, dump your bucket...
Or you can just play on the real thing.
This is a 257B with a concrete saw on it, with a water package to reduce dust. I got to play around on it when they were milling because the crew wasn't using it, was fun. Besides that I couldn't really do anything because they didn't want to let me cut any concrete, haha.