Hello,

this is an old threshing machine used to thresh grain and separate the grain from the chaff. Modern combine harvesters still use the same principals but combine the threshing with harvesting, that's where they got their name from.

A threshing drum hits the grain out of the plant. To separate grain and chaff from straw, the threshed material travels over shaking sieves. The quite large haulms get ejected to the front.
For separating the grain from chaff, a blower blows air through grain and chaff. Due to the chaff's lower density it's blown away and also gets ejected to the front. The heavier grain falls onto a slide and trickles out of the machine's side, where usually a bucket or tub is placed to collect the grain.

These threshing machines are powered externally by stationary steam engines or tractors (for example by a Steamroller or a Steam Tractor) connected with transmission belts.
They do not have an internal engine and can therefore be treated like a trailer.

Enjoy!