So, on Saturday we drove to Perniö and bought a second-hand haymaker from an arable farmer who has about 40 hectares of wheat fields. He hasn't used it for years so we were glad to take it off his hands. It's Danish, probably about 40-50 years old but in good working order, just needs a couple of new tyres. We want to try and get two lots of hay from the front field this summer which will only be possible if it stops raining for more than 24h. The grass is packed with rich nutrients at this time of year so it's important to store the hay for the autumn when the grass is not so nutritious and in short supply. And, the sheep seem to prefer nibbling on freshly mown grass, rather than eat the long grass which is presumably harder work.
Once the hay has been mown, the hayraker lifts it up and piles it into a row (called a window) ready for baling. We won't be baling ours though, we pile the hay onto poles in the old-fashioned way. I'll try and film some of it.
Here's a YouTube video showing something similar (ours is not a John Deere but the mechanism is fairly similar)
Here is another hayraking video - a bit noisier than the previous one and using slightly older machinery but the idea is the same.
Some rakers use a pinwheel system and sometimes these run at the side of the tractor rather than behind it.