It used to be the pump of a refrigarator. It creates air pressure up to 8 bar. Enough to pump up tractor tires, my digging machine's tires, and everything that needs to be pumped up. Every part of a machine that is still usefull gets converted into something usefull. Croats here are masters of improvisation in many fields. They avoid to pay for services of someone else if they can create their own solutions. A way of life one can see is practically everywhere. Only if they really can't do it themselves they go to someone else. They know how to slaughter and process their animals, build houses, barns, till their land, find food in the forest and even medicinal plants. They have a lot of selfreliance and with it a lot of peace of mind. There is not so much they cannot do themselves.