k4 locomotive

Long before there have been machines to work out on and competitive sports to stay moving and before wars were being fought, man didn't think about conditioning as a way of keeping healthy. He simply knew if he didn't hunt, he wouldn't eat if he didn't run, something would hunt him. They were a down economy that focused simply on survival. When tractors were first developed, they used enormous steam engines which were notoriously unreliable and challenging to maintain. These were phased out round the turn in the 20th century and substituted with internal combustion engines that have been more compact yet still powerful and ran on the variety of fuels including kerosene, ethanol and gasoline. By the 1960s many of these engines were phased out and only more effective internal combustion engines that ran on diesel and after this, biodiesel.