Great video explaining how the diff works. Even I could understand it. I have a 1954 Ferguson and like the cub it does not have diff lock. Many times in the bog harvesting the brake were the only method of steering I was able to use because of the weight on the back end and the very rough terrain. The diff lock and live drive clutch are relatively later additions to tractors. Sometime in the 1960's they came on to farm tractors.