 That's what numbers is referring to, no yoke. A yoke was put onto a cow, and they would attach a plow, and that yoke would be linked up with another cow to give them pulling power for digging up, just like they used to do not all that long ago, actually. Really, the tractor is within the last 150 years, right? Before that, you used horses, you used cows to plow, right? Well, that's what they did back then.