One who touches the yoke, the crossbar, the collar, or the beam, even while [they are] in use, is tahor. [One who touches] the handle, the borech, or the guide is tamei. [One who touches] the metal ring, the coulters, or the moldboards is tamei. R’ Yehudah rules tahor regarding the coulters, since their purpose is only to increase the [amount of] dirt.