פירוש על מכשירין 3:8

המוריד את הגלגלים – wheel of His [Divine] Chariot (see Ezekiel, chapter 1), we translate in Aramaic, the wheels of the chariot with horses.

If one lowered wheels or the gear of oxen into water at the time of the hot east wind in order that they might become tightened, this comes under the law of ‘if water be put’. The person brings some wooden wheels or oxen gear down to the river to soak them in water so that they will tighten (seems like this means to expand, thereby tightening the parts) because it is so dry outside. The water that clings to them when he removes them will cause susceptibility to impurity. This is because he intended to use this water.

בשעת הקדים - at the time of the heat, the eastern wind blows, and it is the manner of wooden vessels that they split/break because of the heat, and we bring them down to the water and the splits are attached. That is, they are tightened/wedged in, like squeezed in/pressed in, that is to say, in order that they can be pounded together and that the splits are attached to each other.

If one took down a beast to drink, the water which came up on its mouth comes under the law of ‘if water be put’, but that which came up on its feet does not come under the law of ‘if water be put’. If he intended that its feet should be washed, even the water that came up on its feet comes under the law of ‘if water be put’. At the time of footsoreness or of threshing it always causes susceptibility to uncleanness. In this case he intended the water to go into the mouth of his beast, so it does causes susceptibility. But if he didn't intend to wash off the animal's feet, then the water attached to the feet does not cause susceptibility. However, there are two occasions in which we assume that he wanted the feet to be washed off. First, if the animal has some affliction, "footsoreness," then he must have wanted its feet to be washed off. Alternatively, when he is using the animal for threshing, it can be assumed that he wanted to cool down its feet and the water causes susceptibility.

הרי זה בכי יותן – the waters that are raised in them make fit the seeds to receive ritual defilement, for it is satisfactory for it that these waters are suspended in a vessel to fasten the splits.

If a deaf-mute, an imbecile or a minor took it down, even though his intention was that its feet should be washed, it does not come under the law of ‘if water be put’, because with these the act alone counts, but not the intention. These three categories of people are not legally capable of having intent. Therefore, in order for them to make the water cause susceptibility they would have to actually do something to the water, like put it in a bucket and then use it to wash the animal's feet. Merely being happy that it washed off the animal's feet is not sufficient.

בשעת היחף (at the season of foot sores [of animals or of threshing]- that the animal is weary and tired from the trouble of the path. And similar at the time when it is threshing in the grain, the water that she brings up upon her feet always makes the seeds fit to receive ritual defilement because they are intentional, for the waters are good for her to cool her off and to make her cold. Another explanation: At the time of foot sores and the threshing, at the time of the harvest, he wants that the animal washes its feet in order that they will be clean to thresh the grain.