עגלה של קטן טמאה מדרס, ונטלת בשבת, ואינה נגררת אלא על גבי כלים. רבי יהודה אומר: כל הכלים אין נגררין חוץ מן העגלה, מפני שהוא כובשת.
A child’s wagon is [exposed] to midras contamination, and may taken on Shabbat only when dragged over clothing [not on the dirt floor]. Rabbi Yehudah says: No utensil may be dragged [on the ground] except a wagon because it [only] presses.
@General observations
Contamination of objects sat or lent on by an impure person is called מדרס (midras). mZav 5:1 states: “Anyone who touches a zav, or whom a zav touches, transmits impurity to food, drink and vessels.”[1] Therefore, if someone who is impure as a result of a bodily emission sits or leans on anything, it acquires the same level of contamination as the person from whom the impurity emanates.
Our mishnah states that a wagon may only be dragged on the Shabbat over clothing. The wheels of a wagon may dig out furrows in the dirt, which is a subcategory of the melakhah plowing. When a wagon is dragged over clothing no earth is removed and the dragging does not therefore constitute an act of plowing. Rabbi Yehudah permits the dragging of a child’s wagon in any case because, as he says, the wheels only press the earth down.
[1] For a discussion of this mishnah see FONROBERT, “Woman with a Blood-Flow.”
@Feminist observations
The mishnah speaks in the passive verb-form and avoids stating who leans on the wagon. Hanoch Albeck wrote that the child’s wagon is one with which a child learns to walk.[1] This implies that the child is under the age of two and is probably still being nursed by its mother. Although both men and women can have the zav status (for example, a man who has become impure because of a specific type of genital discharge, Lev 15:1-15, or a niddah, Lev 15:20-22), it is quite probable that the mishnah addresses women who are impure after the birth of a child. Women were, after all, responsible for the care of children until the age of six (see the commentary on Bavli 2/1. bBetsah 16a).
Although a woman is almost certainly implied here, again she is not specifically mentioned. Furthermore it is notable that the dragging of a wagon, an act most probably done by a woman, was halakhically permitted in contrast to the general prohibition on dragging utensils. Throughout Tractate Betsah the approved alteration of general halakhic rules can be observed for acts of labor performed by women.
[1] See also SCHWARTZ, “Child’s Wagon,” 375.