Mishnah Kelim 7:4-5

Sugya Map

• Issue: Defining the threshold of chibbur (attachment) for kitchen apparatus components, specifically regarding tum'at ohel (air-space impurity) vs. tum'at maga (contact).
• Nafka Mina: Whether a component (like a patput—pot support) is functionally integrated into the keli or merely a surface.
• Sources: Mishnah Kelim 7:4-5; Rambam, Hilchot Kelim 17:1-6; Rash MiShantz ad loc.

Text Snapshot

• Mishnah 7:4: "If [the extension] was detached from the stove, whenever it was three fingerbreadths high it contracts impurity by contact and through its air-space."
• Nuance: The Tanna Kamma hinges tum'at ohel on a minimum height of three etzba'ot. If it is lower, it lacks the functional "receptacle" status, rendering it tahor regarding ohel.

Readings

• Rambam (Hilchot Kelim 17:5): Argues that patputim (props) are inherently part of the stove's structure. His chiddush is that their functional utility in holding a pot overrides their physical detachment; if they are sufficiently high, they create an "air-space" extension of the stove itself.
• Rash MiShantz (Mishnah 7:4): Explains that if the patputim were not built by the craftsman as a single unit (mufreshet), they are only subject to impurity if they meet the height requirement, viewing them as secondary attachments rather than intrinsic parts.

Friction

• Kushya: If the patputim are lower than three fingerbreadths, they are tamei via maga but not ohel. Why does the Mishnah suggest they are more susceptible to maga if they are shorter?
• Terutz: Rambam notes that when a component is low, it is perceived as an extension of the stove's body rather than a distinct, potentially "detachable" protrusion. Thus, it loses its status as a "receptacle" (ohel) but gains the status of an inseparable part of the vessel’s body (maga).

Intertext

• Parallel: Eruvin 13b (the concept of lavud), where distances under three handbreadths create a legal fiction of continuity. Kelim here applies a similar, albeit stricter, volumetric logic to tum'ah.
• Responsa: Chazon Ish, Kelim 15:4 discusses these measurements, emphasizing that the "three fingerbreadth" rule serves as the threshold for a "functional cavity."

Psak/Practice

• Meta-Psak: The halacha follows R' Meir: the patputim retain their status as part of the stove for tum'ah purposes regardless of their number (even if four), provided they meet the spatial requirements. In modern kitchen hygiene/ritual contexts, this underscores that functional "extensions" (like stove grates) are considered part of the keli’s kudsha (sanctity/status).

Takeaway

Functional integration is a matter of dimension, not just design: if a part creates a usable space, it is a vessel; if it merely supports, it is a limb of the vessel.