848. The Various Pieces of Utensils

Shabbos 25:12

The doors of a utensil (i.e., a piece of furniture) that may be handled on Shabbos, like a box, chest or cabinet, may be carried separately from the utensil on Shabbos whether they were removed on Shabbos or before Shabbos began. Similarly, if a utensil that may be handled on the Shabbos breaks, whether before Shabbos or on Shabbos, the pieces may be handled on Shabbos so long as those pieces can be used for a purpose similar to utensil's original purpose. For example, broken pieces from a kneading trough can be used as a cover for a jug and broken pieces of glass can be used as the cover for a flask. The same holds true in comparable scenarios. However, if broken pieces cannot be used for a useful purpose, they may not be handled.

Shabbos 25:13

All utensils' covers may be handled on Shabbos so long as they are also considered utensils. If a utensil is attached to the ground, like a barrel sunk into the ground, then if its cover has a handle, it may be carried and if not, then not. Similarly, covers of wells and cisterns may not be handled unless they have handles.  The cover of an oven, on the other hand, may be carried even if it does not have a handle.