Spool

摘要

A packing mounting groove formed in a spool has a wider portion of a large groove width and a narrower portion of a small groove width, and a packing that is mounted in the packing mounting groove has a first portion that fits in the wider portion and a second portion that fits in the narrower portion. A plurality of fixing protrusions formed concentrically on both sides of the second portion are pressure-contacted with a groove wall of the narrower portion to fixedly mount the packing in the mounting groove.