| 摘要 |
<p>A torsional damper mounted to a crank shaft of an internal combustion engine has a hub provided with a rim portion and a fixing portion, and a boss welded to the rim portion. A mass body is arranged in an outer side of the rim portion via a cylindrical elastic body. A seal element of an oil seal mounted to an engine assembly makes contact with an outer circumferential surface of the boss. The hub 11 has a carbon equivalent of 0.5% or less, and a boss has a carbon equivalent of 0.5% or less and a carbon content of 0.2% or more. Induction hardening is applied to a portion of the boss with which the oil element makes contact.</p> |
