| 摘要 |
<p>PURPOSE: To restrain surface pressure and wear of a lifter and further prevent the lifter edge from uneven wear while the lifter diameter is compacted by ensuring the contact range of a nose part having nearly the same area as that in the use of a cam without an admission groove even if the admission groove for making a stem end escape to the cam is provided. CONSTITUTION: A stem end 24 is admitted in an admission hole 30 in the upper surface of a lifter 25 and projected above the lifter to set an intake and exhaust valve 22 to the resting condition. A cam 1 used for a valve system mechanism with this resting mechanism is provided with a circular base part 2, nose part 3 and admission groove 4 formed in at least the nose part 3. The cam width is gradually widened from the elevated halfway part 3b of the nose part 3 contacting the largest offset position Eb most spaced from the center position Ea of the upper surface of the lifter 26 to the most elevated part 3a contacting the center position Ea of the upper surface of the lifter.</p> |
