The pitch circle diameter (PCD) of a gear is a vital measurement when using gears. When you mesh two gears together, the teeth need to mesh to a precise distance, if too deep then the teeth will bind and wear, too shallow and you will get excessive back lash and risk damage to the teeth.
Burping gas that smell strongly of rotten eggs is actually indicative of the presence of sulfur in our stomach. This is the reason why this type of burps is commonly known as sulfur burps. The smell of sulfur burps or rotten egg burps usually comes from the presence of hydrogen sulfide.
Floating Eggs. Eggs can float in water when the air cell has enlarged enough to keep it buoyant. This means the egg is old, but it may be perfectly safe to use. Crack the egg into a bowl and check for an off-odor or unusual appearance - a spoiled egg will have an unpleasant odor when you break open the shell, either when raw or cooked.