Why are reduction gear casings vented?

Venting reduction gear casings is essential to avoid a buildup of pressure within the gear case. As the gears operate, they produce thermal energy and can also generate some vapor from lubricants, especially when elevated temperatures are present. If these gases or vapors accumulate without proper venting, pressure may build up, potentially leading to seal failures or lubrication issues, which could cause damage to the gears or the casing itself.

By allowing air to escape through the vents, the internal pressure is kept at a safe level, preventing any adverse effects that could arise from excessive pressure. This also contributes to maintaining optimal lubrication conditions and ensures that the gears operate smoothly and efficiently without the risk of rupture or catastrophic failure due to over-pressurization.