Bless Our Good-Old Locksmiths
The padlock hole goes unnoticed by most, and some who do notice wave away its purpose as non-existent or insignificant. However, the opening under the lock plays a crucial role in preventing internal rusting.
It provides an outlet to water and moisture content that enters the lock’s insides due to rain or snow. The water could rust the insides, prompting intricate contraption to jam. The hole ensures that there is neither corrosion nor rusting. You can also remedy any jamming with some lubrication and use oil to treat the issue.