Padlocks have been a great security tool for homes and businesses for a long period of time. All of us use, or at least used, padlocks to secure our family and properties against burglars and thieves. They may be one of the oldest types of lock, but they can be dependable and cost a lot cheaper compared to other types of modern locks.
Padlocks come in countless different styles, sizes, shapes and applications. It may surprise you to know that the basic principles of their function and design are all pretty much the same.
However, the bodies of certain types of padlocks (some disc or combination padlocks, for example) are made from alternative materials. Mostly the materials of padlocks have a solid metal body. The solid padlock body is by far the strongest part of the padlock and, as a general rule, the larger the body the larger and more substantial the locking mechanism can be.
The padlock body, also known as the shackle or shank, is where the u-shaped metal exits and re-enters. Whilst the body of the padlock is relatively well protected this part of the lock is exposed and therefore most vulnerable to attack. As with increasing the size of the body, incorporating a more substantial shackle into a design a considerably more secure padlock can be created. Whilst most padlocks use a spring-loaded shackle mechanism, some are incorporate a manually released shackle.
For more about padlocks and how they work, read this article: http://www.explainthatstuff.com/yalelock.html