Naming and History of Padlocks
– The term ‘padlock’ originated in the late fifteenth century.
– The prefix ‘pad-‘ is believed to be related to the Latin word ‘ped’ which refers to the portability of a padlock.
– ‘Pad-‘ is combined with the noun ‘lock’ from Old English ‘loc,’ related to German ‘loch,’ meaning hole.
– Padlocks dating back to the Roman Era, 500 BC – 300 AD, have been discovered.
– Merchants traveling the ancient trade routes to Asia, including China, used padlocks in early times.
– Padlocks have been used in Europe since the middle La Tène period and spread to the Roman world and other cultures.
– Chinese padlocks from the late Eastern Han Dynasty were mainly key-operated locks with splitting springs and partially keyless letter combination locks.
– Different materials such as bronze, brass, silver, and others have been used to make padlocks throughout history.

Components of a Padlock
– A padlock consists of a body, shackle, and locking mechanism.
– The shackle is a U-shaped loop of metal that encloses what is being secured.
– Padlock shackles can swing away or slide out of the body when unlocked.
– There are two basic types of locking mechanisms: integrated and modular.
– Integrated locking mechanisms directly engage the padlock’s shackle with the tumblers.

Viking Age Padlocks
– Viking Age padlocks have been found at archaeological sites such as Birka.
– These padlocks were made of iron and had a long bent rod attached to the case.
– The rod could be inserted into the case and the sleeve for added security.
– Viking padlocks were designed to be durable and resistant to forced entry.
– They played a crucial role in securing valuable possessions during the Viking Age.

Modern Padlock Designs
– Scandinavian-style padlocks, invented by Christopher Polhem, became popular in the 19th century.
– These padlocks had a cast iron body and a stack of rotating disks for enhanced security.
– Cast heart locks, shaped like hearts, were stronger and more resistant to corrosion.
– Machined body padlocks, made from a solid block of metal, were introduced in the early 20th century.
– The laminated padlock, invented by Harry Soref, gained popularity for its low cost and impact-resistant design.

Types and Resistance of Padlocks
Combination locks do not use keys and open when the wheels are lined up correctly.
– A padlock invented by John I. W. Carlson in 1931 had both a combination and a key.
– Electronic padlocks can be active or passive.
– Active electronic padlocks can be rechargeable or have replaceable batteries.
– Passive electronic padlocks do not require electricity and can be unlocked with a programmed electronic key.
– Steel cable padlocks have a variable length locking mechanism limited by the cable’s length.
– They have a wider range of uses compared to other padlocks.
– The cable is bent and passed through a hole to lock it at the desired length.
– Organizations like ASTM, Sold Secure, CEN, and TNO determine the tensile strength and resistance of padlocks.
– Tests are conducted to measure forced and surreptitious entry.
– These tests provide a quantitative measure of a padlock’s security level.Sources: