ANSWER: The lock you’re thinking of purchasing isn’t all that rare. During the Industrial Revolution in England, Midland lock makers produced them by the thousands.
As England moved slowly from an agrarian culture to an industrial one towards the end of the 18th century, locksmiths began designing locks that cost less and had more strength. But burglars kept one step ahead of them. Up to that time, only wealthy merchants could afford strong locks.
The average person had to make do with poorly made penny padlocks to protect his coal storage bin from thieves, and homeowners wanted locks for their doors and windows. With an increase in thievery, people demanded locks for everything from Bibles to carriages to schools and warehouses.
The answer to everyone’s needs was the padlock, a portable, if not somewhat cumbersome, device to protect against forced entry.
Robert Barron invented the double–acting tumbler lock in 1778. The tumbler or lever falls into a slot in the bolt which will yield only if the tumbler is lifted out of the slot to exactly the right height. Barron’s lock had two such levers, each of which had to be lifted to a different height before the bolt could be withdrawn.
Jeremiah Chubb improved on Barron's lock n 1818 . He incorporated a spring into the lock which would catch and hold any lever that had been raised too high by a lock picker. Not only did design add an extra level of security, it showed when someone had tampered with the lock.
Early padlocks offered convenience since people could carry them and use them where necessary. Historians believe the Romans were the first to use padlocks. Roman padlocks had a long bent rod attached to the case and a shorter piece which could be inserted into the case. There’s also evidence that merchants traveling the ancient trade routes to Asia and China used them to protect their goods.
Padlocks have been used in China since the late Eastern Han Dynasty, dating from 25–220 AD. Early Chinese padlocks were mainly "key-operated locks with splitting springs and partially keyless letter combination locks. Chinese craftsmen made them from bronze, brass, silver, and other materials.
Padlocks became known as “smokehouse locks” because people commonly used them to lock their meat in their smokehouses to prevent poachers from stealing it. Designed in England and formed from wrought iron sheet and employed simple lever and ward mechanisms, these locks afforded little protection against forced entry. Contemporary with the smokehouse padlocks and originating in the Slavic areas of Europe were "screw key" padlocks. These opened with a helical key threaded into the keyhole. The key pulled the locking bolt open against a strong spring. Improved manufacturing methods allowed the manufacture of better padlocks that put an end to the Smokehouse around 1910.
Around the 1850s, "Scandinavian" style locks, or "Polhem locks", invented by the Swedish inventor Christopher Polhem, became a more secure alternative to the prevailing smokehouse and screw locks. These locks had a cast iron body that was loaded with a stack of rotating disks. Each disk had a central cutout to allow the key to pass through them and two notches cut out on the edge of the disc. When locked, the discs passed through cut-outs on the shackle. The key rotated each disk until the notches, placed along the edge of each tumbler in different places, lined up with the shackle, allowing the shackle to slide out of the body. The McWilliams company received a patent for these locks in 1871. The "Scandinavian" design was so successful that JHW Climax & Co. of Newark, New Jersey continued to make these padlocks until the 1950s.
Contemporary with the Scandinavian padlock, were the "cast heart" locks, so called because of their shape. A significantly stronger lock than the smokehouse and much more resistant to corrosion than the Scandinavian, these locks had a lock body sand cast from brass or bronze and a more secure lever mechanism. Heart locks had two prominent characteristics: one was a spring-loaded cover that pivoted over the keyhole to keep dirt and insects out of the lock that was called a "drop". The other was a point formed at the bottom of the lock so a chain could be attached to the lock body to prevent the lock from getting lost or stolen. Cast heart locks were very popular with railroads for locking switches and cars because of their economical cost and excellent ability to open reliably in dirty, moist, and frozen environments.
Around the 1870s, lock makers realized they could successfully package the same locking mechanism found in cast heart locks into a more economical steel or brass shell instead of having to cast a thick metal body. These lock shells were stamped out of flat metal stock, filled with lever tumblers, and then riveted together. Although more fragile than the cast hearts, these locks were attractive because they cost less. In 1908, Adams & Westlake patented a stamped & riveted switch lock that was so economical that many railroads stopped using the popular cast hearts and went with this new stamped shell lock body design. Many lock manufacturers made this very popular style of lock.
Each lock consisted of a body, shackle, and a locking mechanism. The typical shackle is a “U” shaped loop of metal that encircles whatever is being secured by the padlock. Most padlock shackles either swung away or slid out of the padlock body when in the unlocked position. Improved manufacturing methods allowed the manufacture of better padlocks that put an end to the Smokehouse around 1910.
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