Lock housing with bolt Cast ironEuropeans began casting steel in the mid-18th century. A hundred years later, the quality of ingot steel was improved using the Bessemer process and the Siemens-Martin process. Cast iron had many advantages over steel plate; it was stable and kept its shape, it was slow to rust and it was less expensive than steel, ideal for manufactured products and machines. It could be embellished, and was considered to be of higher quality and more reliable than lock housings made of steel plate. There was also a good supply of foundries and expertise. It appears to be the United States that took the initiative to begin using cast-iron lock housings; they were modeled on traditional surface-mounted types of door locks made of bronze or cast-iron with wrought keys. Yale & Towne stuck with cast-iron for their entrance door locks for 65 or 70 years before switching to pressed steel plate. The lock housings were manufactured in varying sizes, averaging about W 6.3 cm x L 10.5 cm x H 4.5 cm. Even a bit into the 1950s, when competing manufacturers replaced cast iron with steel, they more or less retained the standard housing sizes. Most of the lock housings can easily be opened for service; the bottom plate is held in place by one or two short screws. In Europe, entrance door locks were manufactured with lock cylinders that were basically the same as those designed by Yale & Towne. TechnologyAmong the older Yale & Towne entrance door locks, there are about ten varieties of bolt mechanisms; see the summary and pictures on the following pages. The lock housing contains the mechanism for transferring the movement of the lock cylinder to the bolt. The bolt can be single or double, always spring-loaded. From the outside, the cylinder lock is opened with a key; from the inside, with a knob. The turning movement of the key or knob is transferred from the cylinder to the turning mechanism in the lock housing via a flat metal rod, the spindle. The spindle fits into an end piece, with which it draws the spring-loaded bolt and opens the lock. The lock is self-locking, which many owners have had the misfortune to discover. Some locks have a small lever on the top of the lock housing that fixes the bolt in open position. Entrance door locks have been manufactured for 150 years in many countries, and even now, in 2011, new versions of this type of lock are still being made. Today’s locks and security solutions Welcome to ASSA ABLOY’s product pages for more information about today’s locks, access control, mobile keys with NFC, door automatics and more. In the ASSA ABLOY solution pages you can experience lock and security solutions for any door opening.