Post 154 ⇒ by Gautam Shah ➔
Lock is a device that prevents access by those without a key or method to open it. It is nominally a self-sufficient entity, housed in a small chamber that houses its mechanism. Locking devices are of two types: One which can be used to lock and open an opening from same side, and Two which can be opened from either side.
Locking devices have been in use for securing the end of the ropes in loops, but lock for security purposes (such as for doors)were perhaps wedges or knots (such as: a thief knot, Gordian knot) on fibre ropes. Egyptians were perhaps the first users of wooden Locks and keys, some 4000 years ago. The first locks were like puzzles that wasted thieves’ time.
Early Pin locks had toothed or serrated keys that activated matching levers. Later improvements included increasing the number of pins to increase security, and changing the orientation and profile of the pins. This established the principle of the modern pin tumbler lock.
Locks are mostly mechanical, but now electro-mechanical and electronic locks are available. New locks get a combination of commands through nodes in a printed circuit board, varied electric current, or a digital messaging system which activates the lever system.
All locks are not intended to prevent unauthorised access through an opening system, but some are used to control the accidental opening or closing of a door system.
PADLOCKS ⊗ Padlocks are portable locks, with their own body and foldable or a separable locking ring. Padlocks can be used over another ring or shackle, or with a chain to tie up separate objects. Ordinary padlocks are susceptible to direct attack to break the shackle or tie chain, without the use of a key or a combination. Padlocks are used to tie up the wrapped around ropes on goods bundles or packages.
LEVER LOCKS ⊗ Levers Locks are flat set of grooved or edge shaped devices which can be rotated or pushed by a matching key to operate or activate a mechanism. Insurance companies, police department and other security agencies desire at least a 5-lever lock for external doors of home security system.
MORTICE LOCK ⊗ Mortice (Mortise in American English) is concealed into a cavity (mortice section) in the stile or thickness of the door shutter. A square section pin projects out on one or both the faces to receive the operative handles. Older mortice lock had a large box, but new generation mortise locks are cylinder locks fitted from the front and back. The locking pin could be one or multiple that come out on the side of the door. The locking device is operated through a key, and an additional bolt -a closing device through a set of handles. The locking pin is square ended but the closing pin is tapered on one face for self closing. Night or safety locks have an extra slider which stops the lock being operative with key from outside. Installation of a mortise lock weakens the structure of the typical timber door, but it is stronger and more versatile than a bored cylindrical lock.
CYLINDER LOCK ⊗ Cylinder locks have the locking mechanism and bolting as two separate systems. Such locks are also available as sets which can be opened by their individual keys and also by a master or common key. Standard cylinder systems include key-in-knob-set cylinders, a rim (also known as night-latch) cylinders. Cylinder locks are small in size and diameter, and are fitted from front and back side of a door shutter, rather than from the edge of a door stile (as in case of mortice lock), so are easier to fit and replace.
ALMIRAH LOCKS ⊗ Almirah locks are found on commercial Mild Steel sheets (CRCA) cupboards. The Locks are housed in a box fixed on the inside face of a shutter. The closing device has three components, a locking lever that is moved through a handle, and accompanying it is two vertical locking bars that move upward and downward. Such devices are also concealed on a street side of main doors of buildings for additional security purposes.
COMBINATION LOCK ⊗ Combination locks are operated by setting a sequence of numbers or symbols, instead of a serrated key in a nominal lock. The sequence is entered by a single rotating dial which interacts with several discs or cams, by using a set of several rotating discs with inscribed numerals which directly interact with the locking mechanism, or through an electronic or mechanical keypad. A combination lock requires a correct permutation and not merely the correct combination of digits. Electronic combination locks are better then their mechanical counterparts. Such locks are used on safes and drawers. Electronic locks work with power-assisted mechanisms. The key combination can be reset, such as for modern Hotel rooms. Floor managers get a combination that can work for all locks of a floor or zone. Such locks are often connected to a central access control system of the plant or building complex, reporting its use.
- ‘The first known combination lock was invented in 1206 by the Arab scholar, inventor and mechanical engineer al-Jazari. He documented the device in his book al-Ilm Wal-Amal al-Nafi Fi Sina’at al-Hiyal (The Book of Knowledge of Ingenious Mechanical Devices). Muhammad al-Astrulabi (ca 1200) also made combination locks, two of which are kept in Copenhagen and Boston Museums. Gerolamo Cardano later described a combination lock in the 16th century. In 1852 a German man by the name of Joseph Loch was said to have invented the modern combination Lock for Tiffany’s Jewellers in New York City. However the rights to his invention were stolen from his business associate who thereby attained all credit of the discovery’.