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A tubular lock and key. A tubular pin tumbler lock, also known as a circle pin tumbler lock, radial lock, or the trademark Ace lock popularized by manufacturer Chicago Lock Company since 1933, is a variety of pin tumbler lock in which a number of pins are arranged in a circular pattern, and the corresponding key is tubular or cylindrical in shape.
The first known example of a tumbler lock was found in the ruins of the Palace of Khorsabad built by king Sargon II (721–705 BC.) in Iraq. [1] Basic principles of the pin tumbler lock may date as far back as 2000 BC in Egypt; the lock consisted of a wooden post affixed to the door and a horizontal bolt that slid into the post.
Interchangeable cores require a notch at the tip of each key to properly align the peaks and valleys of each blade with the combinating pins in the chambers of the mechanism; as a consequence, these keys are always configured and cut from blade tip to bow. Conversely, conventional cylinders and removable cores use a shoulder near the bow of ...
When the different length key pins are aligned at their tops by the insertion of the correspondingly cut key at their bases, the tops of the key pins and, consequently, the bases of the driver pins, form a shear line, so that the cylinder can be turned, rotating the key pins away from the driver pins. When no key or the wrong key is in the lock ...
Most wafer tumbler locks with poor tolerances can be opened with a set of jigglers or try-out keys. These sets of keys are designed with the most common patterns of key available. The key is inserted into the lock like a normal key, and a turning force is applied whilst the key is raked back and forth until the lock opens.
The very first mass production using interchangeable parts in America was Eli Terry's 1806 Porter Contract, which called for the production of 4000 clocks in three years. [18] During this contract, Terry crafted four-thousand wooden gear tall case movements, at a time when the annual average was about a dozen. [ 19 ]
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For example, master keyed pin tumbler locks often have two shear points at each pin position, one for the change key and one for the master key. A far more secure (and more expensive) system has two cylinders in each lock, one for the change key and one for the master key. Master keyed lock systems generally reduce overall security. [2]