Bramah Locks and Keys
The complete Bramah lock can be disassembled into the following parts:
- A brass back plate and lock surface plate. From 1798, these surface plates are marked ‘I [or] J. Bramah’ with the monarch’s crown, or ‘Bramah – 14 [or] 124 Piccadilly’ with or without the monarch’s crown. From 1871, these surface plates are marked with either ‘J.T Needs & Co. Down Street, Piccadilly, W’ (1871-c.1875), ‘J.T Needs & Co. 128 Piccadilly’ (c.1875-1887) or ‘J.T Needs & Co. 100 New Bond Street – Late J. Bramah 124 Piccadilly’ (1887-1904) all being accompanied by the monarch’s crown. Blank lock surface plates or those bearing the terms ‘Bramah[s] Patent’, ‘Patent’, ‘Bramah – London’ etc. are copies manufactured after the original patent expired in 1812.
- A turned brass central cylinder containing a number of intricately cut, folded steel sliders, a cylinder back plate with a pin, a central spring, and a brass collet that fits over the pin. Note: Most Bramah box locks have an inset stud on the rear of the cylinder back plate, however, self-locking versions, as well as some standard versions used a cylinder arm instead – see ‘Operating a Bramah Lock’ below for explanation.
- Two halved steel incised locking plates that engage with the central cylinder and steel sliders.
- A turned brass lock mount and front aperture unit.
- A brass or steel sliding bolt, with or without an attached guide plate. Note: Self-locking Bramah locks didn’t require a guide plate.
- A brass sliding bolt support bracket that attaches to the back plate. Note: Self locking Bramah locks weren’t often manufactured to require this bracket.
- A mounted steel spring that attaches to the back plate. Note: For many standard Bramah locks this spring is mounted underneath the sliding bolt however, for the self-locking Bramah locks this spring is mounted to the right of the sliding bolt.
- A brass or steel link plate that engages with the sliding bolt.
- A key with incised bits at varying different depths at the end of the barrel.
- The key enters the front lock aperture, guided onto the pin; the incised bits at the end of key barrel engage with the spring-loaded steel sliders. These sliders are incised at exact points to correspond with the incised bit depths of the key. When the key is properly pushed in, the slider incisions all align together, allowing the halved steel locking plates surrounding the central cylinder to be unobstructed. The central cylinder is now rotatable.
- The key can now be turned anti-clockwise, rotating the central cylinder that is either, inset with a stud on the cylinder back plate that engages with the guide plate of the sliding bolt, or, affixed with an arm that engages with an incised ridge on the sliding bolt.
- The sliding bolt is deployed at about the 0-180 degree mark and moves from right to left in most cases. Note: For self-locking Bramah locks, the key is turned clockwise by about -45 to -90 degrees; this action rotates the central cylinder and cylinder arm that then engages with an incised ridge on the lock slider, pushing it back against the mounted steel spring, thus disengaging the lock mechanism. The sliding bolt will automatically spring back into its locked position as soon as the pressure from the key turning action is released.
- With the sliding bolt now in the locked position, the key can complete its anti-clockwise turn back to its initial insertion point, where it can naturally ‘pop’ out from the front lock aperture using the initial spring-loaded mechanism behind the sliders.
- Unlocking the Bramah lock is a simple case of reversing the locking procedure; the key is re-inserted, pressed in, and turned clockwise by 360 degrees to its initial insertion point. The key will again ‘pop’ out from the front lock aperture.
