Patent GB-190608892-A (GB)
Title: Improvements in and relating to Letter-boxes.
Inventor: MITCHELL EDWIN KNOX
Filed: 1906-04-12
Granted: 1906-08-23
Abstract: 8892. Mitchell, E. K. April 12. Locks, key; keys; fastenings.-Relates to a lock fastening for letter-boxes &c. which ensures the collections being made in a predetermined order, and in which means is provided for detecting tampering. The letter-box is provided with a falling door 3, Fig. 1, which is fastened when closed by a sliding bolt 7. Lugs 8 on the bolt 7 engage with corresponding lugs 6 on the door, the bolt being operated by a handle 10. When the door is open, the bolt is retained in its unfastened position by a spring catch 14 adapted to be released on the closing of the door. The bolt 7, as shown in Fig. 3, is guided by pins 9 on the casing 2, and is provided with an upward extension 11, a slot 12 in which engages with a pin 13 passing through a slot in the casing 2 and is fixed to the underside of the bolt 50, Fig. 5, which is mounted in the lock casing 15 fixed to the front 2 of the box. The sides of the lock casing are extended forward, as shown in Fig. 6, to form a housing for a detachable casing containing the key as hereinafter described. The bolt 20, Fig. 5, is operated by the bits 26 of the key and is locked with ordinary lever locking-mechanism. In the casing is mounted a toothed disk 22, locked in any one position by a pawl 24, and provided with a dial plate 23, Fig. 6, which extends through the front plate of the casing 15. In succeeding letter-; boxes, each disk is shifted one tooth more forward than the previous one. A casing 29, Fig. 8, containing the controlling-mechanism and key is carried by the collector, and is adapted to be placed in position over the look casing 15, Fig. 6, in the housing formed by the extended sides and a grooved lip 28 thereon. When the casing 29 is in position, a pin 32, Fig. 10, on a dial plate 31 fixed to a toothed. disk 30 mounted in the casing, engages with a slot 25 in the corresponding dial plate on the casing 15, the pin 32, touching the slot at its lower end. The key bits 26 are pushed through the keyhole by means of a knob 61, Fig. 1. As the casing 29 is pushed into position, a pin 27, Fig. 6, on the front plate of the lock casing 15 enters the casing 29 and releases the spring catch 48 from the pivoted lever 42 mounted in the casing 29 and normally preventing the key from rotation by reason of a lug 46 bearing against the cam 62 mounted on the key stem. As the key turns, it operates the locking-mechanism and moves the bolt 20, the pin 13 on which travels to the end of the slot in the front 2 of the letter-box ; at the name time the cam 62 acts on the lug 46 of the lever 42 and causes the end 43 of the same to enter the slot 45, Fig. 6, in. the side of the casing 15, thereby locking the casing 29 in position ; the cam 62 also acts on the arm 40 of another lever 37, and first withdraws its tooth 39 from engagement with the disk 30, and then moves the lever 36 to advance the disk 30 by one tooth by means of the pawl 35.. This rotation of the disk brings the pin 32, Fig. 10, thereon to the upper edge of the slot 25 in the disk 23 and in position to' enter the similar disk in the next letter-box to be' opened. The pin 13 having been moved to the other end of the slot 12 in the bolt .7, the latter can be moved by the handle 10 to disengage the lugs 6 on the door which can then be opened. While the door is open, the bolt 7 is prevented from moving by the catch 14, and thus prevents the re-shooting of the bolt 20, and the consequent withdrawal of the key, so that the casing 29 remains locked in position and cannot be removed till the door is locked. When the key is turned, the several parts return to their normal positions under the action of springs. To prevent and detect tampering, the cam 62, Fig. 8, on the key spindle is provided with the arm 63, the end of which engages in the cross slot 54 in the sliding bolt 50 mounted in the bottom of the casing. The slot 54, as shown in Fig. 11, is provided with a releasing slot 55, and when the device is used in the proper manner and the key is pushed forward to its correct extent carrying the cam 62 with it, the arm 63 comes exactly opposite this releasing slot and passes out thereby without operating the bolt 50. If, however, this is not done, when the key is turned, the bolt 50 is operated therewith, and is then retained in its operated position by the arm 57 engaging teeth 56 on the bolt 50, thereby preventing the return of the key and any subsequent operation thereof. The bolt 50 can only be released by a responsible person who holds a key for the operation of the barrel lock 59 which releases the arm 57. The upwardly-extending lug 53 on the bolt 50 is adapted when the latter is shot to engage under the tooth 66 of the cam 62.