Fig. 53
There are numerous other patterns of asylum and prison locks, such as those illustrated in [Fig. 53]. The lock shown at (a) is arranged to operate with a double-bitted key, while the one at (b) is operated by means of a Yale key.
Nearly all modern locks for this purpose are operated with either double-bitted or Yale keys, and those in common use are cylinder locks. Information regarding these types of locks should be obtained in advance, so that in preparing the plans and specifications, the type selected may be clearly indicated and the arrangements made for any special construction necessary to receive them. As the approved forms of asylum or prison locks are built in the masonry during construction, they must be delivered during the early stages of the erection of the building.
49. Bank and Safe Locks.—Locks for the doors of burglar-proof and fireproof safes and vaults constitute a group distinct from all others. These locks embody the most complicated mechanism, and represent the highest art of modern lock making. The architect in preparing plans of buildings for banks and trust companies is frequently called on to approve or to specify the fastenings for vault and safe doors. While the owners of such buildings will probably predetermine the kind of lock to be employed, nevertheless they will be guided by the advice of the architect in the selection of some particular make. The locks used on such vaults and safes comprise time, or chronometer, locks; dial, or combination, locks; and safe-deposit and subtreasury locks. There is also a device known as a bolt-motor, or automatic lock, which is an allied product. In the manufacture of these special locks, the skill of numerous experts and specialists is required, and as their knowledge is at the disposal of the architect or the engineer, they should be consulted in the selection of such important pieces of mechanism.
Fig. 54
The time lock is illustrated in [Fig. 54], and is a locking device actuated by clockwork. This type of lock is used in connection with the heavy boltwork of a safe door, to prevent it from unlocking except during certain hours determined beforehand. This lock is now recognized as an essential part of the equipment of all first-class, burglar-proof vaults and safes. In its standard form, the time lock has three chronometer movements of the finest construction, each of which is competent to actuate the lock, so that, in this way, almost absolute reliability is insured.
Fig. 55
A dial, or combination, lock is shown in [Fig. 55]. The combination commonly called the dial lock has completely superseded the key lock for use on safe and vault doors. Essentially, the dial lock consists of a bolting mechanism guarded by a set of changeable tumblers, or wheels. These tumblers are actuated by a spindle passing through the door, this spindle being provided on the outer end with a graduated dial. By rotating the dial in a certain manner, the dial can be set and the lock operated. Dial, or combination, locks are made in two grades, or varieties, designed respectively for burglar-proof and for fireproof safes. The lock intended for burglar-proof purposes is heavy and made to resist violence, while the other locks are smaller, simpler, and cheaper, intended only to secure the door against ordinary intrusion. Both of these locks should be absolutely “non-pickable.”