MASTER-KEY LOCKS.—The Yale Duplex Lock.— The use of a master-key, by which a number of locks can be opened by one key in the hands of a janitor or other person in charge, while none of the individual or change keys will interchange, is a feature frequently demanded for hotels and similar places. The Vale duplex system is based upon the principle of using two independ ent and complete Yale escutcheons with corrugated keys in each lock, either es cutcheon operating one and the same bolt. By making a series of these locks, in which ? all the lower escutcheons are set up to the same combination, it is evident that a key bitted to operate the lower escutcheon will be a master-key for the whole series, while, since the upper escutcheons are all set to different combinations, a key for any one of them will not operate any other cf the series. The great number of permuta tions of which the Yale lock is capable permits an indefinite extension of the sys tem, so that upward of 50,000 locks can lie master-keyed in one series, by this sys tem, to one master-key, while the security of the lock against picking or interchange of keys is not at all impaired.
The external appearance of a Yale duplex master-key mortise-latch is shown in Fig. 5.
The Corbin Lock, represented in Figs. 6 and 7, may be operated by either of two keys different in outline. The opera tion of the cylinders in connection with the drivers and pins will be rendered apparent from the illustrations. The pin-chambers in the cylinders being in line, the springs, operating through the drivers, maintain a downward pressure on the pins, in order that when the key is inserted through the slot the lower ends of the pins will enter the clefts of the key, and the upper ends of the pins and lower ends of the drivers will have a regular line of union at the meeting edges of the eylinders, thereby permitting of their rota tion by means of the key. Thus the walls of the inner end of the slot will engage the sides of the other ward, and cause the rod to rotate, thereby bringing the arm of the revoluble plate upward into contact with the tumbler and bolt, and actuating said bolt either to lock or unlock the door. The pins, upon the with al drawal of the key, will assume their normal positions with respect to each other. The minor key will be supplied to the tenants of an apartment-building, for example, and, while it will unlock the door prepared for it, it will be ineffective on any of the other doors of the build ing. the said other doors having locks in which the pins will vary in length, but all of which locks may be opened by a major key.
The Corbin Poet-Office Lock-Box was adopted by the United States Government in 1888, upon recommendation of a special committee of experts, one each from the Treasitry Depart ment, Post-Office Department, and Patent-Office. A portion of their report is as follows: "The locking mechanism of the box possesses a capability of automatic adjustment on the part of the postmaster whereby, in the event of the loss or duplication of the key furnished the box-holder, an instantane ous change of said locking mechanism may be effected by the postmaster with out the necessity of the removal of the lock-ease, and a key of different form fur nished the holder. The box itself has a
metallic front. but instead of being made of wood is constructed of sheet-steel of smooth surface, plated and lacquered. By the use of this box more space is gained for mail-matter. The lock (Fig. 8) ad justs itself to whatever key may he in serted. Any change of key will lock it, but only the key by which it was locked will unlock it. Should a postmaster wish to give a box-renter a different change of key, the lock may be unlocked by the key then in use, and the bolt pressed to the end of the lock. This leaves the key in a directly opposite position from that when it is locked. By removing the old key and inserting a new one, the bolt may be thrown. When the keys are lost and the box is locked, in order to open the box a master-key is inserted inside the box from the rear, and the bolt is thrown from position. when the new key may be inserted as de scribed. This arrangement insures to an office protection against duplicate keys." Time and flank Locks.—Hecent improvements in Yale time locks include an entire rearrangement of parts and introduction of the triple movement, or, by duplication of parts, the sextuple movement, thus avoiding the risk of " locking out One form of triple movement is shown in Fig. 9, and it is arranged so as to be used in connection with the Yale automatic bolt-olierating de vice, or a similar time-lock is adapted to be used for dogging or releasing the bolt-work of a combination-lock. Thesetitne-locks contain high-class watch-movements, and are now in extensive use. The Vale automatic bolt-operating device throws the bolt work automatically at the time indicated by the time-looks, with out requiring any external communication. This has been de vised in order to avoid the use of spindles, or any working parts extending through the door, it having been found that the introduction of liquid explosives through the joint around the spindle constituted a vital point of attack. On the automatic bolt-operating device t here is no external eommunieation whatever, the bolt-work being thrown by springs upon the Aiming of the safe or vault door, and remaining locked until a second set of springs is released at any predetermined time by means of a Hine-lock such as shown above, thus unlocking the door. (See SAFES.) Padlocks.—A solid bronze spring padlock is manufactured by the Union Lock Co., in which the shackle does not draw out like a Scandinavian lock, but is hinged and fast on one end, while the opposite or free end is securely locked by a double bolt, making it impossible to be sprung open, or opened with anything but a key expressly made for each lock, A padlock made by the Ames Sword Co., of Chicopee, Mass., and adopted by the United States Treasury for bonded cars and warehouses, is shown in Fig. 10. It is claimed to be non-pickable, and is made wholly of cast bronze. The key is double-bitted, turning indefi nitely both ways.
Locomotive Condensation : see Engines, Steam Stationary Reciprocating.
Locomotive Crane: see Cranes.