Part 4

=35. Common-Grade Rim and Mortise Locks.= The =rim lock=, as illustrated in Fig. 36, is generally used for buildings of the cheapest class, such as tenements and small houses. As cheapness is the controlling factor in such goods, especially the goods made for speculative building purposes, the quality diminishes with the price. For cheap work, rim locks are used on account of their low cost and because they are easily applied. They also require no trim, such as escutcheon plates, etc., and are complete when the spindle and the knob are furnished with them. Rim locks are made in various sizes and either square or rectangular in shape, the long dimension being placed either horizontal or upright. They may also be obtained with either iron or brass bolts, and are furnished with iron, tinned, or nickel-plated keys. The cheapest grades of rim locks are made with two bolts and one tumbler, while the better grades have an additional stop and a slide bolt with three tumblers.

Rim locks are generally constructed of cast-iron, and in selecting them, a careful inspection should be made of the internal mechanism, choosing only those rim locks in which the bolts and the tumblers are constructed of steel or brass. Rim locks, however, are also made of all steel, and these are coming into general use. They present a somewhat better appearance than cast-iron locks, as may be seen from Fig. 37.

The cast-iron rim lock may also be obtained with an ornamental case. These cast-iron cases, as a rule, are finished in imitation of bronze. Such rim locks, however, are not in general use on account of their somewhat higher cost, and from the fact that their appearance is not greatly improved by the ornamentation.

=Cheap mortise locks=, or =sets=, are also largely used for the more common grades of work. They are sold in sets, that is, with escutcheon plates, etc. of steel or cast-iron, both in plain and ornamental designs, as illustrated in Fig. 38. The cheapest lock sets are fitted with pottery knobs, and the better grade, with metal knobs. All of these locks described are of poor construction, as quality is a secondary consideration.

=36. Medium-Grade Mortise Locks.=—The locks grouped under the term “medium-grade” hardware have been greatly improved in recent years and are adapted to a large range of uses, but they are especially made for residence work. In dwellings of the better class, the best types of rim locks are used for doors in attics and basements, and for closet doors, but for all other doors, the =medium-grade mortise locks= are used. These locks are provided with cast- or wrought-bronze lock fronts, are made with from one to three lever tumblers, and have drop-forge steel cases. The locks are constructed with easy springs, which allow the latch bolt to retreat within the case on one light spring when the door is closed, and when the knob is turned, to operate the latch, both springs act jointly in order to overcome the friction of the knob and to throw the bolt back to central position. The mechanism of an easy-spring, mortise knob lock is illustrated in Fig. 39.

In the group of locks embodying those of medium quality are included the three-bolt locks used for chamber and exterior doors, locks for communicating doors between chambers, and twin, or two-bolt, locks for twin bathroom or toilet-room doors, these being respectively illustrated in Fig. 40 (_a_), (_b_), and (_c_). All of these locks should be used with wrought- or cast-bronze trim, either plain or in design, and in finishes to suit. Locks for exterior doors, where security is important, should be selected with this object in view, and three-tumbler, or three-bolt, locks should be used.

=37. High-Grade Locks.=—There are a number of high-grade door locks and latches in the market for the equipment of first-class buildings, and frequently these locks are especially constructed to meet particular requirements. Among such locks are included, besides high-grade, three-tumbler locks, those that embody the cylinder principle and those that are equipped as master-key locks.

The =unit-cylinder lock=, illustrated in Fig. 41, is made by P. & F. Corbin. This hardware specialty is a new departure in lock making. The mechanism of the lock is contracted into the smallest possible space, occupying only about 1½ in. × 3¼ in. Instead of being mortised into the stile of the door, as is usual with the mortise lock, a piece is cut entirely from the stile, as illustrated in Fig. 42. In order to prevent this operation from weakening the stile of the door, the unit-cylinder lock is provided with heavy escutcheon plates that are strongly ribbed on the back, so that when these plates are secured to the stile at the top and bottom, they supply the rigidity necessary to make up for the notching. As the name implies, these locks are made in a unit, and the keyhole to the cylinder lock is located in the knob. The unit-cylinder lock is made in two styles—with dead-locking latch bolt and with additional dead bolt.

=38. High-Grade Interior Door Locks.=—In Fig. 43 is shown a type of high-grade, =mortise-locking latch= for interior doors. These locks are of the heaviest construction, and are fitted with either brass or bronze fronts. The bolts are operated with two or more tumblers constructed on an improved pattern, and are of fine workmanship. The trim for a lock of this character should be of the very best grade, with knobs of the screwless-spindle type, which will be explained later.

The escutcheons should be of the high-collar or the bracket-bearing type, and should conform to the character of the locks in quality and finish. On the most important work, it is always expedient and usually feasible to obtain expert advice from manufacturers or from dealers representing the manufacturer, whose intimate knowledge of the product will be of great assistance to the architect or owner in making suitable selections. The use of high-grade hardware requires a considerable expenditure, and the necessity for expert advice consequently becomes more imperative if the best results are to be obtained.

=39. Master-Key Locks.=—The type of lock known as the =master-key lock= is generally used for public or office buildings, hotels, and occasionally in the better class of residence work. These locks can be grouped into two classes; namely, the _Yale_, or _cylinder_, and the _lever-tumbler types_, the class first mentioned being the most desirable.

In the lever-tumbler type, illustrated in Fig. 39, the tumblers, or wards, are so arranged that each lock can be operated only by its particular key, the keys for all rooms being different and non-changeable; all of the locks, however, can be operated by a key made for the purpose, termed a =master key=. Each lock of this type has two sets of tumblers; one set is operated by its individual key, and the other, being uniform in all locks of the series, is acted on by the master key. Such locks may be obtained either in the cheaper kind, with one tumbler and twelve changes, or in the most intricate styles of hotel locks, with five tumblers and 48,000 changes in one set, and all operated by one _master key_. The cylinder lock of this type is illustrated in Fig. 44, which shows a Yale & Towne, mortise, front-door lock.

=40. Details of the Yale Type of Master-Key Locks.= The =Yale= type of cylinder lock, which is illustrated in Fig. 45 (_a_) and (_b_), is much preferred, on account of the great security it gives and the small key required by it. This lock is made in three systems; namely, the _regular_, the _concentric_, and the _paracentric_, or _duplex_.

In the =regular system=, one regular cylinder is controlled by the change and master keys, the pin tumblers being cut in two places, so that the change key brings one set of the abutting planes of the tumbler in alinement with the surface of the cylindrical plug. This plug is arranged so that a separate key is required to operate each lock, the other line of cleavage through the blocks being the same with all locks throughout the series, so that they may be opened with the same key.

The =concentric cylindrical arrangement= of this type of lock is shown in Fig. 46 (_a_) and (_b_). Here, there is a larger cylinder encircling the key plug. This is known as the master-ring, or larger, plug, and is indicated at _a_. When the change key is inserted in the key plug _b_, the lower series of breaks in the pins comes into alinement with the outer edge of the plug, as shown at (_a_), and allows it to revolve in the master ring, the cam on the inner side at _c_ actuating the lock. When the master key is inserted, the upper series of breaks comes into alinement with the outer edge of the master ring, as shown at (_b_), allowing the plug and the ring to rotate together with the turning of the key, and thus to produce the same result as that caused by the operation of the change key.

The =paracentric system=, sometimes called the _duplex system_, consists in having two separate cylinders to each lock, as illustrated in Fig. 47. One of these cylinders, generally the upper one, is operated by the change key, and the lower one, by the master key. The interior construction of the lock is so devised that each key performs the necessary function of operating the same bolt, so that the individual lock may always be opened by the change key, and all locks of the series by the master key. This latter system of lock construction is more expensive than the one-cylinder type, but it possesses an advantage in that it provides greater security when a limited number of locks are grouped in one series.

=41.= Owners or officials of large office buildings and industrial works now avail themselves of the master-key system just explained. They are able to obtain mortise locks, rim locks, and padlocks, all arranged to operate with a master key, in one series. In fine residence work, this system is also adopted. Such a system of locking is easily recognized as convenient, especially where subordinates are held responsible for certain rooms or departments to which they, individually, have access, as all of the rooms or departments may be entered by the manager or superintendent by the aid of the master key.

A series of master-key locks may also be “submaster-keyed” by dividing it into subordinate groups. In such a case, each group is operated by a master key of its own, and all the subordinate groups are controlled by a grand master key. For example, a six-story office building could be furnished throughout with locks having non-changeable keys; the doors of each floor could be operated separately by a master key; and the doors of the entire building could be operated by a grand master key. The convenience of such a system is readily apparent in large buildings where each janitor is responsible for a certain floor, and where the head janitor, manager, or owner, has control of all the locks through the grand master key.

In some instances, for additional security and for special work, the corrugations in the keyway are changed in shape so that the manufacturers’ regular type of key will not enter the keyway, or plug, thus allowing no chance for the regular type of key to operate the lock.

=42. Locks for Residence Use.=—The =front-door lock= is distinctly a lock having two bolts; namely, a _dead bolt_ and a _latch bolt_. The latter is operated by the knob, and is so arranged that, by means of stop-work in the lock front, the outer knob may, at will, be set so as not to operate the latch, the latch bolt being operated only from the outside by a key.

The cylinder type of front-door lock illustrated in Fig. 44 is the best lock for this purpose, as it provides the greatest security. This lock is operated by a convenient key of the Yale type, which throws both latch and dead bolt with one insertion into the cylinder.

Three-tumbler, front-door locks and latches are to be had at a low cost, and are used in the cheaper class of dwellings. When the residence has an inner, or vestibule, door, a similar lock is used without the dead bolt; this lock is termed a _vestibule latch_. In all cases the vestibule lock should “key-lock” with the front-door lock, so that one key will operate both. The other exterior doors of a residence should have either Yale locks master-keyed to the front door, for the better class of work, or locks of the 5-inch, three-bolt variety, that are furnished with an extra bolt in addition to the dead bolt, the third bolt being operated by a thumb knob on the inside. When a cheaper trim is wanted, a 4-inch, two-bolt lock, supplemented by a separate mortise or rim bolt, may be used.

For the first- or parlor-floor folding doors, 4- or 4½-inch, two-bolt, mortise locks are ordinarily employed. Where the doors are sliding, a 5½-inch, sliding-door lock with dead bolt and pull, or handle, is provided. The pull, or handle, is operated, or thrown out, when needed by pushing a button, or stop, in the lock. This special type of sliding-door lock is illustrated in Fig. 48.

For bedroom doors, a lock similar to that used on the minor exterior doors is usually employed. The lock for these doors may be either a 5-inch, three-bolt lock, or a 4-inch, two-bolt lock supplemented with a mortise bolt. For communicating doors, it is best to use a three-bolt, knob lock, the latch bolt of which is operated by the knob from either side. Arranged above or below this latch bolt are two dead bolts, each being operated by its respective thumb piece on opposite sides of the door. Locks of this character are made for both swinging and sliding-doors.

=43. Locks for Twin-Closet and Other Interior Doors.=—Twin, or double, doors are sometimes used between rooms in residences to deaden sound or to increase privacy. Such doors should be fitted with the same type of lock as other communicating doors, except that the lock should be provided with two bolts, the same as the lock used for bathroom doors. These locks are arranged with special trim on the abutting face of each door, this trim having only a slight projection, and knobs or lever handles projecting as little as possible, in order to avoid interference on account of the limited space between the doors. Bathroom doors are best fitted with a thumb bolt, either combined with a lock or separate.

In fitting closet doors, it is best to use a two-bolt lock about 4 inches in size, with trim on both sides, so that the door may be operated from inside in case it is accidentally closed on a person in the closet. The possibility of this happening is slight, and usually a saving is effected by using a knob latch without a dead bolt and a pair of knobs with roses.

For basement or attic doors, a cheap type of mortise lock is appropriate, or a rim lock may be used, if cost is a consideration. Where care is exercised in the selection of locks in any one building, great convenience will result from having all the different class of locks about the building of the same grade, so that they may be master-keyed in one set and thus give the owner control, with one key, of all the locks. Each lock, however, will have its own individual, or change, key, and should be selected and ordered with this object in view. Another convenience may be had by ordering each room and closet door keyed alike throughout the house, or alike throughout each floor, so that the loss of a key will cause little or no inconvenience.

=44. Hotel and Office Locks.=—The purpose and use of master-keyed locks has already been explained, but the employment of such locks in large groups, as in the equipment of hotels and office buildings, requires further discussion. The term _corridor door_ designates the entrance from a corridor or a hallway to a bedroom or an office, while _communicating doors_ are those between adjoining rooms. Frequently, these doors are double, and are then known as twin doors, while the term _closet doors_ is self-explanatory. Each of these doors requires a _knob lock_; that is, a lock having the latch bolt operated by the knob and the dead bolt operated by a key. Sometimes, in the case of locks on closet doors, the dead bolt on communicating-door locks is omitted, and a thumb bolt substituted. While all of the locks thus far enumerated are used in hotels, and most of them in office buildings, technically speaking, a _hotel lock_ is a master-keyed knob lock for doors from the corridor to bedrooms, while an _office lock_ is an inverted lock; that is, a lock with the keyhole above the knob. These latter locks are usually master-keyed, especially for the doors from the corridor to the office. Such locks as these may be master-keyed on any of the systems, as previously explained. For office work, a small key is desirable, so that cylinder locks are ordinarily employed, as the key for the operation of such locks may be conveniently carried. For hotels, however, a high-grade lever-tumbler lock with round, substantial keys is desirable, because the keys are liable to hard usage, and should not be convenient to carry in the pocket.

Hotel keys vary widely in arrangement, as well as in size, quality, and price. The kind of action, or mechanism, to be adopted in a hotel lock is frequently determined by the preference and experience of the hotel manager, and it is desirable that he should be consulted in advance; but the location and use of each door should be considered in the selection of the locks for this character of building. It will thus be seen that the subject of hardware for a hotel is one that requires the most careful consideration of the architect.

The grouping of locks in a hotel should be studied, and, usually, the best plan in large hotels is to group all of the locks on each floor under one master key and to provide a different master key for each floor, care being taken to limit the issue of master keys to the smallest possible number of responsible persons. In some cases, a grand master key is also provided that will open all the locks on every floor. This arrangement of the locks entails an additional expense, and also has the disadvantage that, in case the grand master key is lost, all of the locks controlled by it should at once be set to a new combination, in order to prevent access by the person into whose hands the key has fallen. This procedure is both troublesome and expensive.

The foregoing remarks relating to hotel locks apply equally to office locks, especially as to the arrangement for the operation with the master key. In other respects, however, the locks for an office building differ considerably from those used in hotels, for a hotel lock must secure the door both when the room is occupied and when it is not, whereas an office lock is used chiefly to secure it when not occupied. In consequence of this, certain differences in action are employed. All office locks have a latch bolt that is operated by the knob from both sides and yet permits free ingress and egress. Various methods, however, are employed to lock the door against ingress except by means of a key. Sometimes this is accomplished by means of a separate dead bolt operated by a master key from either side; in other cases it is accomplished by a latch bolt only, by providing the latter with a stop-work like a front-door lock. By this arrangement, the outer knob may be stopped so that the latch bolt cannot be operated from the exterior except by the key; and, again, the latch bolt may be dead-locked from the outside by the key. The choice of these arrangements is a matter of personal preference.

=45. Store-Door Trim.=—The technical term =store-door lock= originally designated a heavy rim or mortise dead lock, but is now applied to a combined lock and latch, the former being operated by a key from either side, and the latter by a thumb piece located above the pull handle. Such locks are made in a large variety of sizes and styles, the best being of the cylinder type, as shown in Fig. 49. In this lock, the latch is operated by the thumb piece during the day, while the dead latch secures the door at night.

Plates and handles for the combined store-door lock and latch are also made in many sizes and styles, from the plain rectangular type to the most ornamental forms. Such trim offers good opportunity for effective decoration, and no embellishment is so effective for a store’s entrance door as a pair of handsome plates and handles of appropriate design. For such trim, it is not uncommon to provide an outlay of from $25 to $30 per door. Some of the more elaborate store-door handles are illustrated in Figs. 50 and 51. The trim illustrated in these plates is very carefully selected by the architect to match the style of architecture in which the building is designed, and the finish is selected with as much care.

=46. Padlocks.=—While =padlocks= are not ordinarily included in builders’ hardware, they are extensively used for factories, stables, and other buildings of this character; thus some care should be taken in their selection. Padlocks are made in a great variety of sizes, styles, and qualities, and retail at prices ranging from 10 cents, or less, to $5. Where these locks are exposed to moisture or to the weather, they should be of bronze or of brass, with all of the interior construction of the same material. If required for great security, that is, for places where they are likely to be subjected to violence, they should be very heavy, and preferably provided with steel shackles. Padlocks constructed on the cylinder-lock principle may be obtained, and should always be used where a series of locks that are operated by separate keys and controlled by a master key is employed. Ordinarily, a selection of padlocks should be made only after an inspection of the actual samples, and not according to catalog representations.

=47. Cabinet Locks.=—The locks used in cabinetwork are distinct from builders’ locks, though they are occasionally used in the construction of the finer classes of interior finish, and, consequently, are of interest to the architect. =Cabinet locks= are made chiefly of wrought metal, and in a vast variety of kinds, sizes, and grades, so that care should be exercised in their selection. The leading kind of cabinet locks are drawer, or till, locks; wardrobe, or cupboard, locks; and chest, box, and desk locks. Special locks are also manufactured for many other purposes. For the best work, the Yale, or pin-tumbler, type is desirable where great security is required, but for ordinary uses, other types, with either flat or round keys are available. Many of the cabinet locks admit of being master-keyed, and such locks are employed on lockers in club rooms, armories, etc.

=48. Asylum and Prison Locks.=—For the doors of cells in insane asylums, hospitals, and prisons, locks of special construction are required. For this reason, a distinct class of hardware is manufactured to meet the peculiar conditions that prevail. These locks, which are designed primarily to prevent escape from the rooms, or cells, are exceptionally exposed to attempts at tampering, and are especially constructed to meet these conditions. There is an extensive line of locks for these uses on the market. This line includes both the Yale type and the lever-tumbler type of lock, and these locks are constructed with both solid and barrel keys, thus affording a wide range of selection. All such locks must be made so as to be controlled by master keys.