This section is from the book "Modern Buildings, Their Planning, Construction And Equipment Vol6", by G. A. T. Middleton. Also available from Amazon: Modern Buildings.
Locks can also be made with two, three, or four degrees of mastership; that is to say, they can be divided into sections, sub-sections, and divisions of subsections. Each division has its master key, which we will call a divisional master capable of unlocking all doors in the section, and also of locking out all the other separate keys; each subsection has a sub-sectional master capable of unlocking all doors in its subsection, and of locking out the divisional master and ordinary keys; each section has a sectional master capable of unlocking all doors in its section, and of locking out the subsectional and divisional masters and ordinary keys; while above all is a grand master key, capable of unlocking the whole of the doors and also of locking out all keys below it.
Messrs. Colledge & Bridgen's "Securitas" patent check-action mortice locks are made to differ and master as required, and in this lock the grand master key is made larger than the ordinary keys, and it is therefore impossible to convert an ordinary key into a grand master key by filing.
Fig. 193, A, represents a shop door latch with lever handles. These are made either locking (as illustrated) or non-locking. The form of handle shown is one largely used for ordinary door locks on the Continent, and has the advantages that it is easily grasped and is capable of highly artistic treatment; but on the other hand, it is obtrusive and apt to tear the clothing of persons using the door. Ornamental Suffolk latches (B) are now largely used for shop doors.
Door furniture should be well and substantially made, of suitable materials and design for its particular position. Beyond this it is a matter for individual selection; but a word is necessary on the methods of attachment of the handles of ordinary door furniture. There are now so many simple and effective devices for making these perfectly secure and preventing their working loose that it is quite inexcusable in good work to use the old-fashioned method, which consisted of a set screw in the neck of the handle engaging a sinking on the spindle (see Fig. 193, C). After a very short time these handles work loose, and are a continual source of annoyance. A very simple and effective method of fixing is shown on Fig. 193, D, known as Mace's. The spindle is threaded on the angles, and two opposite sides are grooved. The method of fixing is as follows: The rose is placed in position but not fixed; the handle is then screwed on as far as is required, with the hole for set screw " A " opposite one of the grooved sides of spindle; the set screw is next inserted through the corresponding hole "B" in the collar of rose and screwed up tight; the rose is then turned round so that hole "B" is not opposite to set screw "A," and is screwed on to door in that position, so that it is impossible for the set screw to work loose. Fig. 193, E, shows "Nettlefold's" method, which it will be seen is similar to Mace's, but that the rose is in two parts, the outer portion being screwed on over the plate which is fixed to the door, thus both obscuring and securing the fixing screws.
The "Stanley" (Fig. 193, F) and the "Tudor" (G) lock furniture are two methods of dispensing entirely with the small set screw. The "Stanley" has a hinged wedge in the collar on the neck of the handle, which fits into cross grooves on the spindle. When the handle is in the required position the rose is turned round until the half flange on it covers the wedge and holds it firmly in place, when it is screwed to the door. In the " Tudor "the collar on the neck of the handle and the adjustable collar on the spindle are each provided with flanges which are held together by the groove in the hinged rose. The " Stanley " is slightly more expensive than Mace's, and the "Tudor" considerably more so. There are other devices for securely fixing the handle to the spindle, but all cannot be described here.
An ordinary Norfolk or Suffolk latch is illustrated at (B), Fig. 193. It is the common form of latch for coal-house and outhouse doors, etc., but is adaptable to a variety of designs in various metals for more important positions. In good work nothing commoner than a plain wrought-iron latch should be specified for any position. Some of the cheap cast-iron varieties are absolutely worthless, although a serviceable latch is produced in malleable cast iron.
A tower bolt, a barrel bolt, a cranked tower bolt, a cranked barrel bolt, and a flush bolt, are illustrated respectively at A, B, C, D, and E, on Fig. 194. An indicating bolt for w.c.'s is shown by Fig. 195, whilst Fig. 196 shows the " Acme " dirt-excluding bolt socket for floors. Espagnolette bolts are long bolts of the full height of door or casement, and are in common use in France. They are made to shoot either two or three-way by turning one handle or lever in the centre. A three-way bolt is illustrated by Fig. 197, the third bolt being the short one to enter a staple on the other leaf of the doors or casements.
Among Robert Adams' " Victor " patents are a three-throw self-locking casement bolt, a weather-proof solid tongue concealed casement bolt shooting three ways and self locking, a similar pattern with removable key in place of handle, and a warehouse bolt to shoot two ways and lock the door by turning a handle on the outside, re-entry being effected only by a special key. This bolt is also made with a lever handle on the inside to act as an emergency bolt, pressure against the lever handle from the inside securing immediate exit, while the door can only be opened from the outside by a special key.
Dirt=Excluding Bolt Socket