There is such a great variety of sash fasts in the market that it will be possible to mention but a few. In general, sash fasts consist of two plates secured one to each meeting rail and provided with a bar, catch or cam that locks the two plates, and consequently the two sashes together.
The requirements of a good sash fast are that it shall be burglar-proof, draw the sashes tightly together so as to prevent rattling, be easy to operate and neat in appearance.
The principal point in regard to the burglar-proof quality of the fast is that it shall be constructed so that when locked the arm cannot be forced back by a knife blade inserted from the outside between the sashes. The arm or catch should also have sufficient strength that it will not readily be broken by prying up the lower sash although any window can be opened by using sufficient force.
A great change has taken place in the design of the sash fasts in common use during the past fifteen years. Most of the older styles had a spring attached to the arm which forced it either open or shut, but spring sash fasts are now comparatively little used. The old-style fasts also, were not as a rule efficient for drawing the sashes together, while the later styles are made with this object especially in view.
When the upper lever is turned the lower or locking lever, A, is first thrown out until released from the hook on the upper sash, and then drawn around, and in toward the hub until both levers are on a
Fig. 425. - Cam Sash Fasts. (Ires.) line with the edge of the sash, the upper lever moving through 180 degrees, while the lower lever is moved only 90 degrees. The fast is very simple in its construction, and there is nothing about it that can get out of order.
One great advantage of the "cam" sash fast is that there is considerable play, in and out, to the locking lever, so that if the sashes are at all loose the locking lever, by the action of the cam, draws them tightly together, and so prevents the sashes from rattling in a storm. The locking lever cannot be forced back from the outside. The cam sash fast was first brought out by Hobart B. Ives & Co., but there are now several other cam sash fasts in the market that are made on practically the same principle and in very nearly the same shape; most of these, however, are inferior to the Ives. The Ives fasts are made of both cast and wrought metal in two sizes and several different styles of finish. Fig. 426 shows an entirely new form of sash lock recently placed on the market, which is neat in appearance, very simple in construction and works nicely. This fast is so designed that it will both raise the upper sash and draw it into the lower one, the lever engaging in the hook plate on the upper sash even when the sash is dropped 3/8 of an inch. Two flat springs within the lever plate keep the lever either closed or open, although the security of the lock does not depend upon them.
Fig. 436. - Fitch Sash Lock.
Fig. 427. - Gale Automatic Sash Lock.
The Yale & Towne Manufacturing Co. makes a sash fast (Fig. 428) that is rather a novelty, but which would appear to be especially desirable for windows that are not likely to be often opened, as it acts to draw the sashes firmly together and at the same time forcing them against the top and bottom of the frame. It does not appear to be quite as convenient for ordinary purposes as the fasts shown in Figs. 425 and 426. In order to obtain the best results from cam sash fasts, however, the plates require to be carefully adjusted on the frame, while the screw sash fast has considerable latitude. Several self-locking sash fasts have also been patented, but very few of them have become popular.
Fig. 427 shows what is believed to be the latest self-locking sash fast, and one that seems to be as good as any. The locking catch works by the action of gravity and the window cannot be closed without automatically locking the sashes. This lock would appear to be especially convenient for high windows where the meeting rails are 6 feet or more from the floor, as it can be locked by simply closing the sashes, and to unlock, it is only necessary to push up on the lever H.
There are also several ventilating sash locks which lock the window in different positions when partly open. The Pennington ventilating sash lock, and the Rollins automatic window lock are believed to be the only ones that have proved to be much of a success.
Fig 428 .Yale Screw Sash Fasts.
The simplest device for locking the sashes when partially open is the sash or ventilating bolt, Fig. 429, of which several patterns are made in solid bronze. A lug on the inside of the case keeps the bolt drawn when desired, and by slightly turning the knob the bolt is released and shoots into the strike. The bolt is placed on top of the meeting rail of the lower sash and the strike on the stile of the upper sash. Usually three strikes are placed on the upper sash at intervals of about 2 inches from the meeting rail, so that either sash may be opened 2 or 4 inches as desired. A regular sash fast may be used with this bolt if desired, as although the bolt will lock the sashes when closed, it will not prevent their rattling if loose.
For all first-class work sash fasts should be of bronze metal, but a great many iron fasts lacquered or bronze plated are used. The difference in cost for an ordinary residence, however, hardly warrants the use of the cheaper goods.