The usual tumbler lock for front doors differs from the ordinary lock and latch in having a swivel spindle so that the knobs may be turned independently of each other, and a stop mechanism by which the outer knob may be set, so that the latch can be operated from the outside only by a key, while it is readily drawn by the knob on the inside. The dead bolt is operated by a key from both sides as with inside locks. There are thus two keyholes on the outside and one on the inside of the door. The latch and bolt keys are usually different. The Yale Standard front door lock is made so that both the latch and bolt may be operated by a single key.

The cheapest grade of front door locks do not have the swivel spindle, and when the latch is set it can be operated from the inside only by a thumb piece. Such locks are hardly suitable for good residences.

Vestibule doors of residences should be fitted with a "vestibule latch" made to match the front door lock and operated, when the outer knob is set, by the same latch key, the latch being similar to the front door lock, but with the dead bolt omitted.

The front and vestibule doors of nearly all first-class residences are now usually trimmed with "cylinder escutcheon" locks, with which one small key operates both the latch and dead bolt of the front door and the latch of the vestibule door.

Fig. 385 shows the general appearance of the Yale Paracentric front door lock and its corresponding vestibule latch ; the Yale Standard (tumbler) lock differing only in the locking mechanism.

220 Front Door And Vestibule Locks 200276Fig. 385   Yale Front Door Lock and Vestibule Latch.

Fig. 385 - Yale Front Door Lock and Vestibule Latch.

Sliding Door Locks and Pulls. - The common form of sliding door lock is that shown in Fig. 386, the curved bolt being operated by a key from both sides. The flush pull is pushed into the case when the door is closed, or may be pushed in by the hand, and is thrown out by pushing in the button B. The locking mechanism is usually quite simple, as for sliding doors in residences great security is not often required.

The Yale & Towne Manufacturing Co., and possibly others, make a form of sliding door lock and also a sliding door night latch, that offers as much security as any lock. They also make a lock for communicating sliding doors, with bolts operated by thumb pieces. Sliding door locks for double doors are made with both straight and astragal fronts.

Fig. 386   Sliding Door Lock.

Fig. 386 - Sliding Door Lock.

Fig 387.   Sliding Door Pull.

Fig 387. - Sliding Door Pull.

Locks for sliding doors are also made with an easy spring latch bolt operated by knobs and locked by a key. Knobs, however, cannot ordinarily be used on sliding doors, as they would strike against the frame, the ordinary trim for sliding doors being the cup escutcheon shown in plate, and an extension or jointed key is used that will not project beyond the face, of the door.

If a lock bolt is not deemed necessary, a simple flush pull (Fig. 387) with blank escutcheon plates may be used.