YALE LOCK (OR NIGHT LATCH)
The Yale lock is the common name used to describe a Night latch. Yale is in fact a brand name which is commonly used to describe the range of Night latches available on the market today. Much like the way we use the term “Hoover” to describe vacuum cleaners, most people refer to the Night latch as the Yale. The Yale company in fact manufactures a vast range of locks from padlocks to Mortice locks and Multipoint locking systems.
Night latches where first developed by the Yale Company of Newport, New York in the middle of the nineteenth century. The Yale Company patented many lock mechanisms around this time including combination locks, Safe locks and the pin and tumbler cylinder used in almost all modern Night latches.
HOW A NIGHT LATCH WORKS
All night latches consist of three main parts: a pin and tumbler cylinder, a Lock case and a Keep.
The cylinder is mounted on the exterior of the door and provides the keyhole, pin and tumbler and a connection through the door to the Lock case via the tail piece. The Lock case consists of a spring loaded latch bolt, release knob and locking snib. The keep resides on the door jamb and is the receiver for the latch bolt. As opposed to Mortice locks which are installed “inside” the door, the Night Latch lock case is mounted “ON” the door and the Keep is mounted “ON” the Jamb. When the door is closed the 45 degree edge on the Latch bolt strikes the 45 degree edge on the keep with enough force to compress the latch bolt allowing the door to close. Once the door is fully closed the latch springs back into the keep thus locking the door. To open the key is inserted in the lock the jagged edge of which aligns the 5 or 6 pins allowing key to be rotated which in turn rotated the tail piece which pulls back the bolt and therefore opening the door.
YALE LOCK (NIGHT LATCH) SECURITY
The downside of Night latches is the level of security to provide particularly the most common Traditional version. The spring loaded latch which because of its very nature is prone to “slipping” the old credit charge trick. Because Night latches are installed ON the door and jamb they offer less resistance to someone trying to force the door.
The Yale Lock should never be the only lock on a wooden final exit door. This is reflected in Insurance company's terms and conditions which usually state"
“...all final exit wooden doors should be fitted at least one BS:3621 5 lever mortice lock”.
In fact Night latches are not recognised by insurance companies unless they are a British Standard version. These locks tend to be more expensive less secure the BS 5 lever mortice locks hence we see very few in service.
If you move away from the traditional Yale lock there are more secure versions available these can offer defence from “Slipping” by having a dead locking mechanism. Sturdier lock cases which are secured to a back plate not just screwed into the door. Tougher anti-drill anti-pick cylinders are available. A more robust keep with deeper screws. The Keep can be reinforced by addition of a London Bar.
Albany Locksmiths offer advice on Yale lock (night latch) repair and installations and stock a full range to suit every budget.