The information below will help you to select the right lock or latch for the job. Should you have any further queries, please call us on 0131 444 1149.
There are two sections below: Terminology (containing an A-Z of common terms and descriptions) and Variations (which provides descriptions of some related terms that you might find in our product pages) along with information about Master Keying of cylinders.
ACTION The Action of a catch, latch or lock describes the inward movement of a spring loaded bolt when it is pushed in or withdrawn by a handle and the automatic springing outward when it is released.
BACKSET The backset is the horizontal distance from the faceplate of the latch or lock to the centre of the follower (the square hole for the handle). The same for the centre of the keyhole in the case of a lever mechanism lock, or the centre of the cylinder in a cylinder type lock.
DEADLOCK A deadlock is a lock with just a square bolt, which is locked and unlocked by a key only.
DEADLOCKING This term means an operation by the key, usually an extra turn to prevent the pushing in of the spring bolt of a night latch and its withdrawal by a handle. Automatic deadlocking is available on some mortice and rim nightlatches and this is achieved by a trigger being depressed activating a device in the latch, which stops the bolt being depressed by end pressure when the door is closed.
FLUSH SPRING CATCH A flush spring catch is set in flush with the surface of the hatch or door. It has a spring loaded bevelled bolt, which is operated by a ring pull recessed into the body of the catch.
FOLLOWER The square hole in a latch or two-bolt lock, which takes the spindle of a door handle.
HOLD BACK A manually operated device, which can be used to hold the spring bolt back inside the lock when it is more convenient not to have to use a key or a handle to open the door. The bolt is pushed inside the latch and a slide operated to keep it there. On a mortice nightlatch the slide is located on the faceplate and on the rim nightlatch, on the backcase.
HORIZONTAL LATCH OR LOCK This type of latch or lock is usually used with knob furniture. Knob furniture does not look good if it is too close to the edge of the door. As well as that, care must be taken to position knob handles a sufficient distance from the door stop, to prevent the hand being injured when you draw the door closed. Using a horizontal latch or lock takes care of both of these problems. The keyhole or cylinder hole of a lock is nearest the door stop, with the follower for the knob handle furthest away. Latches are available in 100, 125 & 150mm overall lengths. Horizontal locks come in 125 & 150mm sizes. If you need to use a lock, but the backsets mentioned above are further away than you would like, you could consider using a 100mm upright mortice lock. As mentioned previously, however, always check the position of the hand on the knob has sufficient clearance from the stop to prevent injury.
MECHANISM The Mechanism describes the internal parts of a lock, which come into operation when the key is turned to throw or withdraw the deadbolt.
SILENT ACTION LATCH / ANTIFRICTION DEVICE The silent action latch has a bevelled spring bolt which has the appearance of being in three parts. This is because the middle section of the metal bolt has been removed and replaced by a lightly sprung plastic or nylon tongue. When the door is closed the tongue makes contact with the striking plate first and the action of it being pushed back and down takes the metal bolt with it, reducing contact with the striking plate until it springs into the hole and secures the door. This soft assisted action is very quiet.
Spindle A piece of square steel bar of varying length depending on door thickness and most commonly 8mm thick, driven by the knob or lever to operate a latch bolt. This is normally supplied with the door furniture and variations including:
-- Plain Spindle, which could be termed floating, as it is not mechanically fixed to the handle on either side of the door. This is not a suitable spindle to use with a door closer because it leaves all the strain on the furniture fixing screws. Used with any type of lever furniture which has a retained backplate, or knob furniture with retained revolving roses (called Pitts Rose).
-- Grub Screw Fixing, the wall of the handle neck is drilled and tapped and as it is driven in, the 'V' point of the grub screw locates in a groove in the spindle. Some spindles have split ends, which expand with the force of the grub screw making it secure and suitable for use with a door closer. Grub Screw with a projecting point, similar to the aforementioned except that the spindle has one thin wall which is located opposite the grub screw entry point and as the grub screw is driven home, the point pierces the spindle making it very secure. Recommended for use on doors fitted with a door closer.
-- Duces Spindle, a 19th Century invention (by Joseph Duce), but still in limited use. Used with knob furniture, it comprises of a spindle which has one half threaded with grooves running along the four sides of the threaded part and the other half of the spindle is plain with a small hole through it. The plain end of the spindle is pinned to one of the knobs and pushed through the latch or lock follower and the other knob, which is threaded internally and has a loose rose (called a Maces rose), is screwed down the spindle until it nearly touches the door. A grub screw is then screwed through the neck of the knob and tightened until it fits into one of the grooves. The loose rose is slid down over the neck of the knob covering the grub screw and preventing it from loosening.
-- Microtite Spindle, a very secure spindle for use with knob furniture. Half of the spindle is plain and is pinned to the neck of one knob, this is called the Rim Knob, a loose rose slides down the neck and covers the pin and is screwed to the door when the furniture is being fitted. The other half of the spindle is threaded and has a round tapped collar, which runs along the spindle tightening the unit on to the door. The collar has a 'v' groove all the way round and the other knob called the Micro Knob is recessed to accommodate the collar. A grub screw is then threaded through the neck of the knob and when this is tightened on to the groove in the collar it secures the furniture to the door. Again a loose rose is slid down the neck of the knob covering the grub screw, preventing it from coming loose. The benefits of this type of spindle are that it is: Infinitely adjustable for doors between 35mm and 65mm thick. All the pulling force is transferred through the spindle. No visible grubscrews and ideal for hollow core doors or for doors fitted with a door closer.
-- Taylors spindle, a short piece of plain spindle fixed to a small round back plate, which usually has two screw fixing holes. It is used to make a moving handle into a dead handle. Not a very successful piece of equipment as the tendency is for people to try to turn a handle. Turning weakens the screw fixings and the spindle eventually works free. It should only be used when fitting oval knobs (which have an irregular shape and look better when they are in a vertical or horizontal position). Sprung lever handles (which always return to their normal position) or round shape knobs (which look the same no matter if they are turned) are better left in the moving state.
-- Swivel spindle, Split spindle, some special purpose mortice locks have split followers and a spindle, which has one side able to turn while the other side is held by a stop in the lock, a swivel or split spindle needs to be used with these locks. The swivel spindle has two parts, which are permanently held together, but can revolve independently of one another. This needs a lock with a clear follower so that the spindle can pass through. To operate properly the swivel spindle has to be retained in the exact middle of the follower, which can be tricky. Some are supplied with both sides of the spindle threaded and grooved just like a Duces spindle to take a grub screw fixing.
UPRIGHT LATCH OR LOCK Unlike the horizontal lock, on the upright lock the handle follower and the keyhole or cylinder hole are positioned one above the other and, therefore, have the same backset. Upright latches are usually only used to keep the case size the same as the lock. It is easier on site to have doors with the same size of mortice for all locations. This applies to locks for bathroom & W.C. doors.