TECHNICAL FIELD OF THE INVENTION

The invention relates to a lockbody comprising a lock housing, a face plate, a latch, first means for moving the latch at least partially out of the lock housing and second means for moving the latch at least partially into the lock housing. The invention relates also to a lock striking plate provided with an opening for the latch of the lockbody, and to a lock system comprising a lockbody of the invention and a striking plate of the invention. The invention relates further to a method for dead-locking a lock system, said lock system comprising a lockbody as well as a striking plate.

PRIOR ART

Prior known lockbodies, for example Abloy® 4190 and Abloy® 4925 manufactured by Assa-Abloy Oyj, are provided with two latches, one being the actual locking latch and the other a so-called dead-locking bolt. In the Abloy® 4190 lockbody, the latch is ejected by the dead-locking bolt to a dead-locked position, whereby the latch is not releasable e.g. with a press lever and the latch is in a dead-locked position. Being impossible to control, the dead-locking bolt always collides with the striking plate of a door as the door closes thereby causing extra friction. In the Abloy® 4925 lockbody, the dead-locking bolt operates in such a way that, when the door is closed, the dead-locking bolt is pushed inside the lockbody, the latch being in a dead-locked position for night mode, the lock being unlocked either from the inside by a turning knob or from the outside by a key cylinder. In most lockbodies with similar functions, this action is implemented the same way. With lockbodies, in which dead-locking is based on having the dead-locking bolt urged within the lockbody, the dead- locking is releasable by increasing a clearance between the frame and the door leaf along a section in alignment with the striking plate. With lockbodies, in whose dead-locked position the press levers are also locked by virtue of the same dead-locking mechanism, such as in Abloy® 4925, it is possible to damage the dead-locking mechanism and open the door by the press lever.

Moreover, the dead-locking bolt causes friction and is quite sensitive to changes in door clearances.

Another problem encountered in some prior known lockbodies is that a dead- locked lock is easy to break, for example by applying a major force to the handle of a dead-locked lock, thereby breaking the lock assembly.

Lockbodies are also available on the markets, in which the night/day mode has been worked out by effecting the press lever function with a specific diagonal bolts and the dead-locking function with a latch and a dead-locking bolt, such as for example in the lockbody Assa/Ruko 1362. Such a lockbody makes it necessary, as the door is closing, to overcome the sliding frictions of three latch bolts, the door locking action causing noise, especially in the night locking position.

In some prior art locks, it is impossible to have control over the dead-locking bolt e.g. by a key cylinder function, the consequence being that, if the deadlocking bolt ends up behind an obstruction, for example in the hole of a striking plate, the door cannot be opened without special measures. In lockbodies, the setting of day and night modepositions is effected as a rule by adjusting mechanically a slide button present in the lockbody's face plate, making the manipulation of a lockbody relatively easy. On the other hand, switching the handedness of a lockbody requires in most cases that all diagonal bolts be replaced.

OBJECT AND DESCRIPTION OF THE INVENTION

It is an object of this invention to provide an improvement regarding at least some of the foregoing problems. It is among the objects of the invention to provide a lock, which is dead-lockable readily and reliably, which has a deadlocking feature not easily broken, and which in normal use exhibits no significant extra friction with respect to a lock that is not dead-lockable.

The invention, as presented in the characterizing parts of the appended independent claims, resolves at least some of the foregoing problems.

A lockbody according to the invention, capable of providing an improvement relating to the foregoing problems, is characterized by what is set forth in the characterizing part of the independent claim 1.

A typical lockbody according to the invention comprises a lock housing, a face plate, a latch, first means for moving the latch at least partially out of the lock housing, and second means for moving the latch at least partially into the lock housing. A typical lockbody according to the invention is characterized by further comprising a dead-locking bolt, a dead-locking magnet that can be arranged to the dead-locking bolt, a trigger bolt that can be arranged to a first position for preventing a movement of the latch into the lock housing and to a second position for allowing a movement of the latch into the lock housing, a trigger magnet that can be arranged to hold the trigger bolt in its second position, and a slide. A typical lockbody according to the invention is further characterized in that the trigger bolt can be arranged to an operative connection with the dead-locking bolt and the slide.

The lockbody's lock housing, face plate, latch, first means for moving the latch at least partially out of the lock housing, and second means for moving the latch at least partially into the lock housing, according to the invention are components of a lock known as such for a person skilled in the art. Examples of the first and second means for moving the latch will be presented further in connection with the description of the drawings. Means can be e.g. totally mechanical means, which are operated by means of a key, a handle, i.e. a press lever, or a turning knob. On the other hand, the means can also be operated by means of various electrical systems, for example by means of a press button or an electric key. In a solution according to the invention, the first means for moving the latch at least partially out of the lock housing and the second means for moving the latch at least partially into the lock housing can be one and the same or separate means.

In the solution according to the invention, the dead-locking bolt is not movable from the lockbody but, instead, it moves within the lockbody. The dead-locking bolt is moved, among others, by means of a dead-locking magnet arranged therein. The dead-locking bolt moves to a dead-locked position when the lockbody is subjected to a sufficient external magnetic force, typically a magnetic force which supersedes that of the trigger magnet. According to one embodiment of the invention, the dead-locking bolt is replaced by a solenoid for pivoting the trigger bolt thereby. In this case there is no need for either a deadlocking magnet or a counter-magnet of the striking plate.

The lockbody according to the invention does not have a traditional deadlocking bolt that would project out of the face plate, the result being less friction when the door is closing. The lockbody has a structure, which is simpler than before and has several feasible applications (for example wood and metal doors), since the latch can be arranged to be dead-locked so that it is deadlocked whenever the latch is located in the opening of the striking plate. The lock system according to the invention is also burglarproof, as the dead-locked lock cannot be unlocked by increasing the clearance between the frame and the door leaf along the section in alignment with the striking plate. The only way of unlocking the dead-locked lock is by breaking a wall or the like on the other side of the striking plate. However, such activity causes considerable noise. The dead-locking cannot be released by increasing the clearance, because the lockbody according to the invention is dead-locked by arranging the trigger bolt within the lockbody behind the latch in such a way that the latch cannot move into the lockbody.

The latch cannot be dead-locked when the door is open, the lockbody thus being applicable also in doors with a mandatory latching feature, such as fire doors. The press lever function can be disengaged from the unlocking function by having the press lever move freely between the end positions without being in contact with the unlocking mechanism. This function prevents the deadlocking mechanism from damaging in case a major force is applied to the press lever. Due to a release element, double doors can be provided with "emergency bars", such that either one of the bars can be used for opening the entire

doorway. For example, such "emergency bar" may first move the counter- magnet for releasing the door from a dead-locked position and the continued pressing of the bar opens the door completely. This would be a distinct advantage over current fire doors, which typically must be opened in a specific sequence. The arrangement according to the invention would also serve to avoid damaging the doors when opening the same, thus reducing property maintenance costs incurred, for example, by having to open fire doors unnecessarily because of vandalism.

The latch of a lockbody according to the invention is not dead-locked when the door is open, since the trigger magnet retains the trigger bolt in the second position, in which the latter allows a movement of the latch into the lock housing. However, the lockbody according to the invention can be arranged in a position where it always dead-locks itself when the door is closed. This represents a particular benefit over many prior art solutions, in which the latch may be dead-locked even when the door is open, whereby the dead-locked latch hits against the striking plate when closing the door. When the press lever function is disengaged, the dead-locking will be neither broken nor released even if the press lever were violated by applying a major force against it. The lockbody according to the invention is openable with a key regardless of whether it is dead-locked or not.

According to one embodiment, the trigger bolt can be retained in its second position by means of a spring instead of a trigger magnet. However, a magnet offers clear advantages over a spring, for example: a magnet does not require an inter-component mechanical link unlike a spring, a magnet can be generally arranged in a smaller space than a spring, a magnet is not subject to mechanical movement and fatigue as opposed to a spring.

For the above reasons, the lockbody according to the invention may also be used variously in access control. For example, the arrangement according to the invention can be used in such a way that the control system always receives information regarding a status of the latch, i.e. whether it is inside or

outside the cylinder, as well as regarding the means used for moving the latch (a key, a press button, etc.).

The solution according to the invention provides a locking system, wherein a lockbody can be influenced inductively by means of a striking plate. In addition, the functions of a lockbody can be controlled for example electrically by means of a striking plate, with no wires required for the lockbody fitted in a door. This is particularly beneficial for the reason that wiring is in many cases inconvenient and sensitive to faults.

It is also possible to provide fittings for the lockbody, such as conventional key cylinders and surface fittings.

The trigger magnet can be arranged in any suitable place on the lockbody, such as on that side of the lockbody which is parallel to the face plate, or on any other side of the lockbody. The trigger magnet can also be arranged either inside the lockbody, to the lockbody itself, or on the outer surface of the lockbody. According to one preferred embodiment of the invention, the trigger magnet can be arranged as a portion of the lockbody wall on that side of the lockbody which is parallel to the face plate, i.e. on the back panel of the lock.

According to one embodiment of the invention, the trigger bolt is arrangeable to pivot arout its axle for an angle α. According to one embodiment, the angle α is within the range of 0°-50°, preferably 1-35°, especially preferably 5-15°. By pivoting it around its axle, the trigger bolt can be arranged to a first position for preventing a movement of the latch into the lock housing and to a second position for allowing a movement of the latch into the lock housing.

According to another embodiment of the invention, the trigger bolt can be arranged to move perpendicularly relative to its plane for its top and bottom positions, i.e. to the second and first positions.

According to yet another embodiment of the invention, the lockbody further comprises a transmission rod arranged in operative connection with a turning

cam, said transmission rod being arrangeable to a contact with a slide. A lockbody according to still another embodiment of the invention comprises additionally a switch lever that can be arranged to retain the transmission rod in contact with the slide. The lockbody according to the invention may also include a limit spin for the dead-locking bolt, which is arranged to disengage the transmission rod from contact with the slide. These elements are known as such, and operation thereof will be described in more detail further along with a description of the drawings.

The lockbody according to the invention may further include a switch lever magnet arranged to hold the switch lever stationary. Such a switch lever magnet is known per se from prior art lockbodies and it offers the advantage of holding the switch lever in a fixed position even when a door or the like is subjected to a jolting force.

In one embodiment of the invention, a latch included in the lockbody reaches an opening in the striking plate as the door is closing and the latch protrudes into the opening of the striking plate. After the latch has protruded into the opening of the striking plate, a means, which is for example a magnet, present in the latch, in the striking plate, in the dead-locking bolt and/or in the lockbody, has such an effect that the dead-locking bolt dead-locks the latch, for example by a rear portion of said latch, with the help of an appropriately shaped trigger bolt. When releasing the lock, the latch has its dead-locking released and the latch is able to dislodge itself from the opening of the striking plate, while at the same time the dead-locking bolt and the trigger bolt move into a position from which the latch can be dead-locked again as the latch reaches the opening of the striking plate.

The lockbody does not necessarily require a press lever, but in one embodiment of the invention the lock is releasable only by using a key cylinder or a door knob.

In a still further embodiment of the invention, the lockbody includes also a second dead-locking magnet arranged on the other side of the dead-locking

bolt. In such a case, the subsequently described lock striking plate must of course be also provided with two counter-magnets. It is obvious for a person skilled in the art that the number of dead-locking and counter-magnets may also be other than the above, such as three, four, five, six or seven.

The invention relates also to a lock striking plate, which is provided with an opening for the latch of the lockbody and which is typically characterized by comprising a counter-magnet.

The above-described embodiments relating to a lockbody apply in appropriate aspects to a striking plate according to the invention as well.

Such a striking plate according to the invention is preferably intended for use in collaboration with a lockbody according to the invention. However, the striking plate is, of course, equally usable with other types of lockbody.

According to one embodiment of the invention, the counter-magnet is arranged on a counter-magnet slide arranged to be movable. Thus, the counter-magnet may include both magnetic poles, N- and S-poles, side by side. In an embodiment, in which the striking plate is provided with a stationary counter- magnet, it is feasible to arrange the lock so that in its locked condition it is always dead-locked.

According to one embodiment of the invention, the counter-magnet is arranged on a counter-magnet slide arranged to be linearly movable in the direction of the plane of the striking plate. When the counter-magnet is linearly moved in the direction of the plane of the striking plate, a remarkably small space will be needed behind the striking plate in the direction perpendicular to the striking plate. Another advantage is at least the fact that the counter-magnet can be removed completely away from the position in which it faces directly towards the dead-locking magnet of the lockbody whenever the face plate of the lockbody is arranged in alignment with the striking plate.

In an embodiment, in which the striking plate is provided with a counter-magnet slide arranged to be movable, it is also possible to arrange the lock into such position where it is not dead-locked when it is locked. This is explained more precisely in connection with a description of the drawings.

The counter-magnet may have its polarity reversed and the reversal can be effected for example by means of a solenoid, in which case the striking plate comprises also a solenoid. The striking plate may typically comprise also a motor for moving the counter-magnet in such a way that a particular part of the magnet, which faces the dead-locking magnet, has its polarity reversed.

A striking plate, having a reversible magnetic polarity, can also be used for example in cabinet assemblies, the supervision of whose use is desired. This concerns, among others, medicine cabinets in hospitals and other storage facilities for hazardous materials.

The striking plate is suitable, among others, for installation as a surface mounting, which is often a relevant type of installation for example in medicine cabinets or the like. A solenoid/identification unit is installable for example in such a way that the employed power source comprises for example batteries, with no wiring required. The striking plate is also integrable as a part of the rest of the lock system.

In one preferred form of the invention, the striking plate may also include a release element, which first disengages the dead-locking and then removes the latch out of the opening of the striking plate. A notable example of such a structure is the above-mentioned door with "emergency bars".

The invention relates further to a lock system, which comprises a lockbody according to any of the inventive embodiments and a lock striking plate according to any of the inventive embodiments and in which the counter- magnet has an attraction force for the dead-locking magnet which typically supersedes that of the trigger magnet for the trigger bolt.

Such a lock system according to the invention, wherein the counter-magnet is more powerful than the trigger magnet, can be used to provide a system in which the lock becomes dead-locked every time the counter-magnet is arranged such that, upon entering within its range of power, the dead-locking magnet pulls the dead-locking bolt to the dead-locked position. In this case, the dead-locking bolt must not include a limit pin, by means of which the transmission rod prevents a movement of the dead-locking bolt towards the face plate, the trigger bolt being thus also unable to access behind the latch to establish a dead-locking.

According to still another embodiment of the invention, the lock system has the counter-magnet of its striking plate arrangeable perpendicular to the deadlocking magnet when the lockbody has its face plate in alignment with the striking plate. When using a movable counter-magnet, a desired part of the counter-magnet can be arranged perpendicularly to the dead-locking magnet when the lockbody has its face plate in alignment with the striking plate, i.e. when the lock is in its locked position. In other words, the door is hence also in a closed position.

The lock system according to the invention provides a lock, which is simple in design and the status (dead-locking on/off) of which can be readily switched inductively from the frame. The inventive solution also serves to avoid door wiring and to achieve a good mechanical strength for the lockbody. In addition, the lockbody can be installed with desired prior art fittings and means of identification.

The lock system according to the invention is also of the same size as currently available typical lock systems, its installation being thus easy and economical even to existing doors in the process of converting the premises for other purposes. The installation of a lockbody according to the invention to an existing door, such that the door is presently converted into a so-called "supervised" door, takes typically about 30-60 minutes. With traditional systems, the same conversion work takes about 60-90 minutes, nor is the work always even possible without removing the door. In the event that a door is

fitted with a lockbody according to the invention to begin with, the lock is later readily convertible into an electric one by replacing the striking plate.

In one embodiment of the invention, the striking plate or the lockbody is provided with a movable counter-magnet slide, comprising a magnet capable of providing either an attractive or repelling force. By applying this effect on an appropriately designed transmission rod of the press lever present in the lockbody, the press-lever effected opening action can be denied if necessary. The dead-locking magnet associated with the dead-locking bolt can be given an appropriate shape so as to have it in contact with the transmission rod, whereby, as the dead-locking bolt moves away from the striking plate to the second position, the dead-locking magnet pushes the transmission rod back to contact with the slide. The appropriately shaped dead-locking magnet is partly or entirely, yet at least over its section coming to contact with the transmission rod, coated with some wear-resistant material, for example ceramics, aramid, polytetrafluoroethylene. Instead of an appropriately shaped dead-locking magnet, the transmission rod may have in association therewith a second limit pin, which is similar to the first one and which, while the dead-locking bolt is moving away from the striking plate to the second position, pushes the transmission rod into contact with the slide.

The above-described embodiments relating to a lockbody and a striking plate apply in appropriate aspects to a lock system according to the invention as well.

The invention relates further to a method for dead-locking a lock system, said lock system comprising a striking plate and a lockbody which comprises a lock housing, a face plate, a latch and a dead-locking bolt. A typical method is characterized in that the dead-locking bolt is moved by means of a magnet within the lock housing between the face plate and the lock housing's back panel, which is substantially parallel to the face plate. Thus, the method according to the invention comprises moving the dead-locking bolt only within the lock housing, not out of it at all. As a matter of fact, the face plate does not even need an opening for the dead-locking bolt. The dead-locking bolt as such may be any dead-locking bolt of the prior art, which is further arranged to carry

a magnet at its end closer to the face plate. This results in remarkably less friction in the process of opening and closing a door or the like.

According to a preferred embodiment of the invention, the magnetic force is derived from the striking plate, i.e. the counter-magnet is arranged on the striking plate.

The above-described embodiments relating to a lockbody, a striking plate and a lock system apply in appropriate aspects to a method according to the invention as well.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail with reference to the accompanying drawings, in which

Fig. 1 shows schematically a lock system according to a first embodiment of the invention in a latched position,

Fig. 2 shows the lock system of fig. 1 in an unlocked position,

Fig. 3 shows the lock system of fig. 1 in a dead-locked position,

Fig. 4 shows a lock system according to a second embodiment of the invention in locked condition,

Fig. 5 shows a lock system according to a third embodiment of the invention in latched position,

Figs. 6 and 7 show a lockbody according to a fourth embodiment of the invention in cross-section.

DETAILED DESCRIPTION OF THE ILLUSTRATED EXAMPLES

In fig. 1 , the door is closed and the lock is latched for a day mode. A spring 17 has pushed a latch 1 into an opening 8 of the striking plate 7. A transmission rod 11 fixed to a turning cam 18 is retained by a switch lever 12 in contact with a slide 16, and therefore the lock is releasable by using a press lever function. The transmission rod 11 uses a limit pin 20 fixed to the dead-locking bolt 4 as a means for preventing movement of the dead-locking bolt 4 towards the face plate 3, and the dead-locking bolt 4 stays in the second position. The deadlocking bolt 4 being retained in this second position, the trigger bolt 6 remains also in the second position and is thereby prevented from accessing behind the latch 1 to effect dead-locking. Hence, a trigger magnet 22 is not needed in this mode to retain the trigger bolt 6 in a top position and, if the press lever is turned, the trigger bolt does not move but continues to remain in the second position. The figure also depicts a key cylinder 19. The trigger bolt has its axle 6 ¹ parallel to the face plate 3, as well as to the plane of the figure and, thus, the cross-sectional plane of the lockbody depicted in the figure. If the limit pin 20 is removed, the lockbody in the illustrated condition will be dead-locked whenever the striking plate 7 and the face plate 3 are in alignment with each other, but the dead-locking is nevertheless releasable by operating a press lever.

In fig. 2, the turning cam 18 is in a pivoted position and the lock is in an unlocked position. The turning cam 18 has been pivoted and the slide 16 has been pushed by the transmission rod 11 to the second position, i.e. to the top position in this embodiment. The slide 16, which has been pushed to the top position, has turned a transmission element 13 with the result that the transmission element 13 has withdrawn the latch 1 away from the opening 8 of the striking plate 7 into the lockbody and the door is openable. In the condition depicted in this figure, the trigger bolt 6 is in the second position, which has allowed for a movement of the latch 1 into the lock housing 2.

The slide 16 and the transmission element 13 depicted in fig. 2 can also be linked to each other, for example by means of rivets. Preferably, however, the slide 16 and the transmission element 13 are capable of moving in relation to each other.

Fig. 3 shows the lock in night mode. The latch 1 is located in the opening 8 of the striking plate 7. The switch lever 12 has been shifted to a night mode position, whereby the switch lever 12 does not retain the transmission rod 11 in contact with the slide 16. The attraction force between a counter-magnet 14 and a dead-locking magnet 5 has displaced the dead-locking bolt 4 towards the striking plate 7 to the first position. The dead-locking bolt 4, which has shifted to the first position closer to the striking plate 7, has pivoted the trigger bolt 6 to a first position behind the latch 1 , in which it dead-locks the latch 1 , i.e. prevents movement of the latch 1 into the lock housing 2. The dead-locking bolt 4, which has shifted to the first position closer to the striking plate 7, has through the intermediary of the limit pin 20 withdrawn the transmission rod 11 out of contact with the slide 16. In the situation according to the figure, the lock is not releasable by means of the press lever of the turning cam 18, because the transmission rod 11 is not in contact with the slide 16 and, thus, unable to move the slide 16. The illustrated condition reveals one advantage of the invention: dead-locking cannot be broken, even if the press lever were broken by applying a major force against it. Since the dead-locking is established by the trigger bolt 6, pivoted to a position behind the latch 1, the dead-locking cannot be disengaged or broken even by increasing a clearance existing between the striking plate and the face plate.

In fig. 4, which shows a second embodiment of the invention, the lock system is provided with a movable counter-magnet slide 9, which is fixed to the striking plate 7. The counter-magnet slide 9 can be controlled for example with a solenoid 15, which is fixed to the striking plate. In the illustrated example, the counter-magnet slide 9 carries two magnets with opposite poles: a first counter- magnet segment 23 and a second counter-magnet segment 10. The counter- magnet slide 9 can be shifted for applying a magnetic repelling force or attraction force to the dead-locking bolt 4 from the direction of the striking plate 7. In the situation shown in fig. 4, the counter-magnet slide 9 has been shifted, for example by means of a solenoid, to such a first position in which the first counter-magnet segment 23 effects on the dead-locking magnet 5 of the deadlocking bolt 4 with an attractive force. Being in a night mode position, the switch lever 12 has not retained the transmission rod 11 in contact with the slide 16

and the attraction force of the first counter-magnet segment 23 has pulled the dead-locking bolt 4 towards the striking plate 7 to the first position. In the illustrated example, the press lever function is not active as the transmission rod 11 has been disengaged from contact with the slide 16. From the illustrated situation, the transmission rod 11 can be re-engaged into contact with the slide 16 by applying a magnetic repelling force to the dead-locking magnet 5 from the direction of the striking plate 7. According to the illustrated example, the deadlocking magnet 5 is shaped so that it is in contact with the transmission rod 11 , whereby, as the dead-locking bolt 4 is moving away from the striking plate 7 to the second position, the transmission rod 11 is repelled by the dead-locking magnet 5 back to contact with the slide 16. The appropriately shaped deadlocking magnet is preferably coated, at least over its section coming to contact with the transmission rod 11 , with some wear-resistant material, for example ceramics. Instead of the dead-locking magnet 5 shaped according to the illustrated example, a second limit pin similar to the limit pin 20 and capable of pushing the transmission rod 11 into contact with the slide 16 while the deadlocking bolt 4 is moving away from the striking plate 7 to the second position, may be arranged in connection with the transmission rod 11. This second limit pin has not been depicted in the illustrated examples. Both of these solutions can be used also in other shown examples. In the situation shown in fig. 4, the lockbody becomes dead-locked every time the door is closed, because the transmission rod 11 is not retained by the switch lever 12 and consequently the dead-locking bolt 4 is not prevented by the limit pin 20 from moving towards the striking plate 7.

In the illustrated second embodiment, it is also possible to disengage the switch lever 12 from service by any means known per se, for example by means of a pin. On the other hand, the switch lever 12 may also be eliminated completely, as indicated in fig. 5. In the embodiments of figs. 4 and 5, the counter-magnet 10, 23 is arranged on the counter-magnet slide 9, which is movable linearly in the direction of the plane of the striking plate 7, for example along a screw 24 arranged in connection with the solenoid 15.

Fig. 5 shows a lock system according to a third embodiment of the invention, wherein the counter-magnet slide 9 has been shifted to a second position, in which the second counter-magnet segment 10 acts upon the dead-locking magnet 5 of the dead-locking bolt 4 with a repelling force, which is why the dead-locking bolt 4 has been carried to the second position, i.e. a position in which it has moved away from the striking plate. In the illustrated situation, the transmission rod 11 is in contact with the slide 16. Because the transmission rod 11 is in contact with the slide 16, the lock can be opened by using a press lever function. In the illustrated situation, the dead-locking bolt 4 has pivoted the trigger bolt 6 to a second position for allowing movement of the latch 1 into the lock housing and, thus, the latch is not dead-locked.

Figs. 6 and 7 show a lockbody according to a fourth embodiment of the invention in cross-section. In fig. 6, the trigger bolt 6 is in the second position for allowing movement of the latch 1 into the lock housing 2. The trigger bolt 6 is attracted and thereby retained in the second position by a trigger magnet 22.

In fig. 7, the dead-locking bolt 4 has moved towards the face plate 3 and pulled the trigger bolt 6, such that the latter has pivoted about its axle 6' to a first position behind the latch 1 for preventing a movement of the latch 1 into the lock housing 2. With respect to the situation shown in fig. 6, the trigger bolt 6 has pivoted about 30-40° around its axle 6\ If a high-force attempt is made to push the dead-locked latch 1 into the lockbody 2, the force will be applied via the trigger bolt 6 to a bent corner 27 between the bottom 26 and back panel 25 of the lock housing, which corner is very sturdy. This guarantees a high breaking strength. The pivoting angle α of the trigger bolt about its axle 6 ¹ can be varied according to the thickness and depth of a lockbody for making the dead-locking as sturdy as possible.