This invention relates to locks and is intended for use in mortise locks.

Cylindrical mechanism of mortise lock which contains a frame, barrels fixed therein on both sides of the frame, cores which can rotate and have a groove on butt-ends, and a key with a projection on its tail end for the rotation of the cores is known (EP No 0022233 Al).

In the above-mentioned and other known cylindrical mechanisms the frame is made at different lengths (from 60 to 130 millimeters) dependent on the thickness of entry doors. Since the ends of the frame of the cylindrical mechanism go beyond the door plane at a length which equals or exceeds the thickness of cover planks of the mortise lock, it becomes possible to break out with a grampus the cover planks of the mortise lock and through clutching, bending and stretching the end of the frame of the mechanism break out half of the frame (its thin section) at the point where the frame is fixed to the mortise lock, after which it, and accordingly, the entry door, can be opened with the help of an ordinary wire picklock by moving the bolt of the mortise lock.

The purpose of this invention is to exclude the possibility of mechanical effect on the frame of the mechanism, increase reliability, reduce the size and accordingly, use of material.

The above purpose is achieved by following:

The frame is made at a length which is less than the minimal thickness of accepted standard entry doors, and it is additionally equipped with key guides, and through rings cores are fixed in the immovable barrels with their butt-end contour and have butt-ends projections for the rotation of the key. Moreover, the length of the key is selected according to the thickness of the door and on the stepped part of the key a groove is made. The guides are made as inserts on which projections are made corresponding to the contour of cross-section of the frame, and these projections are intended for placing in the shaped holes of mortise lock cover planks. Moreover, in the center of the cylindrical part of the projections a round hole is made for guiding the key. The guides are also made as cover planks which have on their butt-ends a round hole for guiding

the key. The groove made on the stepped part of the key is cross-cut, and the projections of the butt-ends of the cores are in the shape of a segment their flat parts interact with the ends of the flat bottom of the key groove when rotating the cores with the key. The rings fastening the cores in the barrel are hardened.

The substance of the invention is illustrated in designs where in Fig. 1 the cylindrical mechanism is shown, with a key guide made as an insert, in Fig. 2 A-A profile of Fig. 1 is given, in Fig. 3 view B on Fig. 1 is illustrated, in Fig. 4 the cylindrical mechanism is shown with the key guide made as a cover plank, in Fig. 5 the lengthwise view of the working part of the key is shown, and in Fig. 6 C-C profile on Fig. 5 is given.

The cylindrical mechanism of mortise lock (1) comprises the frame (2), barrels fixed therein on both sides (3,4) wherein cores (7,8) which can rotate are fixed through rings (5,6) with their butt- end contours, and which have segment projections (9, 10) in their butt-ends and radial holes in which the balls (11) and locking inserts (12) are placed with butt-ends having spherical grooves which correspond to the diameter of the balls (11), key guides made as inserts (13, 14) with projections (15, 16) where, in the center of the round part holes (17,18) are made, placed in the shaped holes on cover planks (19, 20) of the mortise lock (1) which are designed for the frame (2) of the mechanism, cover plates (21, 22) which have on their butt-ends round holes (23, 24) for guiding the key and are fixed to the door on both sides, the key (25) with a cross-section groove (26) made with a flat bottom (27) on its stepped part.

The cylindrical mechanism of mortise lock operates as follows:

Through hole (18) on projection (16) of guiding insert (14) the key (25) is inserted in the hole of the core (8) and by slightly exhorting pressure turns to the appropriate direction, and when the end parts of the flat bottom (27) of the groove (26) made in the cross-section direction the key are aligned to the flat parts of the segment projection (10) on the butt-end of the core (8), the key (25) takes its final position and in that position, through the balls (11), shifts the locking inserts (12) to the respective position, freeing the core (8) from the barrel (4), after which it turns the core (8) with the help of the key (25), and the lock is locked or unlocked.

The new technical solutions in the cylindrical mechanism of mortise lock exclude the possibility of any mechanical effect on the frame, ensure increased reliability, reduce the sizes of the lock and use of materials.