WO1997034739A1

WO1997034739A1 - Burglary tool for door lock

Info

Publication number: WO1997034739A1
Application number: PCT/SE1997/000394
Authority: WO
Inventors: Sven-Åke CARLSSON; Johan Eriksson
Original assignee: Carlsson Sven Aake; Johan Eriksson
Priority date: 1996-03-18
Filing date: 1997-03-07
Publication date: 1997-09-25
Also published as: NO304360B1; NO975274L; NO975274D0; SE9601024D0; SE504865C2; SE9601024L

Abstract

A tool for forcing a door lock that has a lock cylinder which is surrounded by a protective ring on the outside of the door, wherein the tool includes a slide hammer that includes a shaft which carries a chopping bit on one end thereof, and wherein an impact weight is guided by the shaft for movement therealong. The chopping bit (3) is connected to the shaft (2) by means of a coupling (33, 34) that enables the chopping bit (3) to move relative to the shaft (2) to a limited extent in the longitudinal direction of the shaft (2), and the impact weight (4) is intended to strike against the chopping bit (3).

Description

Burglary tool for door lock

The present invention relates to a door lock forcing tool of the kind defined in the preamble of Claim 1.

The tool thus includes a slide hammer which engages a shaft that carries a chopping bit at one end thereof and that includes an impact weight which is guided for movement along the shaft.

The known technology is represented in US-4 458 415 and US-5 109 739.

There occurs the need to break open a door of an apartment when the occupier of the apartment is in immediate need of assistance. One option in this regard is for a policeman to break in the door with the aid of an axe or some corresponding tool. A forced entry of this nature is highly expensive for the police authorities, the insurance company with which the apartment is insured, and the owner of the apartment. Another alternative is simply to summons a locksmith and to open the door with an appropriate tool without incurring too much damage. This latter option also incurs the cost of the locksmith s services . Furthermore, it may be too hazardous to wait for the arrival of a locksmith, which may be from thirty minutes to an hour, before opening the door.

The invention therefore addresses the problem of providing a manually operated tool by means of which a door lock can be forced with no damage or only minimal damage to the door and surrounding woodwork and with the minimum of delay. This object is achieved with a tool according to the following Claim 1.

Further developments of the tool are set forth in the depending claims.

Doors that are fitted with so-called patent locks will, as a rule, include a lock cylinder that is exposed on the outside of the door. The lock cylinder is surrounded by a protective ring which is screwed to the outside of the door with penetrating screws. In Scandanavia, the lock cylinder will normally be of the type designated "Scandinavian Oval Standard Cylinder", and sold, for instance, by ASSA and having model designation 701.

The lock cylinder is held axially to the door lock mechanism by two screws that engage in the inner end of the lock cylinder.

Fundamentally, the inventive tool includes a slide hammer having a chopping bit or chisel means on one end. Thus, the slide hammer includes s straight shaft that extends through a hollow cylindrical impact weight and carries at its one end a chopping bit which is intended to be struck by the impact weight. The other end of the shaft carries a break-wrench that includes an opening which corresponds in shape to the cross- sectional shape of the standard cylinder. The shaft and the wrench means must be sufficiently strong to enable the oval standard cylinder to be twisted free from the door lock, after having removed the protective ring. The protective ring is removed by placing the chopping bit against the outer periphery of the protective sleeve with the edge of the bit parallel with the ring axis, and then splitting open the ring, by striking the impact weight against the chopping bit. The chopping bit is then turned through 90° so as to bring the edge of the bit parallel with the outer surface of the door panel, wherewith the edge of the chopping bit is placed against one of the ring fastener screws and the screw then severed with the aid of the slide hammer. The next ring fastener screw is then severed in the same way. The lock cylinder is now exposed and the wrench means on the other end of the shaft can be fitted onto the cylinder. The shaft now extends generally at right angles to the cylinder axis and forms a lever by means of which the lock cylinder can be rotated manually about its axis, such that the lock cylinder fastener screws are broken off and therewith enable the l'ock cylinder per se to be removed. The lock follower is now exposed and the bolt of the lock mechanism can be retracted by turning the follower, e.g. with a screwdriver or with an equivalent device carried by the tool.

A significant feature of the inventive tool is that the chopping bit is a separate unit which is intended to be struck by the impact weight, and that the connection of the shaft to the hammer is adapted to allow relative movement of the shaft and the chopping bit in the axial direction.

Because the shaft must be given a high mechanical strength sufficient to withstand the bending forces required to twist loose the lock cylinder, and because the shaft must have a significant length to enable manual application of the required torque and because the wrench means must also be given significant strength, the shaft and the impact weight will obtain a heavy mass. It has been found that when the shaft is connected rigidly to the chopping bit, it is not possible to apply manually with the aid of the impact weight an impact force that is sufficiently powerful to accelerate both the shaft and the wrench means such as to split the lock ring. This problem has been overcome, by providing a clearance coupling between the shaft and the chopping bit so that the chopping bit can move freely relative to the shaft, and by applying the impact force generated by the impact weight directly against the chopping bit.

According to one embodiment of the invention the wrench means that fits the lock cylinder may also carry a tool that can be brought into engagement with the exposed follower of the lock mechanism for retraction of the lock bolt.

The invention will now be described in more detail with reference to exemplifying embodiments thereof and also with reference to the accompanying drawings.

Figs 1 and 2 are mutually perpendicular side views of an inventive tool.

Fig. 3 is schematic view taken on the line II-II in Fig. 2.

Fig. 4 is a schematic horizontal sectional view of a door fitted with a patent lock.

Fig. 5 is a front view of the lock shown in Fig 4 with the tool applied for splitting a protective ring around the lock cylinder of the lock.

Fig. 6 illustrates the tool applied for chopping away one protective ring fastening screw. Fig. 7 shows the wrench means applied to the lock cylinder after having removed the protective ring.

Fig. 8 illustrates schematically the follower of the door lock mechanism exposed when removing the lock cylinder.

Figs. 1 and 2 illustrate a twist hammer 1 that includes a shaft 2 which extends through a hollow-cylindrical impact weight 4 that can be moved along the shaft 2. The shaft carries at one end thererof a chopping bit unit 3 which includes a chopping bit or chisel 31 and a blind-bottom sleeve 32 whose wall includes an -axial slot 33. A radial locking pin 34 extends through the slot 33 and is connected to the shaft 2. The locking pin thus enables the chopping bit unit 3 to move axially in relation to the shaft 2 to a limited extent. The chopping bit unit 3 has an impact surface 35 that is struck by the impact weight 4. The shaft 2 carries at its other end a wrench means 5, which has a wrench plate 51 that extends parallel with the long axis of the shaft 2. The wrench plate 51 has an elongated opening 56 whose shape corresponds to the cross-sectional shape of a standard non-round cylindrical lock cylinder. The wrench also includes a base plate 52 that is connected centrally to the shaft 2, and further includes stiffening flanges 53 disposed between the plates 51 and 52 on the underside of the opening 56.

The wrench may also be provided with dogging means 55 in the form of a flat element which is pivotally mounted on hinge means 54 on the outside of one flange 53, so as to normally lie against the outside of the flange and, when used, to be swung out to a position in which it is normal to the flange 53. Fig. 4 illustrates a conventional patent door lock fitted to the outside of a door. The lock includes an upper lock cylinder 60 which is surrounded by a protective ring 70. The ring is secured to the outside 80 of the door panel by screws 71. The cylinder 60 is fastened to the door lock mechanism 90 by penetrating screws 62 which engage the inner end of the cylinder 60. The cylinder 60 includes a dogging means 63 which engages a follower 92 (cf Fig. 8). The lock bolt 93 of the lock mechanism can be retracted, by turning the follower 92.

Fig. 5 shows from above the slide hammer in a position in which the chopping bit or chisel is applied to the upperside of the ring 70 at its thinnest point. The ring 70 is now split with the aid of the slide hammer, wherewith the impact weight 4 need not accelerate the shaft 2 and the wrench 5 when striking against the chopping bit 3.

Fig. 6 shows the slide hammer applied with the edge of the chopping bit 31 placed between the ring 70 and the surface 80 of the door panel for severing one of the fastener screws 71 {cf Fig. 4) after splitting and opening out the ring 70.

When both screws 71 have been chopped off, the ring 70 loosens and the wrench 5 can be fitted to the lock cylinder 60 so as to enable to apply torque via the shaft 2 and therewith subject the cylinder 60 to a powerful turning moment, such as to break- off the lock cylinder securing screws 62, 63.

The driving element (the follower) of the lock mechanism that retracts the lock bolt 93 when turned has an opening in which the cylinder dogging means 63 normally engages. The dogging means 55 on the wrench can now be inserted into the follower opening (cf Figs. 2 and 3) and the lock bolt retracted with the aid of the tool 1, therewith enabling the door to be opened.

A door can be opened with the aid of the inventive tool and in the aforesaid manner in a very short space of time, in the order of one minute, with the minimum of damage to the door and to the lock mechanism.

Claims

1. A tool for forcing a door lock that has a lock cylinder which is surrounded by a protective ring on the outside of the door, wherein the tool includes a slide hammer that includes a shaft which carries a chopping bit on one end thereof, and wherein a impact weight is guided by the shaft for movement therealong, characterized in that the chopping bit (3) is connected to the shaft (2) by means of a coupling (33, 34) that enables the chopping bit (3) to move relative to the shaft (2) to a limited extent in the longitudinal direction of the shaft (2); and in that the impact weight (4) is intended to strike against the chopping bit (3).

2. A tool according to Claim 1, characterized in that the shaft (2) carries on its other end a lock cylinder gripping means.

3. A tool according to Claim 2, characterized in that the gripping means (5) has the form of a wrench (5) having a wrench opening that fits around a non-round lock cylinder.

4. A tool according to any one of Claims 1 - 3, characterized in that the shaft carries at its other end a dogging means (55) that is configured for insertion into the follower (92) of the lock mechanism and for causing the follower to rotate so as to retract the lock bolt (93) of the lock mechanism (90), after having removed the lock cylinder (60) and its protective ring (70).