Metal working – Means to assemble or disassemble – Tumbler lock
Patent
1989-02-28
1991-01-08
Gorski, Joseph M.
Metal working
Means to assemble or disassemble
Tumbler lock
29264, B23P 1900
Patent
active
049824937
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to an extraction device for lock cylinders in door locks or the like.
Loss of the key for a lock equipped with a lock cylinder has the result that the lock in question can be opened only with a considerable loss of time and expenditure of funds. In connection with doors there additionally exists the danger that the door itself will be damaged, particularly if the free end of the lock cylinder projecting from the door is additionally protected by a safety fitting which makes the attachment of a tool impossible.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a device which permits access to the locking bolt of the lock by extracting the lock cylinder.
This is accomplished according to the invention by a supporting bridge including a passage bore for a self-tapping screw to be screwed into the lock cylinder to be extracted and serving as the tension rod and two through-going lifting screws disposed in the end region of the supporting bridge and oriented in parallel with the passage bore. In the case of use, the supporting bridge with the self-tapping screw inserted is placed in front of the lock cylinder to be extracted and initially the self-tapping screw is screwed into the keyway. The free ends of the lifting screws held by the supporting bridge are advanced toward the door by screwing until they come to lie against the door. Then, they are further screwed in alternatingly turning each one only a slight partial turn so that the stress on the self-tapping screw serving as the tension rod will increase progressively in the axial direction until finally the locking means in the lock cylinder are sheared off and the lock cylinder can be extracted toward the outside. Although two lifting screws are provided which are turned independently of one another, it is possible to exert the necessary axial force on the self-tapping screw without generating bending stresses. The arrangement of two lifting screws here has the advantage that the alignment of the supporting bridge with respect to the axis of the self-tapping screw can be effected while adapting it to the conditions of the respective lock and the respective safety fitting since the two lifting screws can be advanced independently of one another. With unfavorable fitting situations there even exists the possibility of placing corresponding adapters underneath.
An additional feature of the invention further provided is further provided that the self-tapping screw is configured as a flat-head screw and the passage bore is provided with a countersink to receive the screw head. This has the advantage of the best possible introduction of force between the supporting bridge and the self-tapping screw so that it is ensured, in this way, that the self-tapping screw will not tear off.
As a further feature of the invention, the supporting bridge, on its side facing the lock cylinder, is provided with two recesses each accommodating a supporting foot on which one of the lifting screws is rotatably supported. The arrangement of such a supporting foot has the advantage that pressure acting on the door fitting or the door panel is reduced to such an extent that the surface can no longer be damaged there. Additionally, it is also possible to provide the standing surface for the supporting foot with a coating of an elastically deformable material. In this way it is ensured that, if the supporting bridge is pulled slightly "askew" relative to the lock fitting or the door panel, there will not be generated any edge pressures which would lead to damage of the surface. Due to the fact that the supporting feet are each guided in a recess in the supporting bridge, it is ensured during operation that "skewed pulling" due to non-uniform turning of the lifting screws is limited to a minimum and no undue bending stresses are able to affect the self-tapping screw.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described in greater detail with reference to the schematic drawings of an embodiment t
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patent: 3816988 (1974-06-01), Kitts
patent: 4059883 (1977-11-01), Osborne
patent: 4261093 (1981-04-01), Steffer et al.
patent: 4307983 (1981-12-01), Blough et al.
patent: 4338806 (1982-07-01), Cox
patent: 4586233 (1986-05-01), Markisello
patent: 4707903 (1987-11-01), McCartney
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