Tumbler in a cylinder lock

The spring loaded tumbler is provided with a casing and a core. Latter has a limited travel towards the key passage, and is located in a stepped drilling in the cylindrical core. A sliding sleeve element is located on the core, which has a corresponding shape to that of the stepped drilling. The tumbler according to the present invention can be inserted in normal cylinder locks and effectively prevents unauthorized opening without the use of a key or damage to the lock.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The invention relates to a tumbler in a cylinder lock having a core pin and 
a spring-loaded housing pin, which are supported in a radial bore of the 
cylinder housing and in a bore of the cylinder core, respectively, and 
which are brought into alignment by an insertable key introduced into the 
key channel. 
2. The Prior Art 
Cylinder locks having two-part tumblers are well known and have a high 
degree of security. However, unlocking methods have now been developed 
with which these cylinder locks can be opened without keys and without 
externally apparent damage to the locks. 
SUMMARY OF THE INVENTION 
It is now the object of the invention to devise a cylinder lock of the 
above type which cannot be opened with these methods. 
This object is attained in accordance with the invention by providing that 
the core pin has a sheathlike slide element, which is disposed behind the 
head of the core pin and is displaceable in the longitudinal direction 
with respect to the bore and to the core pin. The effective portion of the 
tumber always remains movable if the aforementioned unlocking methods are 
used, so that its measurements cannot be learned. Unlocking methods 
involving the use of force also fail, because once again the effective 
portion of the core pin cannot be fixed in place. 
The tumbler according to the invention is simple to mass produce. No 
modifications to the other parts of the cylinder lock or to the key are 
necessary. The cylinder lock can be adequately secured against the above 
unlocking methods by using at least one tumbler according to the 
invention, along with the usual tumblers, in the cylinder lock. 
By manufacturing the tip of the core pin as a separate part and securing 
the tip with an interference fit on the pin body, it becomes possible to 
make the tip from a material that is especially secure against being 
drilled open. If the tip is made from a hard metal material, wearing down 
of the tip from use is moreover largely avoided. 
The embodiment of the tumbler in which the core pin has a bore, in which a 
locking pin that is displaceable in the longitudinal direction with an 
outward limitation by a stop is supported, and disposed in the bore is a 
compression spring, which presses in a biased manner upon the locking pin, 
which in turn presses against the housing pin additionally prevents 
unlocking methods in which the core and housing pins are separated so that 
the rotor can be rotated briefly. 
Further advantageous embodiments are disclosed in the dependent claims.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
In a known manner, the lock cylinder shown in FIG. 2 has a stationary 
cylinder housing 12, which is located in a cylindrical sheath 11 and in 
which a cylinder core 13 is rotatably disposed. The cylinder housing 12 
and the cylinder core 13 have radial bores 17a and 17b, in which 
spring-loaded tumblers are displaceably supported. One spring 16 is 
located in each housing bore 17a, supported against the sheath 11 and 
pressing in a biased manner against a housing pin 15, which in turn 
presses a core pin 10 radially inward against a key that is to be 
introduced into the key channel 14. 
As FIG. 1 shows, the core pin 10 has a tip 3, which includes a connecting 
portion 3a and a head 3b having a control face. The head 3b may also have 
a plurality of control faces, however, to increase the number of locking 
possibilities in a known manner. The tip 3 preferably comprises a hard 
metal material, or some other mechanically resistant material that is 
secure against being drilled open and is wear-resistant, and is secured 
with an interference fit in a bore in the pin body or shaft 5. 
A sheathlike slide element 1 is displaceably supported on the body 5. Both 
the slide element 1 and the body 5 are offset in diameter in stepped 
fashion on the outer end, so that the slide element 1 is outwardly 
displaceable in a manner limited by a stop and has a wider sheath portion 
1a and a narrower sheath portion 1b. Inwardly, the sheath portion 1b of 
the slide element 1 is limited by a stop in the form of the radially 
outwardly protruding head 3b. 
In FIGS. 3a and 3b, a core pin 30 is shown which besides the slide element 
1 additionally has a locking pin 24. The locking pin is supported in a 
stepped bore 27 in the pin body 26 such that it is outwardly limited by a 
stop. A compression spring 25 is located in the stepped bore 27, supported 
against the tip 3 and pressing in a biased manner against the locking pin 
24, which on its outer end rests on the housing pin 15. The tension of the 
spring 25 is selected such that the locking pin 24 does not move the 
housing pin 15 out of its position that locks the cylinder. In the 
position shown in FIG. 3a, however, the spring 25 does have a tension 
great enough that the locking pin 24 follows the housing pin 15 
substantially without any delay when the two pins are separated from one 
another. 
The mode of operation of the locking pin 24 is shown schematically in FIG. 
3b. The housing pin 15 is briefly moved here, by a known unlocking method, 
into an unlocked position, while the core pin 30 remains in its original 
position. Nevertheless, the cylinder core cannot be rotated, because the 
locking pin 24 projects beyond the shear plane 32 and locks the cylinder. 
The core pins 10 and 30 can be inserted into the usual stepped bores 17b in 
the cylinder core 13. Because of the stepped embodiment of the bore 17b 
and a corrresponding stepped embodiment of the slide element 1, the 
displaceability of the slide element 1 and of the entire core pin 10 or 30 
toward the key channel 14 is limited. 
The core pin can also be embodied as shown in FIG. 4. In this core pin 43, 
the body is manufactured in one piece and has a cylindrical shank 41 and a 
head 40 having an approximately hemispherical control face. A cylindrical 
slide element 42, which is somewhat shorter than the shank 41, is 
displaceably supported on the shank 41. Upon a displacement in the axial 
direction, the sheathlike slide element 42 meets a stop at the head 40 in 
the inward direction and a stop on the housing pin 15, not shown here and 
embodied as described above, in the outward direction. The core pin 43 is 
particularly cost-effective in its manufacture and is particularly well 
suited for a cylinder lock having a serrated type of key. 
The above-described core pins 10, 30 and 43 have an annular gap 18 or 48, 
respectively, between the slide element 1 or 42 and the head 3 or 40, 
respectively. These gaps are approximately 0.4 mm wide, viewed in the 
longitudinal direction of the core pin and are formed because the slide 
element is shorter by 0.4 mm than the body of the corer pin. The slide 
element may be between 0.3 mm and 0.7 mm shorter than the body. A 
compression spring 19 (shown only in FIG. 3a), which presses the slide 
element 1 against the shoulder of the pin body 5, or the slide element 42 
against the housing pin 15, can be disposed in the gaps 18 and 48, 
respectively. The tension of this compression spring is comparatively low 
but assures that the gap 18 is maintained when the core pin 10, 30 or 43 
is displaced outward. In the version of FIG. 4, this compression spring 
has the further advantage that the slide element 42 in this case also 
assumes the mode of operation of the locking pin 24. The slide element 42 
and the compression spring thus effectively prevent the lock from being 
unlocked by separating the core and housing pins, and also at the same 
time assure that the effective portion of the core pin always remains 
movable during attempts to force the lock or gauge its measurements. 
When the lock is opended by an authorized person using the proper key, the 
tumbler according to the invention functions in the same manner as a 
conventional tumbler.