Anti-theft device for automobile wheels

Anti-theft device for nuts/screws of automobile wheels, comprising a barrel (10) rotatably subassembled with a lock cylinder plug (18) the tumblers (24) of which are placed in position by simple insertion of the key (23), which key, however, once inserted and turned, cannot be withdrawn inasmuch as a projection (28) on the key (23) then lies behind a shoulder (20) on the barrel. This subassembly may be rotatably locked upon the fastener element or removed therefrom using but one hand.

The present invention relates to a device for preventing the theft of 
automobile wheels having a barrel which extends over a polygonal head of a 
wheel nut, within which barrel there is arranged a lock cylinder plug the 
tumblers of which projecting beyond the cylindrical surface of the plug 
and entering in an anti-theft position into annular grooves formed in the 
inner wall of the polygonal head, can be brought by the key into a 
position in which they are retracted from the annular grooves. 
One such device is known from West German OS No. 2 301 920 in which the 
collar of the lock cylinder is provided on its inner side with a radially 
directed extension which engages into a recess in the barrel which is 
adapted and shaped thereto. This coupling is necessary so that, upon 
removal of the barrel and the lock cylinder, the key which has been 
introduced into the center of the lock cylinder will, upon its turning 
motion, move the tumblers out of their position of engagement with the 
annular grooves on the inner wall of the polygonal head. Upon turning, to 
be sure, the barrel must be held fast on the other hand so that when the 
key is turned the corresponding control of the tumblers can take place. 
The object of the present invention is to provide a device of the 
afore-mentioned type which is simple to manufacture and more advantageous 
in use, in that the mounting and removal of the barrel and lock cylinder 
plug can be easily effected with one hand. 
This object is aided in its solution in the manner that the key (23), which 
by mere insertion positions the tumblers (24) which are seated in the lock 
cylinder plug which is arranged rotatably with respect to the barrel (10), 
has a projection (28) which lies in the plane of the key slot (30) in 
which, when the key (23) is inserted and turned out of a basic position, 
moves behind a shoulder of the barrel (10). 
As a result of this arrangement there is provided a device of the 
afore-mentioned type of high value in use for preventing the theft of 
automobile wheels. The barrel and the lock cylinder plug form a structural 
unit which, by means of the key introduced into the lock cylinder plug, 
can be coordinated in a very simple manner with the polygonal head of the 
wheel nut and also removed. Due to the combining of the barrel and the 
lock cylinder plug into a single structural unit, parts will be less 
easily lost upon mounting and removal. If the barrel is pushed together 
with the lock cylinder plug, onto the polygonal head, the key is first of 
all to be inserted into the lock cylinder plug, with the lock cylinder 
plug in its basic position. After pushing on the barrel and the removal of 
the key, the barrel together with the lock cylinder plug is already held 
in turnable but non-removable manner on the polygonal head. If the barrel 
is to be removed together with the lock cylinder plug, the lock cylinder 
plug must be brought into the basic position by means of the key. 
Thereupon, the key is turned so that its projection comes behind the 
shoulder of the barrel. A pull on the key then carries the barrel along 
with it and withdraws it from the polygonal head of the wheel nut. This 
can very easily be done with a single hand and can be effected by a layman 
without any great difficulty. Since barrel and lock cylinder plug are 
combined to form a single structural unit, there is also less danger of 
dirtying oneself when removing the barrel. 
The annular shoulder is formed of a spring lock washer (20) which is 
snapped into an annular groove (21) of the barrel (10) and locks the 
cylinder plug (18) in the barrel (10) in a manner so as to prevent it from 
being pulled out, the lock washer having a transverse slot (22). This 
provides a most favorable construction for the structural unit comprising 
the barrel and the lock cylinder plug. The lock washer which serves for 
axially securing the inserted lock cylinder plug in place is at the same 
time used to form the shoulder. The transverse slot in the lock washer 
which is in any event present permits passage of the projection of the 
key, upon the insertion of the latter into the lock cylinder plug. 
In order that the lock cylinder plug remains substantially protected 
against dirt, the front surface of the barrel (10) is covered by a 
protective cap (27) which can be clipped thereon. 
The sealing O-rings (13, 15) are provided on the inner wall of the barrel 
(10), the rings resting respectively against a front fillet (6) of the 
polygonal head (5) and against a cylindrical section (4) on the other side 
of the polygonal head (5). This provides further assurance against 
dirtying. Therefore no dirtying can take place from the direction of the 
polygonal head. 
In order to achieve a stable structural shape which is favorable from the 
standpoint of mounting technique, the polygonal head (5) passes at its 
free end into a protruding collar (7) which extends into an annular 
opening (19) which is formed by the side flank (14') of a shoulder (14) of 
the barrel (10) and the cylindrical surface M of the cylinder plug (18).

The device has a wheel nut 1 which, via its internal thread 2, fits over a 
stud, not shown. By means of a thickened, barrel-shaped collar 3, the nut 
1 engages in centering fashion in the cavity provided on the wheel. 
Adjoining the collar 3 is a cylindrical section 4 which passes into the 
polygonal head 5. The latter is a hexagon head. The front side of the 
polygonal head 5 forms a fillet 6. On the other side of this fillet the 
polygonal head 5 then has a protruding collar 7. 
In the extension of the inner thread 2 there is provided, within the nut 1, 
a cavity 8 from which, in the embodiment shown by example, there extend 
four parallel annular grooves 9 which are equally spaced apart. 
The barrel, which is to be placed on the polygonal head 1 bears the 
reference number 10. Its inside diameter is adapted to the outside 
diameter of the cylindrical section 4 and of the corners of the polygonal 
head 5. At its insertion-side end, there extends from the barrel cavity 11 
an annular groove 12 in which a sealing O-ring 13 lies. At the other end 
of the barrel cavity 11 there is a radially inwardly directed projection 
forming a shoulder 14 against which another sealing O-ring 15 rests. The 
sealing function can also be obtained by a single sealing ring which 
extends over the entire length between the sealing points 13 and 15 and 
has a bead which engages into the annular groove 12. The shoulder 14 forms 
a mounting opening 16 for the collar 17 of a lock cylinder plug 18. 
Between the cylindrical surface M of said plug and a flank 14' of the 
shoulder 14 there is formed an annular opening 19. 
A split ring comprising a lock washer 20 serves to hold the lock cylinder 
plug 18 in axially non-displaceable manner within the barrel. The lock 
washer is recessed, on the front of the collar 17, in an annular groove 21 
of the shoulder 14 which extends from the mounting opening 16. The lock 
washer has a recess transverse slot 22 whose minimum width is somewhat 
larger than the thickness of the key. 
When the key 23 is not introduced, the tumblers 24 protrude beyond the 
cylindrical surface of the lock cylinder plug 18. 
The barrel 10 forms, at its free end, an annular bead 25 which cooperates 
with a catch shoulder 26 of a protective cap 27 which is of dish shape in 
cross section. The cap is provided with a grip collar 27' on its edge. 
The key 23 for the lock cylinder plug 18 is provided on its narrow edge 
adjacent the tumbler cutouts with a notch 29 which forms a projection 28. 
When the key 23 is inserted into the key slot 30, the notch 29 is on a 
line with the lock washer 20. 
If the wheel nut 1 has been screwed onto a stud and is to be secured 
against unscrewing, the barrel 10 is pushed over the polygonal head with 
the key 23 inserted into the lock cylinder plug 18. This is possible since 
in such case the tumblers 24 have the position shown in FIG. 8. The 
movement of the barrel 10 is limited by its front edge coming against the 
collar 3 and by the shoulder 14 of the barrel 10 which comes against the 
free end of the polygonal head 5. In this position, the sealing O-ring 13 
surrounds the cylindrical section 4 on the other side of the polygonal 
head 5 while the other sealing O-ring 15 lies in the front fillet 6 of the 
polygonal head 5. The protruding collar 7 of the polygonal head 5 is then 
introduced into the annular opening 19 between the side flank 14' of the 
shoulder 14 and the cylindrical surface M of the lock cylinder plug 18. 
Furthermore, the tumblers 24 lie in the planes of annular grooves 9 of the 
polygonal head 5. If the key 23 is now withdrawn from the key slot 30, the 
tumblers 24 are led beyond the cylindrical surface M of the lock cylinder 
plug 18 and extend into the annular grooves 9. The barrel 10 can now be 
turned together with the lock cylinder plug 18 but it cannot be withdrawn 
from the polygonal head 5. It is also possible to turn the lock cylinder 
plug 18 with respect to the barrel 10. The protective cap 27 can now be 
placed on, its clip shoulder 26 extending over the annular bead 25 of the 
barrel 10; see FIG. 6. 
If the barrel 10 together with lock cylinder plug 18 are to be removed, the 
protective cap 27 is first of all taken off. Thereupon the key 23 is 
inserted into the key slot 30 of the cylinder plug 18. The complete 
insertion of the key is possible only in the basic position of the lock 
cylinder plug in which the key slot 30 is aligned with the transverse slot 
22 of the lock washer 20. Only then does the projection 28 go behind the 
plane of the lock washer 20 and the shoulder formed by it. The key 23 is 
now turned together with the lock cylinder plug 18, for instance into the 
position shown in FIGS. 9 and 10. The projection 28 thus lies behind the 
shoulder and the lock washer 20. If the key 23 is now pulled, the 
projection 28 carries the barrel 10 along with it via the shoulder-lock 
washer 20 and pulls the barrel from the polygonal head. This operation, as 
well as the placing-on of the barrel, can easily be effected with the use 
of a single hand. 
Instead of development as a nut the threaded fastener element may also be 
developed as a wheel bolt.