Theft protection cable and circuit including said cable

A theft protection electric cable includes at least one conducting core, a sheath which is least partially insulating, and a suitable connection. The cable is characterized in that it is connected between a source of electrical voltage and a user member by at least one contactor (3), said contactor receiving information concerning the conducting or non-conducting state of the cable and including a spring or switch (11, 34) for interrupting the passage of electricity as a function of said information.

The present invention relates to a theft protection electric cable of the 
type comprising a conductive inner core and an insulating outer sheath, 
and also to a circuit including said cable and intended particularly, but 
not exclusively, for self-propelled land, water, or air vehicles. 
These days, motor vehicle theft is reaching epidemic proportions. The 
existence of an ignition key which the owner takes away constitutes a 
first precaution, with said ignition key acting simultaneously to switch 
off the engine's ignition circuit and to mechanically lock the steering 
column. Vehicles are usually stolen by fraudulently switching on the 
engine, either by means of counterfeit ignition keys, or else by means of 
temporary electrical connections which short-circuit the security devices, 
and in particular the key-operated switch block. The aim of the present 
invention is to prevent this second type of theft. 
In order to establish temporary electrical connections to the starter and 
to the engine, the most usual technique consists in stripping the ends of 
an electric cable and in making a connection to its core. The present 
invention seeks to remedy this drawback by preventing access to the core 
of an electric cable when a portion of the cable is stripped. 
French patent document FR-A-647 129 already describes an elastic electrical 
conductor. Regardless of its diameter or its length, this conductor is 
constituted by a steel wire wound in tight coils to constitute a genuine 
traction spring which may be bare or insulated when in use. When the 
conductor is insulated, it is housed inside an elastic insulating tube. An 
elastic electrical conductor is thus obtained capable of being elongated 
to several times its initial length without damaging or fatiguing its 
metal coils. 
U.S. Pat. No. 2,820,149 (ROTH) describes a device for preventing motor 
vehicle theft whereby the ignition key block is connected to the contact 
breaker by a cable comprising a metal sheath, an insulating layer, and a 
rectilinear core. The insulating layer is spiral-wound and under tension 
such that when the cable is broken, the insulating sheath retracts, 
thereby giving rise to a short-circuit between the conductive core and the 
outer metal sheath which is connected to ground. Such a circuit does not 
prevent a parallel connection being set up between the ignition key 
housing and the contact breaker, which is in turn connected to the 
ignition coil. 
U.S. Pat. No. 2,563,335 (ISTRATI) describes a security device controlled by 
a lever located inside the vehicle cabin, which device disconnects the 
ignition system from the battery when the lever is in a given position. 
Here again, the device does not prevent parallel connections from being 
established, thereby enabling the vehicle to be used fraudulently. 
The electrical supply circuit of a vehicle is in the form of a succession 
of lengths of interconnecting members each providing a particular 
function, and in particular there are the following lengths: battery to 
ignition keys; ignition key to starter relay; ignition key to ignition 
coil; ignition coil to contact breaker; etc... 
When a wire has been cut or ripped out at one end, its other end remains 
connected, and as a result it may be used for bypassing a member, e.g. the 
ignition key block. 
A first aim of the present invention is to prevent a portion of the 
original circuit being used to establish a parallel circuit after a 
connection has been disconnected. 
However, if the contactors remain in condition, it would naturally still be 
possible to connect a replacement cable between the two end contactors. 
Thus, a second aim of the present invention is to prevent the connectors 
or contactors delimiting a length which has been disconnected at one of 
its ends or which has been interrupted at some point along the cable from 
being used after such a disconnection. 
To this end, the present invention provides not only for interruption of 
the current path by means of end contactors for the cable, but also for 
contactor locking to prevent further use thereof without disassembly which 
takes time and requires special tools. Under such conditions, a vehicle 
cannot be started very quickly, thereby dissuading potential thieves. 
According to the present invention, the theft protection electric cable 
comprising at least one conductor core, a sheath which is insulating at 
least in part, and connection means, is characterized in that it is 
connected between a source of electric voltage and the user member by 
means of at least one contactor, said contactor receiving information on 
the conducting or non-conducting state of the cable, and having means for 
interrupting the current path as a function of said information. Thus, a 
break at some point along the cable not only interrupts the current path 
at the point of breakage, but also at the contactors. 
In accordance with another characteristic of the invention, the information 
concerning the conducting or nonconducting state of the cable acts on 
contactor locking means. 
Advantageously, the information is transmitted by the cable itself, i.e. by 
the core or by the sheath. Said information may be transmitted by 
mechanical means, by electrical means, or by other means. It indicates to 
the contactor whether the cable is conducting or is non-conducting. An 
interruption at any point along the cable causes a switchover from the 
conducting state to the locked non-conducting state. 
In the case where the core and the sheath are free to move relative to each 
other, the establishment of an electric current path may be due to the 
relative position between the conducting wire (or core) and the insulating 
sheath, and in this case physically breaking the core gives rise not only 
to an interruption of the current path along the core, but also to the 
housing being locked. 
In accordance with another characteristic of the invention, once assembled, 
the core is under mechanical tension and it maintains mechanical contact 
between the parts of the connection housing. 
In accordance with yet another characteristic of the invention, the core is 
spiral-wound, with the sheath being inextensible, and the length of the 
spiral at rest is shorter than the length of the sheath. 
Naturally it is desirable for the outer sheath to be as strong as possible. 
Thus, it is preferable for the outer sheath to be made from a plastic 
material which is reinforced with longitudinal fibers of a substance which 
is strong in traction. In particular, once it has become possible to make 
contact with one end of the conductor, it is important that the sheath 
cannot easily be pulled away to allow a thief to connect a spare cable to 
the other end of he connection. Advantageously, the outer sheath is made 
of a plastic material which is difficult to cut, such as Rilsan reinforced 
with longitudinal fibers which may be made of an aromatic polyamide or 
Kevlar, or else may be made of steel. 
The security obtained in this way by the structure of the cable is fully 
justified only in a case where the ends of the cable are sealed inside 
tamper-proof contactor blocks. Thus, the present invention relates to a 
circuit implementing the invention and characterized in that the core is 
connected at each end to a moving connection part inside a contactor, said 
connection part being capable of being locked inside the contactor fixed 
on the vehicle. 
The spiral core may be wound on or integrated in an insulating elastic 
reinforcement member. Thus, the functions of conducting electricity and of 
applying mechanical tension are disassociated, thereby making it possible 
for the core of the conductor to be constituted by an electric wire 
without any special mechanical characteristics other than the presence of 
regions of reduced mechanical strength at its ends. 
It has been observed that it is not necessary for the tension exerted on 
the cable to result from the cable itself. Consequently, the cable, or 
more precisely its core, may be rectilinear and/or linear, with the 
tension being applied by means of springs. It may also be wound only along 
a small portion of its length. 
In one embodiment, the cable core interconnecting the two contactors is 
linear, at least in part, with the tension established between the two 
contactors causing, at each end, a part fixed to the end of the core to be 
pressed against a conducting zone while compressing a spring, the 
conducting zone being connected to a source of electricity or to a user 
apparatus. 
Thus, it is the spring in each housing operating under compression which 
provides the tension on the core rather than its own spiral structure. 
However, for assembly purposes, it is necessary for the sheath to be 
removably mounted on the housing. Even if locking means are provided, said 
sheath should always be fairly easy to disassemble. If the movements of 
the sheath and the electric wire are independent so as to allow relative 
sliding of the core in order to interrupt the path of electrical current, 
the theif may be able to gain access to the core which has not been 
interrupted, said core still being electrically conductive. 
Advantageously, the circuit including the theft protection cable in which 
the electric wire is capable of moving relative to the sheath, said wire 
still being connected at at least one of its ends to a contact part 
capable of sliding inside a contactor and being loaded by a spring, is 
characterized in that the contact terminal is protected by a sleeve which 
is longer than the terminal. 
It thus becomes impossible to make a parallel connection after removing the 
sheath without breaking the central wire. In order to facilitate relative 
movement between the core and the sheath, balls may be disposed between 
these two components. Such balls transfer a radial force (e.g. when an 
attempt is being made to cut the cable using pliers) into a longitudinal 
force which is applied to the sheath, thereby giving rise to an 
interruption action in the housing. Advantageously, the balls may be 
replaced by small truncated cones which bear against the core during an 
attempt at cutting the cable in order to pull it in one direction and push 
it in the opposite direction. In this case, one of the end contactors 
opens. 
The present invention also seeks to cover the case where the insulating 
sheath and the conductive core are mechanically fixed together, which is 
the case that applies to ordinary cables where the conductive wire is 
embedded in an insulating sheath. 
According to yet another characteristic of the invention, in a theft 
protection circuit including an electric cable, with at least one end of 
the cable core being fixed to a moving part inside a housing, the moving 
part is pressed against a conducting surface by compression means, with 
second means preventing contact of the moving part with the conducting 
surface once the cable has been subjected to traction. 
Thus, the conducting core may be embedded in an insulating sheath and fixed 
thereto, whether or not the sheath is reinforced. Preferably, the sheath 
should withstand shear and drilling, and since any attempt to apply shear 
always gives rise to traction on the cable, said traction gives rise to 
disconnection, i.e. the spring is compressed and the part inside the 
housing is displaced. The presence of the locking means prevents contact 
from being re-established without action by a specialist who will need to 
disassemble the housing. The body of the contactor itself is fixed to the 
member which is to be protected or else to a panel when the ignition key 
area is to be protected. 
The present invention provides security when the sheath is subjected to an 
attempt at dismantling, as in the case where the core is cut supposing 
that the core can move relative to the sheath. In a cable comprising a 
conducting core and an insulating sheath surrounding the core, the core 
and the sheath being capable of being subjected to relative translation, 
at least one end of the cable core being fixed to a moving part inside a 
box, the cable is characterized in that a sleeve is fixed to the sheath, 
with the sleeve surrounding the core and penetrating inside the housing in 
such a manner as to come into abutment against a plate bearing an electric 
contact, the moving part includes a zone of reduced diameter at its front 
end capable of passing through an opening formed in a plate fixed inside 
the housing, and a spring is disposed between the bottom of the contact 
part and the contact-carrying plate. 
According to another characteristic of the invention, the contact-carrying 
plate is provided with resilient lugs whose free ends bear either against 
the side wall of the bottom of the part, or else against the side wall of 
the part. These lugs serve to constitute locking abutments preventing 
current from being re-established after an attempt has been made at theft. 
Thus, in accordance with the present invention, once the core has moved 
relative to the sheath, the electric current path is interrupted both if 
the core is cut and if the sheath is disassembled. 
In another embodiment, at least one conductive wire connected at each end 
to electric current interrupting means is embedded inside the sheath. When 
the conductive wire is cut at the beginning of sheath shearing, a signal 
is provided indicative of the existence of a fraudulent maneuver, which 
signal may trigger an alarm. The main circuit is preferably cut when this 
conductor is cut. 
In this case, the means for interrupting the electric current comprise at 
least one electromagnetic switch connected in series in the main feed 
circuit. 
Advantageously the sheath is removably mounted on the top end of the 
ignition head, with the cable core being fixed to a skirt which 
establishes contact between the core and a conductive area on the ignition 
head when the sheath is suitably mounted.

In FIG. 1, it can be seen that the cable is constituted by an electric wire 
1 constituting the spiral-wound core. This wire has the elasticity 
required to constitute a kind of spring. The spiral is included inside an 
insulating sheath 2 made of "Rilsan" (registered trademark), for example, 
having longitudinal reinforcing threads 2a made of aromatic polyamide or 
of steel, for example, so as to have considerable resistance to attempts 
at cutting it. Given the strength of the sheath 2, if it is cut, then the 
wire 1 will automatically be cut too. Once the cable has been cut, the 
wire 2 retracts inside the sheath. Naturally, the length of each cable is 
determined to correspond to the exact path between a sealed metal 
contactor box located inside the engine compartment or beneath the vehicle 
floor, and the key-operated contactor which is generally situated in the 
vicinity of the steering column. The electric wire 1 is fixed at each end 
to respective contact parts 4. In addition to their conventional function, 
these contact parts also act as traction elements for maintaining the 
spiral conductor wire 1 under tension. The connection between the wire 1 
and the terminal 4 is advantageously weakened in the transverse direction. 
To this end, prior to assembly, disks D (which may be split disks) are 
disposed behind the connection parts 4 on the inside-cable side in order 
to keep the core 1 under tension. At this moment the tension is close to 
the breaking point of the wire 1. The tension is continuously applied to 
the spiral by external items mounted in a contactor. 
The connection part 4 (which may be cylindrical in section for example), 
may have a radial hole in which a conductive peg may be inserted connected 
to the high voltage terminal of the engine electricity circuit. In the 
embodiment shown in FIGS. 2 and 3 (from which the housing of the contactor 
has been omitted), reference 16 indicates the wall against which the 
contactor housing is mounted, and the part 4 passes through an orifice 8 
provided in a plate 9 which is fixed to the connection housing. The plate 
9 is insulating but it has a conducting surface 10 on its side inside the 
housing (to the left in the figure). The surface 10 is connected to the 
positive terminal of the battery, for example. 
Assembly takes place as follows. The part 4 is inserted inside the 
insulating connection part 9 via orifice 8, 8a. At this moment, the 
conductor 1 is still maintained under tension by the disks D. The 
tension-maintaining disk D is then separated into two portions and is 
removed from the housing being assembled. In the embodiment shown in FIGS. 
2 and 3, the peg has been replaced by a peg 12 which is fixed to the part 
4. Under the influence of the extraction force exerted by the sprial wire 
1, the part 4a is pulled to the right of the figure (FIG. 3), bringing the 
end thereof into contact with the conducting surface 10, thus establishing 
contact at one end of the cable. The same applies to the other end. The 
cable is thus under tension between its two connection parts 9 and remains 
in this position until an attempt at fraud occurs. When the cable is cut, 
the wire 1 is cut and it retracts inside the sheath as mentioned above. 
This traction releases the contact exerted by the cap 4a on the surface 10 
and contact is also broken, as shown in FIG. 2. Further, since contact 
cannot be directly re-established, it is impossible to interconnect the 
two parts electrically. 
FIG. 4 shows a variant embodiment in which the spirally-wound wire 1 is 
terminated at each end by a head 12. As before, the wire 1 passes through 
a hole 8 provided in an insulating part 9 bearing a conductive peripheral 
zone 10. Between the part 9 and the end 4 of the conductive wire 1 there 
is a return spring 11 whose coefficient of compressibility is considerably 
less than that of the spring constituted by the wire 1. Thus, during 
normal assembly and use of the cable in accordance with the invention, the 
core 1 applies tension to the part 4 causing the branches of the U-shaped 
member 12 to come into contact with the conducting zones 10 of the part 9. 
The spring 11 is compressed and contact is normally established. However, 
when the wire 1 is cut (as shown in FIG. 4), the return spring 11 moves 
the part 4 away from the conducting zone 10 and contact is broken. Locking 
is provided to prevent the contact 4 from returning to the zone 10. It is 
also possible to provide for the rod 4 to move so far that it falls inside 
the housing. As before, contact cannot be re-established fraudulently and 
after such an operation it is necessary to mount a new cable on the 
vehicle. 
FIG. 5 is a face view of a connection plate 9 and on this part there can be 
seen an outer conducting zone 10, and a slot 8a for passing the rod 4 and 
leading into a hole 8. The connection plate 9 is included inside a 
tamper-proof security housing 3. 
In the embodiment shown in FIG. 6, the conducting wire 1 is spiral-wound on 
a reinforcement member 21 having constant longitudinal elasticity, e.g. 
neoprene. At each end of the reinforcement member 21, the wire 1 
penetrates into the reinforcement member so as to emerge radially 
therefrom and be soldered (or more generally be electrically connected) to 
a peg 4, with the assembly being put into position under tension. 
Alternatively, as shown in FIG. 7, the turns of the core 1 may be embedded 
inside the reinforcement member 21. As a result the core-constituting 
electric wire 1 need not necessarily have considerable elastic 
characteristics, since the required elasticity is provided by the 
reinforcement member. 
Preferably, the reinforcement member 21 is made of neoprene having a Shore 
hardness lying between 100 and 140, and is under a tension of about 700 g 
giving an extension of 5% to 6%. In this embedded core embodiment, it is 
practically impossible to strip the wire. 
However, the relative hardness of the neoprene gives rise to the core 
retracting less when the conductor is cut. Also, the cable is connected 
between two contactors in which contact can only be maintained by tension 
in the conductive core, regardless of the contour which the cable is 
caused to follow inside the vehicle. 
FIGS. 8 and 9 show one of the housings 3, respectively in the conducting or 
contact position and in a non-conducting position. These figures again 
show a connector tab 4 having a head 12, and an insulating plate 9 with a 
central orifice and a conducting peripheral zone 10. A return spring 11 is 
interposed between the plate 9 and the head 12. Naturally, the coefficient 
of compressibility of the spring is much less than that of the spring 
constituted by the assembly of the core 1 and the reinforcing member 21. 
In FIG. 8, the branches of the U-shaped head 12 are pressed against the 
conducting zones 10 of the part 9 under the effect of the traction exerted 
by the core 1. A retractable abutment 13 is disposed beneath the part 12, 
with the abutment 13 being biased by a spring 15 included in a recess 14 
fixed to the wall 17 of the housing. When the cable is put into place, the 
abutment is retracted into the recess 14, thereby compressing the spring 
15. Reference 16 indicates a fixed wall of the vehicle. 
When a theft attempt is made on the cable, the part 12 is moved back as 
shown in FIG. 9, thereby disconnecting the cable 1 from the electricity 
supply. However, during this movement, the abutment 13 no longer bears 
against the head 12. As a result it projects out from the recess 14 
thereby preventing the head from returning rightwards in the figure, i.e. 
the abutment 13 prevents contact from being re-established. Contact is 
therefore permanently broken. As a result, even a small displacement of 
the core 1 gives rise to permanent loss of any possibility of 
re-establishing the circuit. 
Naturally, any other conventional locking device could be implemented. The 
vehicle is thus immobilized, and it can only be put back into working 
order by a technician re-establishing the necessary connections. 
FIG. 10 is a vertical section through a contactor showing the sheath 2 
being fixed to a housing 3 by means of a cable guide 20. The conducting 
core 1 is fixed to a connector 4a whose front portion projects partially 
therefrom outside the housing 3. This fixing may be provided by soldering 
and crimping in the conventional manner for connector tabs in motor 
vehicles, or else it may be provided by means of a screw, or else by a 
combination of both means. The presence of a screw connection makes it 
possible to adjust the tension in the cable, with unscrewing being 
prevented by subsequent soldering. The moving part is constituted by a 
cylindrical body 4 within which the connector tab 4a is fixed. The rod 4a 
is connected to the core 1 at 19. In accordance with a characteristic of 
the invention, the cylindrical body 4 extends at its rear end in the form 
of a disk 12 whose outside diameter is greater than the diameter of the 
cylindrical body 4. 
Resilient arms 18 bear against the periphery of said disk, and their 
function is described below. The housing 3 is closed by a cover 6 which 
may be screwed into place with an epoxy glue of the type known under the 
name "Loctite" (registered trademark) being interposed. 
In the position shown in FIG. 10 (conducting position) the front portion of 
the cylindrical part 4 bears against a conducting area 10. The cylindrical 
part is held in place and contact is established under the effect of the 
tension applied by the core 1. This tension compresses a spring 11 against 
an insulating plate 9 which is disk-shaped and which carries the 
conducting area 10. An identical spring is disposed inside the housing at 
the other end of the cable, and the two springs 11 are calibrated so that 
the tension exerted on the cable is in the range one to two kilograms in 
order to avoid accidental disconnection. In addition, the plate 9 serves 
to hold the resilient arms 18 at their front ends, with their rear ends 
resting against the flange 12. The cover 6 has an opening 7 through which 
there passes an electric cable C which is connected, for example, to the 
positive terminal of the storage battery. The conductor C is naturally 
connected to the conducting area 10. The spring 11 bears firstly against 
the rear face of the insulating plate 9 and secondly against the bottom of 
the cavity provided inside the cylindrical body 4. 
When the cable is sheared, the tension exerted thereon by the pair of 
springs 11 at each of its ends is interrupted. Consequently, the part 4 
moves backwards under the action of the spring 11 expanding away from the 
point of shear, and the same happens to the corresponding part in the 
other housing. During this movement, the resilient arms 18 snap down along 
the body 4, and contact is lost between the body 4 and the circuit 10. By 
snapping down onto the body 4, the resilient arms 18 constitute abutments 
preventing the part 4 from moving back towards the zone 10, and 
consequently preventing electrical contact from being re-established. 
FIGS. 10 and 22 show two diametrically opposite arms, but naturally there 
could be any suitable number for obtaining the desired result. If 
necessary, notches could be provided in the disk 12 in order to lock the 
arms 18 after they have been released. Any other locking device could also 
be used. 
Naturally, the core 1 must be capable of sliding freely inside the sheath 
2, and preferably the core is coated on the outside with a layer of Teflon 
or with any other low coefficient of friction material in order to 
encourage the core to slide freely whenever it comes into contact with the 
sheath. 
FIG. 12 is a section in a vertical plane in which the core 1 is fixed to 
the contact part 4 which comprises a body whose section matches the 
internal section of the housing 3 and which extends towards the core in 
the form of a connector tab 4a. The rear portion of the housing is closed 
by a cover 6. 
In FIG. 12, the outer edge of the part 4 comes into contact with a 
ring-shaped conducting zone 10 which is connected to the voltage source or 
to a user apparatus. The important thing is that in the event of a 
fraudulent manoeuver, the electrical circuit should be broken, and the 
other end of the cable may have either a housing or else a spring-loaded 
connector tab for providing the required mechanial tension. The housing 3 
is bonded to the chassis of the vehicle 16 or to some other fixed wall by 
means of a flange 3a, e.g. by riveting or by welding. Naturally, in this 
case the inside surface of the housing 3 is insulating apart from the 
conducting zone 10. The sheath 2 is terminated at its front end (at its 
housing end) by an annular zone 2a which is pressed against the front face 
3b of the housing 3 by a nut 20. 
As shown in FIG. 12, the sheath can be disassembled by unscrewing the nut 
20 while the cable is under mechanical tension and a path is provided for 
electric current. At this moment, the sheath can move back by a few 
millimeters, even if it is incompressible. This movement is also limited 
by the fact that the inner core cannot be subjected to additional tension 
without breaking, thereby reducing the scope for maneuver. 
However, it would theoretically be possible to make a connection to the 
connector tab 4a by sliding a conductor between the front face of the 
housing 3b and the ring 2a of the sheath. In order to mitigate this 
drawback, a sleeve 24 is preferably provided surrounding the connector tab 
4a so that direct access thereto is prevented under such circumstances. 
The sleeve may be insulating and fixed to the body 4 or else it may be 
constituted by an isolated metal wall of the body 4. Making a hole through 
the sleeve gives rise to additional tension on the wire 1 which will 
break, thereby interrupting the current path. 
FIG. 13 shows the case where the core 1 has been broken without there 
having been any attempt at dissassembling the sheath at the end shown. As 
can be seen in the figure, the break in the wire 1 releases the spring 11 
and consequently moves the piston constituted by the body 4 to the right 
of FIG. 13. As a result, the body 4 is retracted and current is 
disconnected from the wire 1. During this retraction movement, the 
abutment 13 moves downwardly and prevents the body 4 from returning 
towards the conducting zone 10. In order to avoid electrical problems, the 
bottom 6 of the housing 3 may be connected to ground, for example. 
In the examples described so far, the core is always capable of sliding 
relative to the sheath. The embodiment shown in FIGS. 14 and 15 is 
intended to produce the theft-preventing effect against the cable being 
torn out, whereas the other embodiments described concern the cable being 
cut. 
In FIG. 14, the core 1 of the cable is imprisoned within and fixed relative 
to a sheath 2. The end of the cable is stripped so as to enable the core 1 
to be fixed, e.g. by soldering, to a connector tab 4a, which is in turn 
fixed to the contact part 4 without traction on the wire. As mentioned 
above, the part 4 is movable inside a contactor (which may be cylindrical 
in shape), with the housing 3 thereof being fixed to the chassis or the 
bodywork of a car by a flange 3a which is screwed or spot-welded into 
place. The inside of the housing is advantageously coated with an 
insulating layer 28 or with a sleeve of plastic material having a low 
coefficient of friction. The connector tab 4a is metal and conductive. In 
the example shown in FIGS. 14 and 15, there is also a spring 11 inside the 
housing bearing against the front face 3b of the housing and also against 
the face 4c of the moving part 4. In normal operation, as shown in FIG. 
14, this spring is slightly compressed by virtue of its dimensions 
compared with the dimensions of the housing. As shown in this figure, the 
bottom 4b of the part 4 is pressed against the conducting surface 6 or 
against the annular zone 10 by the pressure from the spring 11 with the 
face 4b coming into contact in such a manner as to ensure that the contact 
area is not less than the cross-sectional area of the cable core 1. The 
zone 10 may be constituted by two contacts which close the control circuit 
to the trigger of a thyristor which controls the main current. 
In accordance with the present invention, locking means are provided inside 
the housing 3. In the embodiment shown, these locking means are 
constituted by a collar 25 of resilient material whose rest diameter is 
less than the diameter of the area 4b of the contact part 4, supposing it 
to be cylindrical. The collar 25 is fixed in the bottom of the housing. 
When a fraudulent maneuver causes traction to be exerted on the conductor 
wire or on the sheath with a force which is greater than the resistance of 
the spring 11, the part 4 moves leftwardly in FIG. 14, i.e. towards the 
front of the contactor housing 3, and the spring 11 is compressed by an 
amount which is a function of the traction force which is applied to the 
cable. As it moves, the part 4 disengages from the collar 25 by spreading 
out the edges thereof, thereby leaving the collar in position at the end 
of the housing. To this end, the face 4c of the part 4 may be slightly 
frustoconical (FIG. 14) in order to facilitate disengagement, or else it 
may be cylindrical (as shown in FIG. 15). The movement of the part 4 
breaks the electrical contact existing between the surface 10 and the core 
1. When the force is released to the action of the spring 11 returns the 
part 4 to the right. However, during this return movement, it bears 
against the leading edge of the collar 25 by means of its surface 4b and 
presses the collar against the wall 6. The presence of this collar 
prevents any contact being established between the part 4 and the contact 
10, and as a result there remains a gap 25a between the part 4 and the end 
6. Contact cannot be re-established without dismantling the housing. 
The collar 25 could be replaced by two or more resilient insulating arms of 
plastic material as described above. If their coefficient of elasticity is 
sufficient, the snap-action force obtained in this way may make it 
pointless to provide a spring 11, with the face 4b of the part 4 being 
applied with the appropriate pressure against the area 10. Naturally, 
after the part 4 has been pulled away it can move freely inside the 
housing 3, but this does not matter since the arms or the collar 25 
prevent the current path from being re-established. 
In this embodiment, only the ends of the core are under tension, and the 
cable is free between its two contactors. In addition, contact is ensured 
in a positive manner. However, breaking contact at one or other of the 
ends of the cable does not ensure that contact is broken at the other end, 
supposing it is of similar structure. 
It is possible to provide two contact parts 26 inside the housing 3 such 
that when the part 4 moves forwardly, these contact parts serve either to 
close an alarm circuit or an anti-theft circuit supposing one exists on 
the vehicle, or else to cause a short-circuit suitable for blowing a fuse 
if one of the terminals 26 is ground and the other has a voltage applied 
thereto, or else to interrupt the circuit at the other end of the cable. 
Naturally, any locking means may be used which ensure that a gap 25a 
subsists between the part 4 and the wall 6 after traction has been applied 
to the cable. Thus, for example, the peripheral wall of the part 4 may 
constitute a cam which modifies the position of a locking ratchet. Under 
such conditions, the application of any traction to the sheath interrupts 
the current path at the end thereof where said traction is applied. 
In the position shown in FIG. 15, the isolated part 4 masks access to the 
conducting area so that it is not possible to reach it using a piece of 
wire. 
As in the above embodiments, it is necessary to have a housing only at the 
electricity source end. However, as a security precaution, it is desirable 
to mount a second housing at the user member end, e.g. the ignition coil 
end, as well. However, the existence of a theft protection cable in 
accordance with the invention is particularly useful for the lengths of 
electric circuit which connect the battery to the ignition key and the 
ignition switch to the ignition coil. 
FIGS. 16, 17, and 18 show another embodiment in which the core 1 of the 
cable is surrounded by a sheath 2 and is fixed thereto. The end of the 
core 1 is fixed to a contact part 4 capable of moving inside the housing 
3. Forward displacement (towards the cable) of the part 4 is limited by a 
plat 19 fixed inside the housing 3. The plate 19 has a central opening 33 
through which the front portion 4a of the part 4 may pass. A single 
locking arm 18 is shown in the figures. 
Naturally, in accordance with a characteristic of the invention, the core 1 
is under tension either by means of a spring tab located at the other end 
of the cable, or else by similar means. Thus, in normal operation, the 
front portion 4a of the part 4 is engaged through the opening 33. It thus 
comes to bear against the contacts 10 of a contact-carrying plate 9 which 
is also movable within the housing 3. The plate 9 is urged to the right in 
the figure by a skirt 24 which is hollow and fixed to the sheath 2, and 
through which the core 1 passes. Thus, when the sheath 2 is screwed onto 
the body of the housing 3 by means of a nut 20, the skirt 24 moves to the 
right in the figure until contact is established between the plate 9 and 
the portion 4a. The core 1 is fixed to the end 12 of the part 4 and a 
spring 11 is interposed between the end 12 and the plate 9. Screwing the 
sheath by means of the nut 20 gives rise not only to the part 4 being 
brought into contact with the conducting area 10, but also to the spring 
11 being compressed. Mechanical and electrical contact is thus established 
between the core 11 and the conducting area 10. 
FIG. 16 shows the device in its normal operating position with the user 
member being fed from the battery or the alternator. 
FIG. 17 shows the position of the members after the core and the sheath 
have been sheared at some point (not shown). At this moment, the tension 
exerted on the core disappears. As a result the spring 11 expands, thereby 
moving the part 4 to the right in the figure such that the front 4a of the 
part 4 loses contact with the conducting area 10. Contact is thus broken 
and no current can flow along the core 1. As mentioned below, contact 
cannot be re-established simply by applying traction to the core because 
of the locking means which are present. 
FIG. 18 shows the case where the sheath has been dismounted. At this 
moment, the nut 20 being unscrewed releases the force exerted by the skirt 
24 on the plate 9. The spring 11 is thus free to expand through the 
orifice 23 and it moves the plate 9 away from the front portion 4a of the 
part 4. Here again contact is broken between the area 10 and the part 4. 
The part 4 remains in its original position and, as mentioned above, 
contact can only be re-established by intervention of a specialist. 
FIGS. 19 and 20 are views along arrows F and F1 of FIGS. 16 and 18 showing 
the plates 9 and 19. Each of them has a central opening, respectively 30 
or 33, with the opening 33 serving to pass the core 1 and the leading end 
4a of the part 4, while the opening 30 serves to pass the core 1. 
Resilient arms 18 are fixed to the plate 9. These arms extend 
perpendicularly to the surface shown so only the ends 31 thereof can be 
seen. These arms pass through notches 32 provided in the periphery of the 
disk 19. 
FIGS. 21 to 23 are diagrams showing the positions of the arms 18 in the 
cases shown by FIGS. 16 to 18. In FIG. 21, the free ends of the arms (of 
which there are four in the example shown, but there could be fewer or 
more) come into abutment on the outside of the disk 12 constituting the 
rear portion of the part 4. Thus, the part 4 can move to the right in the 
figure or rearwardly by deforming the arms 18. By virtue of the resilience 
of the arms 18, this motion causes the ends of the arms to bear against 
the outside wall of said part. This position is shown in FIG. 22. Thus, if 
the core 1 is pulled after being broken, the part 4 tends to be returned 
forwardly. However, the ends of the arms 18 bear against the 
abutment-forming collar 12 thus limiting the forwards displacement and 
opposing any re-establishment of electrical contact. The distance between 
the plates 9 and 19 remains the same in both cases. 
FIG. 23 shows a contrasting case corresponding to that shown in FIG. 17. In 
this case, the sheath has been dismounted. At this moment, the effect of 
the spring 11 is to displace the plate 9 forwardly in the figure so as to 
move it away from the plate 19. Naturally, as it moves, it takes the arms 
18 with it so that the ends thereof come down from the collar 12 and press 
against the side wall of the part 4. Here again, if the sheath is 
reassembled, the ends of the arms 18 slide along the side wall of the part 
4 and come into abutment against the collar 12 so as to move it 
rightwardly (as shown in FIG. 22), thereby making contact impossible, yet 
again. Naturally, after an attempted theft, contact may be re-established 
but only by qualified personnel using specialized tooling. 
Thus, by virtue of the dispositions of the present invention, a vehicle is 
protected against attempts at theft either by shearing the cable which 
causes the part 4 to move rearwardly, or else by dismounting the sheath 
which causes the contact-carrying plate 9 to move forwardly, with the 
passage of electrical current along the core being interrupted in either 
case. 
Another embodiment is shown in FIG. 24. In this embodiment, the sheath 2 is 
made of plastic material or the like and is not particularly strong. A 
conductor 35 is embedded inside the sheath. As is conventional in motor 
vehicle electrical circuits, the conductor 35 is connected by a multi-pin 
connector between two pins 38a and 38b at the same time as the main 
conductor is connected. The pin 38a situated at the voltage feed end is 
connected firstly to the voltage source and secondly to the coil 43 of an 
electromagnet whose core is connected to an armature suitable for opening 
or closing a switch 34. The switch 34 is shown in the closed position and 
the other circuit components are shown in their operating positions. The 
coil of the electromagnet 43 may be connected to the voltage source via a 
suitable circuit so that the switch 34 remains closed so long as 
electrical current flows along the conductor 35. Naturally, any other 
means for switching off a current could be used, e.g. a thyristor. The 
switch 34 is connected firstly to the voltage source and secondly, via the 
housings 3, to the conducting core 1 so as to convey electricity to the 
terminal 27 of a user member. A voltage is applied to the conductor wire 
35 which runs via the plug pin 38b and through a member 36 to ground. It 
is also possible to provide two conducting wires within the sheath 2 which 
are isolated from one another and which have their ends put into 
electrical contact by the connector tab 38b being engaged with a 
complementary connector. These two wires then constitute the circuit for 
setting up a holding current through the solenoid 43. FIG. 24 shows the 
wire 35 as a rectilinear conductor, however it is preferable for this wire 
to be wound in a spiral inside the sheath in order to make it difficult to 
identify during cutting. 
This circuit operates as follows: in normal operation, the switch 34 is 
closed and conveys voltage via the housings 3 and the core 1 to terminal 
27 of the user apparatus. Simultaneously, the solenoid 43 is powered and 
the circuit is looped to ground via the conductor 35. If the sheath is 
disconnected, the solenoid is no longer powered since contact is 
interrupted at one or other of the pins 38, and consequently the contactor 
34 opens, thereby preventing current from flowing along the conducting 
core 1, and consequently taking voltage away from the terminal 27. 
Similarly, if the sheath is cut, the wire 25 is also cut and the contact 
24 opens automatically so that it is no longer possible to start the 
vehicle, supposing the circuit described is connected to the ignition 
coil. Preferably, the switch 34 is provided with means for preventing it 
from being immediately put back into operation. The effectiveness of this 
theft protection circuit is then considerably reinforced. In this 
embodiment, the information concerning conduction along the circuit 
constitutes an electrical signal analogous to the mechanical signal used 
above. 
FIG. 25 shows an ignition distributor comprising a body 37 and a cover 39. 
The top of the cover has a cylindrical tube 49 extending therefrom and 
terminated by a threaded portion for engaging a nut 20 fixed to the sheath 
2 of an electricity feed cable. The core 1 of this cable is connected to a 
conductive skirt 24 which, under pressure from the nut 20 being screwed on 
the tube 49 urges the core 1 into electrical contact with a conducting 
area 10 connected to the high tension inlet tab. The cover 39 is fixed to 
the body 37 in conventional manner, i.e. by resilient toggles 40, or else 
by screws. The other end of the core 1 is connected to the coil by an 
assembly of the type described above such that when the sheath 2 is 
dismounted, it becomes impossible to pass an electric current along the 
core. 
A recess 42 extends transversely to the top of the tube 49 and a locking 
member or part is housed therein, as shown in FIG. 26. This member 
includes a spring 55 and a locking plate 53 which is biassed by the spring 
55. The front portion of the plate 53 has a notch 54. Initially, the plate 
53 bears against the outer surface of the skirt 24 under pressure from the 
spring 55. When the nut 20 is unscrewed, the skirt 24 rises under the 
action of the spring 11 so that the edges of the notch 25 move under the 
groove 41 in the skirt 24. Thus, the skirt 24 is locked in its upper 
position and contact can no longer be established between the core 1 and 
the conducting area 10, nor can a conductor be passed through the skirt. 
Naturally, the space between the electrodes of the skirt 24 and the 
conducting area 10 is large enough to avoid arcing. 
The plate 53 can be released solely by opening the recess 42 which firstly 
requires a certain amount of time and which secondly requires a special 
tool in order to allow the skirt 24 to move back into the tube. Naturally, 
the distance between the level of the plate 53 and that of the groove 31 
in its in-use position is greater than the length of the screw thread 13 
so as to ensure that the plate 53 cannot be broken by screwing, and the 
plate 53 is also made to be sufficiently strong. It is also possible to 
provide an opening in the skirt 24 to receive the plate 53. 
Thus, it is no longer possible to obtain access to the high voltage inlet 
tab after the sheath has been dismounted, since the skirt 24 remains 
locked in its high position inside the tube, while the end of the skirt 24 
is solid. 
However, it is possible to separate the distributor head from the 
distributor body. A thief may have a spare distributor head. In order to 
avoid this drawback, metal rods 48 are provided inside thebody 37 at the 
periphery thereof and extending along the entire length of the body, said 
rods being interconnected at their bottom ends by a bracket 51. 
The top portions of the rods 48 may be level with the top surface of the 
body 37 or they may project therefrom and engage in cavities provided for 
the purpose. The bracket 51 is kept away from the end of the body 37 by a 
return spring 57. In FIG. 25, the cover 39 is mounted on the body 37 and 
provides contact. When the cover is dismounted, the return spring 57 
causes the rod 48 to project from the top surface of the body and a new 
cover cannot be mounted thereon since the high position of the rods 48 is 
locked by a housing 52 containing a pin or other locking means. In order 
to put the assembly back into working order, it is necessary to change the 
housing 52 or to recompress its spring. Thus, the rods 48 can only be 
retracted back into the body 37 by resetting the locking means 52, and 
this takes time. 
The ignition coil is advantageously fixed to the distributor cover. 
Previously, the coil has been connected to the distributor by a suitably 
insulated electrical cable. This is because ignition coils were made using 
windings insulated by an oil that might leak. However, now that dry coils 
are available, there is no longer any need to separate the coil from the 
distributor, thus eliminating an electrical connection. 
In FIG. 27, the feed current arrives at the coil 65 via an external wire 2 
connected to the battery by means of the contactor on the dashboard. The 
wire 2 is connected to the coil 65 by a device including a security 
contactor 3. Contact is established by screwing the nut 20 on the neck 61 
of the coil. The coil 65 is connected by a switch device 68 to the contact 
breaker which, by breaking current in the primary circuit gives rise to 
very high tension in the secondary winding. As in the prior art, this very 
high tension is conveyed to a graphite electrode in contact with a 
distributor arm (not shown), with the distributor arm being driven by a 
mechanical take-off from the engine, such that the speed of distribution 
is directly proportional to engine revolutions. 
The housing of the coil 65 is integrated in the cover 39 of the 
distributor. In the example shown, the bundle of electrical connections to 
the spark plugs is connected sideways relative to the cover, 
perpendicularly to the body of the distributor, and the end piece 64 of 
each wire is in the form of a cylinder (only two of which can be seen in 
the figure). The cover 39 bears against the body 37 of the distributor via 
a ring 39a which covers the top edge of the body 37. 
In accordance with the invention, the cover 39 is hinged to the body 37 
about a shaft 66 terminated by two end plates 67. In the example shown, 
the shaft 66 is on the opposite side to the connection end fittings 64. 
Naturally, the distributor arm (not shown) projects inside the cover and 
comes into contact with successive conducting areas for each of the end 
fittings at a moment when high tension is available. The distributor cover 
is closed onto the body thereof by means of one or more toggles 40 having 
one end hinged to the body 37 and the opposite end bearing resiliently 
against the ring 39a. 
The cover may also be held down on the body by means of a screw 69 as shown 
in the figure. The head of the screw 69 bears against the ring 39a and its 
shank penetrates into a blind hole 73 having a nut 70 fixed therein by a 
pin 72 and biassed by a return spring 71. If, after opening the cover 39, 
a thief seeks to remove the toggle 40, he removes the pin 72 from the nut 
70 and the spring 71 causes it to rise inside the bore 73. Then, if he 
tries to put a replacement cover in place of the original cover, there is 
no way of tightening a screw 69 since the nut 70 is free inside the bore 
73. It is thus impossible to start the vehicle fraudulently by using a 
flying coil since, in any event, the distributor cover cannot be properly 
fastened to the body of the distributor. 
Naturally, if the cover 39 is not hinged to the body 37 by means of a fixed 
shaft but is hinged by means of a loop passing through the cover 39, and 
having its ends penetrating into the body 37, these ends constitute the 
pins 72 so as to make it impossible to mount a spare head, regardless of 
whether the head includes its own coil or not. The loop may also be 
connected to an electric security circuit for preventing the engine from 
being started if it is broken.