GB2289658A - Disabling device for a shaft - Google Patents

Abstract

A disabling device for an operating shaft and to a fitted machine, in particular, an anti-theft disabling device for the steering shaft of a motor vehicle, comprises a shaft having a rotatable part 10 connected to a steering wheel and a rotated part 11 connected to the road wheels, the device having an enabled condition in which rotation of the rotatable part causes rotation of the rotated part and a disabled condition in which a sliding coupler 40 disconnects the parts so that rotation of the rotatable part does not cause rotation of the rotated part, characterised in that a key-controlled operating cam 30 transfers the said parts from the disabled to the enabled conditions. A security housing for the device is also provided, and means to limit the rotation of the disabled shaft. <IMAGE>

Description

DISABLING DEVICE FOR AN OPERATING SHAFT, AND FITTED MACHINE FIELD OF THE INVENTION This invention relates to a disabling device for an operating shaft and to a fitted machine.

The device is likely to have particular utility in relation to the disabling of the steering shaft of a movable machine i.e. a motor vehicle, for use as an anti-theft device, and will so be described below, though it can be used to disable any shaft utilising full or partial axial rotation.

BACKGROUND TO THE INVENTION Vehicle theft, particularly car theft, is an increasing problem. As is well known, cars in particular are stolen not only by so-called joy-riders, but also for re-sale, possibly in another country. Insurance companies are proposing to raise their premiums generally, to the disadvantage of careful car owners, and especially when an anti-theft device is not fitted to the vehicle or not used.

Thus there is a widespread need for an inexpensive but effective vehicle anti-theft device.

DISCLOSURE OF THE PRIOR ART A number of vehicle anti-theft devices and arrangements have been proposed over the years.

A widely-used device mechanically locks a foot pedal to the vehicle steering wheel; however, the device is exposed to view and can be severed by the use of a suitable tool.

Another known device mechanically couples the gear lever to the handbrake i.e. a bracket embraces the gear lever, and a sleeve covers the handbrake lever, the connection being such that the gear lever has only limited permitted movement; typically, the gear lever will be positioned so that one of the gears is selected, and the device is then put in place to prevent that gear being deselected.

However, this device can be overcome by simply removing the gear knob, to permit the bracket to be slid over the end and so released from the gear lever. It has also been known for thieves alternatively quickly to cut off the top of the gear lever, to permit release of the bracket.

Both of the above known mechanical devices have to be secured by the vehicle driver, and the driver may not be willing to spend the time required to effect securement each time the vehicle is left unattended, particularly if for example the driver is short of time or has become less lissom.

An alternative anti-theft device is a secondary switch fitted in series with the ignition switch and situated in a concealed position within the vehicle; however the concealment position must be communicated to all authorised drivers of the vehicle, who could otherwise be left stranded. Also, the concealment position is easily ascertained in advance by a determined thief. Furthermore, the device suffers the same disadvantage as the mechanical devices above, in that the secondary switch may perhaps be awkward to reach, yet must be switched to the "ignition disconnected" condition each time the vehicle is unattended in order to be of use, and this operation may not always be performed.

Steering wheel locks, whereby a peg is locatable in a hole in the steering shaft to prevent rotation of the shaft, are known and widely used, but can often be wrenched free with an appropriate tool. Additionally, force can be applied to rotate the steering wheel against the resistance of the peg, until the peg breaks, rendering the lock thereafter inoperative.

Usually, following the overcoming of the anti-theft device (if fitted and used), the intending vehicle thief will break open the console surrounding the electrical ignition switches of the vehicle, and manually connect the wires necessary to start and drive the vehicle.

STATEMENT OF THE INVENTION We seek to provide a mechanical anti-theft device which overcomes or reduces the disadvantages of the above known devices. In preferred embodiments of the invention the device is operated by the vehicle ignition key, and becomes activated automatically upon rotation and withdrawal of the key, and so does not require additional driver effort or time.

Thus, according to one feature of the invention we provide a disabling device for an operating shaft, the shaft having a rotatable part and a rotated part, the device having an enabled condition whereby rotation of the rotatable part causes rotation of the rotated part and a disabled condition in which rotation of the rotatable part does not cause rotation of the rotated part, characterised in that key-controlled means transfer the said parts between the disabled and enabled conditions.

Desirably the key controlled means is also designed to transfer the said parts between the enabled and disabled conditions.

Alternatively, a resilient bias means acts upon the first coupling means to bias it away from the second coupling means; thus, the resilient bias means transfers the parts from their enabled condition to their disabled condition, and the key-controlled means transfers the parts from their disabled condition to their enabled condition.

Preferably, the rotatable part carries drive means and first coupling means, the first coupling means being slidably engageable with the drive means. Preferably also the drive means is an acircular drive rod.

Desirably, the rotated part carries second coupling means, the second coupling means being positively engageable with the first coupling means to transmit rotation of the drive means to the rotated part. The positive engagement between the first and second coupling means ensures that in the engaged condition of the device there is a substantially solid rotational connection between the rotated part and the rotatable part of the operating shaft.

Usefully, the key controlled means includes an operating cam connected to a lock means, the operating cam being contactable with the first coupling means, rotation of the correct key in the lock means causing the operating cam to urge the first coupling means into engagement with the second coupling means.

Conveniently, a release mechanism is located between the operating cam and the lock means, whereby the parts transfer to their disabled condition only upon removal of the key from the lock means.

Preferably, the operating cam includes a first part and a second part, the said parts being connected by a bridge, part of one of each of said first and second parts being to opposite sides of the drive means, the first part of the cam being connectable to a lock means, the second part of the cam being connectable to electrical switches of a machine.

According to another feature of the invention we provide a housing for the device, the housing having weakened regions adapted to break under applied load. Preferably, the housing has a cylindrical part mounted between two support collars, and the weakened regions are a pair of circumferential fracture rings on the cylindrical part, one adjacent each of the collars.

Usefully, the housing carries two axially aligned bosses, one boss for receiving a lock means, the other boss for receiving electrical switches for a machine. If the machine is a motor vehicle, the electrical switches can include the vehicle ignition switch and starter motor switch.

We also provide a machine fitted with a disabling device for an operating shaft. Preferably the machine is a motor vehicle and the operating shaft is a steering shaft. In such a machine, it is known to connect electrical wiring to the steering shaft, or to the hub of a steering wheel, for the operation and control of a unit, for example a driver safety unit such as an air-bag adapted to inflate upon vehicle impact whereby to shield the driver from injury by the steering wheel, and in severe impacts from impalement on the steering shaft.

It is usually considered desirable to have a permanent electrical connection to such unit; thus the sensor for triggering the release of a safety air-bag is typically remote from the steering wheel, and is electrically connected thereto, most commonly by way of one or more continuous wires or cables.

When the device of the invention is in the "enabled" condition, permitting normal rotation of the shaft by the steering wheel, the permitted angular turning of the steering wheel is limited by the steering mechanism of the vehicle, to a maximum extent as allowed by the design of the vehicle manufacturer. However, if at least part of the steering shaft (the lower part, remote from the steering wheel) is operatively disconnected from the steering wheel, the in-built design limitation on the freedom of the steering wheel to turn (or be turned) is no longer operative, and the aforementioned wires or cables can in consequence be severed.

It is a further feature of this invention to provide a rotation limiting means operative to limit the permitted turning angle of the steering wheel when the disabling device is in the disabled condition, whereby to avoid or reduce the possibility of damage to the wires or cables (by turning of the steering wheel through an excess angle).

Preferably the rotation limiting means is "permanently engaged" as part of the vehicle steering mechanism, and is designed and fitted so as to allow a greater range of turning of the wheel than the existing steering mechanism.

Thus with this preferred arrangement, with the device in the enabled condition it is still the normal steering mechanism which limits the rotation of the steering wheel (so that the user is unaware of the presence of the rotation limiting means); but with the device in the disabled condition (permitting free turning of the steering wheel) it is the rotation limiting means as herein described which limits the permitted turning angle of the steering wheel.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be further described, by way of example, with reference to the accompanying drawings, in which: Fig.l is a schematic side view of a motor vehicle with a disabling device according to the invention fitted to the steering shaft; Fig.2 is a view of the device, and part of the steering shaft of the vehicle of Fig.1; Fig.3 is an exploded view of the device of Fig.2; Fig.4 is a plan view of the operating cam of the device of Fig.2; Fig.5 is a view on the line V-V of Fig.3; Fig.6 is a view on the line VI-VI of Fig.5; Fig.7 is a view along the line VII-VII of Fig.3, with the spring removed for clarity; Fig.8 is a view along the line VIII-VIII of Fig.3, with the spring removed for clarity; Fig.9 is a partial view along the line IX-IX of Fig.8; Fig.10 is a partial view along the line X-X of Fig.8; Fig.ll is an exploded view of a housing for the device; Fig.12 is a sectional top view of the cylindrical housing part; Fig.13 is an exploded view of a lock barrel to cam connector; Fig.14 is a view of a release mechanism for the device; Fig.15 is a side view of the primary plate of the release mechanism of Fig.14; Fig.16 is a side view of the secondary plate of the release mechanism of Fig.14; Figs.17-19 are partial side sectional views of the spring loaded pin part of the release mechanism of Fig.14; Fig.20 is an exploded side view of part of another embodiment of disabling device according to the invention; Fig.21 is a section on the line XXI-XXI of Fig.20; Fig.22 is a section on the line XXII-XXII of Fig.20; Fig.23 is a section on the line XXIII-XXIII of Fig.20; Figs.24-27 are schematic views of the sliding operator of the Fig.20 embodiment in various orientations of operation; Fig.28 is a sectional view of a rotation limiting means according to the invention; Fig.29 is a view of the support plate and sliding block of Fig.28; Fig.30 is a partial view along the line XXX-XXX of Fig.28; Fig.31 is an end view of the support plate and sliding block of Fig.29; Fig.32 is a side view of the sliding block; Fig.33 is a side view, partly in section, of an alternative rotation limiting means according to the invention; Fig.34 is an end view of the slotted collar used with the embodiment of Fig.33; and Fig.35 is a side view (not to scale) of the sliding block used with the collar of Fig.34.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Fig.l shows a motor driven vehicle 1, in this embodiment a passenger car. The vehicle has a steering column 2, which is a hollow tube, and which houses a rotatable steering shaft 10,11 (not seen in Fig.l). The steering shaft connects a manually grippable steering wheel 3 to a steering mechanism (not shown); the steering mechanism is connected to the front wheels 4 of the car in known fashion.

The disabling device of the invention is used to disconnect the lower (in its position of use) steering shaft 11 from the upper steering shaft 10.

The disabling device, more fully described below, in a preferred embodiment is controlled by the same key (the "ignition" key) used to control the switch or switches for the vehicle electrics. Thus, the device is adapted to cooperate with a conventional motor vehicle key and lock barrel (not shown), so that when the ignition lock is turned to the key withdrawal position, the device is disabled and the steering wheel 3 (and upper steering shaft 10) is disconnected from the steering mechanism.

The ignition key typically will have a range of rotation of approximately 1300, and four operating positions i.e. a "zero" position, for insertion and withdrawal of the key; a "first" position, in which some of the vehicle's electrics are connected to the vehicle electrical battery i.e.

"switched on"; a "second" or engine running position, in which all of the vehicle's electrics are switched on; and a "third" position, in which the vehicle's starter motor is activated.

As more specifically shown in Fig.2, the steering shaft comprises an upper shaft 10 (the rotated part i.e. by the vehicle steering wheel 3), and a lower shaft 11 (the rotatable part, to be rotated by the upper shaft 10 when the device 12 is in its engaged condition). The disabling device 12 is mounted in driving/non-driving relation between the upper and lower shafts.

The upper and lower shafts are each rotatably mounted within bushes 13, which bushes are secured to the steering column 2 (not shown in Fig.2).

As more clearly seen in the exploded view of Fig.3, the device comprises a hexagonal drive rod 20, an operating cam 30, a sliding coupler 40 (the first coupling means) and a fixed coupler 50 (the second coupling means).

One end of the drive rod 20 is secured to the upper shaft 10, the other end mounts a location rod 21. The upper shaft 10, drive rod 20 and location rod 21 are all concentric. The fixed coupler 50 is secured to the lower shaft 11, and is concentric therewith. A compression spring 22 is mounted between the sliding coupler 40 and the fixed coupler 50, biassing the couplers apart.

In this embodiment the operating cam 30 comprises a pair of cam plates 31a,31b, rigidly connected together by a bridge 32 (Fig.4). Each of the cam plates has a square recess 33,34 passing therethrough (in another embodiment the recesses are blind); the recess 33 is for connecting the cam plate 31a to the output of the ignition key lock, which is located in a housing for the lock barrel (not shown), the recess 34 is for connecting the cam plate 31b to the switches controlling the vehicle electrics (not shown).

Thus one key (the ignition key) can be used to turn the operating cam to control the disabling device, and simultaneously to operate the vehicle electrics. In other embodiments of the invention other means of making connection from the lock to the operating cam and from the operating cam to the electrical switches are used.

In this embodiment the recesses 33,34 are aligned, so that the electrical switches are coaxial with the lock barrel.

In the assembled condition (see Fig.2), the operating cam 30 straddles the rod 20, with one cam plate 31a,b to either side of the drive rod 20. The operating cam 30 does not contact the drive rod 20 and is freely pivotable relative thereto. It will be understood that the operating cam 30 is mounted for pivoting on and with the lock (about an axis perpendicular to that of the shafts 10,11), and through an angle at least as great as the range of rotation of the key and the lock, without contacting the drive rod 20.

The positioning of the operating cam, and the size of the bridge 32, are thus chosen to permit and accommodate free rotation of the drive rod 20 about its longitudinal axis throughout the range of the cam's pivoting.

As seen also in Figs.5-7, the sliding coupler 40 comprises a drive plate 41, a first guide tube 42, and part-annular sections 43,44. The drive plate has a central hexagonal aperture 45, to cooperate with the drive rod 20 for rotational drive, with freedom for axial sliding. The part-annular wall sections 43,44 define part-annular spaces 46,47 around the first guide tube 42.

The first guide tube 42 houses the first end of the spring 22.

As seen in Figs.8-10, the fixed coupler 50 comprises a second guide tube 51, and an outer wall 52. The outer wall 52 has an annular region from which two part-annular wall sections 53,54 extend, the wall sections 53,54 being of a size to fit closely within the spaces 46,47 of the sliding coupler.

Thus in the enabled condition of the device, with the sliding and fixed couplers in close axial proximity, the wall sections 53,54 of the fixed coupler and the wall sections 43,44 of the sliding coupler form a substantially continuous annulus around the first guide tube 42. In this engaged condition, rotational drive motion can be transmitted from the upper shaft 10 to the lower shaft 11, via the drive rod 20 to the sliding coupler 40, and so to the fixed coupler 50 (and the lower shaft 11).

In this embodiment the wall sections 43,44 and 53,54 are not symmetrical relative to their respective coupler, so that there is only a single relative angular position in which the couplers can engage. By this means, when the device is enabled the angular relationship between the steering wheel and the front wheels of the vehicle will always be the same, with which the driver of the vehicle will become accustomed. In another, though less preferred, embodiment the wall sections are chosen to permit more than one relative angular position for the couplers.

As seen in Fig.7, the edges of the wall section 43 are cut on chords, and the edges of the wall section 44 are cut on diameters (the corresponding mating edges of the wall sections of the fixed coupler being similarly cut - see Fig.8). It has been found that such an arrangement helps the coupler wall sections to "run across" each other smoothly whilst rotating to the enabled condition. In other embodiments, other forms for the wall sections are used.

The second guide tube 51 is sized to surround closely the location rod 21, to maintain the concentricity of the components of the device. The second guide tube is itself surrounded by the second end of the spring 22 i.e. the second end of spring 22 fits in the annular space between the second guide tube 51 and the outer wall 52 (and axially extending wall sections 53,54 from outer wall 52). The step 24 (Fig.3) between the hexagonal drive rod 20 and the location rod or shaft 21 bears upon the end of the second guide tube 51.

In another embodiment the location rod is fixed to the lower shaft, and the second guide tube is fixed to the drive rod; in yet another embodiment a circular hole in the end of the hexagonal drive rod provides a guide for a location rod fixed to the lower shaft.

It will be understood therefore that in the embodiment shown the spring 22 is located between the first guide tube and the second guide tube; in another alternative embodiment, the spring is located externally of the couplers and the guide tubes are in sliding contact. In the latter embodiment, the sliding contact of the location rod within the second guide tube, and the sliding contact of the second guide tube within the first guide tube, ensure the concentricity of the components of the device.

In yet other alternative embodiments, the manufacturing tolerances of the drive rod 20 and the corresponding central aperture of the sliding coupler are sufficiently tight to maintain the concentricity of the shafts 10,11, so that in a first alternative embodiment the need for the first guide tube (42) is avoided, and in a second (though less preferred) alternative embodiment the need for the location rod (21) and the second guide tube (51) is avoided.

In Fig.2, the device is shown in the disabled condition, with the sliding coupler 40 biassed away from the fixed coupler 50 (to the left as drawn) by spring 22. The wall sections 43,44 of the sliding coupler are disengaged from the wall sections 53,54 of the fixed coupler, so that rotation of the upper shaft 10 is transmitted to the sliding coupler 40 by the drive rod 20, but this rotation is not transmitted to the fixed coupler 50 nor to the lower shaft 11. Thus, the upper shaft 10, and the steering wheel 3 connected thereto, are disconnected from the steering mechanism and the vehicle wheels 4, and will thus rotate freely when the steering wheel 3 is turned, preventing the vehicle 1 being driven in directions determined by the angular position of the steering wheel.

When it is desired to enable the device, rotational pressure is applied to the ignition key, and thus to the operating cam 30 (in a clockwise direction as viewed). The cam surface 35 is thus caused to ride upon drive plate 41 of the sliding coupler 40. Since the axis of rotation of the operating cam 30 (the centres of the square recesses 33,34) is fixed relative to the steering column, this rotation causes movement of the sliding coupler to the right as viewed, against the action of the spring 22.

It will be understood that it is necessary to align the spaces 46,47 of the sliding coupler with the wall sections 53,54 of the fixed coupler, and this can be achieved by rotating the upper shaft (i.e. rotating the steering wheel) whilst maintaining the rotational force on the cam 30; when the spaces 46,47 are aligned with the wall sections 53,54, the couplers will become engaged. A maximum of one complete turn of the steering wheel 3 will be necessary to ensure the correct alignment is achieved. Rotation of the operating cam can then continue until the flat edge 36 contacts the drive plate, and this corresponds to the second position of the ignition key. However, the shaping of the cam surface 35 is chosen to allow substantially the same extent of engagement of the sliding coupler 40 with the fixed coupler 50 at the "first" ignition key position as at the "second" ignition key position, when the vehicle is drivable.

The shaping and positioning of the operating cam 30 in relation to the sliding coupler 40 is chosen to provide a large movement of the sliding coupler (to ensure repeatable engagement with the fixed coupler), and yet ensure that in the disabled condition there is a reasonable clearance between the couplers. This is done with the intention that any long-term "weakening" of the spring 22 does not cause the couplers to "rest" with the walls sections 43,44 and 53,54 i.e. in partial engagement.

Further rotation of the ignition key (and operating cam), and thus further movement of the sliding coupler, can occur i.e. with the corner 37 contacting the drive plate 41, so that the ignition key can be rotated to the third position necessary to activate the vehicle's starter motor.

However, it is desired that at least three quarters of the wall sections 43,44 and 53,54 are in contact when the ignition key is in its second position, and the car is being driven.

In an alternative embodiment, the cam surface 36 is curved; however, we prefer the form as drawn, so that in the enabled condition a flat surface of the cam contacts the drive plate 41; pivoting moveMent of the cam out of this condition is resisted by the spring 22.

In another alternative embodiment, in which the device is key-controlled independently of the ignition key control of the vehicle electrics, it will be understood that the operating cam 30 can be of different construction.

Usefully the cam will retain cam plate 31b in addition to cam plate 31a for a balanced construction, but this is not essential, nor of course is it necessary for the (balanced) cam 30 to provide a secondary drive i.e. a recess 34 or similar is not required.

In a further alternative embodiment, the drive rod 20 is not hexagonal, but is of another acircular section. In yet a further alternative embodiment, the drive rod is circular, but is fixed eccentrically to the upper shaft.

In each embodiment, the fixed coupler has an aperture corresponding in shape and position to the drive rod.

In another embodiment the device is "reversed" i.e. the drive rod is fixed to the lower shaft and the fixed coupler is fixed to the upper shaft. It will also be understood that embodiments wherein the operating cam acts "below" (in the position of use) the drive rod, and to the "side" of the drive rod, are also within the scope of this invention.

In addition, it is known for the ignition lock on certain vehicles to be mounted so that the axis of rotation of the key is not perpendicular to the axis of the steering shaft(s); typically the axis of rotation is canted towards the driver, to ease insertion and rotation of the key in the lock. Accordingly, the device may readily be adapted to work with such a "canted" lock axis. Thus in one suitable embodiment, where the angle of cant is small, the axis of rotation of the operating cam is parallel to the axis of rotation of the key, and thus is not perpendicular to the steering shaft(s); in this embodiment, the form of the cam would be necessarily complex, to provide the required movement of the sliding coupler along the axis of the steering shaft(s). In another suitable embodiment, the operating cam has its axis of rotation perpendicular to the axis of the shaft (i.e. as in the embodiments shown in the drawings), and there is a flexible coupling between the lock and the operating cam.

In the embodiment shown (see Fig.2), the steering column 2 can be of a single external diameter, encasing the upper and lower shafts and the device; however, in another embodiment local steering column enlargement, or slotting of the steering column, is provided to accommodate a radially extending operating cam 30.

Preferably a housing 60 (Figs.11,12) surrounds the device, to prevent or deter unauthorised access thereto. There is also shown in Fig.13 a connector between the lock barrel and operating cam. Thus, the device is protected by a housing, which in this embodiment also securely holds the key-controlled lock and the vehicles ignition switches; the housing entirely encloses the section of steering column in which the device is mounted.

Thus part of an existing steering column can be modified locally to accommodate the device, and the housing 60 can be fitted, preferably welded, around the section of the column holding the device, and thereby accommodating the lock and the ignition switches. In a preferred embodiment, however, the device is fitted as original equipment in a specially prepared steering column and provision is also made for fitting the housing. This avoids the need to modify an existing steering column before the device and housing 60 can be fitted as a retro-fit.

The housing 60 of Fig.ll comprises a cylindrical central section 61, and two support collars 62,63. The central section 61 carries two bosses 64,65 (see also Fig.12) within which can be located the barrel of the ignition lock and the switches for the vehicle electrics respectively.

The central section 61 is of a material and generally of a wall thickness designed to be substantially impenetrable, i.e. it is resistant to being sawn, drilled or attacked with leverage or hand operated cutting tools. Adjacent each of its ends, however, the central section 61 has a groove 66,67 where the wall is thinned; in a preferred embodiment the wall is alternatively or additionally locally perforated. The grooves 66,67 thus provide "fracture rings", so that the central section 61 may be more easily "circumferentially broken".

The support collars 62,63 are permanently fixed to the respective steering column 2, as by welding, and in use fit over the ends of the central section, and over the fracture rings. It is necessary that the support collars surround the ends of the central section and extend beyond the grooves 66,67, preferably extending beyond the grooves by three times the width of each groove. The central section 61 is secured to its support collars 62,63 by permanently fixing the cylindrical wall of the collars to the wall portions 68 of the central section, which wall portions lie outside the fracture rings. Such fixing can, for example, be by spot welding, shear screws or non-return screws; if shear or non-return screws are used, suitable holes will be provided in the support collars and in the wall portions 69.

The housing is made to fit around the device, and this should preferably include the bush 13 of the upper shaft 10, so that this bush cannot be loosened by attack on the outside of the steering column adjacent the bush.

Additionally, the upper shaft 10 has an abutment to prevent it passing its respective bush 13. Thus, it is not possible to gain access to the device from along the steering column.

The lock barrel (not shown) is housed within boss 64, and is connected to the operating cam 20 by way of linkage socket 69 and linkage bar 70. The linkage socket 69 has a square lug 71 which fits into the square hole 33 in cam plate 31a, and has a square hole 72 which accepts an end of the linkage bar 70. Linkage bar 70 has a (spring biassed) ball bearing 73 which is retained by recess 74 in hole 72.

The other end of the linkage bar 70 is fitted into another linkage socket which is in turn connected to the lock barrel; in another embodiment the other end of the linkage bar is connected directly to the lock barrel.

The linkage bar 70 is waisted, to provide a breakage zone, should (unauthorised) force of a sufficient magnitude be applied to one or other of its ends. It is desirable that the rotation of the lock barrel within the boss 64 be limited to the extent required for the various key positions, so that excessive key rotation is resisted by the boss 64, and not by the linkage bar 70.

If an attempt is made to gain unauthorised access to the device, e.g. by applying force to the boss 64, the fracture rings and the linkage bar are designed to break, so that the central housing section 61 will become free to rotate within the collars, denying further leverage upon the steering column or the device.

In another embodiment, the central housing section, having been broken at the fracture rings, will then bind on the inside cylindrical surfaces of its support collars; the support collars may be specially prepared e.g. roughened, for this purpose. In such an embodiment, the fractured central section would not freely rotate; this embodiment is thus not preferred where a bound central section could be easily accessed and used to impart leverage upon the operating shaft or upon the device, but may be suitable in some locations where access to the housing is either prevented or awkward.

Furthermore, the strength of the central section walls at points 75 are selected to be stronger than at points 76, so that any leverage obtained upon the boss 64,65 will only serve to break off the respective boss (exposing only a small aperture 77,78) and not to break open the housing.

As a further vehicle anti-theft feature it will be understood that if one or both of the bosses is broken off, whilst the broken end of the linkage bar 70 may be visible, the broken end will be tapering, and substantially of truncated conical form, and available only through the minimally-sized apertures 77,78, so that it will not be possible to obtain sufficient purchase upon linkage bar 70 to rotate the operating cam and enable the device.

In an alternative embodiment of housing, there is provided only a single boss, but the boss is of a size to accommodate both the lock barrel and the electrical switches, the linkage from the lock passing through or past, and operating, the electrical switches.

It will be understood that in the embodiment shown in Figs.

2 and 3, the device becomes disabled when the ignition key is rotated to the key withdrawal or "zero" position. It is believed that this will be satisfactory for many users, but in an alternative arrangement the key needs to be removed from the lock barrel before the device becomes disabled whereby to overcome the possible concern that if the driver switches of the engine whilst the vehicle is moving he will disconnect the steering wheel from the wheels of the vehicle; one possible means to achieve this is shown in Figs.14-19.

As is typical in this field, the lock barrel 80 has a limited amount of travel A along its axis within its housing 164. Upon insertion of the key (not shown), the barrel moves to the left hand end of its travel (shown in dotted outline); upon withdrawal of the key the barrel moves to the right hand end of its travel (shown in solid lines).

Secured to the output peg 81 of the lock barrel 80 is a primary plate 82. As seen in Fig.15, primary plate 82 is shaped as substantially a quarter of a circle. Another peg 83, which is coaxial with the output peg 81 of the lock, fits into an aperture 84 in a secondary plate 85; thus, peg 83 maintains the alignment of the primary and secondary plates.

Secured to the primary plate 82 is a bar 86, which fits into a cut-out 87 in the secondary plate. The bar 86 causes any pivoting of the primary plate (into the paper as viewed in Fig.14) to be matched by a corresponding pivoting movement of the secondary plate 85.

Located between the primary and secondary plates is a housing 90 for a spring loaded pin mechanism (see Figs.1719). The spring loaded pin mechanism comprises an outer pin 92 which is biassed by spring 93 outwards of the housing 90 towards the primary plate 82, and an inner pin 94 which is mounted within the outer pin and biassed by spring 95.

The condition of the spring loaded pin mechanism in Fig.17 corresponds to that of Fig.14, i.e. the key withdrawn condition. Upon insertion of the respective key (not shown), the lock barrel moves to the position shown in dotted outline in Fig.14; the primary plate is correspondingly moved to the left, compressing the outer pin spring 93. Thereafter the key is rotated to enable the device, and to start the engine of the vehicle 1, whereupon the primary and secondary plates move together under the action of the peg 86 in cut-out 87.

During this movement, the surface of the primary plate (within the arc shown in dotted outline in Fig.15) moves across the head of the outer pin, and the surface of the secondary plate (within the arc shown in dotted outline in Fig.16) moves across the end of the inner pin (Fig.18).

When the plates have rotated to the position in which the device is enabled, the inner pin 94 is caused to enter a hole 88 in the secondary plate 85 (Fig.19). The secondary plate is then fixed in position, and will not rotate back with the primary plate. Only following removal of the key from the barrel, causing the primary plate to move to the right (as drawn) and release the inner pin from the hole 88, will the secondary plate become free; the secondary plate will be pivoted back to the start condition (Fig.14) by a spring (not shown), in known fashion. Thus, the device will remain enabled until the key is removed from the barrel.

Secondary plate 85 is coupled to the operating cam by a linkage bar (such as bar 70) fitted into acircular aperture 89.

It will be understood that other known means to ensure the device remains enabled until key withdrawal could be used; one such alternative means is that in current use upon the conventional steering locks of motor vehicles.

In the alternative embodiment of Fig.20, the upper steering shaft 110 carries a circular first location rod 123, which in turn carries a hexagonal drive rod 120, which in turn carries a circular second location rod 121. Each location rod, and the drive rod, are mounted concentrically to the upper steering shaft 110, and rotate therewith.

The second location rod 121, in the assembled condition of the device, locates within a fixed coupler (such as fixed coupler 40); thus, the second location rod 121 acts to maintain the concentricity of the parts of the device, as described more fully in the copending application.

The first location rod 123 is a sliding fit inside the sliding operator or sliding actuator 130 of the device; thus, the first location shaft 123 is a clearance fit inside the aperture 131 of the sliding operator (see Fig.21).

In the assembled condition of the device, the sliding coupler 140 is slidably located upon the hexagonal drive rod 120.

The sliding operator is slidable (to the left and right as drawn in Fig.20) along the first location rod 123, but does not rotate therewith. The sliding operator 130 has a keyway 132 cut into its periphery, which keyway engages with a keying lug (not shown) fixed to the inside surface of the steering column (not shown), preventing rotation of the sliding operator. In this embodiment the keyway 132 is open at both ends, but in an alternative embodiment it is closed at one or both ends, to limit the longitudinal travel of the sliding operator.

It will be understood therefore that the sliding coupler 140 is in permanent rotational engagement with the drive rod 120, and thus with the upper steering shaft 110, whereas the sliding operator 130 is rotationally fixed relative to the vehicle, with the first location shaft being rotatable therewithin.

The sliding coupler has wall portions 143,144 by which it may be engaged with a fixed coupler (not shown), as more fully described in the copending application.

In the assembled condition of the device, the sliding coupler is in permanent engagement with the sliding operator, but is rotatable relative thereto. The sliding coupler has a circular boss 148 carrying a circular flange 149, which flange fits into an undercut 133 (Fig.22) on the sliding operator, being retained by a part-circular cowl 134 (Fig.23). In another embodiment, the sliding operator carries the circular boss and flange, whilst the sliding coupler carries the undercut and cowl.

Thus the sliding coupler can rotate independently of the sliding operator, but any axial movement of the sliding operator is transmitted to the sliding coupler. In this way, movement of the sliding operator can effect positive engagement of the sliding coupler with, and positive disengagement of the sliding coupler from, the fixed coupler.

The sliding operator 130 carries a plate 190 (Fig.21), secured, as by welding, to a flattened side of the operator. The plate 190 has a cut-away portion 191 defining an operating surface 192, which surface is generally flat in the region contacted by the operating lever 193. Movement of the sliding operator is effected by the curved end 194 of the operating lever 193 sliding across the operating surface 192.

In another embodiment of sliding operator, the cut-away portion, and the operating surface provided thereby, are provided directly in the wall of the sliding operator, i.e.

the operator itself is directly cut away, rather than having a cut-away plate secured thereto.

The operating lever 193 is pivoted by operating bar 170 (Fig.21). The remote end of the operating bar 170 is connected directly to the vehicle ignition lock (not shown), though in another embodiment the bar 170 can be waisted to provide a breakage point in the event that unauthorised driving of the vehicle is attempted.

The axis of the operating bar 170 is fixed relative to the vehicle, as by a bush or bushes (not shown) surrounding the bar 170 and mounted in the wall of the steering column, so that pivoting of the operating bar causes the operating lever 193 to urge the sliding operator to the left or right as drawn in Figs. 24-27.

The sliding operator 130 is caused to move by a force acting to one side only of the axis of the operating shaft 110. This is in contrast to the operating cam of the Fig.2 embodiment of the copending application, wherein the operating cam bridges the axis and has a pair of surfaces acting upon opposed sides of the rear plate of the sliding coupler. However, the tendency of the sliding operator 130 to twist under the action of the offset or unbalanced force is resisted by the close sliding tolerance between the aperture 131 and the first location rod 123, and by the keying lug within the keyway 132.

In Fig.20, the angular orientation of the operating lever 193 corresponds to the "key withdrawn" position of the vehicle's electrical switches and lock. In this orientation, the sliding coupler will be disengaged from the fixed coupler, so that the device is in the disabled condition.

In Fig.24, the sliding operator is shown with the operating lever pivoted through 300. In this orientation, the curved end 194 of the operating lever engages the substantially flat part of the operating surface 192, and the sliding operator has been caused to move slightly to the right as drawn.

In Fig.25, the sliding operator is shown with the operating lever pivoted through 600. In this orientation, the sliding operator (and sliding coupler) has been urged almost fully to the right (through approximately 90% of its travel), so that the sliding coupler will be in rotational engagement with the fixed coupler.

In Fig.26, the sliding operator is shown with the operating lever pivoted through 900. In this orientation, the sliding operator has been urged to the right to its fullest extent, so that the sliding coupler is fully engaged with the fixed coupler.

In Fig.27, the sliding operator is shown with the operating lever pivoted through 1200. In this orientation, the curved end 194 of the operating lever is maintained in contact with the sliding operator by the curved region 195 of the operating surface.

The shaping of the operating surface and the operating lever can be chosen to provide that one or more of the angular orientations shown in Figs. 24-27 correspond to the "first" , "second" and "third" ignition key positions, e.g.

600 may be the "first" position in which some of the vehicles electrics are connected to the battery; 900 may be the "second" or engine running position; and 1200 may be the "third" position, in which the vehicle's starter motor is activated. It is desirable that the 900 orientation corresponds to the engine running position, since at this orientation the lever will act to resist the tendency of any vibration to disengage the sliding coupler from the fixed coupler, as might otherwise occur whilst the vehicle is being driven.

When it is desired to switch off the vehicle, and withdraw the ignition key, the operating lever 193 is rotated back to the key withrawal orientation shown in Fig.20. During this pivoting action, the curved end 194 of the operating lever engages the wall of the cut-away adjacent the corner 196 (Fig.26), and urges the sliding operator (and thus the sliding coupler) to the left (as drawn in Fig.20), positively disengaging the sliding coupler from the fixed coupler. It will be understood that the shaping of the curved end of the operating lever, and the shaping of the cut-away portion, will be chosen to ensure that repeatable disengagement can be effected.

Thus, the arrangement disclosed in this application does not require a spring or other resilient bias means to effect disengagement of the couplers, so that the sliding coupler and fixed coupler are not each required to house a respective end of the spring (as described in relation to the Fig.2 embodiment of the copending application). Thus, the mating shafts and tubes of the couplers are required only to ensure concentricity of the couplers, assisting in the effective engagement of their wall sections.

It will be understood that in this embodiment the vehicle's electrical switches must be located to the same side of the device as the lock, rather than to the opposite side as in the Fig.2 embodiment of the copending application. Thus, the operating bar 170 can pass through an annular array of switches located between the lock housing and the device, or else can activate switches located within the lock housing adjacent the axis of the bar.

In an alternative embodiment, the keyway 132 and its lug can be removed; rotation of the sliding operator can be prevented by an extension of the operating rod 170, extending from the right of the operating lever as drawn in Fig.21, and into a longitudinal slot in the cut-away plate.

Such an embodiment would have the further advantage of providing additional support for the operating rod and lever, in addition to the bush or bushes by which they are mounted. In a further alternative embodiment, both of an extended operating lever and slot, and a keyway 132 and lug, are provided, which may be preferred in some circumstances.

It will be observed from Fig.21 that the sliding operator has an overall substantially cylindrical form, so that it is adapted to fit within the steering column without the need for local enlargement of the column.

It will be understood that the operating lever as disclosed in the Fig.20 embodiment may be replaced by a rack and pinion arrangement acting upon the sliding operator, the rack being located upon the sliding operator and the pinion being mounted upon the operating bar. In such an embodiment, the rack and pinion could be duplicated on the opposed side of the sliding operator, to provide a drive to the vehicle's electrical switches, for example.

For use on a vehicle having electrical wiring or the like connected to the steering shaft or hub of the steering wheel, it is desirable to limit the "free" rotation of the steering wheel in the disabled condition of the device.

The rotation limiting means 200 of Fig.28 comprises an Archimedean spiral 201 which is connected to, and is thus rotatable with, the upper steering shaft 10 of the vehicle.

The spiral 201 partly surrounds the end of the steering column 202, within which column the upper steering shaft 10 is rotatably mounted. As shown in Fig 30, the spiral 201 is mounted upon annular plate 203, which plate 203 is rigidly connected to the upper steering shaft 10.

Rigidly connected to the steering column 202, adjacent the spiral 201, is a support plate 207. In this embodiment the support plate has a part-circular wall to engage with the steering column, and is welded to the steering column; however, in other embodiments the support plate has a collar or bracket for surrounding the steering column and fixing the support plate thereto.

Mounted upon the support plate 207 are a pair of upstanding arms 209a,209b. The arms 209a,b locate a sliding block 211 (Fig.29), which carries two teeth 213a,b. The teeth 213a,b are part-annular, and are adapted to fit between adjacent walls of the spiral 201.

It will be understood that the teeth may be of any form suitable to locate between adjacent walls of the spiral for the full range of rotation of the spiral. In one other embodiment the teeth are circular pegs. In another embodiment the teeth are circular and rotatable, so as to spread any wear.

It will also be understood that in another embodiment only one tooth is carried by the sliding block; in yet another embodiment more than two teeth are carried thereby.

The sliding block 211 is able to slide (leftwards and rightwards as viewed in Fig.29) along the channel 215 between the arms 213a,b, in response to rotational movement of the spiral.

The spiral has an inner stop 217 and an outer stop 219, which stops 217,219 limit the angular rotation of the spiral (about the axis of the shaft 10), and thus of the upper steering shaft connected thereto. Thus, the sliding block can move between an innermost position (as drawn in Fig.28), corresponding to the limit of clockwise rotation of the spiral (and upper steering shaft), and an outermost position corresponding to the limit of anti-clockwise rotation of the spiral. In another embodiment, the spiral may be of opposite "hand", so that clockwise rotation causes outwards movement of the sliding block.

Alternatively, the limits of movement may be provided in the channel, to limit the sliding movement of the block, and so indirectly to limit the rotation of the spiral and upper steering shaft.

As seen from Figs. 31 and 32, the sliding block 211 has a body portion 221 and a shoulder portion 223, which are separated by a neck portion 225. The arms 209a,b have respective facing flanges 227a,227b, which are embraced by the sliding block 211, so that the sliding block 211 is retained thereby.

In the embodiment shown, the spiral can complete approximately four 3600 rotations, so that the electrical wires or cables need to cater for a rotation of 14400 (or alternatively 7200 in each direction from a central position). However, in other enibodiments, the spiral has a limit of rotation of more or less than 14400, as desired by the user or operator.

In other embodiments, the spiral is fixed directly to, or is a part of, the rear wall of the steering wheel (i.e.

that wall facing away from the driver when the vehicle is in normal use). In such an embodiment, the wires connected to the air-bag could pass through an aperture in the centre of the spiral back plate.

An alternative rotation limiting means is shown in Fig.33.

The rotation limiting means 300 is located adjacent the threaded spline 299 adapted to receive a steering wheel (not shown).

The rotation limiting means 300 includes a thread 301 machined on the upper steering shaft 310, which thread is almost totally surrounded by a collar 307. The collar 307 is substantially cylindrical, but is slotted along its length (Fig.34); within the slot 315 is retained a sliding block 311.

The sliding block 311 has recesses 325 machined in its sides adapted to slidably receive projections 327 of the slot 315. The sliding block 311 has two teeth 313, adapted to mate with the thread 301.

The length of thread required is determined by the desired number of rotations to which the steering wheel is to be limited, plus the number of teeth of the sliding block. In the embodiment shown, there are slightly less than six thread rotations and the sliding block 311 has two teeth, giving a possible rotation of the steering wheel of slightly less than four complete rotations.

In the embodiment shown, the thread is of rectangular section, though in other embodiments it is other suitable form, e.g. triangular. The pitch of the thread 301 is chosen both to fit the space available and to permit the position of the sliding block within the collar to be readily measured by electronic means, such as a linear transducer or potentiometer.

The upper steering shaft 310 is machined so that a step or bush 309 remains adjacent to the thread 301, the step 309 having an outer diameter greater than the outer diameter of the thread 301. The step 309 abuts shelf 303 of the steering column 302, limiting the rightwards (as viewed) movement of steering shaft 310. In this embodiment, shelf 303 is integral with steering column 302, but in an alternative embodiment it is a separate ring affixed thereto.

The step 309 locates one end of the collar 307, the other end of which collar is located by annular bush 304.

Annular bush 304 also locates a step 308 of the upper steering shaft 310, limiting the leftwards (as viewed) movement of the steering shaft. The bush 304 is secured to the steering column 302 by a screw 305, retaining both the rotation limiting means 300, and the upper steering shaft 310 in position. In other embodiments, the bush 304 and shelf 303 contact the respective diameters of the upper steering shaft 310, to radially locate the steering shaft also.

A screw 306 secures the collar 307 to the steering column, to prevent rotation of the collar. In another embodiment, the collar 307 and the bush 304 are integral, e.g. being machined from a single length of tube.

In an alternative embodiment, the bush 304 and collar 307 are secured to the steering column 302 by fixing means other than screws, e.g. as by rivets or other suitable permanent fixing means.

The surface of the sliding block 311 adjacent the outer diameter of the collar carries a part of the measuring means (not shown) for determining the axial position of the sliding block, and thus the rotational position of the steering wheel. The measuring means may suitably be a linear transducer or potentiometer, another part of which may be secured to the inside surface of the steering column 302, or else to the collar 307, for example.

In the assembled condition of the rotation limiting means 300, as the upper steering shaft 310 is rotated in a first angular direction, the thread 301 and mating teeth 313 cause the sliding block 311 to move along the slot 315, until one of the teeth 313 engages a first end 317 of the thread. Rotation of the shaft in a second angular direction causes the sliding block to move in the opposite direction along the slot 315 until the other of the teeth 313 engages the second end 319 of the thread.

Thus, in the embodiment shown, the thread 301 has two closed ends 317 and 319. In an alternative embodiment the thread is open towards the splined end 299 of the steering shaft, and an annular collar is fitted to provide an abutment for the sliding block 311. In another alternative embodiment, the open-ended thread has a peg or stud inserted therein to provide an abutment for the sliding block at one of its ends.

It will be noted that when the steering shaft is disabled, the steering wheel is limited to a fixed number of rotations, but that the steering shaft can be re-enabled in any one of that limited number of rotations. If enablement of the steering shaft were to occur in a rotation of the limiting device other than the rotation in which disablement occurred, then the range of the vehicle's normal steering would be artificially restricted in one of the steering directions. It is thus proposed that the driver be provided with a measurement unit and display, preferably electronic, that will show him where, in rotations, he disabled the steering shaft, and when, by rotating the (disabled) steering wheel, he has achieved the same position to correctly re-enable the steering shaft.

To provide such a unit, a measuring means such as a linear transducer or potentiometer, can be fitted to measure the relative position of the sliding block 211 or 311. It is envisaged that the callibration should be in tenths of a rotation of the steering wheel from zero at one stop position through the number of complete rotations plus any part rotation to the opposite stop position.

The output of the measuring means, indicative of the position of the sliding block, is shown on a small display screen visible to the driver.

When the vehicle ignition is turned to "off", thereby operating the steering shaft disabling device, the electronic circuits of the measurement unit and display would be activated. This would cause the position of the sliding block to be shown by readings, preferably as digit(s), on the display screen, which would at the same time be illuminated (or the indicators themselves illuminated) to make the readings clear. The reading at the moment the circuit was activated would become fixed in one half of the display screen whilst the other half of the screen would show the actual instantaneous position of the sliding block. As the (disabled) steering wheel is rotatedwithin the limits set by the rotation limiting means, the readings in the second half of the display screen would change. When the key is inserted to re-enable the device and start the vehicle, the steering wheel will be rotated until the reading in the second half of the screen corresponds to the fixed reading in the first half of the screen. The ignition key may then be fully turned, the steering shaft re-enabled, and the engine started.

Such a unit and display can be further refined. In a first refinement, if the two sets of readings on the display screen do not correspond, they flash intermittently, and set off an audible bleeper to warn the driver that he is attempting to re-enable the steering shaft whilst in the wrong rotation of the limiting device. In a second refinement, an electrical circuit is arranged so that the starter motor is disabled when the readings do not correspond.

However, it is known that the direction of the front wheels of a vehicle, and thus the angular orientation of the lower steering shaft, can change following removal of the ignition key, for example if the vehicle rolls on uneven ground prior to application of the hand brake. In such an event, the recorded relationship between the sliding block and the channel is no longer true in their relationship to the two parts of the disabled steering shaft. Thus, some tolerance must be built into the system to allow for angular movements of the lower steering shaft. For example, a comparator can be included to compare the fixed reading of the measurement unit with the variable reading, and only allow the engine to be started if the difference between the readings is less than a predetermined value.

Also, as above stated, preferably the disabling device can only be re-enabled at one relative angular position, so that for incorrect alignment of the upper and lower steering shafts to occur, the inadvertent angular movement of the lower steering shaft would need to be greater than one full rotation of the shaft.

Desirably, the circuit of the measuring means (and comparator, if fitted) should be de-activated when the ignition key is turned to the second position, i.e. when the device is substantially re-enabled. Alternatively, the measuring means may be permanently active, with the readings being displayed on the screen, though it will be understood that the readings serve no purpose whilst the vehicle is in normal use, and so may be an unwanted distraction to the driver.

It is proposed that the electronic circuits of the unit are housed behind the display screen, or

Claims (24)

1. Disabling device for an operating shaft, the shaft having a rotatable part and a rotated part, the device having an enabled condition in which rotation of the rotatable part causes rotation of the rotated part and a disabled condition in which rotation of the rotatable part does not cause rotation of the rotated part, characterised in that key-controlled means transfer the said parts between the disabled and enabled conditions.

2. Disabling device for an operating shaft, the shaft having a rotatable part and a rotated part, the device having an enabled condition in which rotation of the rotatable part causes rotation of the rotated part and a disabled condition in which rotation of the rotatable part does not cause rotation of the rotated part, characterised in that a key-controlled means transfers the said parts from the disabled to the enabled conditions.

3. Disabling device according to claim 2 in which resilient bias means effects the transfer of the said parts between the enabled and disabled conditions.

4. Disabling device according to claim 2 in which the key controlled means transfers the said parts between the enabled and disabled conditions.

5. Disabling device according to any of claims 1-4 in which the rotatable part carries first coupling means, and in which the rotated part carries second coupling means, the said first and second coupling means being cooperable in the enabled condition.

6. Disabling device according to claim 5 in which the first and second coupling means are cooperable in only one relative angular position.

7. Disabling device according to any of claims 1-6 in which the rotatable part carries drive means.

8. Disabling device according to claim 7 in which the drive means is an acircular drive rod.

9. Disabling device according to any of claims 1-8 in which the key-controlled means includes an operating means, and in which the operating means is one of a rotatable cam and a slidable sleeve.

10. Disabling device according to any of claims 1-9 in which the key-controlled means includes a lock means and a release means, and in which the release means is effective to permit transfer of the said parts from the enabled condition to the disabled condition only upon removal of the key from the lock means.

11. Disabling device according to any of claims 1-10 having rotation limiting means operative to limit the permitted turning angle of the rotatable part when the device is in its disabled condition.

12. Disabling device according to claim 11 for a shaft having a rotational freedom of movement of more than 3600, the device having measurement means to permit, after disabling of the device, re-enabling of the device in the desired position.

13. Disabling device according to claim 12 in which the measurement means includes one of an Archimedean spiral or a helical groove.

14. A housing for a disabling device according to any of claims 1-13, the housing having weakened regions adapted to break under applied load.

15. Housing according to claim 14 having a cylindrical part mounted between two support collars, the weakened regions being are a pair of circumferential fracture rings on the cylindrical part, one adjacent each of the collars.

16. Housing according to claim 14 or claim 15 for the operating shaft of a machine, the housing also having regions for containing switches for the machine.

17. A machine having an operating shaft with a disabling device according to any of claims 1-13 fitted thereto.

18. A machine according to claim 17 in which part of the key-controlled means is connected to one or more control switches for the machine.

19. Disabling device constructed and arranged substantially as described with reference to Figs. 2 and 3, or to Fig.20 of the accompanying drawings.

20. A housing for a disabling device constructed and arranged substantially as described with reference to Figs. 11-13 of the accompanying drawings.

21. A first coupling for a disabling device constructed and arranged substantially as described with reference to Figs. 5-7 of the accompanying drawings.

22. A second couling means for a disabling device constructed and arranged substantially as described with reference to Figs. 8-10 of the accompanying drawings.

23. Operating means for a disabling device constructed and arranged substantially as described with reference to Fig. 4. or to Figs. 21-23 of the accompanying drawings.

24. A measuring means for a disabling device constructed and arranged substantially as described with reference to Figs. 28-32, or to Figs. 33-35 of the accompanying drawings.