Anti-theft hand brake

Abstract: In an anti-theft hand brake arrangement for a motor vehicle having a ratchet release mechanism operable by a push button (1), exposed at the end of a handbrake lever, the push-button incorporates a cylinder lock. In the locked condition, the push-button may still be depressed, but without acting on the ratchet release mechanism, whilst in the unlocked condition an abutment member (12) at the inner end of the push-button (1) is so positioned as to engage a release member (6) of the ratchet release mechanism when the push-button is depressed, thereby to release the brake ratchet.

Description: THIS INVENTION relates to an anti-theft mechanism operable to prevent the release of a vehicle hand brake to immobilise the vehicle and prevent unauthorised use thereof. A motor vehicle hand-brake customarily includes a hand-brake operating lever with an associated ratchet mechanism arranged to hold the operating lever, and thus the brake, in an "applied" position once the hand brake has been operated and after manual effort has been removed from the lever, until subsequent release of the handbrake by operation of a manually operable release member, such as a push-button, serves to lift a pawl from the ratchet of the ratchet mechanism whilst the lever is returned to the "released" position. A motor vehicle having such a hand-brake is herein referred to as being "of the kind referred to". It has been previously suggested to apply a locking mechanism to the hand-brake in a vehicle of the kind referred to such that the ratchet-release member can only be moved, to release the pawl from the ratchet, when the associated lock is released. For example, it has been proposed in GB2193937 to replace the push-button ratchet release button on the end of the conventional hand-brake lever with a push-button having a cylinder lock incorporated therein, such that the push-button can only be depressed when the lock is unlocked. Unfortunately, locking mechanisms of the latter type have proved, in practice, to be ineffective, for the locking detent or the like employed by the lock can readily be fractured and the push-button driven inwardly to release the hand-brake by applying a sharp blow with a hammer to the end of the release button. It is an object of the present invention to provide an improved anti-theft hand-brake arrangement which is not susceptible to circumvention in the last-noted manner. According to one aspect of the present invention there is provided an anti-theft handbrake arrangement for a motor vehicle of the kind referred to, wherein a manually actuable ratchet release mechanism is provided which includes a push-button exposed at the end of a generally tubular handbrake lever within which extends a brake release rod movable longitudinally downwards in the tubular handbrake lever to release the handbrake ratchet mechanism, and wherein the push-button incorporates a cylinder lock characterised in that the brake release rod carries a slide at its upper end within the tubular handbrake lever, said cylinder lock carrying an abutment member at its lower end within the tubular handbrake lever which is rotatable, with the lock, between locked and unlocked positions, said slide having an upwardly open recess for receipt of said abutment member in the locked position and the slide further having an upwardly presented face around said recess, said abutment member being of non-circular cross-section or being eccentric with respect to the axis of said cylinder lock and the recess being of complementary cross-section or of corresponding eccentricity, so that, in the locked position of the lock and abutment member, the push-button may be depressed without acting on the release rod, because the abutment member enters said recess without interference whilst in the unlocked condition thereof the abutment member is so positioned as to strike said face when the push-button is depressed, thereby moving said slide and brake release rod downwards, to release the brake ratchet. According to another aspect of the invention, there is provided a kit of parts, for adaption of an existing vehicle hand-brake lever to incorporate an anti-theft arrangement according to the first-noted aspect of the invention, said kit comprising an assembly including a tubular body part having a lower end adapted to fit a stub of an existing tubular brake lever, a push button slidable longitudinally within said tubular body part and exposed at an upper end of said body part, the assembly further comprising a slide slidable longitudinally within said body part below said push button, a lower end of said slide being adapted to receive an end part of a brake release rod of such existing handbrake lever, left after part of the existing brake release rod has been cut off, said lock carrying an abutment member at its lower end within said body part which is rotatable, with the lock, between locked and unlocked positions, said slide having an upwardly open recess for receipt of said abutment member in the locked position and the slide further having an upwardly presented face around said recess, said abutment member being of non-circular cross-section or being eccentric with respect to the axis of said cylinder lock and the recess being of complementary cross-section or of corresponding eccentricity, so that, in the locked position of the lock and abutment member, the push-button may be depressed without depressing the slide, because the abutment member enters said recess without interference whilst in the unlocked condition thereof the abutment member is so positioned as to strike said face when the push-button is depressed, thereby moving said slide downwards. Embodiments of the invention are described below by way of example with reference to the accompanying drawings, in which:- FIGURE 1 is a view in axial section showing the free end of a lockable vehicle brake lever embodying the invention, FIGURE 2 is a view, similar to Figure 1, of a variant, and FIGURE 3 is a view in section along the line III-III of Figure 2. Referring to the drawing, in a vehicle of the kind referred to, a vehicle handbrake mechanism (not shown in detail) comprises, in conventional manner, a tubular hand-brake lever and a ratchet mechanism whereby the hand-brake, once applied, will not be released until a pawl of the ratchet mechanism is disengaged from the ratchet by depression of a brake release rod 8 running within the tubular hand-brake lever. The mechanism comprises a generally cylindrical slide 6 slidable axially within the hand-brake lever and urged by a compression spring 3 into a position in which the pawl of the ratchet mechanism is engaged with the ratchet. The spring 3 is coaxial with slide 6 and with the lever and encircles the slide 6 at the lower region of the slide. The mechanism further comprises a generally cylindrical push-button 1 also slidable axially within the tubular hand lever and projecting from the free end of the latter. The push-button 1 is urged axially outwardly from the hand lever by means of a further compression spring 3' encircling an intermediate part of the push button 1. The push-button 1 incorporates a cylinder lock connected with an abutment member 12 at the lower, inner end of the push button 1. The abutment member 12 is of non-circular cross-section, for example of oblong cross-section. In one rotational position of the abutment member 12 about the longitudinal axis of the lever, which position is adopted in the "locked" condition of the cylinder lock, the abutment member 12 is in complete register with a correspondingly shaped (for example oblong) recess 14 in an upwardly directed face 16 of the slide 6 whereby, upon axial depression of the push-button 1 in this "locked" condition, the abutment member 12 will merely move axially down into the recess 14 until the limit of axial inward movement of the push button 1 is reached, without the slide 6 being forced downward. However, in another rotational position of the abutment member 12 about the longitudinal axis of the assembly, adopted in the "unlocked" position of the cylinder lock, the abutment member 12 is out of register with the recess 14, (for example, where the member 12 and recess 14 are both oblong in cross-section, the longer sides of the oblong cross-section of the member 12 lie at right angles to the longer sides of the oblong cross-section of the recess 14). Thus, upon depression of the push-button 1, the abutment member 12 engages the upwardly presented face 16 of the slide 6 around the recess 14, whereby the slide 6 is forced axially inwardly and downwardly, thereby moving the release rod 8 correspondingly to release the pawl of the ratchet mechanism and allow the brake lever to move to the position in which the brake is released. It will be appreciated that a similar effect might be obtained by making the member 12 and recess 14 eccentric with respect to the axis of the cylinder lock. In Figure 1, the push-button 1 is shown in the "unlocked" position to the left of the vertical line A-A and in the "locked" (and depressed) position to the right of the line A-A. It will be appreciated that forcing the push-button 1 inwardly when the cylinder lock is in the locked condition will not release the handbrake and, indeed, the push-button 1 can be moved inwardly readily in the locked state without forcing. In the "unlocked" condition, the hand-brake mechanism works in exactly the same way as a conventional mechanism. The mechanism illustrated in Figure 1 is intended to be applied to a conventional handbrake of an existing vehicle by a modification procedure which entails cutting the end portion from the existing tubular handbrake lever, cutting the existing brake release rod and screw-threading the end thereof and thereafter fitting the remainder of the components shown in the drawing. Alternatively, and preferably, the end of the brake release rod may be kept plain and the slide 6 may have a plain bore to receive the end of the brake release rod and the slide 6 may be bonded to the brake release rod by adhesive. In the drawing, references 10 and 8 respectively indicate the parts of the original tubular lever and push rod remaining after such a conversion procedure. As a result of the conversion procedure, the upper end of the original tubular brake lever is replaced by a tubular casing comprising a cylindrical outer sleeve 2 and a longitudinally split inner sleeve 7 which is a close fit within the outer sleeve and is held together by the latter. The outer sleeve 2 is longer than the inner sleeve 7 and the lower end of the outer sleeve 2 fits closely over the upper end of the cut-back lever 10, whilst the lower end of the longitudinally split inner sleeve 7 abuts an internal circlip 9 within the sleeve 2 which circlip 9 engages the lower end of sleeve 7 to retain the latter. The composite tubular casing 2, 7 encompasses the push button 1, slide 6 and springs 3 and 3', as well as location rings 4 for the springs and circlips 5 which retain the rings 4 and which circlips are engaged in circumferential grooves in the interior of the split sleeve 7. The lower spring 3 acts between the lower ring 4 and an annular shoulder on slide 6 and the upper spring 3' acts between the upper ring 4 and an annular abutment around the push-button 1. In assembly, the remainder of the components shown are applied to the cut back lever 10 and rod 8 by fitting the lower end of a cylindrical outer sleeve 2 over the end of the cut-back lever and rotating the sleeve, and with it the components therein, to screw the slide 6 onto the threaded end of the modified rod 8 until an internal abutment in the sleeve 2, afforded by internal circlip 9, engages the end of the cut-back tubular lever 10. The sleeve 2 and the remainder of the mechanism may thereafter be conveniently held in place by an appropriate adhesive between the outer surface of the cut back tubular lever and the inner surface of the lower end of the sleeve 2, such adhesive being applied directly before fitting the casing 7, 2 to the lever 10. The radially outer part of the push button 1, within which the barrel of the lock is rotatable by means of the appropriate key (not shown) is, of course, retained against rotation in the sleeves 2, 7 in a manner permitting longitudinal movement along the axis of the lever. This may be done, for example, by providing the upper location ring with a radially outwardly projecting lug engaging in a longitudinal groove in the interior of the sleeve 7 and further providing the upper location ring 4 with a radially inwardly projecting lug engaging in a longitudinal groove in the periphery of the push button 1. The slide 6 is preferably retained in a like manner, by the lower location ring 4, against rotation, whilst permitting longitudinal movement along the axis of the brake lever. Referring to Figure 2, there is illustrated a variant in which, as compared with Figure 1, the number of components which must be specifically suited to a particular vehicle handbrake is minimised as is the work and skill necessary for fitting the mechanism to an existing vehicle handbrake. Thus, the arrangement of Figure 2, as compared with the arrangement of Figure 1, additionally comprises an adaptor sleeve 20 adapted to fit over the hand-brake lever of a specific model of car or other vehicle and which is provided, at its upper end, with an externally screw threaded tubular cylindrical portion 30 of standard form and size externally and further comprises an adaptor cap 21 which is externally of a standard shape and size and has a plain cylindrical blind bore of a size to receive the brake release rod of the handbrake of a specific model of vehicle. Externally, the cap 21 is cylindrical over its length, apart from an upper portion which tapers frusto-conically upwards to provide a reduced-diameter upper end of cap 21. The end of the brake release rod which is received within the blind bore in cap 21 is plain and unthreaded, the cap 21 being secured on the brake release rod solely by adhesive. The cap 21 is received within a central blind bore extending from the lower end of a modified (as compared with Figure 1) slide 6' and is held captive therein by a circlip 22 accommodated in a peripheral groove around said blind bore and projecting into the latter below the cap 21. The outer sleeve, referenced 21 in Figure 2, is internally threaded at its lower end and is screwed onto a collar 11 which in turn is internally screw threaded and is screwed onto the screw thread at the upper end of the adaptor 20. Alternatively, the lower end of sleeve 2' may simply be a push-fit over a plain smooth peripheral surface of a variant collar 11. In either case, the sleeve 2' is secured to the collar 11 by adhesive. In installation of the assembly of Figure 2, after cutting the brake release rod and the brake lever as before, the adaptor 20 is fitted over the remaining portion of the hand brake lever and is bonded thereto with adhesive. As illustrated in Figure 3, a bolt or bolts 25 may be extended through the adaptor and the existing brake lever to hold the adaptor in place whilst the adhesive sets. The appropriate cap 21 is then applied to the free end of the remaining section of the brake release rod, being again bonded thereto by adhesive and the remainder of the assembly, of standardised form, is then screwed onto the adaptor 20. As the lock assembly moves downwards during screwing of the latter onto the handbrake lever adaptor 20, the bore in sleeve 6 receives the upper end of the cap 21 and descends over the latter. Initially, the tapered upper end of the cap 21 engages in the bore in sleeve 6 and subsequently engages within the circlip 22 so that, as said downward movement of the lock assembly continues, the circlip 22 is expanded radially outwards, by said tapered end, into the peripheral groove which receives it, allowing the cylindrical portion of the cap 21 to pass the expanded circlip 22. When the assembly is fully in position, the lower end of the cap 21 clears the circlip 22, allowing the latter to spring radially inwards once more beneath the cap 21, thereafter holding the latter 21 captive with respect to the slide 6 and thereby retaining the brake release rod against axial movement relative to the slide 6. The sleeve 11 is adhesively bonded both to the sleeve 2 and to the adaptor 20 to prevent subsequent unauthorised removal. It will be appreciated that, with the embodiment of Figure 2, in particular, the only steps required, in addition to straightforward assembly, are the cutting of the existing handbrake lever at the appropriate position, (which need not be done particularly accurately since the adaptor 20, fitting the remaining part of the existing lever, itself provides the datum and attachment for the remainder of the assembly), and the cutting of the existing brake release rod at the desired position, (which may, for example, be done with the assistance of a simple template, temporarily mounted on the adaptor 20 after fitting of the latter). It will be appreciated that, in the embodiments described with reference to the drawings, the invention provides a simple and convenient means of immobilising a vehicle, which is nevertheless neat and unobtrusive in appearance. Furthermore, as noted above, the structure of the preferred embodiments is such that it can readily be fitted to an existing handbrake lever. Indeed, as will be recognised by those skilled in the art, some of the components encompassed by the sleeve 2, 7, may simply be components extracted from the standard hand-brake lever during the modification described. It is contemplated that anti-theft arrangements such as described with reference to Figures 1 and 2, may be incorporated in existing vehicles by a professional conversion service, for example on a "while-you-wait" basis. Thus, (assuming the preferred arrangement of Figure 2 to be adopted) an engineering company providing such a service may maintain a stock of adaptors 20 and caps 21 for various vehicles and a supply of the standardised assemblies forming the remainder of the parts to be fitted and may thus fit such an anti-theft arrangement quickly and economically to any of a wide range of vehicles. It is also contemplated that anti-theft arrangements incorporating the invention may be fitted to vehicles ab initio , by vehicle manufacturers. The components necessary for such a conversion may also be sold as a kit of parts, for fitting by vehicle owners, with instructions as to the manner in which an existing handbrake may be modified using the kit, to incorporate the anti-locking mechanism.

Claims: An anti-theft handbrake arrangement for a motor vehicle, wherein a manually actuable ratchet release mechanism is provided which includes a push-button (1) exposed at the end of a generally tubular handbrake lever within which extends a brake release rod (8) movable longitudinally downwards in the tubular handbrake lever to release the handbrake ratchet mechanism, and wherein the push-button incorporates a cylinder lock characterised in that the brake release rod carries a slide (6) at its upper end within the tubular handbrake lever, said cylinder lock carrying an abutment member (12) at its lower end within the tubular handbrake lever which is rotatable, with the lock, between locked and unlocked positions, said slide (6) having an upwardly open recess (14) for receipt of said abutment member (12) in the locked position and the slide (6) further having an upwardly presented face (16) around said recess, said abutment member (12) being of non-circular cross-section or being eccentric with respect to the axis of said cylinder lock and the recess (14) being of complementary cross-section or of corresponding eccentricity, so that, in the locked position of the lock and abutment member, the pushbutton (1) may be depressed without acting on the release rod, because the abutment member (12) enters said recess (14) without interference whilst in the unlocked condition thereof the abutment member (12) is so positioned as to strike said face (16) when the push-button is depressed, thereby moving said slide (6) and brake release rod (8) downwards, to release the brake ratchet. A kit of parts, for adaption of an existing vehicle handbrake lever to incorporate an anti-theft arrangement according to claim 1, said kit comprising an assembly including a tubular body part (2,7) having a lower end adapted to fit a stub of an existing tubular brake lever, a push button slidable longitudinally within said tubular body part (2, 7) and exposed at an upper end of said body part (2, 7), the assembly further comprising a slide (6) slidable longitudinally within said body part (2, 7) below said push button, a lower end of said slide being adapted to receive an end part of a brake release rod of such existing handbrake lever, left after part of the existing brake release rod has been cut off, said lock carrying an abutment member (12) at its lower end within said body part (2, 7) which is rotatable, with the lock, between locked and unlocked positions, said slide (6) having an upwardly open recess (14) for receipt of said abutment member (12) in the locked position and the slide (6) further having an upwardly presented face (16) around said recess, said abutment member (12) being of non-circular cross-section or being eccentric with respect to the axis of said cylinder lock and the recess (14) being of complementary cross-section or of corresponding eccentricity, so that, in the locked position of the lock and abutment member, the pushbutton (1) may be depressed without depressing the slide, because the abutment member (12) enters said recess (14) without interference whilst in the unlocked condition thereof the abutment member (12) is so positioned as to strike said face (16) when the push-button is depressed, thereby moving said slide (6) downwards.

Inventors: TAYLOR MICHAEL, TAYLOR, MICHAEL
Applicants: TAYLOR GERALD, TAYLOR, GERALD
Application year: 1990
Main classification: B60R25
IPC codes: B60R25