GB2147068A - Brake actuation - Google Patents

Abstract

A device, functioning within a tubular or other suitably-formed housing and either embodied, or subsequently introduced, into a system controlling, by flexible cables, brakes or other mechanisms. Traction, applied from a plurality of sources such as brake-levers, is selected by a slide 11A, 11B and pin 14 arrangement to be the maximum of the sources and is communicated to front or rear cycle- brakes, for instance, with a maximum displacement force limited by a lever 20 which engages stops 27. The maximum traction selection part and the displacement limiting part may be separate (Figs. 2, 8, not shown) and are interconnected by an interlinking cable. An interconnected succession of secondary sub-assemblies progressively expands traction-distribution to operate multiple mechanisms. The device, optionally incorporating a stop-light switch, facilitates safe single-handed, differential dual-control of cycle brakes. All housings contain a suitable, sealed-in lubricant. <IMAGE>

Description

SPECIFICATION Improvements in the actuation of mechanisms of Bowden cables My invention will enable traction, as applied from any source or from any combination of a plurality of such sources, to be conveyed therefrom by flexible traction-cables and variably or definitively applied to the actuation of either a single objective mechanism or to a plurality of such mechanisms The said flexible traction-cables consist of concentric inner and outer elements typified under the general designation of Bowden cables, but which herein will be henceforward briefly termed cables.

Broadly, the invention, hereinafter termed the device, comprises a mechanical assembly in a unified form or divided, actually or conceptually, into two sub-assemblies which are herein respectively defined as primary and secondary parts. When actually divided, the said two parts may be remotely separated and operatively inter-linked by a single cable in such a manner as to provide that their respective functions are concomitant, as in the said unified assembly. Housings, enclosing the respective components, may be of generally tubular or rectilinear form, constructed to allow access to the said components, so as to facilitate assembly thereof or adjustments thereto; and manufactured from any material suitable to all operational requirements.

In operation, traction is first conveyed by cable from any or all of the initial points of application to the said primary part wherein, by its particular function, the maximal traction is selected and imparted to a single reciprocative traction-bar, whereby it is further conveyed either directly to the secondary part of the unified assembly or to an inter-linking cable which further conveys the traction to a separate, remotely-stationed secondary part.

In the eventuality that traction could be applied to the primary part from one source alone, due to failure of the remaining source or sources, the device would not thereby be so affected as to diminish its ultimate effect.

In the further eventuality wherein one of the aforesaid objective mechanisms should be rendered inoperative for any reason, then all the applied traction would automatically be diverted to the mechanism remaining operative, consequent upon a particular function within the relative secondary part. An additional function of the said secondary part provides for the pre-activation by a selectable amount, at the commencement of applied traction, of any specific objective mechanism or for the simultaneous activation of the said mechanisms.

When the device is embodied, for instance, in the braking system of a bicycle, tricycle, motorcycle, wheel-chair or other comparable means of conveyance, the rider or driver thereof is resultantly enabled to operate all brakes in the said system by merely using any brake-lever. This evident advantage also concurrently enables the said rider or driver to use either hand, for example, in order to give road-signals, or for any other purpose, whilst retaining full dual braking control by the other hand. The device provides an additional facility whereby the rear braking mechanism may be selected for pre-application and at a predominant intensity, thus, especially on a slippery or otherwise hazardous road-surface, introducing an important measure of safety into the control of the said conveyances. The device may also be readily adapted to operate an integral brake warning-light switch.As a variant from the embodiment cited, the cables emerging from any secondary part and basically serving to directly activate objective mechanisms may, instead, each be operatively connected to an additional separate secondary sub-assembly. The purpose of this procedure would be to provide a progressively expanding field of traction distribution, held to reasonable limits chiefly by the necessity for reinforcement of all involved components in proportion to the consequent acretion of stresses.

Where, however, a single source of tractionapplication is alone required for a particular purpose, the function of a primary part becomes unnecessary, and the said source is, instead, connected directly to a separate secondary sub-assembly.

It is accordingly manifest that the aforesaid features, pertaining to the general function and particular applications of the device, constitute improvements in the cable-operation of mechanisms.

The respective housings of the device may be lightly infused with a suitable lubricant and sealed so as to prevent any substantial exudation, except for an acceptable amount of beneficial seepage into the operating cables. The said sealed-in lubricant also serves to render the housings reasonably resistant to detrimental weather conditions. The device and its functions are hereinafter further described with the aid of the accompanying drawings wherein, by way of example, a tubular form of housing is mainly illustrated and which, for reasons of simplification and clarity, largely relate to its embodiment in the braking system of a bicycle, normally fitted with independent front and rear brakes, individually and respectively operated by two brake levers; but the generality of the device's wider applicability is not, of course, thereto restricted.

With general reference to the said drawings, components may be affixed or attached by means other than those shown, which are merely in the nature of examples. The device may be readily manufactured by standard methods and equipment.

Figure 1 is a schematic diagram of a unified assembly of the device, as actuated from two sources of traction, and wherein all components of the primary and secondary parts are contained within a single housing.

Figure 2 is a schematic diagram showing the relevant portions of remotely-separated primary and secondary sub-assemblies, appropriately modified so as to be operatively interlinked by a single cable.

Figure 3 is an exploded sketch showing an example of primary part components actuated from two traction sources.

Figures 4 and 5 are each part-sectioned representations of a primary part or primary sub-assembly, adapted for actuation from three and four traction sources respectively.

Figure 6 shows a composite traction-bar assembly as used when traction is to be applied from three or four sources.

Figure 7 shows an example of a secondary traction-lever unit.

Figure 8 shows diagrammatically how, by means of an expanding series of interlinked secondary sub-assemblies, traction may be variably communicated to multiple mechanisms.

Referring now to Fig. 1, the housing 1 may be tubular or rectilinear in cross-sectional form and is enclosed at each end by an end-cover 2a, secured by screws 4. Traction is conveyed to the primary part of the device from the brake-levers (not shown) by respective cables, the inner element 8 of each of which, passing through its outer sheath 6, ferrule 7, sealingwasher 5, hole 3 in end-cover 2a and through one of the springs 10, is secured to an attachment-point 9 on one of the slotted sides 11 a or 11 b by any suitable connection means.The cable-holes 3 in either end-cover 2a and in guide-bracket 26 may, if necessary, be varied in profile so as to provide for the passage of any particular type of lug (8a in Fig. 3) affixed to any inner cable 8 in order to be connected at any of the respective attachment-points 9 which the relevant components are so adapted to incorporate. The slots 1 2a and 1 2b in the respective slides 11 a and 11 b are each engaged by one arm of the pin 14 which is transversely affixed in the traction-bar 1 3 in an equi-disposed position. The said slides 11 a and 11 b, along with the respective slots 1 2a and 1 2b therein, are of identical form, longitudinally dimensioned so as to be compatible with the maximum linear tractive movement which may be operationally required by the device.Any degree of the said linear tractive movement in either or both of the slides 11 a and 11 b, relatively responding to the operation of their respective brakelevers, is accordingly communicated by the said pin 14 to the said traction-bar 1 3 which thereby, when extended into the secondary part in the particular manner hereinafter described, serves resultantly to actuate the objective brake mechanisms.

Tractive movement is accretionally opposed by springs 10, by the flexure of the retractionsprings in the braking mechanisms (not shown) and, eventually, by the operational pressures exerted within the said braking mechanisms. Each of the springs 10 serves merely to retain its associated brake-lever in the pre-application position when not in use and to ensure that lugs cannot become inadvertently disconnected from their respective attachment-points because of cable slackness.

The relatively light compressive strength of the said springs 10 needs, therefore, to be sufficient only for these specific purposes.

Hereinafter, to assist this description, occasional reference will also be made to Fig. 2.

Before traction is applied to the device, the traction-bar end-stop 24 abuts, in the unified assembly, against the interior face of the rear end-cover 2a. In the case of a separate primary sub-assembly (shown in Fig. 2), the endstop 24a, adapted to include a cable attachment-point 9, abuts against the interior face of end-cover 2b and serves to facilitate cablelinkage either to a separate secondary subassembly or to some other mechanism. Continuing to refer to Fig. 2, when the said cablelinkage is directed to a separate secondary sub-assembly, the single cable enters the said sub-assembly through its front end-cover 2b and is connected to an attachment-point 9 in the end-stop 24a affixed to the front end of traction-bar 1 3b.

The traction-bar 1 3 in the unified assembly (Fig. 1) and the traction-bar 1 3a in the separate primary sub-assembly (Fig. 2) are slidably positioned interjacent with the respective slides 11 a and 11 b, forming therewith mutually supportive combinations which are additionally supported and guided in operation by the interior surface of the housing 1 and by the guide-screws 15, the spigots of which are slidably engaged in the respective guidegrooves 1 6 formed in slides 11 a and 11 b.

Fig. 3 shows examples of the said slides 1 a and 11 b, the slots 1 2a and 1 2b, the transverse traction-pin 14 and the traction-bar 1 3, clarifying, in an exploded view, the operational relationship of the said components.

The said slides may, however, be located and guided within the said housing by matched splines or by other suitable means. The traction-bar 1 3 in the unified assembly (Fig. 1) and the traction-bars 1 3a and 1 3b in the respective primary and secondary sub-assemblies (Fig. 2) are each proportionately supported by guide-brackets 1 7 affixed within the said respective housings 1 in the positions shown. The rear portion of the traction-bar 1 3 (Fig. 1) and of traction-bar 13 (Fig. 2) are each further supported by a guide-bracket 26 in which two cable-holes 3 are provided and through which pass the cables 8 before emerging from the respective secondary part or sub-assembly.The forward end of traction bar 1 3b in the said separate secondary subassembly embodies an additional end-stop 24a and is supported by an additional guidebracket 1 7. The foregoing descriptive particulars relate mainly to the primary functions of the device, whilst the following will relate both to the particular secondary functions and to the general operation of the complete device.

Referring again to Figs. 1 and 2, with additional reference to Fig. 7, the respective traction-bars 1 3 and 1 3b are each so formed as to provide a longitudinal aperture 25 within which an eccentrically-pivoted tractionlever 1 9 is mounted. The said unit 1 9 comprises the lever 20 featuring a rearward arm 20a and a cross-member 20b on each end of which, one of two catch-points 20c is formed.

The said lever 20 also carries two shackles 22, each pivotally mounted thereon by one of the two swivel-pins 23 and both being formed so as to provide cable-lug attachment-points 9, to which cables 8 are connected by suitable cable-lugs 8a. The said cables 8 pass through holes 3 in guide-bracket 26, endcover 2a and thence to the respective brakes or other mechanisms.

It will be seen that all movalbe components of the device, being constantly subject either to tractional or. retractional strains, are thus substantially unaffected, during operation, by vibrational, gravitational or other extraneous forces. Henceforward, to assist this description, the terms front end or forward end will relevantly denote the end at which traction is applied to the device or any part thereof; the term rear end likewise denoting the end towards which the said traction is conveyed.

Before traction is operationally applied, the respective traction-bars and components mounted thereon are retained in the rearward position by the combined effects of springs 10, where relevant, and of the flexure of retraction-springs in the objective mechanism (not shown). In this position the traction-lever unit 1 9 lies in an equi-disposed attitude, balanced therein by equality of tension in the cables 8 leading to the brakes or other said mechanism.By means of pre-operational, differential regulation of the relevant tensionadjusters (not shown), which are either inte gral with the said objective mechanisms or additionally-positioned intermediately in the cable layout, a corresponding rotational change of attitude in the traction-lever unit 1 9 is produced wherein, when tractive movement commences, one or the other of the catchpoints 20c will engage with the relevant check-block 27. In this condition of interference, forward tractional movement of the relevant traction-bar 1 3 or 1 3b imparts pre-activated traction to the particular cable endued with the higher tension, traction being concurrently withheld from the other cable 8 endued with the lower tension.Continued forward tractive movement separates the engaged catch-point 20c and check-block 27, leaving the traction-lever unit 1 9 free to oscillate and allocate compensated traction to both cables 8. The period during which the aforementioned pre-tractional effect on one or the other of the objective mechanism obtains, when considered as a proportion of the maximum tractive movement for which the device is intended to be operable, may be pre-determined by dimensional variations in the form of the traction-lever 20 and in the positioning of the check-blocks 27. The said period, along with the degree of abruptness in the commencement and termination thereof, is also affected by the nature of any variations in the respective profile forms of the contacting faces on the catch-points 20c and those 28 on the check-blocks 27.The said contactfaces 28 on each of the identically-formed check-blocks 27 are inclined as shown at a suitable pressure-angle, whilst the contactfaces on the catch-points 20c are involutely curved so that, when in operational contact, the resultant function is analogous to that of the engagement of contiguous teeth in a rackand-pinion, spur-gear mechanism. The difference in the respective forms of the said contacting faces may, optionally, be reversed, so that the catch-point faces are plane and the check-block faces are involutely curved.

When the applied traction is completely released, all moving parts of the device are retracted by the compressed or flexed springs, as relevant, by which the said traction is opposed, the said traction-lever unit 1 9 adopting the original oscillatory attitude conforming to any pre-regulated difference in cable-tension. The sloping ramps 29, buttressing the contact-faces 28 on the check-blocks 27 and extending longitudinally within the device, serve also, during the said retraction, to constrain the traction-lever unit 1 9 to a centralized position, wherein it becomes clear of any interference, as a result of the wedge-effect of the said sloping ramps acting, where relevant, on the rear surfaces of the respective catchpoints 22c.

When the device is intended for operation from more than two brake-levers or other sources of traction-application, these are each respectively connected by a cable 8, passing through a sealing washer 5, end-cover 2a provided with an appropriate number of cableholes 3 and through spring 10 (see Fig. 1), to a relatively-positioned slide 11 c or 11 d as is relevant. The said cables 8 are attached by suitable means to the said slides at attachment points on their forward ends. Figs. 4 and 5 show examples in cross-section of 3slide and 4-slide operation respectively in which the said slides 11 c and 11 d are concentrically arranged, within the housing 1, around the cylindrical portion 1 8a of composite traction-bar 1 3c in a unified assembly, or 1 3d in a separate primary sub-assembly.At this point, concomitant reference to Fig. 6 may assist consideration of the said Figs. 4 and 5.

The said Fig. 6 is a half-sectional illustration of a four-slide version of a composite tractionbar involving a four-pin spider 14b (Fig. 5) but it is generally typical also of a three-slide version featuring a three-pin spider 1 4a (Fig.

4), the relevant components of both the said versions bing therein jointly identified. The respective mechanisms are contained in a housing 1 and the said cylindrical portion 1 8a is, in both of the said versions, a tubular forward extension of the boss 1 4c of the relevant spider 1 4a or 1 4b. The traction-pins on the said spiders are located in a similar position in relation to the longitudinal slots 1 2c or 1 2d in the respective slides 11 c or 11 d, as is the traction-pin 14 (Fig. 1) to the slots 1 2a and 1 2b in the dual slides 11 a and 1 b.Continuing to refer to Fig. 6, the rear face of spider-boss 1 4c features a recess 1 4e into which the suitably-formed fore end 1 8d of the rear rectilinear portion of the tractionbar 1 8b (in a unified assembly) or 1 8c (in a separate primary sub-assembly), projecting forward from the slot 1 7a in guide-bracket 17, is non-rotatably secured at 1 4f by screws, pins or other pertinent means adequately substantial to carry the maximal traction-loading.

The said cylindrical portion 1 8a of each assembled composite traction-bar 1 3c or 1 3d extends to the forward ends of the relevant slides 11 c or 11 d, serving thereby to support and guide the said slides during operation and, where applicable, retaining the cablelugs 8a of primary cables 8 in their respective attachment-points 9, thus supplementing the aforementioned function of springs 10 (see also Fig. 1).

Fig. 7 shows an example of a typical traction-lever unit 1 9 and is mainly to clarify the description included heretofore in relation to Fig. 1.

Fig. 8 shows, diagrammatically, the method hereinbefore described whereby a cable-interlinked, expanding system of traction-distribution is achieved by means of a succession of secondary sub-assemblies interconnected as shown. The unit A is either a secondary part of a unified assembly or a separate secondary sub-assembly (see Figs. 1 and 2), each interlinking cable being optionally furnished with a means of tension-adjustment B to provide differential unit-regulation. The respective materials, forms and dimensions of components, as hereinbefore described and illustrated, serve mainly to exemplify the intrinsic operational principles of the device and may, of couse, be respectively varied in accordance with manufacturing and other relevant requirements.

Claims (14)

1. A unified mechanical assembly in a cylindrical housing, embodied within a system controlling the actuation of brakes by means of flexible traction-cables and providing, within a primary part, a plurality of longitudinally-movable slides respectively connected by cables to a matching plurality of tractionapplication sources, the said slides being biased individually against the applied traction by a light compression-spring and collectively operating to select and further communicate the maximally applied traction to a central interjacent traction-bar, movable longitudinally by any combination of the said slides, a longitudinal slot in each of which slidingly engages one of a similar plurality of tractionpins relatively positioned and affixed to the said traction-bar, which, supported by guidebrackets appropriately stationed within the said housing, extends into a secondary part wherein the said traction becomes communicated to an eccentrically-pivoted traction-lever unit located on its fulcrum-pin within a longitudinal aperture, formed in the said tractionbar, and librating in accordance with the tensional difference in two cables respectively connected therefrom, to the said brakes by means of cable-attachment points on two shackles freely mounted on the said tractionlever unit by respective pivot-pins equi-disposed about the said fulcrum-pin, the said tensional difference in the said cables corresponding to pre-tractional regulation of tension-adjusters associated with the respective brake-mechanisms, thereby constraining the said traction-lever unit into a relative attitude wherein, during a selectably early proportion of the maximum tractive movement engendered as aforesaid, interference between either one of two catch-points on the tractionlever and one of two relative check-blocks, affixed with the said housing, prevents traction from being imparted to either one of the objective brake-mechanisms, as may be relevant, the total traction becoming concurrently diverted to pre-activation of the complemental brake-mechanism until a point in the continuative tractive movement is reached, as predetermined by dimensional variations in the form and position of involved components, at which the engaged catch-point is operationally forced to disengage from the relevant checkbody, leaving the said traction-lever unit thereafter free to oscillate and thereby to convey equalized traction to both brakes during the remainder of the applied tractive movement, following which, upon the eventual release of all applied traction, all movable components are retracted, by the flexed springs in or associated with the said brakes, to their respective pretractive positions, any rearward interference between either catch-point and the relevant check-block being cleared, during the said retraction, by sliding, wedgewise contact between the sloping ramps, buttr.ssing each check-block, and the rear surface of either relevant catch-point, thus constraining the said traction-lever unit into a central, equidisposed attitude at that particular point in the said retractive movement. (See Figs. 1 to 7 inclusive).

2. A device as claimed in Claim 1 whereof the said primary and secondary parts are respectively constructed as individuallyhoused, remotely-separable sub-assemblies operationally interlinked by a single cable, serving practicably as a traction-bar extension and enabling the said two sub-assemblies to function concomitantly as in the said unified assembly (see Fig. 2).

3. A device as claimed in Claims 1 and 2 embodied as a subsequently additional element in a system of flexible-cable-actuated mechanisms.

4. A device as claimed in Claims 1 to 3 inclusive whereof the respective housings and components, being respectively and functionally identical with those aforementioned, are of appropriately varied physical forms.

5. A device as claimed in Claims 1 to 4 inclusive with general applicability to other cable-actuated mechanisms.

6. A device as claimed in Claims 1 to 5 inclusive, the movable components of which, being continually subject to respectively opposing tractional and retractional forces, are substantially unaffected at all times by any extraneous physical influence.

7. A device as claimed in Claims 1 to 6 inclusive which may be located and positioned in any attitude without diminution of function.

8. A device as claimed in Claims 1 to 7 inclusive wherein the traction conveyed as aforesaid to a separate primary sub-assembly is, designedly, wholly communicated to a single objective mechanism, thus bypassing any secondary mechanism.

9. A device as claimed in Claims 1 to 8 inclusive wherein the particular primary functions will be resultantly undiminished when, because of inadvertent mechanical failure, traction is applied only from a single source.

10. A device as claimed in Claims 1 to 9 inclusive wherein all traction, communicated as aforesaid to a relevant secondary mechanism, is thereby concentred and imparted to any succeeding mechanism which alone remains operational because of any mechanical failure which may be pertinent.

11. A device as claimed in Claims 1 to 10 inclusive, from the relevant secondary mechanism whereof, the emergent cables are each connected to a further secondary sub-assembly of the device, thus providing a progressively expanding system of traction-distribution, limited in extent chiefly by the accretion of stresses from the additional mechanisms (see Fig. 8).

1 2. A device as claimed in Claims 1 to 11 inclusive which, optionally, is adapted to incorporate an integral switch serving to operate a lamp indicating tractional activity within the device.

1 3. A device as claimed in Claims 1 to 1 2 whereof the said housings respectively contain an appropriate quantity of suitably-characterized lubricant.

14. A device as claimed in all the preceding Claims, arranged and adapted to operate substantially as hereinbefore described with reference to the accompanying drawings.