GB2226112A

GB2226112A - Brake lever arrangement

Info

Publication number: GB2226112A
Application number: GB8829425A
Authority: GB
Inventors: Andrew Alexander Grey; Raymond Stuart Bailey
Original assignee: Automotive Products PLC
Current assignee: Automotive Products PLC
Priority date: 1988-12-15
Filing date: 1988-12-15
Publication date: 1990-06-20
Anticipated expiration: 2008-12-15
Also published as: GB8829425D0; GB2226112B

Abstract

A manually operable brake lever arrangement includes a brake lever (4) which, when pulled towards a handlebar (22), moves an operator lever (8) pivotally mounted on a mounting bracket (16) to operate a device such as a brake master cylinder (56). The brake lever is pivoted to the operator lever by a pin (6) and further connected by a screw jack comprising a screwed shank. <IMAGE>

Description

BRAKE LEVER ARRANGEMENT This invention relates to a manually operable brake lever arrangement to operate a brake of a bicycle, tricycle or quadracycle vehicle, for example a motor cycle, when provided on handlebars of such a vehicle.

A known manually operable brake lever arrangement comprises a bracket mounted or mountable on handlebars, a lever for grasping, the lever being pivotably mounted on the bracket to pivot about an axis and being formed integrally with an operating portion which is pivotable with the lever about said axis in response to manual effort applied to the lever, and the pivoting of the operating portion being to operate a brake actuating system.

When such a known brake lever arrangement is mounted on handlebars and operably connected with the brake actuating system, the brake lever, provided it is not being grasped, normally assumes an at rest position relative to the bracket and handlebars, from which rest position the brake lever has to be pivoted to cause operation of the brake actuating system to apply the brake actuated thereby. In order to grasp the lever to apply the brake, the fingers on a hand of the vehicle rider have to span a gap between the lever and that adjacent part of the handlebars held by the rider's hand. The size of that gap and the disposition of the lever relative to the handlebars in the lever at rest position may not suit every rider, nor in the case of racing motorcyclists the riding style of every rider nor be appropriate for every circuit on which racing is held.To reduce or avoid the above mentioned disadvantage it is known for the racing motorcyclist or a mechanic to bend a metal brake lever to alter its shape and disposition relative to the handlebars, or a set formed by a plurality of interchangeable brake levers can be provided each lever being of a different shape and being mountable one in place of another on the bracket by means of a nut and bolt which is removable to enable levers to be changed.

An object of the invention is to provide a brake lever arrangement which avoids the need for bending the lever or the need to provide a set of differently shaped interchangeable levers.

According to the invention there is provided a manually operable brake lever arrangement to operate a brake of a bicyle, tricycle or quadracycle vehicle when provided on handlebars of such a vehicle, said brake lever arrangement comprising a bracket mounted or moultable on said handlebars, an operator device pivotably mounted on the bracket so as to pivot about a first axis to operate a brake actuating system, a lever for grasping and mounted on the operator device so that manual effort applied to the lever moves the lever from a rest position and pivots the operator device, when said lever is in said rest position and the bracket is mounted on the handlebars a point on said lever being spaced from said handlebars by a spacing gap having a width equal to the distance between said point and said handlebars, the lever being pivotably mounted on said operator device to pivot about a second axis, and said lever being adjustably pivotable about the second axis so that the rest position of the lever relative to the bracket can be varied where- by the width of said spacing gap can be selectively varied.

The brake actuating system may be an hydraulic system comprising a master cylinder acted on by the operator device and connected by a conduit to a slave cylinder which acts to operate brake pads or shoes to apply retarding effort, or the actuating system may be a completely mechanical system transmitting movement from the operator device to apply retarding effort, for example movement transmission from the operator device may be by Bowden cable.

The invention will now be further described, by way of example, with reference to the accompanying drawings in which: Fig. 1 is plan view partly fragmented or in section illustrating an embodiment of a brake lever arrangement formed according to the invention in combination with a brake master cylinder.

Fig. 2 is a section on line II - II in Fig.

1; Fig. 3 is an end view in the direction of arrow III in Fig. 1 (but on a slightly larger scale than in Fig. 1), of the master cylinder and bracket combination, and Fig. 4 (though on the same scale as Fig. 3) is a section on line IV - IV in Fig. 1, showing the master cylinder and its reservoir.

Referring to the drawings, a brake lever arrangement 2 comprises a brake lever 4 pivotably mounted, by means of a pivot pin 6, on an operator lever 8 in the form of a plate pivotably mounted, by means of a pivot pin 10, between a pair of parallel flanges 12 and 14 on a mounting bracket 16. The lever 4 is shown in an at-rest position. The axes of the pivots 6 and 10 are substantially parallel. The mounting bracket 16 has an end face 18 in which a part-cylindrical recess 20 is formed to co-operate with handlebars 22 shown in dash lines, to which handlebars the bracket 16 is clamped in any suitable known manner (not shown). The handlebars 22 are of a bicyle or tricycle vehicle. The vehicle can be driven by an engine, and may be a motorcycle.

At the pivot point 6 the brake lever 4 is formed with a tenon type tongue portion 24 having substantially flat and parallel opposite faces 26 and 28. The tongue portion 24 rotatably fits in a recess 30 in an end of the operator lever 8 having in that end another recess 32 offset towards the upper face of the lever 8 and containing a small block 34. The block 34 is pivotably connected to the operator lever 8 by a pivot pin 36. Block 34 is integral with a screw threaded rod or bolt shank 38 freely extending in a bore 40 in a lug 42 on the brake lever 4. That bore 40 is intersected by a recess or slot 44 in the lug 42.

The slot 44 contains a nut or wheel 46 having a knurled periphery. The wheel 46 screw threadably engages the bolt 38 to form a screw-jack therewith. Opposite main faces of the wheel 46 are in close proximity to or in rubbing contact with the two longer side faces of the slot 44, and preferably the screw thread bolt on the bolt 38 is fairly fine. The periphery of the wheel 46 projects from the slot 44 at least at the uppermost side of the lug 42. Though wheel 46 may as an alternative, or in addition, project from the slot 44 at the lowermost side of the lug 42.

When the wheel 46 is manually rotated (by thumb or finger) in one rotary sense or the other it drives tne bolt shank 38 in one linear direction or the other along the bore 40. Because the operator lever 8 is relatively stationary, the movement of the bolt 38 causes the brake lever 4 to pivot about the pivot 6 to vary the width 48 of the gap between a point 50 on the brake lever and the handlebars. By rotation of the wheel 46, the at-rest position of the manually graspable brake lever 4 relative to the handlebars 22 can be varied between the limit positions indicated at 52 and 54. It is possible to perform the adjustment of the brake lever 4 by rotating the wheel 46 whilst the vehicle is being ridden and is on the move.

The brake actuating system is an hydraulic system comprising a master cylinder 56 integral with the bracket 16. The master cylinder 56 has a body 58 containing a piston 60. A transfer lever 62 is pivoted on the mounting bracket 16 to connect the operator lever 8 with the piston 60.

The body 58 defines a bore 64 having an outlet 66 to which a pipe can be connected using screw-threaded aperture 68. A blind, threaded bore 70 co-operates with a bolt 72 securing an hydraulic fluid reservoir 74 to the body 56. Bypass and reservoir ports 76 and 78 connect the bore 64 to the reservoir 74.

The piston 60 has main and secondary cup seals 80, 82 and a blind bore 84 in one end in which a compression spring 86 is housed to bias the piston 60 away from the outlet 66 and an input member in the form of a wear resistent pad 88 at the other end. A guide pin 90 extends axially through the spring 86 and is connected to the body 56 by a plate 92.

The bracket 16 comprises a part-cylindrical portion 92 having a bore 94 concentric with the bore 64, the two parallel flanges 12 and 14 each having a through hole 96 in which the pivot pin 10 is secured, and a webbed portion 98 having the end face 18 in which the part-cylindrical recess 20 is formed. The bracket 16 also has a slot 100 in which the transfer lever 62 is located.

A rod in the form of a set screw 102 is in threaded engagement with the operator lever 8. The set screw 102 forms a movable abutment member locked in position by a locknut 104.

The transfer lever 62 is pivotally supported by a pivot pin 106 secured to the bracket 16. The transfer lever 62 has a convex abutment surface in the form of a lobe 108 for reaction against the pad 88 and a ce1ave abutment surface in the form of the longitudinal groove 110 to co-operate with a part-spherical end portion 112 of the set screw 102.

To operate the master cylinder a rider applies a pulling force to the brake lever 4 which, because of the connection provided by the wheel 44 and bolt 38, rotates in combination with the operator lever 8 about the pivot 10. The rotation of the operator lever 8 causes set screw 102 to react against the transfer lever 62 which rotates about the pivot pin 106. The lobe 108 transfers the load applied to the transfer lever 62 to the pad 88 thereby dis-placing the piston 60 to increase the hydraulic pressure in the master cylinder 56.

The travel ratio for the master cylinder and brake lever arrangement is the ratio of the linear movement of the piston 60 obtained for a specified linear displacement of a known point on the brake lever 4 frown the at-rest position. The known point is the effective position where the applied manual force acts.

The travel ratio is variable by rotating the set screw 102 which will move axially thereby altering its position of contact with the transfer lever 62. If for example, the set screw 102 contacts the transfer lever 62 near to the pivot pin 106 then the travel ratio will be high as a small movement of the brake lever 4 will produce a relatively large axial displacement of the piston 60. The principle underlying the variation in travel ratio is disclosed in our published European Patent Application No. EP.0173513A3.

In the brake actuating system, the pipe connected to the master cylinder 56 is also connected to a slave cylinder (not shown) which operates a brake to retard a wheel of the vehicle. The brake can be a disc brake or a drum brake. When friction material in such a brake wears and becomes thinner, the distance that a piston of the slave cylinder must move outwardly therefrom to apply the brake increases. To achieve that increased displacement of the slave piston the piston 60 in master cylinder 56 has to be displaced by an increased amount when the lever 4 is pulled. It may happen that the brake applying movement of the brake lever 4 is restricted by the brake lever coming in to abutment with the handlebars 22 before piston 60 has been sufficiently displaced. To avoid that, the at-rest position of the brake lever 4 can be moved nearer to the limit position 52 by rotation of the wheel 46 to ensure that the gap 48 that the brake lever can be pulled through is wide enough to allow full application of the brake.

For an alternative brake actuating system in which a brake is operated by a Bowden cable in which an inner cable slides in an outer sheath, the bracket 16 can be modified by leaving off the cylinder 58 and the transfer lever 62, and the locknut 102 can be left off the operator lever 8; instead a nose part 120 of the operator lever 8 can be modified for connection to an end of the inner cable and the bracket 16 can be arranged for connection to an end of the outer sheath.

Claims

1. A manually operable brake lever arrangement to operate a brake of a bicycle, tricycle or quadracycle vehicle when provided on handlebars of such a vehicle, said brake lever arrangement comprising a bracket mounted or mountable on said handlebars, an operator device pivotably mounted on the bracket so as to pivot about a first axis to operate a brake actuating system, a lever for grasping and mounted on the operator device so that manual effort applied to the lever moves the lever from a rest position and pivots the operator device, when said lever is in said rest position and the bracket is mounted on the handlebars, a point on said lever being spaced from said handlebars by a spacing gap having a width equal to the distance between said point and said handlebars, the lever being pivotably mounted on said operator device to pivot about a second axis, and said lever being adjustably pivotable about the second axis so that the rest position of the lever relative to the bracket can be varied whereby the width of said spacing gap can be selectively varied.

2. A brake lever arrangement as claimed in Claim 1, in which the lever is pivotable about the second axis by means of an adjustment device interposed between the lever and the operator device and operable to selectively vary the rest position of the lever and thus selectively vary the width of said spacing gap.

3. A brake lever arrangement as claimed in Claim 2, in which adjustment device is a screw-jack.

4. A brake lever arrangement as claimed in Claim 3, in which screw-jack device comprises a nut or wheel, and said adjustment device is operable by rotation of the nut or wheel.

5. A brake lever arrangement as claimed in Claim 4, in which a portion of the periphery of the nut or wheel projects from the operator device.

6. A brake lever arrangement as claimed in any one of Claim 2 to 5, so arranged that when mounted on handlebars and the vehicle is being driven and on the move, the adjustment device is operable.

7. A said vehicle having handlebars on which is mounted a brake lever arrangement as claimed in any one preceeding claim.

8. A vehicle as claimed in Claim 7 comprising a brake actuated by an hydraulic system comprising a master cylinder operated by said brake lever arrangement.

9. A vehicle as claimed in Claim 7 comprising a brake actuated by movement trasmitted by a Bowden cable actuated by said brake lever arrangement.

10. A manually operable brake lever arrangement to operate a brake of a bicycle, tricycle or quadracycle vehicle when provided on handlebars of such a vehicle, said brake lever arrangement being substantially as hereinbefore described with reference to the accompanying drawings.

11. A bicycle, tricycle or quadracycle vehicle having handlebars on which is mounted the brake lever arrangement claimed in Claim 10.