Title of Invention

A BRAKE SYSTEM FOR A MOTORCYCLE

Abstract A brake system includes a housing (11) with a swing lever (26), and an equalizer (33) connected to the swing lever. A left hand brake lever is operatively connected to a rear drum brake through the equalizer. The left hand brake lever is also connected to a front disk brake through the equalizer and the swing lever. A rear hand brake lever is connected to the front disk brake through the swing lever. The right hand brake lever is operated to apply the front disk brake. The left hand brake lever is operated to simultaneously apply the both front and rear brakes. The housing (11) has an equalizer stopper (14), and a port (21) connected to the front disk brake through a brake line (6) Advantageously, the port is defined in the equalizer stopper.
Full Text

BRAKE SYSTEM FOR A IfoTORCYCLE
The present invention relates to brake systems for use in a motorcycle.
A conventional motorcycle typically includes a right hand brake lever mounted on a right handlebar and adapted to apply the front brake, a clutch lever mounted on a left handlebar, a gearshift pedal on the left side of the motorcycle, and a brake pedal on the right side of the motorcycle and adapted to apply the rear brake.
Another type of motorcycle such as a scooter includes a variable speed gear mechanism and eliminates the use of a clutch lever and a gearshift pedal- Such a motorcycle includes a right hand brake lever pivoted to apply the front brake, and a left hand brake lever or a pedal for applying the rear brake. During braking, a relatively large load is exerted on the front wheel, whereas a relatively small load is exerted on the rear wheel. To that end, a disk brake is used as the front brake so as to provide stronger braking, whereas an economical drum brake is used as the rear brake. When the right hand brake lever is operated, a piston is moved within a master cylinder so as to develop a hydraulic pressure. The hydraulic pressure causes operation of the front disk brake to apply the front brake. When the left hand brake lever is operated, the rear drum brake is applied through a drive wire. The two levers must therefore be operated with good balance. Such a conventional brake system is thus difficult to operate.

It is, therefore, an object of the present invention to provide a brake system for a motorcycle, wherein a left hand brake lever or a pedal is operated to apply both front and rear brakes so as to improve operability and performance
According to the present invention, there is provided a brake system for a motorcycle which comprises a housing including a cylinder bore, a piston axially movable within the cylindrical bore, a swing lever extending in a direction substantially perpendicular to the axis of the housing and having one end pivotally mounted to the housing, a first link extending substantially parallel to the axis of the housing and having an elongated slot connected to the swing lever at a location intermediate the length of the swing lever, said first link being operatively connected to the right hand brake lever, an equalizer extending substantially perpendicular to the axis of the housing and operatively connected medially to a left hand brake lever on a left handlebar or a foot pedal on the right side of the motorcycle, a second link extending substantially parallel to the axis of the housing and pivotally connected to one end of the equalizer, said second link having an elongated slot connected to the other end of the swing lever, a push member disposed between a middle portion of the swing lever and the piston, said push member being operable to move the piston, an equalizer stopper provided on one axial end of the housing and contacted with the one end of the equalizer to thereby limit displacement of the equalizer when the left

hand brake lever or the foot pedal is operated to pull the equalizer, a port defined in the equalizer stopper and communicated with the cylinder bore of the housing, a brake line for connecting the port to the front brake, and a connecting member for connecting the other end of the equalizer and the rear brake.
By this arrangement, when the right hand brake lever is pivoted, the first link is pulled to cause rotation of the swing lever. The push member is then operable to push the piston within the housing so as to develop a hydraulic pressure. This pressure is sent to the front brake through the port and the brake line for application of the front brake. With the first link and the push member connected to the swing lever at a location intermediate the length of the swing lever, a pulling force as developed during rotation of the right hand brake lever is substantially directly transmitted through the first link to the push member. In other words, a braking force applied to the front wheel by the front brake corresponds to the amount of operation of the right hand brake lever.
When the left hand brake lever is pulled or the foot pedal is pushed down, the equalizer is pulled to thereby apply the rear brake through the connecting member which is connected to one end of the equalizer. At the same time, the second link, which is connected to the other end of the equalizer, causes the swing lever to rotate. The push member is then operable to move the piston within the housing to apply the front brake.

In the event that the front brake fails due, for example, to leakage of brake fluid, the left hand brake lever is pulled or the foot pedal is pushed down to pull the equalizer. The piston can be moved without any resistance. Also, the equalizer is contacted with the equalizer stopper and then pivoted about the point of contact. The left hand brake lever is now able to pull the connecting member so as to apply the rear brake-
Conveniently, the port is defined in the equalizer stopper. This arrangement eliminates the need for a boss and thus, simplifies the profile of the housing.
In a preferred embodiment, the housing includes a retainer ring fitted therein and positioned in opposite relation to the piston with respect to the push member. The retainer ring is contacted with the push member so as to limit the position to which the piston is returned. This arrangement maintains brake performance. The piston can be machined or made with higher manufacturing tolerance than a conventional piston since the retainer ring directly limits the position of the piston when it is returned.
In another preferred embodiment, an adjusting screw is mounted to one end of the swing lever. The adjusting screw is contacted with the housing so as to limit the position to which the piston is returned. This alternative arrangement also maintains brake performance.
The housing may have a bleeder opening communicated with the port. In this way, air can readily be removed from brake fluid through the bleeder opening. The cylinder bore

may also be communicated with either the bleeder opening or the port.
In a preferred embodiment, the swing lever is bifurcated and has a connecting portion located at its one end and pivotally mounted to the housing, a first arm extending from the connecting portion to the other end of the swing lever along one side of the housing, and a second arm extending from the connecting portion to the other end of the swing lever along the other side of the housing, with the second arm being longer than the first aarm. The first link is connected to one end of the first arm opposite the connecting portion, and the second link is connected to one end of the second arm opposite the connecting portion. The push member is located between the connecting portion and the first link and extends between the first arm and the second arm.
By this arrangement, the first and second arms are pivoted about the connecting portion when the first link is pulled as well as when the second link is pulled. This arrangement also brings about a reduction in the axial dimension required to mount the push member to the housing. Connection of the first and second arms through the push member increases the strength of the swing lever.
The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments when taken in conjunction with the accompanying drawings in

which:
Fig. 1 is a schematic view of a brake system for a
motorcycle according to one embodiment of the present
inventions-Fig. 2 is a vertical sectional view showing the
internal structure of a housing illustrated in Fig. 1;
Fig. 3 is a front view of the brake system shown in
Fig. 1;
Fig. 4 is a right side view of the brake system shown
in Fig. 3;
Fig. 5 is a top plan view of the brake system shown in
Fig. 3;
Fig. 6 is a rear view of the brake system shown in
. •' .-' '
Fig. 3;
Fig. 7 is a left side view of the brake system shown in Fig. 3;
Fig. 8 is a bottom view of the brake system shown in Fig. 3;
Fig. 9 is a view similar to that of Fig. 3, but showing the state in which a left hand brake lever is operated when brake fluid leaks from a cylinder bore;
Fig. 10 is a front view of another embodiment of the brake system according to the present invention; and
Fig. 11 is a general view of a modified form of the brake system.
Pig. 1 illustrates a brake system for a motorcycle according to one embodiment of the present invention. In

this embodiment, both right and left hand brake levers are used to apply brakes. Specifically, a left hand brake lever 1 on a left handlebar 2 and a right hand brake lever 3 on a right handlebar 4 are pulled to operate a front disk brake 5 and a rear drum brake 7. The front disk brake 5 is installed on the front wheel (not shown) of a motorcycle and connected to a housing 11 through a brake line 6 such as a flexible hose. Reference numeral 21 denotes a port of the housing 11 which is intended to receive one end of the brake line 6. The housing 11 has a cylinder bore 12 within which a brake fluid is contained, and a piston 24 movable within the cylinder bore 12 whereby the brake fluid is pushed out of the cylinder, through the brake line 6, and into the front disk brake 5. The brake is then applied to the front wheel.
The rear drum brake 7 is operated through a drive wire 39 so as to apply the brake to the rear wheel (not shown).
Referring to Fig. 2, the housing 11 is attached to the body (not shown) of the motorcycle and cast from aluminum or other suitable materials. The housing 11 has a central axis 0-0 along which a cylinder bore 12 is defined. The cylinder bore 12 includes a reduced diameter bore section 12A within which the piston 24 is slidably received, and an enlarged diameter bore section 12B defined below the reduced diameter bore section 12B within which a closure member 25 is disposed. An annular groove 12C is formed in the open lower end of the enlarged diameter bore section 12B to receive a retainer ring 43 which will later be explained.

For the purpose of illustration, one side of the housing 11 shown in Fig. 3 is its front side. The housing 11 has a front bracket 13. As better shown in Fig. 4, the front bracket 13 extends forwardly from the upper end of the housing 11. The front bracket 13 has a threaded hole 13A to threadingly receive a tube 36B of a left brake cable 36. The threaded hole 13B is located on near the central axis 0-0 of the housing 11. An equalizer stopper 14 is formed in the upper end of the housing 11 and located at the right side of the front bracket 13. As better shown in Fig. 5, the equalizer stopper 14 extends forwardly further from the front bracket 13 and has a rectangular shape- The equalizer stopper 14 has a lower, contact surface 14A with which an arcuate projection 33D of an equalizer 33 is contacted.
An intermediate bracket 15 is located in front of and intermediate the length of the housing 11. As shown in Fig. 3, the intermediate bracket 15 is adapted to support a tube 39B of the rear brake drive wire 39. The intermediate bracket 15 has a stopper surface 15A with which one side of the equalizer 33 is contacted. The stopper surface 15A serves to position the equalizer when the equalizer 33 is pulled through the drive wire 39 by means of a spring disposed within the rear drum brake 7.
A rear bracket 16 is located in an opposite relation to the front bracket 13 with respect to the axis 0-0. As shown in Fig. 6, the rear bracket 16 extends rearwardly from the right side of the housing 11. The rear bracket 16 has a threaded hole 16A to threadingly receive a tube 38B of a

right brake cable 38.
A lever mount 17 is formed in the lower end of the housing 11 and extends sidewardly from the left side of the housing 11. A swing lever 26 is pivotally mounted to the lever mount 17. Two protrusions 18 are located on the right side of the housing 11 and at opposite sides of the axis 0-0 so as to secure one end of corresponding springs 40. A rectangular hole 19 is defined in the lower side of the housing 11 and extends through the enlarged diameter bore section 12B of the cylinder bore 12. A push pin 35 is allowed to enter the hole 19 so as to move the piston 24.
A hose fitting 20 is located at a location intermediate the length of the housing 11 and extends rearwardly and leftwardly from the housing 11. The hose fitting 20 has a cylindrical shape. As shown in Fig. 2, the reduced diameter bore section 12A of the cylinder bore 12 is communicated with the interior of the hose fitting 20. The hose fitting 20 is adapted to receive one end of a hose 42 which will later be described.
The port 21 extends in a fore-and-aft direction and is open at a front side 14B of the equalizer stopper 14. The bottom of the port 21 is located behind the central axis 0-0 of the housing 11 as shown in Fig, 4. Advantageously, the port 21 is formed in the equalizer stopper 14 as a boss. One end of the brake line 6 is connected to the port 21. The port 21 is communicated with the reduced diameter bore section 12A of the cylinder bore 12 through a bleeder opening 22. The bleeder opening 22 is defined in the upper

side of the housing 11. As shown in Fig. 7, the bleeder opening 22 extends in a direction perpendicular to the central axis 0-0 of the housing 11. The bleeder opening 22 extends in substantially the same plane as the port 22. The bleeder opening 22 also extends in the lateral direction of the housing 11 and has a reduced diameter section 22A communicated with the reduced diameter bore section 12A of the cylinder bore 12. The bottom of the bleeder opening 22 is communicated with the port 21. The bleeder opening 22 serves to remove air from the brake fluid and is normally closed by a plug 23.
The piston 24 is axially slidable within the reduced diameter bore section 12A of the cylinder bore 12. As shown in Fig. 2, the piston 24 is held within the cylinder bore by the closure member 25. The closure member 25 is inserted within the enlarged diameter bore section 12A of the cylinder bore 12 and has a cylindrical shape. The closure member 25 also serves to prevent leakage of the brake fluid. The piston 24 is pushed by the push pin 35, whereby the brake fluid in the enlarged diameter bore section 12A of the cylinder bore 12 is sent to the front disk brake 5 through the brake line 6. When pushing of the piston 24 is stopped, the piston 24 is biased in such a direction that the piston 24 is moved out of the cylinder bore 12. The retainer ring 43 acts to return the piston to a predetermined position.
The swing lever 26 is located in the lower end of the housing 11 and extends in the lateral direction of the housing 11. As shown in Fig. 8, the swing lever 26 is

bifurcated and includes a U-shaped end 27 located at one side of the housing 11, a first arm 28 extending from the U-shaped end 27 to the other side of the housing 11 along the rear side of the housing, and a second arm 29 extending from the U-shaped end 27 to the other side of the housing 11 along the front side of the housing 11. A bolt hole 27A is formed in the U-shaped end 27. A bolt 30 extends through the bolt hole 27A and cooperates with a nut to pivotally attach the U-shaped end 27 of the swing lever 26 to the lever mount 17. The second arm 29 is longer than the first arm 28.
Referring to Figs. 3 and 6, a link aperture 28A is formed in one end of the first arm 28 opposite the U-shaped end 27 for connection with a first link 31 which will later be described. A link aperture 29A is formed in one end of the second arm 29 opposite the U-shaped end 27 for connection with a second link 34 which will later be described. Also, a pin aperture 28B is formed intermediate the length of the first arm to receive one end of the push pin 35. Similarly, a pin aperture 29B is formed intermediate the length of the second arm 29 to receive the other end of the push pin 35. The link aperture 28A is located intermediate the length of the swing lever 26 although it is formed in the distal end of the first arm 28. This is because the second arm 29 is longer than the first arm 28.
Referring to Fig. 8, the link aperture 28A is separated from the pivot point of the swing lever 26 or the central axis of the bolt hole 27A by a distance LI. The pin

apertures 28B and 29B are separated from the central axis of the bolt hole 27A by a distance L2, The link aperture 29A is separated from the central axis of the bolt hole 27A by a distance L3. In the illustrated embodiment, a ratio of the distance LI and the distance L2 to the distance L3 is 1:1.3 to 1:2.5. This rate is preferably 1:1.8.
As better shown in Fig. 6, the first link 31 is vertically located at the rear side of the housing 11 and extends parallel to the axis 0-0 of the housing 11. An elongated slot 31A is defined in the lower end of the first link 31. Also, a cable aperture 31B is defined in the upper end of the first link 31 for connection with a cable body of the right brake cable 38, The elongated slot 31A of the first link 31 is connected to the link aperture 28A of the first arm 28 through a pin 32.
The equalizer 33 is located intermediate the length or height of the housing 11 and extends in a direction perpendicular to the axis O-O of the housing 11. Also, the equalizer 33 is located above the swing lever 26 and lies in the same plane as the swing lever 26 does. A cable aperture 33A is defined at a location intermediate the length of the equalizer 33 for connection with a cable body 36A of the left brake cable 36. A wire aperture 33B is defined in one end of the equalizer 33 for connection with a wire body 39A of the rear drum brake drive wire 39. A link aperture 33C is defined in the other end of the equalizer 33 for connection with the second link 34. As explained earlier, the arcuate projection 33D is formed in the equalizer 33

adjacent to the link aperture 33C and adapted to contact with the contact surface 14A of the equalizer stopper 14 when the front disk brake 5 malfunctions or fails.
As shown in Fig. 3, the wire aperture 33B is separated from the cable aperture 33A by a distance L4. The link aperture 33C is separated from the cable aperture 33A by a distance L5. In the illustrated embodiment, the distance L5 is twice or thrice as long as the distance L4 (L4:L5 is 1:2 to 1:3), This ratio is preferably 1:2.7.
The second link 34 extends along the axis 0-0 of the housing 11 and parallel to the first link 31. An elongated slot 34A is defined in the lower end of the second link 34 and extends along the axis 0-0 of the housing 11. The upper end of the second link 34 is connected to the link aperture 33C through the upper pin 32. The elongated slot 34A is connected to the link aperture 29A of the second arm 29 through the lower pin 32.
The push pin 35 is located between the first arm 28 and the second arm 29 of the swing lever 26. The push pin 35 extends in the fore-and-aft direction of the motorcycle as well as in a direction perpendicular to the axis O-O of the housing 11. The push pin 35 is in the form of a cylindrical pin. Opposite ends of the push pin 35 is supported in the pin aperture 28B of the first arm 28 and the pin aperture 29B of the second arm 29, respectively. The push pin 35 is centrally enlarged to provide an arcuate surface 35A adapted to push the piston 24. Advantageously, the arcuate surface 35A is able to axially push the piston

24 in a straight line if the push pin 25 is inclined.
The piston 24, the swing lever 26, the first link 31, the equalizer 33, the second lever 34 and the push pin 35 are assembled in an integral fashion to form one of the units of the brake system.
As shown in Fig. 3, the left brake cable 36 is composed of the cable body 36A and the tube 36B. The cable body 36A has one end connected to the left hand brake lever 1, and the other end connected to the cable aperture 33A of the equalizer 33. The tube 36B surrounds the cable body 36A and is formed at its one end adjacent to the threaded hole 13A with threads 36B1. The tube 36B is adjustably threaded into the threaded hole 13A and fixed to the front bracket 13 by a nut 37.
As shown in Fig. 6, the right brake cable 38 is composed of the cable body 38A and the tube 38B. The cable body 38A has one end connected to the right hand brake lever 3 and the other end connected to the-cable aperture 3IB of the first link 31. The tube 38B surrounds the cable body 38A and is formed at its one end adjacent to a threaded hole 16A with threads 38B1. The tube 86B is adjustably threaded into the threaded hole 16A and fixed to the rear bracket 16 by another nut 37.
Referring back to Fig. 3, the rear drum brake drive wire 39 is composed of the wire body 39A and the tube 39B. The wire body 39A has one end connected to the wire aperture 33B of the equalizer 33 and the other end connected to the rear drum brake 7. The tube 39B surrounds the wire body 39A.

One end of the tube 39B is fitted into the intermediate bracket 15.
The two springs 40 extend between the protrusion 18 and the equalizer 33 and between the protrusion 18 and the first link 31, respectively so as to prevent rattling of the left hand brake lever 1 and the right hand brake lever 3.
As shown in Figs. 1 and 2, a reservoir tank 41 is connected to the hose fitting 20 through the hose 42. A predetermined amount of brake fluid is contained in the reservoir tank 41. The reservoir tank 41 is mounted in such a position that the amount of the brake fluid can be visually identified from the exterior of the reservoir tank 41.
The retainer ring 43 is located in the lower end of the housing 11 and serves as a stopper means. As shown in Fig. 2, the retainer ring 43 is located in an opposite relation to the piston 24 with respect to the push pin 35. The retainer ring 43 is fitted in the groove 12C which is, in turn, formed in the enlarged diameter bore section 12B of the cylinder bore 12. When no external force is applied to the piston 24, the push pin 35 is displaced with the piston 24, The piston 34 is returned to a given position when the push pin 35 is brought into contact with the retainer ring 43. The retainer ring 43 is of a conventional structure as > shown in Fig. 8.
Reference will now be made to the process and manner in which the left hand brake cable 36, the right brake cable 38 and the rear drum brake drive wire 39 are connected as

well as the manner of adjustment of the various elements of the brake system.
First, the wire body 39A of the drive wire 39 is connected to the wire aperture 33B of the ecjualizer 33, and the tube 38B is connected to the intermediate bracket 15. Next, the cable body 36A of the left brake cable 36 is connected to the cable aperture 33A of the equalizer 33, and the threads 36B1 of the tube 36B are threadingly engaged with the thread hole 13A of the front bracket 13 and thereafter, fixed thereto by the nut 37. Similarly, the cable body 38A of the right brake cable 38 is connected to the cable aperture 31B of the first link 31, and the threads 38B1 of the tube 38B are threadingly engaged with the thread hole 16A of the rear bracket 16 and thereafter, fixed thereto by the nut 37.
It is then necessary to fill or eliminate any gap which may exist between the pin 32 and the elongated slot 31A of the first link 31 as well as between the pin 32 and the elongated slot 34A of the second link 34. Thereafter, the nuts 37 are rotated to adjust the amount of projection of the cable body 36A of the brake cable 36 and the cable body 38A of the brake cable 38 until the equalizer 33 is brought into contact with the stopper surface 15A of the intermediate bracket 15 under the influence of the spring within the rear drum brake 7. This adjustment not only eliminates rattling of the related elements, but also provides better response when the brakes are applied.
With the push pin 35 inserted into the rectangular

hole 19, the retainer ring 43 is fitted within the groove 12C of the cylinder bore 12. The retainer ring 43 serves to directly limit the position to which the piston 24 is returned.
In operation, when the right hand brake lever 3 is rotated or pulled, the right brake cable 38 causes upward movement of the first link 31 as shown by the arrow A in Fig. 6. The swing lever 26 is then rotated in the direction of the arrow B. This rotation causes the push pin 35 to push the piston 24 in the direction of the arrow A. The brake fluid within the cylinder bore 12 is then sent to the front disk brake 5. The resulting hydraulic pressure causes the front disk brake to operate. A braking force is then applied to the front wheel. Since the first link 31 and the push pin 35 are separated from the bolt hole 27A by a shorter distance, that is, the distances LI and L2, rotation of the right hand brake lever 3 is directly transmitted to the front disk brake 5. This enables accurate adjustment of a braking force to be applied to the front wheel.
When the left hand brake lever 1 is pulled, the left brake cable 36 causes the equalizer 33 to move in the direction of the arrow A as shown in Fig. 3. The drive wire 39 is then pulled to operate the rear drum brake 7 so as to apply a braking force to the rear wheel. Also, with the equalizer 33 pulled in the direction of the arrow A, the swing lever 26 is rotated in the direction of the arrow B through the second link 34. This rotation causes the push pin 35 to push the piston 24, whereby the front disk brake

is operated to apply the front brake as well. At this time, the drive wire 39 is pulled with a greater degree of force since a ratio of the distance L4 between the cable aperture 33A and the aperture 33B to the distance between the cable aperture 33A and the link aperture 33C is 1:2.7. As a result, a greater braking force is applied to the rear wheel On the other hand, the second link 34 is pulled with a lesser degree of force to rotate the swing lever 26 in the direction of the arrow B.
Also, as a ratio of the distance between the bolt hole 27A and the pin apertures 28B and 29B to the distance between the bolt hole 27A and the link aperture 29A is 1:1.18, only 1/1.8 of one rotation of the swing lever 26 is required to push the push pin 35. That is, when the left hand brake lever 1 is operated, the output force is reduced to 1/2.7 due to the equalizer 33. However, the swing lever 26 causes such a reduced force to be increased by 1.8 times greater than is obtained when the right hand brake lever is operated. The left hand brake lever 1 thus serves as an auxiliary means to apply the front brake.
Reference will be made to how the brake system works when the front disk brake 5 malfunctions due, for example, to leakage of brake fluid in the cylinder bore 12 during operation of the motorcycle.
First, the left brake hand lever 1 is rotated to cause the left brake cable 36 to pull the equalizer 33 in the direction of the arrow A. At this time, the swing lever 26 is free to move as shown in Fig. 9. The swing lever 26 is

thus rotated in the direction of the arrow C by a substantial degree. This rotation causes the arcuate projection 3D to be contacted with the pontact surface 14A of the equalizer stopper 14. However, further rotation of the left hand brake lever 1 allows one side of the equalizer 33 to be rotated in the direction of the arrow D. As a result, the drive wire 39 is pulled to apply the rear brake.
With the brake system of the present invention, operation of the left hand brake lever 1 not only causes the rear drum brake 7 to apply, but also gives an auxiliary braking force to the front wheel through the front disk brake 5. To decelerate the motorcycle, it is only necessary to operate the left hand brake lever 1. This gives an appropriate degree of braking force to both the front and rear wheels. This system thus facilitates operation of the brake levers and produces a stable braking force.
The front disk brake 5 is responsive to the amount of operation of the right hand brake lever 3. An intended amount of braking force is thus applied to the front wheel on which loads are exerted during braking. This improves stability of the motorcycle during braking.
Again, when the left hand brake lever 1 is operated, a greater degree of braking force is first applied to the rear wheel, while an auxiliary braking force is applied to the front wheel through the front disk brake 5. In other words, the rear wheel is first locked during braking. This also improves stability of the motorcycle during braking.
Advantageously, the master cylinder is used as the

housing 11 of the brake system with the piston 24, the swing lever 26, the first link 31, the equalizer 33, the second link 34, the push pin 35 and other elements being assembled together. This arrangement eliminates the need for another housing and thus, brings about a reduction in the production cost and size of the brake system.
Advantageously, the housing 11 can be cast from aluminum and other material. Such a material improves the rigidity of the housing. The housing is less deformed if high loads are imposed during braking. The rigid housing enables safe braking and improves operability and durability
Conveniently, the port 21 is formed in the equalizer 14. The equalizer 14 is thus used as a boss for the port 21. This arrangement simplifies the profile of the housing 11 and reduces the size and weight of the brake system.
The bleeder opening 22 is defined in the housing 11 and 22 to permit release of air from brake fluid. This arrangement facilitates assembly of the brake system and provide a stable braking operation. Moreover, the bleeder 22 is communicated with the cylinder bore 12 with its bottom connected to the port 21. This allows communication between the cylinder bore 12 and the port 21 although the port 21 is defined in such a limited place. This arrangement thus reduces the number of machining processes and the size of the housing.
The retainer ring 43, which is commercially available, cooperates with the push pin 35 to directly limit the position of the piston 24 when returned. This eliminates

the need to machine the parts with high accuracy and thus, improves the brake performance and reduces the cost of the brake system. Moreover, the retainer ring 43 can easily be removed from the cylinder bore. This allows ready replacement of the piston 24 and other parts and enables easy maintenance.
One end of the swing lever 26 is pivotally attached to the lever mount 17, whereas the first link 31, the second link 34 and the push pin 35 are all connected to the other end of the swing lever 26. This arrangement reduces the space required to mount the swing lever 26 to the housing 11
The swing lever 26 extends in the lateral direction of the housing 11 and has one end pivotally mounted to the housing 11. The equalizer 33 is located above the swing lever 26 and lies in the same plane as the swing lever 26. In other words, the equalizer 33 is located within the length of the swing lever 26. This arrangement reduces the lateral dimension required to mount the equalizer 33 and thus, the overall size of the brake system.
The swing lever 26 has a bifurcated shape and is composed of the U-shaped end 27, and the first and second arms 28 and 29 extending from the U-shaped end 27 to the other side along the front and rear sides of the housing 11. In addition, those parts operated by the left brake cable 36 are arranged in the front side of the housing 11, whereas those parts operated by the right brake cable 38 are arranged in the rear side of the housing 11. This arrangement reduces the size of the brake system.

facilitates mounting of various parts to the front and rear sides of the housing, and enables easy maintenance of the brake system.
The push pin 35 extends in a direction perpendicular to the axis 0-0 of the housing 11. This configuration reduces the axial size required to mount the push pin 35 to the housing 11. Opposite ends of the push pin 35 are supported by the first arm 28 and the second arm 29. This arrangement resists twisting of the swing lever 26 during operation and improves durability and operability of the swing lever. The arcuate surface 35A is formed intermediate the length of the push pin 35. As such, if the push pin 35 is inclined, the push pin 35 is able to push the piston 24 axially on a straight line. Thus, this arrangement prevents damage and malfunction of the piston 24 due to undesirable contact within the cylindrical bore 12.
In the event that the front disk brake 5 fails due, for example, to leakage of brake oil, the left hand brake lever 1 is operable to pull the equalizer 33 to thereby cause the arcuate projection 33D to contact with the equalizer stopper 14. This contact permits rotation of the equalizer 33 so that a braking force may be applied to the rear drum brake 7 through the drive wire 39. This system ensures safe deceleration and provides a high level of safety.
A braking force developed by the front disk brake 5 during operation of the left hand brake lever 1 is mechanically determined by the manner in which various parts

are mounted to the swing lever 26 and the equalizer 33. Desirable braking forces can be obtained by changing such a manner. The brake system of the present invention can thus be applied to various types of motorcycles.
Referring now to Fig. 10, there is illustrated another embodiment of the brake system according to the present invention. Like parts are given like reference numerals used in the previous embodiment and will not be described herein.
As in the previous embodiment, the brake system includes a housing 51 within which a cylinder bore 52 is defined. A front bracket 53, an equalizer stopper 54, an intermediate bracket 55, a rear bracket (not shown), a lever mount 56, a hdse fitting 57 and other parts are attached to the housing 51. The housing 51 differs from the housing 11 in that, no part is provided below the lever mount 56, no groove is defined, and the lever mount 56 has a contact end 56A with which an adjusting screw 62 comes into contact.
A swing lever 58 includes a U-shaped end 59, a first arm 60 and a second arm 61, as in the previous embodiment. As a feature, a threaded hole 59A is defined in the U-shaped end of the swing lever 58 to receive the adjusting screw 62. The threaded hole 59A corresponds in position to the contact end 56A. The adjusting screw 62 is attached to the U-shaped end 59 of the swing lever 58. The adjusting screw 62 is axially movable within the threaded hole 59A and fixed in position by a nut 63. Contact of the adjusting screw 62 with the contact end 56A limits the amount of rotation of

the swing lever 58 and thus, the position to which the piston 24 is returned.
This embodiment offers the same advantageous effects as the previous embodiment does. In addition, the use of the adjusting screw 62 allows for more accurate adjustment of the position to which the piston 24 is returned, regardless of manufacturing tolerances. Thus, this embodiment brings about a reduction in the machining cost and improves brake performance.
In the previous embodiment, a ratio of the distance LI between the bolt hole 27A and the link aperture 28A and the distance L2 between the bolt hole 27A and the pin apertures 28B and 29B to the distance L3 between the bolt hole 27A and the link aperture 29A is 1:1.8. Also, a ratio of the distance L4 between the wire aperture 33B and the cable aperture 33A to the distance L5 between the link aperture 33C and the cable aperture 33A is 1:2,7. However, the present invention is not limited thereto. Alternatively, the ratio of the distance LI and L2 to the distance L3 may be in the range from 1:1.3 to 1:2.5, depending on the performance and weight distribution of motorcycles- Also, the ration of the distance L4 to the distance L5 may be in the range from 1:2 to 1:3. This alternative ratios may of course be applied to the embodiment shown in Fig. 10.
In the illustrated embodiments, the housings 11 and 51 are cast from aluminum. Alternatively, the housings 11 and 51 may be cast from iron or other material. The housing may also be formed by cutting and other processes.

In the embodiment shown in Figs. 1 to 9, the housing
11 is of a one-piece construction, with the cylindrical bore
12 defined in the interior of the housing 11, and the brackets 13, 15 and 16 located on the exterior surface of the housing 11. The present invention is not limited thereto. For example, a housing may be telescopically inserted into a discrete outer cover with various brackets so as to form a cartridge. This arrangement may also be used in the embodiment shown in Fig. 10.
The drive wire 39 are used in the both embodiments, but may be replaced with a plurality of interconnected bars.
In the embodiments shown in Figs. 1 to 10, the left hand brake lever 1 is pulled to operate the rear drum brake 7. The present invention is, however, not limited thereto. For example, a foot pedal 71 may be mounted to the right side of a motorcycle (not shown) so as to operate the rear drum brake 7, as shown in Fig. 11.
Although the present invention has been described with respect to its preferred embodiments, it is to be understood that various changes and modifications may be made without departing from the spirit and scope of the present invention as defined in the appended claims.




WE CLAIM:
1. A brake system for a motorcycle comprising a right hand brake lever on a right handlebar, a front brake and a rear brake, said brake system comprising:
a housing having a cylinder bore, said housing having an axis;
a piston axially movable within said cylindrical bore;
a swing lever extending in a direction substantially perpendicular to the axis of said housing, said swing lever having one end mounted to said housing for pivotal motion, and an other end;
a first link extending substantially parallel to the axis of said housing and having an elongated slot connected to said swing lever at a location intermediate the length of said swing lever, said first link being operatively connected to the right hand brake lever;
an equalizer extending substantially perpendicular to the axis of said housing, said equalizer being operatively connected medially to a left hand brake lever on a left handlebar or a foot pedal on the right side of the motorcycle;
a second link extending substantially parallel to the axis of said housing and pivotally connected to one end of said equalizer, said second link having an elongated slot connected to the other end of said swing lever;
a push member disposed between a middle portion of said swing lever and said piston, said push member being operable to move said piston;
an equalizer stopper provided on one axial end of said housing, said equalizer stopper being contacted with the one end of said equalizer to thereby limit displacement of said equalizer when the left hand brake lever or the foot pedal is operated to pull said equalizer;

a port defined in said equalizer stopper and communicated with said cylinder
bore of said housing;
a brake line for connecting said port to the front brake; and
a connecting member for connecting the other end of said equalizer and the rear
brake.
2. The brake system as claimed in claim 1, wherein said housing has a retainer ring fitted therein and positioned in opposite relation to said piston with respect to said push member, said retainer ring being contacted with said push member so as to limit the position to which said piston is returned.
3. The brake system as claimed in claim 1, wherein an adjusting screw mounted to said one end of said swing lever, said adjusting screw being contacted with said housing so as to limit the position to which said piston is returned.
4. The brake system as claimed in any one of the claims 1 to 3, wherein said housing has a bleeder opening communicated with said port, said cylinder bore being communicated with either said bleeder opening or said port.
5. The brake system as claimed in any one of the claims 1 to 4, wherein said swing lever is bifurcated and has a connecting portion located at its one end and pivotally mounted to said housing, a first arm extending from said connecting portion to the other end of said swing lever along one side of said housing, and a second arm extending from said connecting portion to the other end of said swing lever along the

other side of said housing, said second arm being longer than said first arm, and wherein said first link is connected to one end of said first arm opposite said connecting portion, and said second link is connected to one end of said second arm opposite said connecting portion, said push member being located between said connecting portion and said first link and extending between said first arm and said second arm.
6. A brake system for a motorcycle substantially as herein described with reference to the accompanying drawings.


Documents:

0038-mas-2000 abstract granted.pdf

0038-mas-2000 claims granted.pdf

0038-mas-2000 description(complete) granted.pdf

0038-mas-2000 drawings granted.pdf

038-mas-2000-abstract.pdf

038-mas-2000-certification document.pdf

038-mas-2000-claims.pdf

038-mas-2000-correspondnece-others.pdf

038-mas-2000-correspondnece-po.pdf

038-mas-2000-description(complete).pdf

038-mas-2000-drawings.pdf

038-mas-2000-form 1.pdf

038-mas-2000-form 19.pdf

038-mas-2000-form 26.pdf

038-mas-2000-form 6.pdf

038-mas-2000-other document.pdf

38-mas-2000 abstract duplicate.pdf

38-mas-2000 claims duplicate.pdf

38-mas-2000 description (complete) duplicate.pdf

38-mas-2000 drawings duplicate.pdf


Patent Number 197902
Indian Patent Application Number 38/MAS/2000
PG Journal Number 20/2006
Publication Date 19-May-2006
Grant Date 02-Jan-2006
Date of Filing 17-Jan-2000
Name of Patentee M/S. HITACHI LTD
Applicant Address 6-6 MARUNOUCHI 1-CHOME, CHIYODA-KU, TOKYO
Inventors:
# Inventor's Name Inventor's Address
1 YUKITOSHI SHIMURA 2322-607 NISHIYAHATA, RYUO-CHO, NAKAKOMA-GUN, YAMANASHI-KEN
PCT International Classification Number B62L 3/00
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA