F O R M 2
THE PATENTS ACT, 1970 (39 of 1970)
COMPLETE SPECIFICATION (See section 10 and rule 13)
1. TITLE OF THE INVENTION
PARKING BREAK ASSEMBLY WITH ROCKER LEVERS
2. APPLICANT(S) I
(a) NAME FORCE MOTORS LIMITED
(b) NATIONALITY INDIAN Company
(c) ADDRESS MUMBAI-PUNE ROAD,
AKURDI, PUNE 411 035, MAHARASHTRA INDIA

FIELD OF INVENTION
The present invention relates to Parking Brake assembly including a brake cable with rocker lever mechanisms and particularly to such assembly wherein straight cables are used with mechanisms avoiding cable bends in order to reduce hand effort & achieve better braking efficiency.
BACKGROUND OF THE INVENTION
The Parking brake system is used to Park / Hold the Vehicle in stationary condition mechanically on straight / inclined surface and particularly in absence of Driver. Brake is applied through Hand Brake lever by the driver and the hand brake force is transmitted through cables to the Back plate in order to restrict the motion of drum provided on Drive line. Once parking brake is applied, the Hand brake lever can be left in as is condition and the Driver may leave the vehicle. The vehicle will stand still on inclined surface. The cable used to transmit the Driver force to the Back Plate assembly should be straight for maximum force transmission but practically this is not possible due to ergonomic position of the Hand Brake lever and packaging constraints on the Back plate side. The cable is routed from Hand brake lever end to back plate assembly which includes number of bends, reducing the efficiency of force transmitted and hence more hand effort needs to be applied to hold the vehicle.
In the Prior art an U.S. Pat. No. 6, 464,046 illustrates a parking brake actuating mechanisms which a first lever acts on a first brake shoe web and a second lever pivoted on the first lever acts on a second brake shoe web. The first lever includes an actuation cable abutment formation against which an actuating cable nipple on the free end of the cable is drawn to move the first lever to increase the effective length of the mechanism and hence move the associated brake shoes. The first lever is of hollow form defining a guide passage which directs the free end of the cable from an aperture in the back plate of the associated brake to a location adjacent the abutment formation to enable the nipple to be engaged with the formation. The second lever may also be shaped to assist in guiding the nipple into the engagement with the abutment formation when the nipple emerges from the end of the passage.

SUMMARYOF INVENTION
It is therefore an objective of the present invention to provide a new rocker lever mechanisms, wherein straight cables are used to transmit the Driver Hand effort force through rocker levers from the Hand Brake lever to the Back plate assembly and thus avoiding the cable bends thereby improving the cable efficiency and hence system efficiency. This will result in Vehicle hold on grade / incline surface with less hand effort.
Two numbers of rocker levers are being used to avoid 90 deg. and 180 deg. bends. Rocker lever mechanisms are being design with Shaft / housing assembly with intermediate alloy bushes and provision for greasing the joint for better lubrication for frictionless joints.
The new / modified design of parking brakes with improved efficiency is herein disclosed and hence reduction in hand effort for parking brake application and holding the vehicle on grade is achieved. Conventionally, in parking brake system when driver applies the Parking brake, the cable passes through intermediate lever to the equalizer and then to the wheels. In earlier design due to bends in cables and offsets in installation, there were more frictional losses. Hence, even with higher hand efforts, the vehicle couldn't be kept holding on a gradient surface.
In current invention the force applied by the driver at the Hand brake lever end is transmitted through cables and rocker mechanisms to the back plate assembly, mounted on the rear axle differential housing, while drum is mounted on the Propeller shaft. With the modified design the design is good force transmitting efficiency is achieved to enable the driver to stop the vehicle with lesser hand effort.
Following design changes are done to improve the design.
1. Design modified to eliminate 90 degree cable bend angle and 180 degree bend angle. The New rocker arm mechanism avoids 90 degree and inversion lever avoids 180 degree bend angle.
2. Rocker lever mechanisms are being design with Shaft housing assembly with intermediate alloy bushes and provision for greasing the joint for better lubrication for friction-less joints.

3. Inner & Outer Cable with coating is used to reduce friction loss.
4. lx19 instead of 7x7 Cable strand used on straight cable to improve travel efficiency.

Rocker lever mechanisms are introduced in the parking brake cable installation, this is done newly for such category of vehicle.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be described with reference to the accompanying drawings in which: Figure 1 is an isometric view of a conventional parking brake system (cable with bends) as
prior art; Figure 2 (a) is an isometric view of the Parking Brake system (Complete Layout) in
accordance with the present invention; Figure 2 (b) is a view of Parking Brake system with Rocker lever mechanism details in
accordance with the present invention; Figure 3 is a sectional side view of the Rocker lever assembly in accordance with the
present invention; Figure 4 is an assembly drawing of the Rocker lever mechanism in accordance with the
present invention; Figure 5 is a sectional side view of Inversion lever mechanism assembly in accordance with
the present invention; Figure 6 is an detailed view (On vehicle) of modified design of rocker lever and inversion
rocker lever in accordance with the present invention.
DETAILED DESCRIPTION
The parking brake is a mechanical secondary braking system used to Park / Hold the vehicle in stationary condition mechanically on straight / inclined surface and particularly in absence of Driver. Parking brake has a mandatory requirement to have 0.15g deceleration and should be able to hold vehicle on grade of 10.2 deg. Parking brake prevents the vehicle from rolling or slipping when parked on a gradient or level surface. A parking brake system mainly consists of three basic components i.e. Hand lever, cables, back plate / drum assembly to convert force to vehicle holding torque. Brake is applied through Hand Brake lever by the driver and the hand brake force is transmitted through cables (flexible type, a force transfer member) to the Back plate assembly (mounted on rear axle differential hosing) in order to restrict the motion of drum, mounted on drive line. Once parking brake is applied, the Hand

brake lever can be left in as is condition and the Driver may leave the vehicle. The vehicle will stand still on inclined surface. The cable used to transmit the Driver force to the Back Plate / Drum assembly should be straight for maximum force transmission but practically this is not possible due to ergonomic position of the Hand Brake lever and packaging constraints on the Back plate side.
The cable has to be routed from Hand brake lever end to Back plate assembly. As shown in Fig 1, the hand brake cable connectivity includes number of bends, which reduces the efficiency of force transmitted and hence more hand effort needs to be applied to hold the vehicle. In this cable routing, each bend in cable contribute to frictional loss which is directly proportional to magnitude of bend angle. All these mechanical components contribute to various mechanical losses in the system which results in significant deviation from predicted performance of the system. Human being can apply certain amount of effort, if the required hand effort to stop the vehicle crosses the limit of application, the vehicle fails to meet the performance brake regulation as per IS 11852.
Though mechanical losses introduced due to numerous components present in the system cannot be completely eliminated, it can be optimized by proper routing of cable and selection of cable configuration such as cable bend angle, cable construction type and cable strands. Therefore to overcome the issue, In this invention subject - Parking brake cable is used with rocker lever mechanisms.
On T3 (light commercial category) vehicle, initial brake trails were done with parking brake cable routed from hand brake lever to back plate assembly. After brake trails it was observed that due to bends in cables and offset in installations, there were more frictional losses resulting in lesser efficiency of the system. Even with maximum driver effort, vehicle could not be hold on gradient. Hence a more efficient new design of the parking brake system with rocker lever mechanisms is invented to hold the vehicle at gradient and to stop vehicle in dynamic / static condition with less hand effort.
Referring to Fig 2 (a) and (b), and Fig 6, the parking brake system is activated by a parking brake lever (1) connected with a primary brake cable (3). The Primary brake cable is further connected with a secondary cable (5) via a rocker shaft lever assembly (4) including a rocker arm / lever (4). The rocker lever as shown in the sectional view Fig 3 is driven by rocker

lever shaft assembly (14). The disclosed rocker arm mechanism avoids 90 degree bend of the primary brake cable (3). The parking brake lever pushes the rocker arm up and down about the rocker shaft through primary cable. Shaft / bush assembly is lubricated with gease to minimize the friction while rotating and transmitting force. The rocker lever mechanism assembly as shown in Fig 4 includes a chassis bracket (12) and a rocker shaft lever mounting bracket (13), and 2 number of pins (16) with split pin (11) at End to ensure locking . The rocker arm therefore eliminates bend in cable routing. The secondary cable is connected with intermediate cable via adjustment lever (6). The adjustment lever (6) is configured to connect the two said cables viz secondary cable (5) and the intermediate cable (7) and mainly serves the purpose of alignment, setting - tightening and or loosening of cables. The intermediate cable (7) is connected to inversion lever (8) as shown in Fig 5. The inversion lever avoids 180 degree bend angle while transmistting force from adjustment lever to back plate cable. The inversion lever assembly includes inversion lever, shaft (18) a circlip (17) and mounting bracket (Welded on chassis). The inversion lever assembly also includes 2 number of pin (16) and split pins (11) for assembly.
The said rocker lever mechanisms are designed with Shaft / housing assembly and intermediate alloy bushes used in between to avoid friction, noise, rusting of the contact surfaces and provision for greasing the joint for better lubrication for friction-less application.
The inner & outer cable is modified with anti-friction coating in order to reduce friction loss between inner and outer cable. Cable strand of 1 x19 instead of 7x7 is used in Intermediate straight cable to improve travel efficiency. Lever mechanism is introduced in cable installation. With the introduction of these features the frictional losses are reduced and it led to a system with optimal hand effort which can be easily applied.
Thus the present invention provides a parking brake actuating mechanism in which the cable without any bends can be used to transmitt forces with minor modifications in the existing design.

Component List:
1. Parking Brake Lever
2. Hand Brake Outer Cover
3. Primary Brake Cable
4. Rocker Assembly
5. Secondary Cable
6. AdjustingLever
7. Intermediate Cable
8. Inversion Lever
9. Brake Plate Assembly with Cable

10. Grease Nipple
11. SplitPin
12. Rocker Lever Chassis bracket
13. Rocker Lever Bracket Assembly
14. Rocker Lever
15. ClutchClevisPin
16. Pin
17. Circlip
18. InversionLeverPivotShaft
Although the foregoing description of the present invention has been shown and described with reference to particular embodiments and applications thereof, it has been presented for purposes of illustration by way of examples and description and is not intended to be exhaustive or to limit the invention to the particular embodiments and applications disclosed. The particular embodiments and applications were chosen and described to provide the best illustration of the principles of the invention and its practical application to thereby enable one of ordinary skill in the art to utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. All such changes, modifications, variations, and alterations should therefore be seen as being within the scope of the present invention as determined by the appended claims when interpreted in accordance with the breadth to which they are fairly, legally, and equitably entitled.

WE CLAIM:
1. A parking brake assembly for a motor vehicle, comprising :
a parking brake lever fastened to a body of the motor vehicle;
a primary brake cable;
a secondary brake cable;
an intermediate cable;
a rocker lever assembly
an inversion lever assembly
and a back plate / drum assembly; wherein,
The said primary brake cable is connected to the secondary brake cable via the
rocker lever assembly and the intermediate cable is connected to back plate via
inversion lever assembly. When force is transmitted from Hand brake lever
through cable to back plate assemly, it pulls the lever in back plate assembly
(mounted on rear axle differential housing). This expands the brake liners
oustside and creates friction against rotating drum mounted on propeller shaft,
there by reducing / stopping the speed of drum / propeller shaft and hence the
Vehicle thereby eliminating any bend any on the cable.
2. The parking brake assembly according to claim 1, In which the said rocker lever mechanisms are designed with Shaft / housing assembly and intermediate alloy bushes used in between to avoid friction, noise, rusting of the contact surfaces. and provision for greasing the joint.
3. The parking brake assembly according to claim 1, wherein, the rocker assembly and inversion lever includes a grease nipple for greasing of Bush / Shaft assembly for better lubrication and friction-less application with noise less operation.
4. The parking brake assembly according to claim 1, wherein the said rocker lever assembly avoids 90 degree cable bend angle and the said inversion lever assembly avoids 180 degree bend angle for cable.

5. The parking brake assembly according to claim 1, further includes adjusting lever to connect the secondary cable and intermediate cable. Adjusting lever is also used for setting of cable.
6. The parking brake assembly according to claim 1, wherein, the intermediate cable is connected with an inversion lever of inversion lever assembly.
7. The parking brake assembly according to claim 1, wherein, cable is provided with anti-friction coating in order to reduce friction loss.
8. The parking brake assembly according to claim 1, wherein, 7x7 Cable strand is used on straight cable in order to improve efficiency.
9. The parking brake assembly according to claim 1, which is conforming to brake regulation as per IS 11852 with Lesser hand effort for meeting the performance.