DESC:FORM 2

THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENT RULES, 2003

COMPLETE SPECIFICATION
(See Section 10 and Rule 13)

Title of invention:
PARKING BRAKE SYSTEM FOR OFF HIGHWAY DUMPER

Applicant:
BEML Limited
A company Incorporated in India under the Companies Act, 1956
Having address:
BEML Soudha, 23/1, 4th Main,
Sampangirama Nagar, Bengaluru,
Karnataka - 560 027, India

The following specification particularly describes the invention and the manner in which it is to be performed.
CROSS-REFERENCE TO RELATED APPLICATIONS AND PRIORITY
[001] The present application claims priority to Indian Patent Application No. 201841035564 titled “Parking Brake System for Off Highway Dumper” filed on September 21st, 2018, the entity of which is hereby incorporated by reference.
TECHNICAL FIELD
[002] The present disclosure in general relates to the field of earth moving machinery, and more particularly, the present subject matter relates a parking brake system for off highway dumper.
BACKGROUND
[003] Generally, The Present Rear Axle Design is a Fully Floating Planetary Axle with Oil cooled Wet Multiple Disc Brakes for Service Brake Actuation & External Caliper Disc Type Parking Brake to Hold the Vehicle in gradients in loaded or un-laden conditions.

SUMMARY
[004] Before the parking brake system for off highway dumper, are described, it is to be understood that this application is not limited to the particular methodologies described, as there can be multiple possible embodiments, which are not expressly illustrated in the present disclosures. It is also to be understood that the terminology used in the description is for the purpose of describing the particular implementations, versions, or embodiments only, and is not intended to limit the scope of the present application. This summary is provided to introduce aspects related to a parking brake system for off highway dumper. This summary is not intended to identify essential features of the claimed subject matter nor is it intended for use in determining or limiting the scope of the claimed subject matter.
[005] In one embodiment, a parking brake system for off highway dumper is disclosed. A Cylinder Service (1) of the brake system contains a cylinder seat arrangement. One end of a Belleville Spring is placed in the cylinder seat arrangement. The piston parking of the brake system consists of cylinder seat arrangement that holds the second end of the Belleville spring (7). The Cylinder Parking (2) connected to the piston parking (6) and the Cylinder Service (1) through ‘O’ rings.
BRIEF DESCRIPTION OF DRAWINGS
[006] The foregoing detailed description of embodiments is better understood when read in conjunction with the appended drawings. For the purpose of illustrating of the present subject matter, an example of construction of the present subject matter is provided as figures; however, the present subject matter is not limited to the specific method disclosed in the document and the figures.
[007] The present subject matter is described in detail with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the drawings to refer various features of the present subject matter.
[008] Figure 1 illustrates Cross-sectional view of the brake system when Vehicle is in Motion, in accordance with an embodiment of the present subject matter.
[009] Figure 2 illustrates Cross-sectional view of the brake system when Vehicle is in Parked Condition, in accordance with an embodiment of the present subject matter.
[0010] Figure 3 illustrates a Cylinder Service that forms the Primary unit for Housing the Belleville Spring, in accordance with an embodiment of the present subject matter.
[0011] Figure 4 illustrates Belleville Springs stacking, in accordance with an embodiment of the present subject matter.
[0012] Figure 5 illustrates assembly of Parking Piston, in accordance with an embodiment of the present subject matter.
[0013] Figure 6 illustrates assembly of Cylinder Parking, in accordance with an embodiment of the present subject matter.
[0014] Figure 7a and Figure 7b illustrates the Compressed Belleville Springs are in the Installed Height condition, in accordance with an embodiment of the present subject matter.
[0015] Figure 8 illustrates assembly of PTFE Packings and the Brake sub assembly for Service Brake & Parking Brake Actuation, in accordance with an embodiment of the present subject matter.
[0016] Figure 9 illustrates complete Brake Assembly, in accordance with an embodiment of the present subject matter.
[0017] Figure 10 illustrates Axle Beam Structure, in accordance with an embodiment of the present subject matter.
[0018] Figure 11 illustrates Brake unit assembled on to the Axle Beam Structure, in accordance with an embodiment of the present subject matter.
[0019] Figure 12 illustrates the Brake unit & Final Drive unit assembled on to the Axle Beam Structure, in accordance with an embodiment of the present subject matter.
[0020] Figure 13 illustrates Stacking Belleville Springs in Series, in accordance with an embodiment of the present subject matter.
DETAILED DESCRIPTION
[0021] Some embodiments of this disclosure, illustrating all its features, will now be discussed in detail. The words "comprising," "having," "containing," and "including," and other forms thereof, are intended to be open ended in that an item or items following any one of these words is not meant to be an exhaustive listing of such item or items, or meant to be limited to only the listed item or items. It must also be noted that as used herein and in the appended claims, the singular forms "a," "an," and "the" include plural references unless the context clearly dictates otherwise. Although any parking brake system for off highway dumper, similar or equivalent to those described herein can be used in the practice or testing of embodiments of the present disclosure, the exemplary, a parking brake system for off highway dumper are now described.
[0022] Various modifications to the embodiment will be readily apparent to those skilled in the art and the generic principles herein may be applied to other embodiments for forging of a bimetal. However, one of ordinary skill in the art will readily recognize that the present disclosure for forging of a bimetal is not intended to be limited to the embodiments described but is to be accorded the widest scope consistent with the principles and features described herein.
[0023] The problem of uneven wear out of friction material (brake liners), high heat generation of disc, distortion of disc (boulders hitting the disc), ineffective actuation (return of brake piston in the brake head assembly) and frequent maintenance of parking brake are the major limitations of External Caliper Disc type parking brake. Further, high heat generation due to dry friction between the Disc & Brake liners results in change of properties of the friction material and causes less efficient in braking, leading to vibration under braking. Furthermore, greater volume of brake fluid is needed to achieve a brake application and is more prone to noise, lacks self - energization requiring greater force to be applied to effect braking.
[0024] The system discloses a system for parking brake for a highway dumper. The system consists of a Belleville spring (7) enclosed in Cylinder service and Piston parking through spring guide. When the breaks are applied, the parking brake oil present in the cavity between cylinder parking and piston parking is forced out. Due the outflow of the oil the Belleville spring in piston parking exerts uniform and high force on the Frictional element through piston parking. The force exerted holds the vehicle in the stationary position. The method minimises damages of the frictional elements.
[0025] In one embodiment, a parking brake system for off highway dumper is disclosed. Referring to Figure 1, the cross-sectional view of the brake system when vehicle is in motion is illustrated. Referring to figure 2, Cross-sectional view of the brake system when vehicle is in parked condition is illustrated.
[0026] Now referring to Figure1 and 2, the figures illustrates different components of the
emergency parking brake system. Following are the different components of the brake system
Cylinder Service (1) Piston Service (5) PTFE Packings for
Parking Brake (9) Damper (13)
Cylinder Parking (2) Piston Parking (6) PTFE Packings for
Service Brake (10) Retraction Spring (14)
Gear Outer (3) Belleville
Spring (7) Disc (11) Retraction Spring
Guide (15)
Gear Inner (4) Spring Guide (8) Plate (12) Hexagon Bolt (16)
Cylinder Seat (17) Piston Seat (18)
[0027] From figure 1 and 2, it is observed, the oil maintained at 90 bar pressure is supplied to the Cylinder Parking (2) through the inlet port of the Cylinder Service (1) to compress the Belleville springs (7). This condition ensures the vehicle is in motion. When parking brake is applied, oil supply at 90 bar is cut – off. The Belleville springs (7) exert mechanical force on the Piston Parking (6) and Piston Service (5). This action pushes out the oil through the Cylinder Parking (2) and the cylinder service ports. This condition ensures the vehicle is parked. Further, the following description will provide the details of the braking system.
[0028] The hydraulic oil (SAE-10) at 90 bar Pressure is supplied to Cylinder Parking (2) through Parking Brake Actuation Inlet Port of Service Cylinder(1) and is structurally designed to compress the stacks of Belleville springs (7) which are enclosed in the Piston Parking (6) (refer Fig.1), this condition is to facilitate the vehicle to be in motion. The brake oil is continuously maintained at 90 bar pressure to keep the Belleville springs (7) in compressed condition. The constant pressure is achieved using PTFE (Poly Tetra Fluoro Ethylene) Packings (10) and 'O' Rings (in tandem) (9) which dynamically seals the high-pressure oil effectively. These seals offer very good resistance to wear and extrusion. When the equipment is parked, i.e. the parking brake switch is in the parking position, the parking brake solenoid is demagnetized and the parking brake oil under high pressure is forced out from the cavity between the Cylinder Parking (2) and the Piston Parking (6) (refer Fig.2), thereby allowing the stacks of Belleville Spring (7) in Piston Parking (6) to exert a uniform & high force on the Friction Elements (Disc, Plate & Damper) through the Piston Service (5), which holds the vehicle in stationary position, for as long as it is required.
[0029] Further, from figure 1 and 2 we observe, the brake system comprises of Discs (11), Plates (12) and Damper (13) which are the primary friction elements used to gradually reduce speed / stop the vehicle. The brake assembly is configured with Cylinder Service (1), Cylinder Parking (2), Gear Outer (3) and Gear Inner (4), these components together act as an enclosure for the braking system. Further from Figure 1 we observe, a Belleville spring (7) positioned in Cylinder Service (1) through spring guide (8). The Belleville Spring (7) regulates the functions of parking brake by actuating the Piston Service (5) and Piston Parking (6) through hydraulic oil pressure.
[0030] The Bronze filled Polytetrafluoroethylene (PTFE) Packings and O rings (9) and (10) are used in tandem and are housed in the same groove for effective hydraulic oil sealing and to constantly maintain the required pressure at high temperature for effective service / parking brake performance. Further, Figure 1 & 2 also illustrates, Retraction Spring (14) placed in the Retracting Spring guide (15) as an Auxiliary item for positive release.
[0031] Now, referring to Figure 3, the figure discloses Belleville Spring (7) enclosed in the Cylinder Service (1). The provision for mounting the Guide Pin is provided in the Cylinder Service (1). The Guide Pin is fastened on to the Cylinder Service Tapped Hole. The Face of the Guide Pin is positioned such that it has complete contact on the Cylinder Service surface.
[0032] Figure 4 discloses the sequence to Stack the Belleville Springs (7). During stacking the first spring is facing in the down position. Ensure the Stacking of the Belleville Springs (7) are opposite to each other to form a Spring Column guided through the Pin. Referring to Figure 5, we observe, the PTFE Packings and ‘O’ rings are assembled on to the Piston Parking (6). During assembly care to be taken to prevent any damages on the Packings to avoid malfunctioning of the Brake Systems which causes internal leakages. Further, from Figure 5, it is observed that the Parking Piston (6) is placed over the Stack of Belleville Springs, which are already assembled in the Cylinder Service (1).
[0033] Further, as illustrated in Figure 6, the Cylinder Parking (2) is connected to Cylinder Service (1) with ‘O’ ring. The Piston Parking (6) with Belleville Springs is held safely between the Cylinder Parking (2), which is fastened to the Cylinder Service (1). In this condition, the gap between the Cylinder Service (1) and Piston Parking (6) exists due to the high tensile force exerted by the stacked Belleville Springs (7). In order to release the Parking Brake manually, Bi-Hex Screws with Flanged Nuts are fastened on to the Piston Parking (6) through the Cylinder Service (1), and the flanged nuts are tightened equally to flush the Piston Parking (6) with Cylinder Service (1), in this condition the compressed Belleville springs (7) are in the Installed Height condition, refer figure 7(a) and 7(b).
[0034] Now, Referring to figure 8, the Piston Service(5) with PTFE Packings and O Rings (in tandem) (10) is assembled on to the Piston Parking (6) and Cylinder Service (1), during assembly care to be taken to prevent any damages on the PTFE Packings to avoid malfunctioning of the brake system. Ensure the Piston Service (5) is uniformly and precisely assembled for easy sliding for actuation of brakes. Further, the Retraction Spring (14) is installed on to the Retraction Spring Guide (15). Using the Hexagonal Bolt (16) the Retraction Spring (14) and Retraction Guide is fastened into the Cylinder Service (1), such that it is held rigidly between Piston Service (5) and Cylinder Service (1). Ensure all the Bolts are maintained at uniform height. The figure - 8 indicates the Brake sub assembly for service brake and parking brake actuation.
[0035] The other Brake sub assembly consist of Gear Outer (3), Gear Inner (4) and Friction Elements consisting of Disc (11), Plate (12) and Damper (13). This Brake sub assembly forms the primary unit for build up the brake unit. Figure (9) forms the complete Brake Assembly, this Brake unit is mounted on to the Axle Beam Structure, which houses all the Axle components such as Differential Assembly, Brake Assembly & Final Drive Assembly. The figure - 10 illustrates Axle Beam Structure, this structure consists of Centre Housing and Housing Extension. The Centre Housing is made of Cast Steel which houses the Differential unit. The Housing Extension is an Integral part of the Centre Housing, houses the Brake Assembly and Final Drive Assembly.
[0036] The figure 11 indicates the Brake unit assembled on to the Axle Beam Structure. The Brake units is mounted on the left hand and right side respectively. Further, the Brake unit and the Final Drive unit assembled on to the Axle Beam Structure. The Final Drive unit is mounted on the left and right side respectively. The Final Drive Transmits the Drive through an angle of 90 degrees, this Planetary Reduction is the second reduction in Axle & consists of Sun, Planet & Ring Gears.
[0037] A vehicle starting from rest needs a lot of torque, but once it is moving, it can maintain speed with only a relatively small amount of torque. A higher gear ratio can then be selected, and engine speed reduced.
Schematic Layout of Power Train:
[0038] A conventional vehicle with the engine at the front and driving wheels at the rear, uses a drive shaft, called a propeller shaft to transmit torque from the transmission to the final drive through the differential. The rear axle assembly, rear axle is a drive axle with wet multiple disc brakes and integral parking brake, planetary final drive transmitting power to the wheels. The rear axle assembly is designed with inbuilt forced oil cooled wet multiple disc brakes with integral parking brake which continuously cools the Friction Elements resulting in non-fade braking & retarding. The service brakes can be operated by air over hydraulic braking system or fully hydraulic braking system. The parking brake system with Belleville Springs (7) are controlled by full hydraulic system, these Brakes are highly reliable and do not require periodic maintenance.
Belleville Spring:
[0039] The Belleville Springs (7) are shallow conical rings formed annular discs, which are loaded in the Axial direction. Belleville Springs (7) offer well developed solutions to the complicated engineering problems through a unique combination of High Force in a small space. Belleville springs (7) offer maximum toughness and therefore are highly reliable and considerably durable. The same load can be achieved at Substantial reduction in Space, thus the Belleville Springs can be designed for extremely high loads, where coil springs are not Feasible at all. They are commonly used in applications requiring high spring force and small deflections. The Belleville spring (7) are also used in applications requiring a high degree of safety, which distinguishes the prominence over helical springs for the following characteristics mentioned.
[0040] The Belleville Springs can be stacked based on functional application: The various combinations for Stacking the Belleville Springs are (a) Stacking Belleville Springs in series (b) Stacking Belleville Springs in parallel (c) Stacking Belleville Springs in series & parallel combination. However, for this application & requirement the system is designed with the Belleville Springs to be Stacked in series. Further, for Stacking Belleville Springs in series single disc springs are assembled 'opposed to each other' to form a spring column. This 'in series' formation is a means of multiplying the deflection of a single disc spring, the force element remains as that for a single spring. The main advantage of this combination are springs stacked in series doubles the deflection of a spring with no increases in load. The characteristic load curve is a representation of the force-deflection behaviour of the spring. Depending upon the dimensional ratios, the characteristic load curve of a disc spring is more or less digressive up to the flat position. In special cases, disc springs can be designed so that deflection beyond the flat position is possible. Typically, Belleville springs are used as modular components. A group of individual Belleville Spring stacks that are stacked facing alternate ways is called a Series Spring stack. The load at a given deflection is proportional to the number of individual springs in the stack. In a series spring stack, the deflection of the stack is the sum of the deflections of the individual springs. The load of the stack is equal to the load on the individual spring. Further, when calculating the spring deflection and load capacity of a stack composed of individual springs or spring packs these facts must be taken into consideration.
[0041] Exemplary embodiments of the parking brake system for off highway dumper discussed above may provide certain advantages. Though not required to practice aspects of the disclosure, these advantages may include those provided by the following features.
[0042] Some embodiments of the parking brake system for off highway dumper use Belleville Springs that are concealed & housed in the service Brake chamber (Wet Multiple Disc Brakes).
[0043] Some embodiments of the parking brake system for off highway dumper are engineered with completely sealed Wet Multiple Disc Brake with integral parking brake which is highly reliable and require no periodic maintenance.
[0044] Some embodiments of the parking brake system for off highway dumper provide Enhanced Parking & Retarder Brake Capacity.
[0045] Some embodiments of the parking brake system for off highway dumper provide Maintenance free Brake system.
[0046] Some embodiments of the parking brake system for off highway dumper provide Enhanced Equipment Safety.
,CLAIMS:1. A parking brake system for a vehicle, the parking brake system comprising:
a Cylinder Service (1), wherein the Cylinder Service (1) consists of a cylinder seat arrangement (17);

a Belleville spring (7), wherein the Belleville spring (7) comprises stack of Belleville spring (7) and wherein a first end of the Belleville spring is positioned in the cylinder seat arrangement (17);

a Piston Parking (6), wherein the Piston Parking (6) consist of a piston seat arrangement (18), and wherein the second end of the Belleville spring (7) is held in the piston seat arrangement (18); and

a Cylinder Parking (2), wherein the Cylinder Parking (2) is connected to the Piston Parking (7) and the Cylinder Service (1).

2. The parking brake system as claimed in claim 1, wherein the Belleville spring (7) are stacked, wherein a first spring is place facing in down position and wherein the subsequent Belleville springs are positioned opposite to each other.

3. The parking brake system as claimed in claim 1, wherein the Cylinder Parking (2) is fastened to the Cylinder Service (1) by a Bi-Hex screw with a flanged nut and wherein fastening creates a gap between Cylinder Service (1) and Piston Parking (6).

4. The parking brake system as claimed in claim 1, wherein a parking bake oil is supplied to the Cylinder Parking (2) through inlet port of the Cylinder Service (1) and wherein the oil flows through the gap between Cylinder Service (1) and Piston Parking (6).

5. The parking brake system as claimed in claim 1, wherein the parking brake oil compresses the Belleville spring (7).

6. The parking brake system as claimed in claim 1, wherein under parking condition, the oil supplied to the Belleville spring is cut off and wherein Belleville spring (7) exerts mechanical force on the Piston Parking (6) and Piston Service (5) and ensures parking of the vehicle.