Claims:1. A brake spider mounted on a front and rear axle, wherein said brake spider comprising:
a spider body including pilot bore for mounting on the front & Rear axle spigot;
an anchor bore for mounting brake shoes; and
a Cam bore for mounting cam bush and camshaft and dust covers;
characterized in that, said brake spider having a variable wall thickness of 5-7mm at said anchor bore which is required for accommodating the brake mounting bolt head and socket clearance.

2. The brake spider as claimed in claim 1, wherein said anchor bore includes a M-type structure at an anchor end..

3. The brake spider as claimed in claim 2, wherein said M-type structure reduces the wall thickness at said anchor end to preferably 7mm.

4. A brake assembly comprising the brake spider as claimed in claims 1-3.
, Description:TECHNICAL FIELD

1) The present subject matter described herein, in general, relates to drum brake assembly, and more specifically to a design of a spider for a drum brake.

BACKGROUND

2) A brake spiders serves as the foundation of the brake assembly. The brake spider is mounted on the front and Rear axle which hold all the brake components that may include but not limited to shoes camshaft bracket, dust shields and pins and springs together on a vehicle.

3) Spiders for brake assemblies have been produced of weldable steel and formed by forging, stamping, casting or the like. The spider on the brake assembly is welded to a stationery axle spindle of the vehicle on which the brake assembly is being utilized. A brake spider is disposed about the axle and supports an anchor pin that extends from the spider. A pair of brake shoes are pivotally mounted at one end on the anchor.

4) The spider has heretofore traditionally been formed of steel as heavy cast or forged members with certain appropriate areas machined and bored to accommodate the brake assembly parts, such as the anchor pins and actuating camshaft, and for mounting the spider to the axle. The mounting is fixed by welding a hub of the spider on the axle.

5) Spider is a very important member of the brake assembly as it has to be able to withstand the vibration stress under dynamic braking conditions and should not fail under vibration and resonance. The spider is the torque carrying member which supports the brake torque for stopping the vehicle on demand . Any material reduction at anchor end will increase stress and increase the complexity of material flow during casting process. Also, the spider is subjected to substantial twisting forces as it transfers braking torque to the axle during braking.

6) Several attempts in the prior art have been made to produce spiders. Reference is made to US5301774A, discloses a composite brake spider for use in braking systems for over the road truck trailers and the like, and a method of making same in which the brake spider is comprised of an inner annular member formed of steel and an outer member formed from ductile cast iron mechanically interlocked to the inner annular member.

7) Reference is further made to a prior art, JP2008069969A, which discloses a brake drum includes a spider having an anchor with as-cast recessed parts and anchor seats machined within the as-cast recessed parts. The as-cast recessed parts provide clearance for a shaft of a cutting tool during machining of the anchor seats. First and second brake shoes are pivotally supported by the anchor. Each brake shoe has a convex web part positioned in communication with one of the anchor seats to transfer braking load to the spider.
8) Reference is made to US8887878B2, which discloses an anchor assembly is provided that permits adjustment of the brake shoes in a drum brake to account for wear. The assembly includes first and second adjuster shafts each having a plurality of threads and first and second pilot connectors. The pilot connectors each have a plurality of threads in engagement with the threads of a corresponding adjuster shaft. The pilot connectors each engage one end of a corresponding brake shoe. Rotation of each adjuster shaft causes longitudinal movement of a corresponding pilot connector in engagement with a corresponding brake shoe along an axis to adjust a position of the brake shoe.
9) Reference is further made to US6279695B1, which discloses an integrated axle spindle and brake spider assembly for axles of heavy duty vehicles such as trucks, and trailer axles.
10) Reference is made to US3572478A, which discloses a brake mechanism comprises a pair of brakeshoes which are displaceable to contact a brakedrum to effect braking thereof.
11) Reference is further made to US4452347A, which discloses a spider for a brake having dual web brake shoes to be utilized at the wheel end of a heavy duty truck or trailer axle includes a pivoting end support plate mounted at a hole therethrough at a first axial location on the axle to extend radially outwardly therefrom to include at its extended end a pair of pivot pins for the support of each of the webs of each brake shoe.
12) The limitation with the existing set up, as discussed above, is that in the current spider, if Brake mounting holes with Socket clearance is included, the wall thickness will reduce and stress will increase. Also to provide socket clearance anchor ribs to be machined from top which will increase the machining time and cost.

13) Further, conventionally customers are using 6.5T front axle and planning to migrate to 7.5T front axle from 6.5T front axle. Thus, there is a possibility that the front axle loads are increased by 1 ton. To address the increase in front axle loading, there is a requirement to enhance the wheel end design. The existing brake mounting hole / Pitch Center Diameter (PCD) at anchor end may be 187.7mm & 191.92mm respectively and it could be increased to 203.42mm. However, with the existing spider design there is fouling of bolt head with cast part. Also the wall thickness is very less.
14) Still further, in the existing design, 10-17 mm uniform cross section is maintained at “Anchor” ends in current design. Which has no manufacturing issues for solidification of molten metal and also the stress in the application. However, due to packaging constraint 10-16 mm uniform thickness could not be maintained.
15) Therefore, there exist a dire need to address these concerns limitation with the existing set up.
SUMMARY OF THE INVENTION

16) The following presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not an extensive overview of the present invention. It is not intended to identify the key/critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concept of the invention in a simplified form as a prelude to a more detailed description of the invention presented later.
17) An objective of the present invention is to provide an improved brake Spider with different offset like 58 / 60 /72 mm offset suitable for Ø393.7mm pneumatically operated S-Cam Drum Brake to suit for BS-VI regulations.

18) Accordingly, in the first aspect, the present invention provides a brake spider mounted on a front and rear axle, wherein said brake spider comprising: a spider body including pilot bore for mounting on the front & Rear axle spigot; an anchor bore for mounting brake shoes; and a Cam bore for mounting cam bush and camshaft and dust covers; characterized in that, said brake spider having a variable wall thickness of 5-7mm at said anchor bore which is required for accommodating the brake mounting bolt head and socket clearance.

19) In the first aspect, in one implementation, the anchor bore includes a M shaped design at anchor end.

20) In the first aspect, in one implementation, the M-type structure reduces the wall thickness at said anchor end to preferably 7mm.

21) In another aspect, the present invention provides a brake assembly comprising the brake spider as mentioned above.

22) Due to the improved brake spider of the present invention, it is able carry the high stress and it is foundation for all other brake components. Further, in the prior art, with reduced wall thickness of 2-4mm issue of solidification and porosity problems were observed. This manufacturing issue was addressed in the present invention by modifying the anchor end.

23) Other aspects, advantages, and salient features of the invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

24) The above and other aspects, features, and advantages of certain exemplary embodiments of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings in which:

25) Figure 1(a) shows the arrangement of the spider with brake assembly, according to the prior art.

26) Figure 1(b) shows the arrangement of the spider with brake assembly, according to one implementation of the present invention.

27) Figure 2 illustrates the exploded view of the brake assembly, according to one implementation of the present invention.

28) Figure 3 illustrates the design of the spider with mounting bolt arrangement, according to one implementation of the present invention.

29) Figure 4 illustrates the Spider Rib profile designed for packaging and strength, according to one implementation of the present invention.

30) Figure 5 illustrates the variable thickness of the brake spider at anchor end, according to one implementation of the present invention.

31) Figure 6 illustrates the uniform cross section maintained, according to one implementation of the present invention.

32) Figure 7 illustrates that brake spider assembled with the assembly for providing the clearance for Brake mounting bolt head and socket clearance and spot face to be done, according to the prior art.

33) Figure 8 illustrates the brake spider with the circular inner core, according to the prior art.

34) Figure 9 illustrates the brake spider assembly according to one implementation of the present invention.

35) Persons skilled in the art will appreciate that elements in the figures are illustrated for simplicity and clarity and may have not been drawn to scale. For example, the dimensions of some of the elements in the figure may be exaggerated relative to other elements to help to improve understanding of various exemplary embodiments of the present disclosure. Throughout the drawings, it should be noted that like reference numbers are used to depict the same or similar elements, features, and structures.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

36) The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of exemplary embodiments of the invention. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary.

37) Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope of the invention. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness.

38) The terms and words used in the following description and claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the invention. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present invention are provided for illustration purpose only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.

39) It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise.

40) By the term “substantially” it is meant that the recited characteristic, parameter, or value need not be achieved exactly, but that deviations or variations, including for example, tolerances, measurement error, measurement accuracy limitations and other factors known to those of skill in the art, may occur in amounts that do not preclude the effect the characteristic was intended to provide.

41) Features that are described and/or illustrates with respect to one embodiment may be used in the same way or in a similar way in one or more other embodiments and/or in combination with or instead of the features of the other embodiments.

42) It should be emphasized that the term “comprises/comprising” when used in this
specification is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

43) Reference is made to Figure 1(a) shows the arrangement of the spider with brake assembly, according to the prior art.

44) In one implementation of the present invention, reference is made to figure 1(b) shows the arrangement of the spider with brake assembly.

45) In one implementation of the present invention, reference is made to Figure 2 which illustrates the exploded view of the brake assembly.

46) In one implementation of the present invention, reference is made to Figure 3 which illustrates the design of the spider with mounting bolt arrangement.

47) In one implementation of the present invention, reference is made to figure 4 which illustrates the Spider Rib profile designed for packaging and strength.

48) In one implementation of the present invention, reference is made to Figure 5 which illustrates the variable thickness of the brake spider at anchor end.

49) In one implementation of the present invention, reference is made to Figure 6 which illustrates the uniform cross section maintained.

50) The Figure 7 illustrates the arrangement of the prior art brake spider that has a structure for providing the clearance for Brake mounting bolt head and socket clearance, spot face, which cuts the ribs at anchor area.

51) The Figure 8 illustrates the brake spider of the prior art. In the design of the brake existing brake spider, when spot face is provided wall thickness at the anchor area will reduce and in the range of 4.5-4.7 mm and it has equal wall thickness at anchor area.

52) In one implementation of the present invention, reference is made to Figure 9 illustrates the dimensional details of the improved brake spider. The wall thickness is improved to 5-7 mm and preferably, 7mm, and includes unequal wall thickness at the anchor area as shown which is critical from the strength point.

53) In one implementation of the present invention, the improved brake spider is manufactured through casting route. Mold flow analysis was done for checking the feasibility of the material flow in the improved spider. With 5-7mm wall thickness no solidification and porosity problems noticed. Soundness level improved.

54) A comparative chart to show the technical effect of the present improved design of the brake spider over the existing brake spider is as below:

Description Prior art brake spider (as shown in figure 8) Improved brake spider
Wall thickness at anchor end 4.0 – 5.0mm 5.0 - 7.0mm
Shape of the feature Round and concentric circles M shaped design at anchor end.
Manufacturability Solidification issue No solidification issue
Design helps easy flow of molten metal during manufacturability
Limitation for the clearance with the interface components. Better compatibility with the interface components
No mounting bolt accessibility Mounting bolt accessibility is available
Can be used for only one mounting hole configuration Can be used for two mounting hole configuration(application)
Strength Poor Better

55) Some of the non-limiting advantages of the present apparatus over the prior art is as follows:
• Current Ø393.7mm brake spider cannot be mounted on the 7.5T front axle as there is fouling of bolt head with spider casting .
• The brake spider is suitable for Ø393.7mm Drum brake.
• Improved spider design is able to withstand torque upto 1600Kgm
• Variable wall thickness (5 -7 mm ) is maintained against 10-16 mm of current design. Variable wall thick of 5-7mm ( at Bolt mtg area) is maintained in the anchor area which helps in manufacturing & also avoids solidification issues & stress requirement in the final application is also met after spot facing
• Spider mounting hole configuration is of 7.5T axle
• Spider offset to be 58mm
56) Although an improved brake spider assembly have been described in language specific to structural features, it is to be understood that the embodiments disclosed in the above section are not necessarily limited to the specific features or methods or apparatus described. Rather, the specific features are disclosed as examples of implementations of the improved brake spider assembly.