FORM -2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
Complete Specification
(See Section 10; rule 13)
SPACER TUBE
ENDURANCE TECHNOLOGIES LTD.
an Indian Company of E-93, Waluj, MIDC, Aurangabad- 431 136, Maharashtra, India.
Inventor: PIMPLE VISHAL
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTIONS AND THE MANNER IN WHICH IT IS TO BE PERFORMED.

FIELD OF THE DISCLOSURE
The present disclosure generally relates to vehicles.
Particularly, the present disclosure relates to a front fork for vehicles, particularly, two or three wheeler vehicles.
BACKGROUND
A front fork of a vehicle, such as a motorcycle, connects a vehicle's front wheel to its frame structure. The front fork includes a spacer tube to secure a main spring with assembled height to achieve a main spring pre-compression. Generally, the spacer tube is of steel (CEW tube). The CEW tube has various disadvantages and limitations.
For example, as the CEW tube rests on the main spring, the CEW tube needs a plain washer between the main spring and the spacer tube for facilitating proper seating of the spacer tube on the main spring. However, the requirement of a plain washer increases the number of parts used in the front fork assembly. More specifically, requirement of a plain washer increases the cost of the front fork assembly. Further, to avoid corrosion the washer needs to be zinc plated which may cause contamination in front fork assembly. This contamination results in poor performance of the front fork assembly.
Furthermore, the steel spacer tube itself is susceptible to corrosion. The corrosion may leads to rust formation and oil contamination.

Accordingly, there is a need for a spacer tube that reduces the number of components of a front fork assembly. Also, there is a need for a spacer tube that has comparatively reduced cost. Further, there is a need for a spacer tube that is corrosion resistant.
OBJECTS
Some of the objects of the present disclosure which at least one embodiment is adapted to provide, are described herein below:
It is an object of the present disclosure to ameliorate one or more problems of the prior art or to at least provide a useful alternative.
An object of the present invention is to provide a spacer tube that reduces the number of components of a front fork assembly.
Another object of the present invention is to provide a spacer tube that is corrosion resistant.
Yet another object of the present invention is to provide a spacer tube that has comparatively reduced cost.
Further, an object of the present invention is to provide a spacer tube that reduces the noise generated by a front fork assembly.
Also, an object of the present invention is to provide a spacer tube that facilitates prevention of contamination of a front fork assembly.

SUMMARY
In accordance with the present Invention, a fork assembly of a vehicle is provided, comprising: a bracket assembly having an under bracket and an upper bracket connected by means of a steering shaft, the bracket assembly fixed on a fork pipe, the fork pipe telescopically moveable inside an outer tube, wherein a polymeric spacer tube is functionally connected by the fork pipe which supports a spring disposed inside the outer tube, to secure the main spring with a predetermined assembled height for obtaining a requisite compression of the main spring, the spacer tube being connected to the fork pipe by means of a fork bolt.
Typically, the fork bolt, spacer tube and main spring configure a fork pipe assembly;
Generally, a housing for the fork pipe assembly duly supported on a piston ring which is connected via a seat pipe to a socket bolt, a cap oil lock being provided around the joint of the seat pipe and the socket bolt.
Typically, the spacer tube is of Delrin,.particularly made of Delrin 500P.
Typically, the spacer tube is made in a multi-cavity mould in a single process step.
Typically, the spacer tube is made by a plastic moulding process.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
The invention will now be explained in relation to the accompanying drawings, in which:
Figure la illustrates a cross-sectional view of a conventional spacer tube design;
Figure lb illustrates a perspective view of the conventional spacer tube design of Figure 1a;
Figure 1c illustrates another cross-sectional view of a conventional spacer tube design;
Figures 2a to 2d illustrate perspective views of a front fork assembly;
Figure 3 a illustrates a cross sectional view of a spacer tube, in accordance with one embodiment of the present invention;
Figure 3b illustrates an enlarged sectional view of Figure 3a depicting a spacer tube;
Figure 3 c illustrates another enlarged sectional view of the spacer tube shown in Figure 3 a;
Figure 3d illustrates a perspective view of the spacer tube of Figure 3a;

Figure 3e illustrates a cross sectional view a spacer tube, in accordance with another embodiment of the present invention;
Figure 3f illustrates a braking load test set up for a spacer tube, in accordance with one embodiment of the present invention;
Figure 4a illustrates test piece of conventional spacer tube with lose burr adhering thereto;
Figure 4b illustrates test piece of spacer tube in accordance with the present invention;
Figure 5a illustrates the conventional spacer of Figure 4a, that get rusted with regular use; and
Figure 5b illustrates the spacer tube of Figure 5a.
DETAILED DESCRIPTION
The invention will now be described with reference to the embodiments shown in the accompanying drawings. The embodiments do not limit the scope and ambit of the invention. The description relates purely to the exemplary preferred embodiments of the disclosed structure and its suggested applications.
The embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the

following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
Referring to Figures 1a to 1c, a conventional spacer tube 10 is disclosed. The spacer tube 10 is functionally connected to a fork bolt 20. The spacer tube 10 is of steel. The spacer tube 10 rests on a main spring 30. The spacer tube 10 composed of steel material needs a plain washer 40 between the main spring 30 and the spacer tube 10 for facilitating proper seating of the spacer tube 10 on the main spring 30. The plain washer 40 is of steel material. The disadvantages and limitations of the conventional spacer tube 10 is disclosed in the background section.
Referring to Figures 2a to 2d, perspective views of a front fork assembly 50 is disclosed. The front fork assembly 1 includes an under bracket 52, an upper bracket 54, a steering shaft 56, a fork pipe 58 and an outer tube 60.
Accordingly, to obviate the disadvantages and the limitations of the conventional spacer tube, a spacer tube 100 in accordance with one embodiment of the present invention, is disclosed in Figures 3 a to 3e.
Referring to Figure 3a to 3e, a spacer tube 100 in accordance with one embodiment of the present invention, is disclosed. More specifically, referring

to Figure 3a various parts associated with a spacer tube 100 is disclosed. The various parts associated with the spacer tube 100 are a fork bolt 72, a main spring 74, a fork pipe assembly 76, a piston ring 78, an outer tube 80, a seat pipe 82, a cap oil lock 84, and a socket bolt 86.
The spacer tube 100 is of Delrin. Delrin is comparatively less expensive as compared to steel material. In one embodiment of the present invention the spacer tube is of Delrin 500P. The Delrin 500P material has the following properties,
• High tensile, compressive and impact resistance;
• Excellent dimensional stability; and
• Excellent thermal stability.
The spacer tube 100 is manufactured by plastic molding technology. The spacer tube 100 of the present invention provides increased productivity because it can be produced in a multicavity mould in single processing. More specifically, the spacer tube 100 is manufactured by means of a plastic molding technology in a way such that there is no need of a washer. More specifically, the spacer tube 100 of the present invention is adapted to have a structure that is a combination of a spacer tube structure and a washer structure of the prior art. Also, the spacer tube 100 of the present invention is adapted to meet product specific requirement.
In one embodiment of the present invention, the spacer tube 100 has an outer diameter of 23 mm, an inner diameter of 20.5 mm and a height of 49.5 mm.

However, the present invention is not limited to any particular dimension of the spacer tube 100.
The spacer tube 100 of the present invention does not rust or get corroded, as the spacer tube 100 is of Delrin. Further, as there is no corrosion of the spacer tube 100, there is no possibility of oil contamination which therefore facilitates good performance of the front fork. Consequently, there is no customer complaint. Further, by elimination of a washer, the number of parts of a front fork assembly is reduced. Accordingly, the assembly time is also reduced due to less number of parts. Additionally, by elimination of a washer, metallic noise is avoided. Moreover, the spacer tube 100 of Delrin has equivalent strength as that of steel material.
The fork bolt (72), said spacer tube (100) and said main spring (74) configure a fork pipe assembly (76). The fork assembly (1) further comprising a housing (80) for said fork pipe assembly (76) duly supported on a piston ring (78) is connected via a seat pipe (82) to a socket bolt (86), a cap oil lock (84) being provided around the joint of said seat pipe (82) and said socket bolt (86).
Referring Figure 3f, a braking load test set up for the spacer tube 100 is disclosed which is self-explanatory. A load 88 is applied on the spacer tube 100 for determination of the strength of the spacer tube 100.
Test Analysis - Cam Drum Test Report of front fork (Referring to Figure 4)

1.
(a) Purpose of Test: Validation of spacer tube with washer - Delrin material
(b) Application: PA Drum
(c) ETL Part No: 'F800116907
(d) Test Request by: R & D
(e) Test Request No: VR00125

2. Ref. /Standard: EES-016
3. Test Conditions: As per EES-016

Temperature 50°C - 70 °C
Mounting Angle 27°
Drum Dia. 1300mm
Duration 100hrs
Quantity 01 set.
Square/Sign Profile cam specification Height 30mm X 2Nos. 20mm X 2Nos Alternately
RPM 120
4. Acceptance criteria:
Observe the test and record the visual observation for leakage, breakage,
rubbing of any parts.
Change in Damping force after test shall be + 20%

5. Daily observation check sheet in FT/R & D/12
a. Test Started on: 13/09/2009
b. Test Completed on: 23/09/2009
6. Test Result:

Sample No. Test Result
LH-VS0852
i Observed no leakage, breakage, rubbing marks on spacer tube. Test Completed 100hrs. Ok
LH-VS0853 Observed no leakage, breakage, rubbing marks on spacer tube. Test Completed 100hrs. Ok

Damping Force (Kgf) LH-VS0820 LH-VS0821

Tension @ 0.3 m/s Tension @ 0.3 m/s
Before Cam drum Test 12.0 12.6
After Cam Drum Test 11.0 12.7
Variation in DF values after test (%) -8.9 0.6
7. Conclusion
Observed No Breakage rubbing marks on both sample.
Spacer tube with washer - Delrin material PASSES the subject test.

SAMPLE INSPECTION REPORT

Sr.
No Parameter Specifi cation Checking Instrument/ L.C. Observation Remark

1 2 3 4 5
1 Inner Dia. 20.5 Vernier Caliper 20.61 20.64 20.63 20.65 20.62
2 Outer Dia. 23 Vernier Caliper 23.10 23.13 23.16 23.15 23.09
3 Length 49.5+0.5 Height Gauge 49.91 49.83 49.81 49.88 49.84
4 Paralliesm 0.10 Dial 0.01 0.06 0.08 0.09 0.07 0.05
5 Radius R2 Radius Gauge R2 R2 R2 R2 R2
6 Inner Dia. 16.00 Vernier Caliper 16.08 16.06 16.01 16.05 15.97
7 Width 1.5Min. Vernier Caliper 1.46 1.40 1.48 1.42 1.45
8
Color Natural (White) Visual White White White White White

9 Breaking Load 500 Kgf UTM 802 833 854 848 830
10 Visual No
moulding defect &
Fleshes Visual OK OK OK OK OK
11 Material Del rin
500P
NC010 Delrin 5 00PNC0 10 As pe r Supptie rT.C.
12 Weight 6.40 GMS
Rema rks: Accepted
Technical Advancements and Economic Significance
The spacer tube of the present invention reduces the number of parts of a front fork assembly. Also, the spacer tube of the present invention is corrosion

resistant. Additionally, the spacer tube of the present invention has comparatively reduced cost. Further, the spacer tube reduces the noise generated by a front fork assembly. Furthermore, the spacer tube facilitates prevention of contamination of a front fork assembly. Additionally, the spacer tube of the present invention facilitates improved performance of a front fork assembly.
Throughout this specification the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.
The use of the expression "at least" or "at least one" suggests the use of one or more elements, as the use may be in one of the embodiments to achieve one or more of the desired objects or results.
Any discussion of documents, acts, materials, devices, articles or the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.
The numerical values mentioned for the various physical parameters, dimensions or quantities are only approximations and it is envisaged that the values higher/lower than the numerical values assigned to the parameters,

dimensions or quantities fall within the scope of the invention, unless there is a statement in the specification specific to the contrary.
The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.
While considerable emphasis has been placed herein on the specific features of the preferred embodiment, it will be appreciated that many additional features can be added and that many changes can be made in the preferred embodiment without departing from the principles of the invention. These and other changes in the preferred embodiment of the invention will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the invention and not as a limitation.

We Claim:
1. A fork assembly (1) of a vehicle, comprising a bracket assembly having an under bracket (52) and an upper bracket (54) connected by means of a steering shaft (56), said bracket assembly fixed on a fork pipe (58), said fork pipe (58) telescopically moveable inside an outer tube (60), wherein a polymeric spacer tube (100) functionally connected by said fork pipe (58) which supports a spring (74) disposed inside said outer tube (60), to secure said main spring (74) with a predetermined assembled height for obtaining a requisite compression of said main spring (74), said spacer tube (100) being connected to said fork pipe (58) by means of a fork bolt (72); thereby said fork bolt (72).
2. The fork assembly (1) as claimed in claim 1, wherein said fork bolt (72), said spacer tube (100) and said main spring (74) configure a fork pipe assembly (76).
3. The fork assembly (1) as claimed in claim 1, wherein said fork assembly (1) further comprising a housing (80) for said fork pipe assembly (76) duly supported on a piston ring (78) is connected via a seat pipe (82) to a socket bolt (86), a cap oil lock (84) being provided around the joint of said seat pipe (82) and said socket bolt (86).
4. The fork assembly (1) as claimed in claim 1, wherein said spacer tube (100) is made of Delrin, particularly made of Delrin 500P.
5. The fork assembly (1) as claimed in claim 2, wherein said spacer tube (100) is made in a multi-cavity mould in a single process step.

6. The fork assembly (1) as claimed in claim 2, wherein said spacer tube (100) is made by a plastic moulding process.