FORM-2
THE PATENTS ACT,1970
(39 of 1970}
&
THE PATENTS RULES, 2006
COMPLETE
Specification
(See Section 10 and Rule 13)
AN ADJUSTABLE CANISTER TYPE SHOCK ABSORBER
ENDURANCE TECHNOLOGIES PVT, LTD.,
an Indian Company of
Kl228, MIDC Industrial Area,
Waluj, Aurangabad - 431136, Maharashtra, India.
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED

FIELD OF INVENTION
The present invention relates to the field of telescopic fork for vehicles. In particular, this invention relates to forks for two wheelers.
BACKGROUND
The suspension system of a two wheeler vehicle is designed so that the spring is always under compression, even when fully extended. To regulate the trim of a vehicle under varying load conditions, preloading of the spring is used. Preloading consists of pre-compression of the spring. If the spring is stressed with forces that are lower than or equal to that of preloading, it is not deformed. Pre-load is used to adjust the initial position of the spring with the weight of the vehicle and the user acting on it.
The difference between the fully extended length of the spring and the length compressed by the weight of the vehicle and the user is termed as "total sag". Total sag is set to optimize the initial position of the spring to avoid a condition when the spring cannot compress any further or a condition when the spring cannot be mechanically extended. The spring is provided with an initial pre-load during manufacturing, herein after referred to as the factory pre-set load. Decreasing the pre-load on the spring below the factory preset load decreases the initial force in the spring thereby increasing the total sag.
Therefore, preloading helps in limiting deformation during compression of the spring.

With preloading higher forces can be obtained within the same stroke of fork by giving initial deflection to the spring with same fork length and provides a good handling or a good road grip.
For high speed travel on smooth roads, preload on the spring is required to be higher than the pre-set preload. Higher pre-loading of the spring is required to keep the tire always in contact with the road surface and to achieve high speed cornering or turning.
For rough road conditions with a lot of undulation and slow travel speeds, the spring is required to absorb higher jerks; hence the suspension spring should be soft to give a driver a comfortable ride. Accordingly, the preload is required to be lower than the pre-set preload.
Prior attempts have been made to develop suspension systems which can be adjusted.
Accordingly, the United States Patent 5947498 teaches a modular telescopic front fork assembly having a removable self-contained damper cartridge which includes a housing, a cover for covering a portion of the housing of said removable self-contained damper and a reciprocating piston rod axially extending from the housing. A suspension spring is positioned about and concentric with the reciprocating piston rod. The modular telescopic front fork is provided with an adjustable spring seat assembly which operates to permit multiple spring preload adjustments. The rotation of the cover enables an upper and lower spring seats of the adjustable spring seat assembly to rotate with respect to one another and hence providing a preload adjustment. The United States Patent 5947498 is complicated in

construction and cannot be easily operated by the user of the two-wheeler depending on the road conditions to provide the required preload.
Thus, the telescopic forks for two wheeler vehicles are not capable of enabling the user to adjust the preload on the spring as per the requirement of the road conditions. Therefore, the user faces the problem of bad road grip at high speed cornering and an uncomfortable bumpy ride when road conditions are bad.
Hence, there was felt a need for a telescopic fork that enables the driver to adjust the preload on the spring.
OBJECT OF THE INVENTION
An object of the invention is to provide a front fork for vehicles with adjustable steps to adjust the spring pre load as per the road conditions or vehicle loading conditions.
Another object of the invention is to provide a front fork for vehicles that provides good riding comfort for the driver.
Still another object of the invention is to provide a front fork for vehicles that provides good vehicle handling capability.
Yet another object of the invention is to provide a front fork for vehicles that is reliable.
One more object of the invention is to provide a front fork for vehicles that
is simple.

Still one more object of the invention is to provide a front fork for vehicles that is efficient.
SUMMARY OF THE INVENTION
In accordance with the present invention there is provided a spring loaded fork pipe for a two wheeler vehicle having an user enabled load adjuster assembly cooperating with the spring to enable a user to preload the spring in a pre-determined manner, wherein the pre-load assembly comprises:
a. a slider component defined by a plate having at least one
projection at one side and abutting a spacer tube having a
washer abutting the spring;
b. an adjuster component having a pre-determined profiled wall
having varying crests and troughs, the adjuster component
adapted to be angularly displaced to enable contouring of the
varying crests and troughs with the projections of the slider
component to operatively slidingly displace the slider
component axially within the fork pipe thereby varying the
preload on the spring;
c. a displacement means to angularly displace the adjuster
component; and
d. locking means to operatively lock the slider component in an
adjusted pre-mating configuration between the projection of the
slider and the crests and troughs of the adjuster component.

Typically, the slider component is circular in shape and is provided with a central hole and at least a pair of slider holes located diametrically opposite each other.
Typically, the projection of the slider component is located along the rim of the plate of the slider component diametrically opposite each other;
Typically, the adjuster component is provided with a boss element protruding opposite the profiled wall of the adjuster component, the boss element having a pre-determined profile.
Typically, the displacement means comprises a knob and a fork bolt, the knob is provided with a head and a shank, the shank having a profiled recess to match the profile of the boss element of the adjuster component, the knob adapted to be angularly displaceable between a first position and at least one second position.
Typically, the projection of the slider component is adapted to rest at the troughs of the adjuster component on displacement of the knob between the first position and the at least one second position.
Typically, the displacement means is provided with a central stepped through axial hole in the fork bolt, the through axial hole of the fork bolt is defined by a wall having at least one first recess at one end, the through axial hole has a First diameter which is substantially greater than a second diameter, the fork bolt is adapted to enclose at least a portion of the shank of the knob and the boss element of the adjuster element.
Typically, the displacement means is provided with at least one a circular notch on the surface of the shank of the knob and fork bolt for accommodating an O-ring.

Typically, the displacement means is provided with a circlip located between the head and the shank of the knob.
Typically, the locking means comprises at least a pair of locking pins adapted to be fitted to the first recess of the fork bolt at one end and the slider holes at the other end.
In accordance with the present invention there is provided a method of operation of a spring loaded fork pipe for a two wheeler vehicle having an user enabled load preload adjuster assembly cooperating with the spring to enable a user to preload the spring in a pre-determined manner, the method comprising the steps of:
a. rotating a knob between a first position and at least one
second position;
b. causing rotation of an adjuster component fitted in rotational
configuration with the knob and subsequently applying a
rotational force on a slider component;
c. preventing the rotation of the slider by means of a
displacement means fitted between the slider component and
the displacement means resulting in a vertical translational
movement between a first vertical position and a second
vertical position on rotation of the rotation knob; and
d. displacement of a spacer tube located below the slider and
the spring thereby compressing the spring with a pre
requisite preload.

BRIEF DESCRIPTION OF THE FIGURES
Other aspects of the invention will become apparent by consideration of the
accompanying drawing and their description stated below, which is merely
illustrative of a preferred embodiment of the invention and does not limit in
any way the nature and scope of the invention.
Figure 1 illustrates a graphical representation of the characteristics of the
suspension of the two wheeler vehicle with the variation of pre load in the
spring;
Figure 2 illustrates an exploded view of a preload adjuster assembly in
accordance with the present invention;
Figure 3 illustrates a cross-section of the assembled preload adjuster in
accordance with the present invention;
Figure 4 illustrates a knob in accordance with the present invention;
Figure 5 illustrates an adjuster component in accordance with the present
invention;
Figure 6 illustrates a slider component in accordance with the present
invention;
Figure 7 illustrates a locking means in accordance with the present
invention; and
Figure 8 graphically illustrates a load deflection chart for the user enabled
preload adjuster assembly.

DETAILED DESCRIPTION
The invention will now be described with reference to the accompanying drawings which do not limit the scope and ambit of the invention. The description provided is purely by way of example and illustration.
Figure 1 shows a graphical representation of the characteristics of the
suspension of the two wheeler vehicle with the variation of pre load in the
spring. The deformation of the spring is plotted along the X-axis and vertical
load is plotted is along the Y-axis. The force exerted by the spring, with
preloading, is:
F = kAy + ky
where k is the force constant and Ay indicates the deformation of preloading.
Without preloading, the portion below the line A in the graphical representation shown in figure 1, in order to obtain maximum amplitude, greater forces must be applied or conversely, with equal force applied the amplitude (Am) will be less.
With preloading, the portion above the line B in the graphical representation shown in figure 1, higher forces can be obtained within the same stroke of fork by giving initial deflection to the spring with same fork length for a good handling or a good road grip.
Referring to the accompanied drawings, an user enabled preload adjuster for a spring of a telescopic fork, in accordance with this invention is generally indicated by the reference numeral 10 and is particularly shown in figure 2 and figure 3 of the drawing.

The exploded view of the user enabled preload adjuster assembly (10), shown in figure 2, comprises a displacement means, an adjuster component (34), a slider component (48) and a locking means. Figure 3 illustrates a sectional view of the assembled user enabled preload adjuster assembly (10). The preload adjuster assembly (10) is enclosed within a fork pipe (59).
The displacement means comprises a knob (12), shown in figure 4, and a fork bolt (14), illustrated in figure 2. The knob (12) comprises a shank (16) and a head (18). The shank (16) is typically cylindrical in shape with varying cross-section. The shank (16) has a first portion (20) having a smaller dimension that a second portion (22). The second potion (22) of the shank (16) is provided with a groove (24) located at the end of the shank (16) distal from the first portion (20) of the shank (16). An O-ring (21) is provided in the groove (24) of the shank (16). A profiled recess (25) is axially provided at the end of the shank (16) distal from the first portion (20). The head (18) is located at the end of the first portion (20) distal from the second portion
(22) of the shank (16). The head (18) is positioned on the first portion (20) along the length of the head (18). The head (18) enables in providing a user a grip for rotating the knob (12). The knob (12) is adapted to be angularly displaced between a first position and at least one second position. A cir-clip
(23) is located between the first portion (20) of the shank (16) and the head (18).
The fork bolt (14) is provided with a wall (26) which defines a through axial hole (27). The fork bolt is typically cylindrical in shape. The through axial hole (27) is of varying diameter and has a first diameter (D) which is

substantially greater than a second diameter (d). The portion of the though axial hole with the first diameter (D) occupies a substantially greater length of the fork bolt (14) as compared to that occupied by the second diameter (d) of the through axial hole (27). The dimension of the first diameter (D) of the through axial hole (27) is slightly greater than the dimension of the shank (16) of the knob (12). The fork bolt (14) is provided with a pair of recess (28) diametrically opposite each other on the wall (26) of the fork bolt (14). A groove (30) is provided on the wall (26) of the fork bolt (14) to accommodate an O-ring (32).
The adjuster component (34), shown in figure 5, comprises a plate having a boss element (36) at one side and a pre-determined profiled wall (38) at having varying crests (40) and troughs (42) formed on the plate. Each trough (42) is located between two crests (40). The height between consecutive troughs (42) is the pitch of the adjuster and determines the steps through which the spring (58) can be pre-loaded. The. boss element (36) of the adjuster component (34) is typically stepped having a first boss portion (44) and a second boss potion (46) of similar/varying cross-sections. The first boss portion (44) is profiled to match the profile of the profiled recess (25) of the knob (12). The first boss portion (44) is positioned within the profiled recess (25) of the knob (12).
The slider component (48), shown in figure 6, is defined by a plate (50) having at least one projection (52) at one side and abutting a spacer tube (54), shown in figure 3, having a washer (56) abutting the spring (58). The spacer tube (54) and the washer (56) enables in transmission of motion from

the slider to the spring (58). The plate (50) of the slider component (48) is circular in shape and is provided with a central hole (60) and at least a pair of slider holes (62) located diametrically opposite each other on the plate (50). The projection (52) of the slider component (48) is located to at the troughs (42) of the adjuster component (34).
The slider component (48) is guided by a locking means which enables in operatively locking the slider component (48), shown in figure 7, in an adjusted pre-mating configuration between the projection of the slider component (48) and the crests (40) and troughs (42) of said adjuster component (34). The locking means comprises a pair of locking pins (64) which are typically cylindrical and elongated in shape. The locking pins (64) are fitted between the recess (28) of said fork bolt (14) at one end and the slider holes (62) at the other end. The locking pins (64) act as guiding rails for the slider component to slide in the event of adjusting the preload on the spring (58).
The operation of the preload adjuster assembly (10) is achieved by rotating the knob (12) from a first position to a second position which in turn rotates the adapter component (34) via the first boss portion (44) and the profiled recess (25) of the knob (12). Due to the rotation of the adapter component (34), the slider component (48) tends to rotate. However, the locking pins (64) restricts the rotation of the slider component (48) and resulting in a vertical translational movement of the slider component (48) along the locking pins (64) which act as guiding rails for the slider component (48). When the knob (12) is angularly displaced in a clockwise direction, the

slider component (48) moves in the vertically upward direction. On the other hand, when the knob (12) is angularly displaced in an anti-clockwise direction, the slider component (48) moves in the vertically downward direction. The vertical translational movement of the slider component (48) along the locking pins (64) causes the spacer tube (54) to move vertically upward/vertically downward direction depending on the vertically upward/vertically downward movement of the slider component (48). The movement of the spacer tube (54) enables in compressing the spring (58) and thereby providing the requisite preload to the spring (58).
TEST RESULTS
Figure 8 graphically illustrates a load deflection chart for the user enabled preload adjuster assembly. The values of the deflection/displacement of the spring are plotted along the X-axis while the load/force applied for preloading of the spring is plotted along the Y-axis. The graph shows the curves for the preload on the spring when the knob is moved through at least 4 positions, namely, step 0, step 1, step 2 and step 3.
The curve 1 illustrates the preload on the spring in case of minimum preloading condition when the knob is in step 0. Lower force is required to cause a certain deflection/displacement of the spring as compared to that in case of step 1, step 2 and step 3. The preloading on the spring increases with the angular displacement of the knob form step 0 to step 3. The maximum preloading of the spring is achieved when the knob is in step 3 wherein higher force is required to cause a certain deflection/displacement of the spring as compared to that in case of step 0, step 1 and step.

TECHNICAL ADVANTAGES
The product as described herein above offers several advancements which include the realization of:
• a front fork for vehicles that provides good riding comfort for the driver;
• a front fork for vehicles that provides good vehicle handling capability;
• a front fork for vehicles that is reliable;
• a front fork for vehicles that is simple;
• a front fork for vehicles with adjustable steps to provide facility of spring pre-load adjustment and maintain same preload in the spring of both fork legs; and
• a front fork for vehicles that is efficient.
While considerable emphasis has been placed herein on the components and component parts of the preferred embodiments, it will be appreciated that many embodiments can be made and that many changes can be made in the preferred embodiments without departing from the principles of the invention. These and other changes in the preferred embodiment as well as other embodiments 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 spring loaded fork pipe for a two wheeler vehicle having an user enabled load adjuster assembly cooperating with the spring to enable a user to preload the spring in a pre-determined manner, wherein the pre-load assembly comprises:
a. a slider component defined by a plate having at least one
projection at one side and abutting a spacer tube having a
washer abutting the spring;
b. an adjuster component having a pre-determined profiled
wall having varying crests and troughs, said adjuster
component adapted to be angularly displaced to enable
contouring of said varying crests and troughs with said
projections of said slider component to operatively slidingly
displace the slider component axially within said fork pipe
thereby varying the preload on said spring;
c. a displacement means to angularly displace said adjuster
component; and
d. locking means to operatively lock the slider component in an
adjusted pre-mating configuration between the projection of
said slider and the crests and troughs of said adjuster
component.
2. The spring loaded fork pipe having an user enabled load adjuster assembly as claimed in claim 1, wherein said slider component is circular in shape and is provided with a central hole and at least a pair of slider holes located diametrically opposite each other.

3. The spring loaded fork pipe having an user enabled load adjuster assembly as claimed in claim 1, wherein said projection of said slider component is located along the rim of said plate of said slider component diametrically opposite each other.
4. The spring loaded fork pipe having an user enabled load adjuster assembly as claimed in claim 1, wherein said adjuster component is provided with a boss element protruding opposite said profiled wall of said adjuster component, said boss element having a pre-determined profile.
5. The spring loaded fork pipe having an user enabled load adjuster assembly as claimed in claim 1, wherein said displacement means comprises a knob and a fork bolt, said knob is provided with a head and a shank, said shank having a profiled recess to match the profile of said boss element of said adjuster component, said knob adapted to be angularly displaceable between a first position and at least one second position.
6. The spring loaded fork pipe having an user enabled load adjuster assembly as claimed in claim 1, wherein said projection of said slider component is adapted to rest at the troughs of said adjuster component on displacement of said knob between said first position and said at least one second position.
7. The spring loaded fork pipe having an user enabled load adjuster assembly as claimed in claim 1, wherein said displacement means is provided with a central stepped through axial hole in said fork bolt, said through axial hole of said fork bolt is defined by a wall having at least one first recess at one end, said through axial hole has a first

diameter which is substantially greater than a second diameter, said fork bolt is adapted to enclose at least a portion of said shank of said knob and said boss element of said adjuster element.
8. The spring loaded fork pipe having an user enabled load adjuster assembly as claimed in claim 1, wherein said displacement means is provided with at least one a circular notch on the surface of said shank of said knob and fork bolt for accommodating an O-ring.
9. The spring loaded fork pipe having an user enabled load adjuster assembly as claimed in claim 1, wherein said displacement means is provided with a circlip located between said head and said shank of said knob.
lO.The spring loaded fork pipe having an user enabled load adjuster assembly as claimed in claim 1, wherein said locking means comprises at least a pair of locking pins adapted to be fitted to said first recess of said fork bolt at one end and said slider holes at the other end.
1 l.A method of operation of a spring loaded fork pipe for a two wheeler vehicle having an user enabled load preload adjuster assembly cooperating with the spring to enable a user to preload the spring in a pre-determined manner, said method comprising the steps of:
a. rotating a knob between a first position and at least one
second position;
b. causing rotation of an adjuster component fitted in rotational
configuration with said knob and subsequently applying a
rotational force on a slider component;

c. preventing the rotation of the slider by means of a
displacement means fitted between said slider component
and said displacement means resulting in a vertical
translational movement between a first vertical position and
a second vertical position on rotation of said rotation knob;
and
d. displacement of a spacer tube located below said slider and
said spring thereby compressing said spring with a pre-
requisite preload.