FORM 2
THE PATENT ACT, 1970,
(39 OF 1970)
&
THE PATENTS RULE, 2003
COMPLETE SPECIFICATION
(SEE SECTION 10; RULE 13)
"VEHICLE SUSPENSION SYSTEM WITH AXLE SKEWNESS ADJUSTMENT"
MAHINDRA TRUCKS AND BUSES LIMITED A COMPANY REGISTERED UNDER THE PROVISIONS OF COMPANIES ACT, 1956 MAHINDRA TOWERS, 3RD FLOOR, DR. G.M. BHOSALE MARGf WORLI, MUMBAI-400 018, MAHARASHTRA, INDIA.
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES AND ASCERTAINS THE NATURE OF THIS INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED

FIELD OF THE INVENTION:-
The present invention relates to vehicle suspension system. More particularly, the present invention is related to the means of adjusting axle alignment with respect to chassis.
BACKGROUND OF THE INVENTION:-
The vehicles which consist of an axle beam for driving and supporting the weight of vehicle are generally provided with a system of suspension assembly (here a leaf spring suspension) which provides a structural link between vehicle frame& axle beam and also acts as a cushioning member to reduce the shock transmitted from grounds to the vehicle during its run. The suspension is mounted on the axle beam and is mechanically fastened to it with some fixing means such as bolts and nuts. Further the leaf spring which consists of an eye each at front and rear end is connected to the vehicle frame via front and rear hanger mounting brackets with the help of a cylindrical pin (hereinafter called as "spring pins"). The rear end may be left free or with no rigid connection inside the rear hanger mounting bracket or a shackle type arrangement may be provided to accommodate the change in length of spring during loading & unloading. Both the hanger mounting bracket (front and rear) are fixed to the chassis frame by means of mechanical fasteners like nut and bolts.
It is very much desirable that the axle beams are properly aligned with the vehicle chassis (or are assembled perpendicularly with respect to the chassis longitudinal axis/long member). Also it is advantageous that the axle beams are parallel to each other in multi axle vehicles. It is seen that such arrangements helps in minimizing tire wear and provides better fuel economy.
For making such kind of alignment arrangements few of methods have been developed. One is by altering the position of saddle assembly with respect to the leaf spring assembly and on the other hand, to fitting an eccentric adaptor at the at the ends of spring mountings. The former method can be time consuming and arduous. Further in the later method it has been proposed to adjust the eccentric adapter from both the sides in order to achieve the alignment which may not be feasible in terms of accessibility of eccentric adapter on both sides.

SUMMARY OF THE INVENTION:-
The Invention speculates on the axle alignment method by relocating the spring pins with respect to the spring hanger mounting bracket.
With respect to the previously known methods as per (Patent no. - US5016906) in which it can be inferred that such a method will need adjustment to be done from both the sides of the hanger bracket (outward as well as inward) but such a method fails when the inward side of bracket is inaccessible so the present invention is more flexible in terms of the accessibility for the ease of proper alignment of axle beams which cannot be achieved with the known invention (as explained earlier).
This invention is focused with an objective to provide the vehicle axle beam alignment with respect to vehicle frame facilitating the alignment even if the inward sides of hanger mounting brackets are not accessible.
As per the invention the vehicle consist of at least one axle transversely located on the chassis frame opposed by two wheels. The said axle is connected by means of a pair of suspensions (here a leaf spring) via a pair of hanger mounting bracket on each side. Left hand (LH) side and Right hand (RH) side. As previously stated, the rear spring hanger bracket incorporates a shackle arrangement in order to accommodate the change in length of spring along the longitudinal direction during loading and unloading. The front spring hanger mounting bracket which consist of a upper portion which is fastened to chassis and lower portion consisting of two dependent legs (outward and inward side) where the front end of the said spring eye is mounted. This said mounting of spring is done with the means of a spring pin as stated earlier, which is inserted in a transverse hole provided in the two legs of the hanger bracket. According to the invention an additional cylindrical plug is inserted in each side of the transverse holes provided at the bifurcated legs of the said hanger mounting bracket. i"hese additional cylindrical plugs consist of an eccentric aperture through which our spring pin passes. In total the spring pin passes through the outward plug provided in one of the leg located on outward side of spring hanger bracket, spring eye at front, and plug provided at the inward leg of the said hanger bracket. Both the outward and inwardly located legs of the said hanger bracket consist of a longitudinal hole passing through, which accommodates a clamping bolt in order to fix the cylindrical plug in order to arrest the relative motion of plug with

respect to said legs and also to fix the relative motion of spring pin with cylindrical Plug-Cylindrical plug consist of an eccentric aperture through which the spring pin passes, and a complete through slit transversely along the length of plug at the bottom half of the plug. An undercut is provided at the bottom half of cylindrical plug so as to facilitate the rotation of plug by sliding it over the clamping bolt. Out of the two cylindrical plugs as provided on outward and inwardly located legs, the one located on the outward leg is provided with an additional slot on the outboard side digging up to some depth in the upper half portion along the direction of plug length. There is another transverse slot provided throughout the leg in the lower half of the cylindrical plug. Both the upper and lower slots as mentioned above are inline so that a tool can be inserted in to rotate the plugs when required.
As per known metnods till current date it is required to rotate and adjust the said plugs located at both outward and inwards with an equal amount or it will result in the spring pin tilt because of the clearance between eccentric aperture in the plug and the spring pin. The magnitude of tilt will also depend upon the clearance between plug and the transverse hole provided in legs. The currently known method poses a limitation to those vehicles where inward side of the hanger bracket is inaccessible for rotating the cylindrical plug. To remove all these above mentioned problems the invention proposed here has an eccentric aperture provided in the cylindrical plugs in the form of D shape. The ends of spring pins are also provided D shape in order to allow in a geometric fix. So when the outward plug is rotated by inserting a tool in the tool-engageable formation on the plug, it rotates the spring pin too along with it because of the D slot fix arrangement provided, this also rotates the inwardly located plug because of the rigid kind of connection existing between two plugs (outward and inward) which is facilitated by the spring pin. This especial arrangement is done in order to further widen scope of applicability of this method on that vehicle also where the inwards side is inaccessible (Because of the presence of chassis or some other vehicle level aggregate) and to remove the tilt error of spring pins as explained above.

OBJECT OF INVENTION:-
It is object invention to make alignment of axle by rotating eccentric aperture plug at fore and aft by the tool applying easy accessible location.
It is also objection invention to make tooling at fore end plug by providing spring pin which will make fore end and aft end plugs always aligned.
It is also objection invention to provide features to distribute load between the multi axles suspension.
STATEMENT OF INVENTION:-
Accordingly the invention provides a vehicle suspension system with axle skewness adjustment comprises at least one axle transversely located on the chassis frame opposed by two wheels, with a pair of suspensions (here a leaf spring) via a pair of hanger mounting bracket fixed to the chassis, on the Left hand (LH) side and Right hand (RH) side, having two dependant legs with fore-and aft slot for accommodating clamping bolt; an aperture in transverse direction provided to said legs of the hanger in a line; a first plug having eccentric hole with D-shape end with tooling facility provided to ihe said fore leg the said hanger; a second plug having eccentric hole with D-shape end provided to the said aft leg of the hanger; a first eye, provided at front end of the said suspension, connected to the said hangers by a spring pin having matching D-shape ends supported in the said plugs and rigidly held by a clamping bolt through the said slot; a second eye, provided at the rear end of the said suspension, connected to shackle to the support.
BRIEF DESCRIPTION OF THE FIGURES:-
In order that the invention may be more clearly understood, an embodiment is
described with reference to the accompanying non-limiting drawings in which:
FIG.1 is a perspective drawing of a tandem axle suspension.
In FIG.2, the side view of the front spring hanger mounting bracket is shown.
FIG.3 is a front view of the front spring hanger mounting bracket.
FIG.4 is front view of the plug located on outward side of vehicle's front hanger
mounting bracket.

FIG.5 is side view of the plug along the direction shown in line BB of Fig.4. The Plug
shown is located on outward side of vehicle's front hanger mounting bracket.
FIG.6 is front view of the plug located on inward side of vehicle's front hanger
mounting bracket.
FIG.7 is side view of the plug along the direction shown in line AA of Fig.6. The plug
shown is located on inward side of vehicle's front hanger mounting bracket.
FIG.8, FIG.9 shows the view of the plug along the direction shown in line CC & DD in
Fig.5 & Fig.7.
FIG.10 shows a perspective view of the spring pin.
FIG.11 is the front view of the spring pin , plug and hanger mounting bracket
assembly showing the mean position.
FIG. 12 is the side view of the assembly showing the spring pin, plug and the hanger
mounting bracket assembly. FIG. also shows the clamping bolt.
FIG.13 is a front view of the adjustable spring hanger according to the invention
showing the spring pin in a position forward of the mean position.
FIG.14 is a front view of the adjustable spring hanger according to the invention
showing the spring pin in a position rearward of the mean position.
DETAILED DESCRIPTION OF THE PRESENT INVENTION:-
In FIG.1 shows tandem axle suspension system where the 1 is a drive axle and 2 is a tag axle. Both the axles are connected to the chassis frame through leaf springs which are further connected to the pair of hanger brackets 11, 12, 13.The front ends of the springs are connected with front hanger mounting brackets, 11 (for the drive axle spring), and 12 (for the tag axle spring). FIG.1 shows an arrangement to distribute the load between drive axle and tag axle suspension. The arrangement consists of a pair of lever 15, a pair of equalizer rod 16, and another pair of lever 17. The rear ends of both the suspensions are connected with the lever 15, 17 through shackle 14. Thus enabling the spring length to change during loading and to distribute the loads between drive and tag suspensions via said lever and rod arrangement.
In FIG.2, the front spring hanger mounting bracket 11 is shown. Numerical 18 shows the two dependent legs of the hanger bracket. 38 represent the fore-and-aft slot provided in the legs 18 to accommodate the clamping bolts.

In FIG.3, Numerical 20 shows the front view of the front spring hanger mounting bracket 11. 20 is fixed to the vehicle chassis with the help of mechanical fasteners like nut & bolts, rivets or any other conventional means of fixing. A fore-and-aft slit 30 is provided at each leg in hanger mounting bracket. 37 represent the aperture provided in the both the dependent legs 18 of the hanger brackets.
In FIG.4, outwardly located cylindrical plug 22 is shown which is rotatably mounted in the aperture 37 provided in outward leg of the hanger mounting bracket. An eccentric hole 41 with D shape ends is provided fore-and-aft in plug 22. The plug 22 is provided with a tool engageable formation in form of cutouts 31 across the upper and lower half of the hole 30.
In FIG.5, The side view of plug 22 shows the cutouts 31. Where the upper half of the cutout 31U is made up to some finite depth but the lower half of the cutout 31L is made throughout the length. Undercut 28 is shown in order to accommodate the clamping bolt and allowing the plug to slide over it during rotation. In FIG.6, 27 represents the inwardly located plug rotatably mounted in the aperture 37 provided in inward leg of the hanger mounting bracket. 42 represent the D slot provided in the plug.
FIG.7 the side view of plug 27 shows the cutout 32 which is made throughout the length in lower portion of plug. Undercut 29 is shown in order to accommodate the clamping bolt and allowing the plug to slide over it during rotation.
In FIG.8, FIG.9 Extent of the undercut 28 & 29 provided on both the plugs (Outward & inward) in unshaded areas is shown.
In FIG.10, numerical 21 designate the spring pin with D shape ends 40.
In FIG.11, The spring pin 21 is mounted eccentrically in plugs 22 and 27. The cutout 31 provided on the outboard surface of plug 22 to accommodate a tool permits the plugs to be rotated in either a forwards direction or rearwards direction with respect to the spring hanger 20. The extent of this rotation is limited by the interaction of the plugs undercut 28 & 29 with the shaft of the clamping bolt. 24 represent the centre of cylindrical plug, 25 represent the centre of the aperture provided in the plug for accommodating the spring pin thus making the aperture eccentric with respect to the

plug centre. This configuration here is termed as mean position, centre 24 being exactly below the centre 25 of aperture provided in plug, shown in FIG.2
In FIG.12 the assembly of spring pin with plugs and hanger mounting bracket is shown. Numerical 26 represents a clamping bolt, When the clamping bolt is tightened the gap in the slits 30 provided at the end of hanger bracket legs 18 gets narrower thus collaosing it and this in turn collapse the plug through undercut 31L & 32 to prevent the relative motion between plug , hanger bracket and plug , spring pin. FIG.12 also shows the spring pin 21 which is inserted in the plugs both at outward and inward leg. The plugs 22 and 27 are provided with D slots 41 and 42 which receive the D shape ends 40 of the spring pin 21 forming a single rigid interlock between plugs and spring pin. Thus removing additional need of a tool engageable formation on plug 27 alike 31 on plug 22. This rigid interlock present allows the inwardly located plug 27 to also rotate by an equal amount by which the outside plug 22 has been rotated.
In FIG. 13 and 14, In FIG. 13 spring pin 21 is shown in a position rearward of the mean position. This is achieved by rotating plug 22 in one sense with respect to the spring hanger until the desired rearward and downward displacement of the spring pin 21 is achieved. The extent of horizontal displacement is indicated by distance 34. The plug 22, 27 may then be fixed in position by tightening the clamping bolt. The extent of rotation of the plugs is limited by the extent of cut out 28. In FIG.14 forward adjustment of spring pin 21 is achieved by rotation of plugs 22 in the opposite sense until the desired relative forward and downward displacement of spring pin 21 is reached. The extent of horizontal displacement is indicated by distance 35. Once again the plugs 22, 27 may be locked by means of clamping bolt. In the method described it is envisaged that a forward and rearward displacement of 4 mm from the mean position may be achieved. It can be seen that the horizontal displacement is always less than the vertical displacement of the spring pin.
It is clear from the invention that this type of arrangement includes all those type of suspension arrangements also where the inside part of the hanger mounting bracket is not accessible. Also it removes the errors like spring pin tilt by rotating the inwardly located plug also with an equal amount from which the outwardly located plug has been rotated. (Spring pin tilt explained earlier).

A suspension for a vehicle having a chassis frame and at least one transversely located axle with said pair of opposed wheels, said suspension including a pair of spring hanger mounting bracket (front and rear) to each opposite side of said chassis frame, and a leaf spring assembly on each side of said chassis frame interconnecting each side pair of spring hangers with opposite ends of said axle in resilient load transfer relationship, each said leaf spring assembly having a leaf spring with a spring eye at one end or either both ends and a spring pin extending through said spring eye and through an aperture in said plugs (aperture providing means) rotatably mounted in one of the said spring hangers having an upper portion by which it is attached to the said chassis frame and a depending portion having a transverse opening in which said plug (aperture providing means) is rotatably mounted , said depending portion being bifurcated from the bottom up in a transverse direction , a horizontal bolt-receiving opening extending fore-and-aft through said depending portion and fore-and-aft through the lower portion of said plugs (aperture providing means), a clamping bolt extending through said bolt-receiving opening, said lower portion of the bifurcated legs and said plugs with a proper clearance permitting the rotation of plugs with a substantial angles, the outward side of the said plugs having a tool-engageable formation thereon to permit adjustment thereof by a tool and the aperture in said plugs being eccentrically located therein.
A suspension as described above wherein said transverse opening in said depending portion is cylindrical and said aperture providing means is in the form of a cylindrical plug fitting rotatably in said transverse opening.
A suspension as described above wherein said fore-and-aft slot in said aperture -providing means permits it to be rotated through an angle up to 35 degrees. A suspension as described above wherein the centre of said aperture-providing means is located vertically below the coinciding centers of said transverse opening and said plugs (aperture providing means) is in its mid position and said centre of said aperture is displaced horizontally and vertically as said plugs is rotated, the vertical displacement being substantially less than the horizontal.
A suspension as described above with said tool-engageable formation on outward side of said plugs. A suspension as described above where in the spring pin has

any sort of locking arrangement between spring pin and plug (pin mounting means) to arrest the relative motion between them.

WE CLAIM:-
1. A vehicle suspension system with axle skewness adjustment comprises at least one axle transversely located on the chassis frame opposed by two wheels, with a pair of suspensions (here a leaf spring) via a pair of hanger mounting bracket fixed to the chassis, on the Left hand (LH) side and Right hand (RH) side, having two dependant legs with fore-and aft slot for accommodating clamping bolt; an aperture in transverse direction provided to said legs of the hanger in a line; a first plug having eccentric hole with D-shape end with tooling facility provided to the said fore leg the said hanger; a second plug having eccentric hole with D-shape end provided to the said aft leg of the hanger; a first eye, provided at front end of the said suspension, connected to the said hangers by a spring pin having matching D-shape ends supported in the said plugs and rigidly held by a clamping bolt through the said slot; a second eye, provided at the rear end of the said suspension, connected to shackle to the support.
2. The vehicle suspension system as claimed in claim 1 wherein a vertical slit is provided at bottom of the said apertures dependant legs.

3. The vehicle suspension system as claimed in claims 1 and 2 wherein the said plug with tooling facility consists a front side of plug provided with vertical front half cut out with finite depth.
4. The vehicle suspension system as claimed in claims 1 and 3 wherein the said plug provided cut out throughout the length at lower half for accommodating clamping bolt.
5. The vehicle suspension system as claimed in claims 1 and 4 wherein the said fore-and-aft slot in said aperture - providing means permits it to be rotated through an angle up to 35 degrees.
6. The vehicle suspension system as claimed in claims 1 and 5 wherein the centre of said aperture-providing means is located vertically below the coinciding centers of said transverse opening and said plugs (aperture providing means) is in its mid position and said centre of said aperture is displaced horizontally and vertically as said plugs is rotated, the vertical displacement being substantially less than the horizontal.

7. The vehicle suspension system as claimed in claims 1 to 6 wherein the vehicle of tandem axle suspension having drive axle and and tag axle connected to the the said legs of hanger brackets fixed to the chassis by connecting each front eye of suspension with the said plugs and spring pins; a first pair of lever and a second pair lever mounted on the hanger brackets for supporting suspension of the said tag axle, a pair of equalizer rod connected to said levers; the rear ends of both the suspensions are connected with the said levers through shackle.