DESC:FIELD OF THE INVENTION
[001] Present invention relates to an axle nut. More particularly, the present invention relates to the ‘Axle Nut’ for axle spindle of a heavy vehicle.

BACKGROUND OF THE INVENTION
[002] Typically, a wheel end assembly of a vehicle is mounted onto the spindle of an axle of the vehicle. The wheel end assembly is mounted onto the axle spindle through a wheel hub. The bearing assembly is mounted on the axle spindle, so as to be rotatable about the axle spindle. An axle nut is connected to an outboard end of the axle spindle. The axle nut provides the necessary clamping force for securing the bearing assembly on the axle spindle. As such, the clamping force from the axle nut maintains alignment of the bearing assembly on the axle spindle. Thus, enabling the bearing assembly to stably and rotatably supports the wheel end assembly, while handling loads and dynamic forces acting on the vehicle.
[003] However, conventional axle nuts have a tendency of loosening from the outboard end of the axle spindle upon prolonged exposure to loads and dynamic forces acting on the vehicle. Upon loosening, the axle nut may rotate about the axle spindle, which varies the clamping force applied by the axle nut on the bearing assembly. In turn, end play of bearings of the bearing assembly can become excessive. The excessive end play of the bearings leads to increased operational noise of the bearings, accelerated wear of the bearings, and vibration of the wheel hub leading to handling problems of the vehicle or the trailer.
[004] In view of the above, there is a need for an axle nut that overcomes one or more of the aforementioned problems associated with conventional art.

SUMMARY OF THE INVENTION
[005] In one aspect, an axle nut for a wheel end assembly is disclosed. The axle nut comprises a nut body adapted to be mounted to an outboard end of an axle spindle. The nut body comprises a plurality of circumferential grooves. The plurality of circumferential grooves are adapted to receive a split pin via one or more through-holes provided on the axle spindle for providing rotational locking to the nut body.
[006] In an embodiment, the nut body comprises a flat inboard face. The flat inboard face is adapted to engage with an outboard end surface of an outboard bearing of a bearing assembly provided on the axle spindle. The flat inboard face is a hardened surface.
[007] In an embodiment, a locking plate is provided to the nut body and mounted to an outboard end face of the axle spindle for rotational locking of the nut body.
[008] In an embodiment, the locking plate is provided on the plurality of circumferential grooves of the nut body.
[009] In an embodiment, the locking plate comprises side portions. The side portions being adapted to overlap on diametrically opposite regions on an outer face of the nut body.
[010] In an embodiment, the side portions are provided on the plurality of circumferential grooves of the nut body.
[011] In an embodiment, the locking plate is provided to an outer face of the nut body.
[012] In an embodiment, the locking plate has a length greater than diameter of an inner surface of the nut body.
[013] In an embodiment, the locking plate is fixed onto the axle spindle through fasteners.
[014] In an embodiment, the axle nut is made by forging.

BRIEF DESCRIPTION OF THE DRAWINGS
[015] Reference will be made to embodiments of the invention, examples of which may be illustrated in accompanying figures. These figures are intended to be illustrative, not limiting. Although the invention is generally described in context of these embodiments, it should be understood that it is not intended to limit the scope of the invention to these particular embodiments.
Figure 1 is a cross-sectional view of an axle nut being mounted on an axle spindle of an axle for locking a wheel end assembly, in accordance with an embodiment of the present disclosure.
Figure 2A is a perspective view of an axle nut, in accordance with an embodiment of the present disclosure.
Figure 2B is a side view of the axle nut provided with a split pin and a locking plate, in accordance with an embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE INVENTION
[016] Various features and embodiments of the present invention here will be discernible from the following further description thereof, set out hereunder.
[017] The present invention relates to an axle nut. More particularly, the present invention relates to an axle nut for an axle spindle of a heavy vehicle. The axle nut is adapted to prevent loosening of a wheel hub of the wheel end assembly during riding of the vehicle, thereby ensuing that optimal clamping force is provided on a bearing assembly of the wheel end assembly at all times.
[018] Throughout the description, references to the term “inboard” correspond to a direction towards the centre of an axle, and references to the term “outboard” correspond to the direction away from the centre of the axle.
[019] Figure 1 is a cross-sectional view of an axle nut 110 mounted on an axle spindle 102 of an axle of a vehicle for locking a wheel end assembly 100, in accordance with an embodiment of the present disclosure. In an embodiment, the axle is that of a heavy vehicle such as a trailer or a semi-trailer. The wheel end assembly 100 comprises the axle spindle 102, a bearing assembly 104a, 104b and a wheel hub 106.
[020] The axle spindle 102 is mounted to an end portion (not shown) of an axle beam 108. In an embodiment, the axle spindle 102 has a circular cross-section. The axle spindle 102 has mounting surfaces at an outer curved surface thereof for supporting the bearing assembly 104a, 104b on the axle spindle 102. In an embodiment, the axle spindle 102 comprises external threads formed at least on an outboard end of the axle spindle 102. Further, the axle spindle 102 comprises one or more through-holes 122 (shown in Figure 2B).
[021] In an embodiment, the bearing assembly 104a, 104b comprises an outboard bearing 104a and an inboard bearing 104b. The inboard bearing 104b is spaced apart from the outboard bearing 104a and is mounted inboard of the outboard bearing 104a.
[022] In an embodiment, the wheel hub 106 is rotatably mounted on the bearing assembly 104a, 104b. The wheel hub 106 is adapted to support at least one wheel (not shown) of the vehicle.
[023] Referring to Figures 2A and 2B in conjunction with Figure 1, the axle nut 110 is mounted on the outboard end of the axle spindle 102. The axle nut 110 is mounted on the axle spindle 102 and is adapted to engage with the outboard bearing 104a. The axle nut 110 has a nut body 130 which is a circular structure having a flat inboard face 112 and an outboard face 114 (shown in Figure 2B) opposite to the flat inboard face 112. The nut body 130 has internal threads formed at an inner surface 116 thereof. The internal threads are provided perpendicularly to the flat inboard face 112. The internal threads of the nut body 130 are adapted to engage with the external threads formed on the outboard end of the axle spindle 102 to facilitate mounting or fastening of the axle nut 110 onto the axle spindle 102.
[024] Further, the nut body 130 comprises an outer surface 126 provided between the inboard face 112 and the outboard face 114. The outer surface 126 is capable of engaging with a tool for enabling fastening of the axle nut 110 onto the axle spindle 102. In an embodiment, the outer surface 126 is provided with a hexagonal profile or an octagonal profile or any other suitable profile, for enabling fastening of the axle nut 110 with the axle spindle 102.
[025] The flat inboard face 112 of the nut body 110 is adapted to be tightened against an outboard end surface of the outboard bearing 104a to a predetermined torque level. The perpendicularity between the flat inboard face 112 and the internal threads of the axle nut 110 facilitates uniform seating of the nut body 130 against the outboard bearing 104a. By tightening the nut body 130 against the outboard bearing 104a, a clamping force is applied to the bearing assembly 104a, 104b mounted on the axle spindle 102. The clamping force applied by the nut body 130 enables the bearing assembly 104a, 104b to stably and rotatably support the wheel hub 106 while handling loads and dynamic forces acting on the vehicle or the trailer.
[026] In an embodiment, the flat inboard face 112 of the nut body 130 is a hardened surface using induction hardening techniques known in the art. This results in reduced wear and tear of the nut body 130 during tightening and re-tightening of the nut body 130 against the outboard bearing 104a.
[027] In an embodiment, a washer 118 (shown in Figure 1) is disposed between the nut body 130 and an outboard end surface of the outboard bearing 104a. The washer 118 assists in providing a snug fit to the nut body 130 against the outboard bearing 104a upon fastening.
[028] Further, the nut body 130 comprises a plurality of circumferential grooves 120 formed on an outer periphery of the nut body 130. The plurality of circumferential grooves 120 may be periodically spaced apart from one another along the outer periphery of the nut body 130. The plurality of circumferential grooves 120 of the nut body 130 can be aligned with the one or more through-holes 122 of the axle spindle 102 by suitably rotating the nut body 130 along the external threads of the axle spindle 102. The plurality of circumferential grooves 120 are adapted to receive a split pin 128 for providing a rotational locking to the nut body 130.
[029] In an embodiment, the split pin 128 is disposed in the through-hole 122 provided at the outboard end of the axle spindle 102. The split pin 128 is adapted to extend through diametrically opposite circumferential grooves 120 by passing through the through-holes 122 provided on the axle spindle 102. By inserting the split pin 128 through the nut body 110 and the axle spindle 102, further rotation of the nut body 110 about the axle spindle 102 can be prevented, thereby providing locking against rotation and loosening of the nut body 110 from the axle spindle 102.
[030] Referring Figure 2B, in an embodiment, a locking plate 124 is provided to the nut body 110, particularly to the outer face 114 of the nut body 130, to prevent loosening and outboard movement of the nut body 130 from the axle spindle 102. In an embodiment, the locking plate 124 has a length greater than a diameter of the inner surface 116 of the nut body 130. After inserting the split pin 128 in the plurality of circumferential grooves 120 of the nut body 130, the locking plate 124 is mounted to an outboard end face of the axle spindle 102. In an embodiment, the locking plate 124 is provided/inserted on the plurality of circumferential grooves 120 of the nut body 130. In an embodiment, the locking plate 124 is mounted to the outboard end face of the axle spindle 102 by fasteners such as bolts, wherein the fasteners engage with the axle spindle 102. Upon mounting the locking plate 124, side portions 132a, 132b of the locking plate 124 overlap diametrically opposite regions on the outer face 114 of the nut body 130. Thus, even in case of failure of the split pin 128 under dynamic loads acting on the nut body 130 and the axle spindle 102, the locking plate 124 provides sufficient locking against loosening and outboard movement of the nut body 130 from the axle spindle 102. In an embodiment, the side portions 132a, 132b of the locking plate 124 are provided/inserted on the plurality of circumferential grooves 120 that are provided on diametrically opposite regions on the outer face 114 of the nut body 130.
[031] In an embodiment, the axle nut 110 is manufactured by forging, which causes metal grains in the axle nut 110 to elongate and align along the direction of applied force, resulting in a denser and more uniform microstructure having lesser internal voids and imperfections compared to conventional axle nuts manufactured by casting. Therefore, the forged axle nut 110 in accordance with the present embodiment of the invention has greater strength, greater resistance to wear, greater fatigue resistance and better impact resistance compared to conventional axle nuts manufactured by casting.
[032] Advantageously, the split pin and the locking plate of the present invention provide a fool proof locking of the axle nut against rotation and outboard axial movement of the axle nut from the axle spindle. Hence, optimum clamping force can be applied to the bearing assembly at all times when the vehicle or the trailer is subjected to loads and dynamic forces during operation. Thereby, optimum end play of each of the inboard bearing and the outboard bearing can be maintained, mitigating operational noise of the bearings, excessive wear of the bearings and vibration of the wheel hub. Accordingly, handling problems of the vehicle or the trailer due to excessive end play of the bearings can be avoided.
[033] While the present invention has been described with respect to certain embodiments, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the scope of the invention.
List of Reference Numerals
100 – Wheel end assembly
102 – Axle spindle
104a – Outboard bearing
104b – Inboard bearing
106 – Wheel hub
108 – Axle beam
110 – Axle nut
112 – Flat inner face of the axle nut
114 – Outer face of the axle nut
116 – Inner curved surface of the axle nut
118 – Washer
120 – Plurality of circumferential grooves of the axle nut
122 – Plurality of through-holes of the axle spindle
124 – Locking plate
126 – Outer surface of axle nut
128 – Split pin
130 – Nut body
132a, 132b – Side portions of the locking plate
,CLAIMS:WE CLAIM
1. An axle nut (110) for a wheel end assembly (100), the axle nut (110) comprising:
a nut body (130) adapted to be mounted to an outboard end of an axle spindle (102), the nut body (130) comprising a plurality of circumferential grooves (120),
the plurality of circumferential grooves (120) being adapted to receive a split pin (128) via one or more through-holes (122) provided on the axle spindle (102) for providing rotational locking to the nut body (130).

2. The axle nut (110) as claimed in claim 1, wherein the nut body (130) comprising a flat inboard face (112), the flat inboard face (112) being adapted to engage with an outboard end surface of an outboard bearing (104a) of a bearing assembly (104a, 104b) provided on the axle spindle (102),
wherein the flat inboard face (112) is a hardened surface.

3. The axle nut (110) as claimed in claim 1 comprising a locking plate (124) provided to the nut body (130) and mounted to an outboard end face of the axle spindle (102) for rotational locking of the nut body (130).

4. The axle nut (110) as claimed in claim 3, wherein the locking plate (124) is provided on the plurality of circumferential grooves (120) of the nut body (130).

5. The axle nut (110) as claimed in claim 3, wherein the locking plate (124) comprising side portions (132a, 132b), the side portions (132a, 132b) being adapted to overlap on diametrically opposite regions on an outer face (114) of the nut body (130).

6. The axle nut (110) as claimed in claim 5, wherein the side portions (132a, 132b) are provided on the plurality of circumferential grooves (120) of the nut body (130).

7. The axle nut (110) as claimed in claim 3, wherein the locking plate (124) is provided to an outer face (114) of the nut body (130).

8. The axle nut (110) as claimed in claim 3, wherein the locking plate (124) has a length greater than diameter of an inner surface (116) of the nut body (130).

9. The axle nut (110) as claimed in claim 3, wherein the locking plate (124) is fixed onto the axle spindle (102) through fasteners.

10. The axle nut (110) as claimed in claim 1 is made by forging.

Dated this 8th day of February 2024.
RAMKRISHNA FORGINGS LIMITED
By their Agent & Attorney

(Adheesh Nargolkar)
of Khaitan & Co
Reg No IN/PA-1086