FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
PROVISIONAL SPECIFICATION
(See Section 10; rule 13)
TITLE OF THE INVENTION
Fail Safe Wheel End Arrangement To Prevent Wheel Detachment In Case Of Axle Shaft Failure In Driving Front Axle


APPLICANTS
TATA MOTORS LIMITED, an Indian company
having its registered office at Bombay House,
24, Homi Mody Street, Hutatma Chowk,
Mumbai 400 001 Maharashtra, India

INVENTORS
Shirish Shankarrao Pandav and Dhananjay Raghunath Shinde
Both are Indian Nationals
of TATA MOTORS LIMITED an Indian company
having its registered office at Bombay House,
24 Homi Mody Street, Hutatma Chowk,
Mumbai 400 001, Maharashtra, India
PREAMBLE TO THE DESCRIPTION
The following specification describes the invention


FIELD OF INVENTION
This invention relates to fail safe wheel end arrangement to prevent Wheel detachment from driving front axle FA-101 in case of axle shaft failure.
BACKGROUND OF THE INVENTION
The axle in the subject matter is a front driving axle which goes on vehicles for off-road application. It has been observed that the problem of wheel detachment from the vehicles in the field, due to overloaing. Upon analysis of the same, it was found that the wheel end was not firmly secured to the axle housing and the need arose of modifying the axle design for the same.
SUMMARY OF INVENTION
The wheel hub inner and outer taper roller bearings are preloaded by an Intermediate lock nut, provided on the wheel hub. Tubular spacer and shims are provided to correctly adjust the hub play. Then the wheel hub and drive shaft assembly is secured completely in place by tightening the external lock nut, provided on the hub end drive shaft. This prevents the Intermediate lock nut from getting loosened and helps maintain the specified hub play.
OBJECTS OF INVENTION
The main objective of this invention is to prevent the wheel detachment from axle in case of Hub end drive shaft (6) failure and hence to avoid an accident.
Yet another objective is to retain the hub play and prevent damages to bearings and seal, due to Drive shaft (6) failure.
BRIEF DESCRIPTION OF INVENTION
The wheel hub bearings of taper roller type (4) and (5) are preloaded against the Drive shaft (6) & Wheel hub (3) shoulders, by tightening the double lock nut (7), on


the hub end drive shaft (6). There is no positive locking provided between the Wheel hub (3) & Inner taper roller bearing (4). As a result, in case of drive shaft (6) failure, the wheel hub (3) tends to come out of the ball head assembly (2), slipping out of the inner race of bearing (4), thereby causing excessive bearing play and subsequent damage to the bearings and seals. Also the wheel hub (3) detachment from the ball head housing assembly (2) can cause an accident, leading to severe injuries to passengers.
The wheel detachment problem can be solved by changing the method of wheel bearing retention arrangement. This calls for minor changes in the design of present Wheel hub (3) and Ball head housing (2), without affecting the wheel track of the axle. Also this arrangement, elaborated in the later segment, would retain the bearing play without causing the damage to the bearings and associated parts in case of axle shaft failure, hence minimizing the cost/risk of failure.
BRIEF DESCRIPTION OF DRAWINGS
Fig. 1 shows an existing wheel end arrangement
Fig. 2 shows the modified wheel end/hub-bearing arrangement
Fig. 3 shows an enlarged view of modified wheel end/hub-bearing arrangement.
DETAILED DESCRIPTION OF INVENTION
Referring to the drawings wherein the showings are for the purpose of illustrating a preferred embodiment of the invention only, and not for the purpose of limiting the same,
With reference to figure 2 & 3, the bearings (4) and (5) are preloaded with the help of lock nut (4). The preloading is done by tightening the nut (9) on the wheel hub (3). This entire wheel end assembly comprising Ball head housing (2), Wheel hub (3), Taper roller bearings (4) and (5), lock nut (9) and tubular spacer and shims (8) is done outside and later mounted onto the axle ball head (1) at King pin supports. The tubular spacer and shims combination is selected so as to adjust the bearing play


within the specified limits. This ball head assembly is secured in place by another lock nut (7), tightened on the drive shaft against the Wheel hub end. The lock nut (7) is tightened till the intermediate lock nut (9) is secured firmly between the Inner bearing (4) and drive shaft (6), so as to prevent loosening of nut (9).
This arrangement locks the wheel hub (3) to the ball head housing (2) through Taper roller bearing (4). So in case of the drive shaft failure, the axial outward movement of the wheel hub (3), from axle housing (1), is prevented by intermediate locknut (9) which is held against the taper roller bearing (4), which is subsequently butting against the wall in ball head housing (2).
This design improvement in the present axle is done with minor modifications in the Ball head housing and Wheel hub without affecting the wheel track.
The foregoing description is a specific embodiment of the present invention. It should be appreciated that this embodiment is described for purpose of illustration only, and that numerous alterations and modifications may be practiced by those skilled in the art without departing from the spirit and scope of the invention. It is intended that all such modifications and alterations be included insofar as they come within the scope of the invention as claimed or the equivalents thereof.
Dated this 30th day of March 2009
TATA Motors Limited By their Agent & Attorney

(Kaxuna Goleria)
of I)e PENNING & De PENNING