FORM 2
THE PATENTS ACT 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See Section 10; rule 13)
TITLE OF THE INVENTION
Gear Box Assembling Process and Equipment for Pressing Bearings
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
INVENTOR
GAVANDI SUDHIR S
An Indian National
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 particularly describes the invention and the manner
in which it is to be performed.

TITLE OF INVENTION:
Gear box assembling process and equipment for pressing bearings
FIELD OF INVENTION:
The invention generally relates to gear box assembly and particularly to a pressing of bearings on shafts in gear box assembly. More particularly to a gear box assembling process and an equipment to avoid a bearing press load exerted on a lower half of the gear box assembly.
BACKGROUND OF THE INVENTION:
A gearbox assembly transmits selective speed and torque from power source to the vehicle wheels. The gearbox assembly is regularly subjected to load, fatigue, friction and heat during assembling process. Some times it leads to seizer of gearbox if the bearings are not properly pressed. To overcome these factors proper lubrication is provided to the sliding parts. In addition, to minimize the effect of friction and heat the shafts inside the gearbox assembly are fitted with appropriate bearings at ends. It is also important to avoid any excessive load exerting on gearbox housing which may lead to permanent deformation of housings resulting in poor performance or failure of gearbox. The failed gearbox requires to be removed from the vehicle and calls for replacement of defective parts or entire gearbox.
In conventional gear box assembly the bearings are fitted in the lower half of the gear box assembly and then the shafts are placed in the bearings. Another set of bearings are fitted in the upper half of the gear box assembly. After mounting the upper half of the gear box assembly on the lower half, a hallow metallic dollies are kept on the bearings resting on the inner race of bearings in upper half. The metallic dollies envelopes the shafts. Both the dollies are hammered down progressively till both the lower half and upper half of the gear box assembly touch each other.

Hammering is time taking, and is an unsafe act. Also, hammering may lead to bearing failure. Moreover the shafts on which the bearings are to be fitted will get distorted due to the load exerted by the bearings on shaft. During assembly of bearings with shafts, a load of around four tons will be exerted on the shafts due to interference fit. Under such load the lower half of the gearbox assembly will get distorted. Hence there is a need to provide a system and method to avoid the load exerted on lower half of the gear box assembly during bearing pressing.
OBJECT OF THE INVENTION
The primary object of the present invention is to obviate the above mentioned drawbacks.
Another object of the invention is to provide a gear box assembling process and an equipment to avoid the bearing pressing load exerted on the lower half of the gear box assembly.
Yet another object of the present invention is to provide a gearbox assembling process and an equipment to press fit the lower half cast housing with the upper half casting housing of the gear box assembly.
Yet another object of the present invention is to provide a gearbox assembling process and equipment to avoid damages or distortion to the gearbox housing during assembling of the bearings on a shaft.
SUMMARY OF THE INVENTION
The various embodiments of the present invention provide a gear box assembling process and an equipment to avoid a bearing pressing load exerted on the lower half of the gear box assembly. The gearbox assembling equipment comprises a base

structure having a fixture provided for mounting said gear box assembly. The gear box assembly comprises an upper half casting housing mounted on the lower haft casting housing, a plurality of shafts having threaded ends at top and a plurality of bearings for interference fit with said plurality of shafts. The base structure at its top portion includes a base plate with plurality of holes. A bracket with plurality of holes corresponding to said base plate is slidably mounted below said base plate. A plurality of hydro pneumatic cylinders is provided on said base plate. A piston or rod of said hydraulic cylinder is connected to said bracket to reciprocate said bracket over plurality of guides. Said bracket is actuated to slide over said guides by pneumatic cylinder. A thrust plate is provided above said base plate. A plurality of suspenders is bolted to said thrust plate towards one end and other end of said plurality of suspenders includes a threaded coupler for coupling with shafts in said gearbox assembly. The suspenders reciprocate through the plurality of holes in said base plate and said bracket. A plurality of sliding dollies is bolted below said holes in said bracket for pressing bearings on shaft during gearbox assembling process.
According to present invention, the fixture includes a gearbox orientation pin and a locating bore for precise mounting of said gearbox. The suspenders are bolted to the thrust plate to restrict its movement during gearbox assembling process and to avoid the pressure exerted on the gearbox assembly. The load on the unequal sized bearings is adjusted by varying the guide plate on bracket. By actuating the hydro pneumatic cylinder the dollies mounted on the bracket starts moving down and rest on the inner race of bearings on gearbox to assemble the bearings on shaft without applying pressure on gearbox assembly. The bearing pressing continues till the bearings rests on collars of shafts. At this position the upper half cast housing touches the lower half cast housing at joint face. The suspenders are mounted on the thrust plate which rests on the base plate when the suspenders are lowered by actuating pneumatic cylinder. When the pressing of bearings is in progress, the

pressing force is borne by thrust plate and base plate to avoid the pressure exerted on lower half cast housing during bearing pressing.
According to embodiment of the present invention, the gear box assembling process for pressing bearings on shafts, comprising steps of mounting a top half casting housing on a bottom half cast housing of said gear box assembly on a fixture provided on a base structure. The plurality of shafts is inserted through the plurality of bearings in said gearbox assembly up to free diameter of shafts. The shafts includes a thread ends at the top. Then the plurality of suspenders mounted on base plate of said support structure are actuated for connecting said thread end on said shaft with a threaded couplers in said suspenders to suspend said plurality of shafts. Then the bracket with sliding dollies provided on said support structure is actuated for pressing said plurality of bearings on inner race of the bearings. The top half cast housing is press fitted with the bottom half cast housing simultaneously while pressing bearings on shaft. The threaded couplers are then disengaged from said shafts and the suspenders are actuated to move to top position to take out the gearbox assembly. According to present invention, while pressing the bearings on shafts the suspenders are firmly held up by thrust plate. With this the pressing load will be borne by suspenders and the thrust plate and no load will be exerted on the lower half cast housing.
According to present invention, the diameter of said plurality of bearings to be pressed with shafts is not equal. The load on the unequal sized bearings is adjusted by varying the guide plate on said base structure. The suspenders along with threaded couplers are actuated by a hydro pneumatic cylinder. The threaded connectors are engaged manually with said shafts. By actuating said hydro pneumatic cylinder said dollies mounted on said bracket starts moving down and rest on the inner race of bearings on gearbox to assemble the bearings on shaft without

applying pressure on gearbox assembly. The bearing pressing will continue till the bearings rests on collars of shafts. At this position the upper half cast housing touches the lower half cast housing at joint interface. The suspenders are mounted on thrust plate, when the suspenders are lowered by actuating pneumatic cylinder, the thrust plate rest on the base plate. When the pressing of bearings is in progress, the pressing force is borne by thrust plate and base plate. This mechanism will avoid any pressure being exerted on lower half during bearing pressing. The bearings may be single row bearing or double row bearing as a result the guide is provided to avoid skewing of base plate during bearing pressing.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a cross sectional view of the gear box assembly, according to one
embodiment of the present invention.
FIG. 2 shows a perspective view of the gearbox assembling equipment, according to
embodiment of the present invention.
FIG. 3 shows a sectional view of the first stage of the bearing pressing process with
both the upper half and lower half of the gearbox assembly placed on each other,
according to present invention.
FIG. 4 shows a sectional view of second stage of bearing pressing process when the
suspenders are lowered and connectors are engaged, according to present invention.
FIG. 5 shows a sectional view of third stage of bearing pressing process when the
dollies are lowered and in contact with bearings, according to present invention.
Fig. 6 shows a sectional view of fourth stage of bearing pressing process when the
bearing pressing is complete and bearings are touching to shaft collars, according
present invention.
FIG. 7 shows a sectional view of fifth stage of bearing pressing process when the
connectors are disengaged and suspenders moved up to take out the gearbox
assembly, according to present invention.

FIG. 8 shows an exploded plan view of the gearbox assembling equipment, according to present invention.
DETAILED DESCRIPTION
Referring now 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.
The various embodiments of the present invention provide a gear box assembling process and an equipment 31 to avoid the bearing pressing load exerted on the lower half cast housing 7 of the gear box assembly 30. The cross sectional view of the gear box assembly 30 is as shown in FIG. 1. The gearbox assembly 30 includes a lower half cast housing 7 and an upper half cast housing 8, The upper half cast housing 8 is placed on the lower half cast housing 7, with counter shaft 1 and main shaft 2 inserted through the bearing 3 and bearing 4 in upper half 8 up to free diameter of the shafts. Both the housings are joined with a studs and nuts after assembling the upper half with lower half. The drive shaft 9 is fitted to the lower half cast housing 7 with bearing. The counter shaft 1 and main shaft 2 is locked in the bearing 5 and bearing 6. The bearing 5 is a roller bearing and fitted in drive shaft bore. The bearing 6 is fitted in lower half cast housing 7 of the gearbox assembly 30 and is held in position with circlip. A bearing 3 and bearing 4 is fitted in the upper half cast housing 8 of the gear box assembly 30, both the bearings are held in position with circlips. The bearing 3 and bearing 5 holds the counter shaft 1. The bearing 4 and bearing 6 holds the main shaft 2. The bearing 3 and bearing 4 includes an interference fit with shafts 1 and 2, as a result a force is applied on the lower half of the gearbox assembly. According to present invention, the shaft 1 and shaft; 2 are suspended from the top by using an gear box assembling equipment 31 while pressing the bearing 3 and bearing

4 to avoid the load exerted on lower half cast housing 7 of the gearbox assembly 30. The Shafts 1 and 2 includes a threaded ends at the top.
The perspective view of a gearbox assembling equipment 31 is as shown in FIG. 2. The gearbox assembling equipment 31 comprises a base structure 29 having a fixture provided for mounting said gear box assembly 30. The fixture 26 comprises a gearbox locating bore 27 and a gearbox orientation pin 28 for precise mounting of gearbox on the fixture. The gear box assembly 30 (FIG. 1) comprises an upper half casting housing 8 mounted on the lower haft casting housing 7, a plurality of shafts having threaded ends at top and a plurality of bearings for interference fit with said plurality of shafts. The base structure 29 at its top portion includes a base plate 22 with plurality of holes. A bracket 21 with plurality of holes corresponding to said base plate 22 is slidably mounted below said base plate 22. A plurality of hydro pneumatic cylinders 11 is provided on said base plate 22. A piston or rod 19 of said hydraulic cylinder 11 is connected to the bracket 21 to reciprocate said bracket 21 over the plurality of guides 23 and 24. The bracket 21 is actuated to slide over said guides 23 and 24 by pneumatic cylinder 12. A thrust plate 20 is provided above the base plate 22. A plurality of suspenders 13 and 14 is bolted to the thrust plate 20 towards one end and other end of said plurality of suspenders 13 and 14 includes a threaded coupler 15 and 16 for coupling with shafts 1 and 2 in said gearbox assembly 30. The suspenders 13 and 14 reciprocate through the plurality of holes in said base plate 22 and the bracket 21. A plurality of sliding dollies 17 and 18 is bolted below said holes in said bracket 21 for pressing bearings 3 and 4 on shaft 1 and 2 during gearbox assembling process.
According to present invention, the suspenders 13 and 14 are bolted to the thrust plate 20 to restrict the movement of the suspenders 13 and 14 during gearbox assembling process and to avoid the pressure exerted on the gearbox assembly 30.

The diameter of said plurality of bearings to be pressed with shafts is not equal. The load on the unequal sized bearings is adjusted by varying the guide plate on said base structure 29. The bearing 3 is a single row bearing and bearing 4 is a double row bearing, as a result their pressing action will start with 5mm gap. To avoid skewing of common plate 24 due to this, guide 13 is provided. The load on the unequal sized bearings is adjusted by varying the guide plate 23 and 24 on bracket 21. By actuating the hydro pneumatic cylinder 11 the dollies 17 and 18 mounted on the bracket 21 starts moving down and rest on the inner race of "bearings 3 and 4 on gearbox to assemble the bearings on shaft 1 and 2 without applying pressure on gearbox assembly. The pressing will continue till the bearings 3 and 4 rests on collars of shafts 1 and 2. At this position the upper half cast housing 8 touches the lower half cast housing 7 at interface. The suspenders 13 and 14 are mounted on the thrust plate 20, when the suspenders are lowered by actuating pneumatic cylinder 12, the thrust plate 20 rests on the base plate 22. When the pressing of bearings is in progress, the pressing force is borne by thrust plate 20 and base plate 22. This mechanism will avoid any pressure being exerted on lower half 7 during bearing pressing. The exploded view of the gearbox assembling equipment 31 is shown in FIG. 8
FIG. 3 to FIG. 7 shows a sectional view of the first stage, second stage, third stage, fourth stage and fifth stage of the bearing pressing process, according to present invention. In first stage of gear box assembling and bearing press process the sub assembly of upper half cast housing 8 is placed on the lower half cast housing 7, with shafts 1 and 2 inserted through bearing 3 and 4 in upper half 8 up to free diameter of the shafts, as shown in FIG. 3.
In second stage of the gearbox assembling and bearing press process, the suspenders 13 and 14 along with threaded coupler 15 and 16 are lowered by actuating the pneumatic cylinder 12. Then the threaded connectors 20 and 21 are engaged

manually with shafts 1 and 2, as shown in FIG. 4. When the suspender 13 and 14 are lowered the thrust plate 20 rests on the base plate 22. When the pressing of bearings 3 and 4 is in progress, the pressing force is borne by thrust plate 20 and base plate 22. This mechanism will avoid any pressure being exerted on lower half 7 during bearing pressing. The bearing 3 is a single row bearing and bearing 4 is a double row bearing, as a result their pressing action will start with 5mm gap. To avoid skewing of common plate 24 due to this, guide 13 is provided.
In third stage of the gearbox assembling and bearing press process, the sliding dollies 17 and 18 bolted to the bracket 21 is lowered by actuating a twin hydro pneumatic cylinder 11 to come in contact with bearings 3 and 4. The dollies 17 and 18 will start moving down and rests on the inner race of bearings 3 and 4. The bearing pressing will continue till the bearings 3 and 4 rests on collars of shafts 1 and 2, as shown in FIG. 5.
The fourth stage of the gearbox assembling and bearing pressing process is as shown in FIG. 6. At this stage the bearing pressing is complete further the bearings 3 and 4 are resting on the collars of shafts 1 and 2. Simultaneously, upper half cast housing 8 touches the lower half cast housing 7 of the gearbox assembly at joint interface.
The stage 5 of the gearbox assembling and bearing pressing process is as shown in FIG. 7. The dollies 17 and 18 are retracted and after manually disengaging the threaded connectors 15 and 16, the suspenders 13 and 14 are withdrawn to take out the gearbox assembly. The present invention is applicable to assemble two separate units in which interference fit bearing assembly is required. The exploded plan view of the gearbox assembling equipment is as shown in FIG. 8.

ADVANTAGES
• To provide a gear box assembling process and equipment to avoid the bearing pressing load exerted on the lower half of the gear box assembly during bearing pressing.
• To assemble the gearbox without causing any damages or distortion of gearbox housing during the press fit assembly of the bearing on two shafts.
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.

We claim:
1. A gearbox assembling equipment, comprising;
a base structure having a fixture provided for mounting said gear box; said gear box assembly having a upper half casting housing mounted on lower half casting housing, a plurality of shafts having threaded ends at top and a plurality of bearings for interference fit with said plurality of shafts; said base structure at its top portion having a base plate with plurality of holes, a bracket 21 with plurality of holes corresponding to said base plate is slidably mounted below said base plate;
a plurality of actuators provided on said base plate; a piston or rod of said actuators is connected to said bracket to reciprocate said bracket over plurality of guides;
a thrust plate provided above said base plate 22, a plurality of suspenders bolted to said thrust plate towards one end and other end of said plurality of suspenders includes a threaded coupler for coupling with shafts in said gearbox assembly, said suspenders reciprocates through said plurality of holes in said base plate and said bracket, said suspenders are actuated to suspend said shafts during gearbox assembling process;
a plurality of sliding dollies bolted below said holes in said bracket for pressing bearings on shaft during gearbox assembling process;
2. The equipment according to claim 1, wherein said fixture having a gearbox orientation pin and gear box locating bore for precise mounting of said gearbox;
3. The equipment according to claim 1. wherein said suspenders are bolted to said thrust plate to restrict the movement of said suspenders during gearbox assembling process and to avoid the pressure exerted on said gearbox assembly.

4. The equipment according to claim 1, wherein the load on the unequal sized bearings is adjusted by varying the guide plate on common plate.
5. The equipment according to claim 1, wherein said plurality of actuators provided to reciprocate said bracket over plurality of guides is a hydro pneumatic cylinder.
6. The equipment according to claim 1, wherein said actuators for provided for suspending said suspenders is a pneumatic cylinder.
7. The equipment according to claim 1, wherein the diameter of said plurality of bearings to be pressed with shafts are not equal.
8. The equipment according to claim 1, wherein said bearing may be single row bearing or a double row bearing.
9. The equipment according to claim 1, wherein said guide is provided to avoid skewing of base plate during bearing pressing.

10. The equipment according to claim 1, wherein the load on the unequal sized bearings is adjusted by varying the guide plate on said base structure.
11. The equipment according to claim , wherein said thrust plate 20 is provided to resist the bearing pressing force exerted on lower of cast housing of gearbox assembly.
12. A gear box assembling process for pressing bearings on shafts, comprising steps of;

mounting a top half cast housing on a bottom half" cast housing of said gear box
assembly on a fixture provided on a base structure;
inserting a plurality of shafts through a plurality of bearings in said gearbox
assembly up to free diameter of shafts; said shafts having thread ends at top;
actuating a plurality of suspenders mounted on base plate of said support structure
for connecting said thread end on said shaft with a threaded couplers in said
suspenders to suspend said plurality of shafts;
actuating a bracket with silding dollies provided on said support structure for
reciprocating on a guide plate for pressing said plurality of bearings on inner race of
the bearings;
press fit assembling of top half cast housing with the bottom half cast housing
simultaneously while pressing bearings on shaft; and
disengaging said threaded couplers from said shafts and actuating the suspenders to
move to original position to take out the gearbox assembly.
13, The process according to claim 12, wherein said threaded couplers are engaged manually with said shafts.
14, The process according to claim 12, wherein the suspenders 15 and 16 along with threaded coupler 20 and 21 are actuated by an pneumatic cylinder.
15, The process according to claim 12, wherein said thrust plate is rested on the base plate when said suspenders are lowered by actuating pneumatic cylinder.
16, The process according to claim 12, wherein by actuating a said hydro pneumatic cylinder said dollies mounted on said bracket starts moving down and rests on the inner race of bearings on gearbox to assemble the bearings on shaft without applying pressure on gearbox assembly.

17. The process according to claim 12, wherein said bearing pressing will continue till said bearings rests on the shafts and the upper half cast housing touches the lower half cast housing of gearbox assembly at the joint interface.
18. The process according to claim 12, wherein resting of thrust plate on base plate while pressing bearings on shaft to avoid the bearing pressing force exerted on the lower half cast hosing of gearbox assembly.