5In yet another embodiment,
the
output shaf
t is arranged in line with
the
input shaft.
In
yet another embodiment,
the
input shaft,
the
countershaft and
the
output shaft are
splined shafts.
BRIEF DESCRIPT
ION OF THE ACCOMPANYING DRAWING
A
transmission system for a
tractor
,
of the present disclosure
,
will now be described
5
with the help of the accompanying drawing, in which:
Figure 1 illustrates a cross
-
sectional view of a conventional sliding mesh gearbox;
Figure 2 illustrates a cross
-
sectional view of a transmission system, in accordance
with an embod
iment of the present disclosure;
Figure 3 illustrates a sectional view of the transmission system, in accordance with
10
another embodiment of the present disclosure; and
Figure 4 illustrates a
nother
cross
-
sectional view of the transmission system depicting
a
n arrangement of a dog clutch assembly, in accordance with an embodiment of the
present disclosure.
LIST OF REFERENCE NUMERALS
15
100
–
Conventional arrangement
105
–
First
forward driving gear
110
–
First forward driven gear
115
–
Countershaft
120
–
Outpu
t
shaft
20
125
–
Shifter
rod
6
130
–
Shifter fork
135
–
Idler gear
200
–
Transmission
system
202
–
Housing
205
–
First
forward driving gear
5
210
–
First
forward driven gear
215
–
Countershaft
220
–
Output
shaft
225
–
Shifter
r
od
230
–
Countershaft spacer
10
235
–
First
spacer
240
–
Reverse
driven gear
245a
–
First
bush
245b
–
Second
bush
250
–
Shifting sleeve
15
255
–
Shifter fork
260
–
Second s
pacer
265
–
Circlip
7
270
–
Dog clutch assembly
275
–
Second forward driving gear
280
–
Second forward driven gear
285
–
I
nput shaft
290
–
First idler gear
5
295
–
First shaft
298
–
Second idler gear
DETAILED DESCRIPTION
Figure 1 illustrates a cross
-
sectional view of a conventional sliding mesh gearbox 100
(hereinafter also referred to as gearbox 100).
Typically, the gearbox 10
0 is used in
10
tractors. The gearbox 100 comprises
an input shaft (not shown in figures), a
countershaft 115, and an output shaft 120. The input shaft receives power from an
engine of a
tractor
. Further, the input shaft is coupled with the countershaft 115.
Forward/reverse driving gears, which are mounted on the countershaft
115
, are
selectively
engaged with
the
respective forward/reverse driven gears that are mounted
15
on the output shaft
120 to transfer power from the input shaft to the output shaft 120
.
The
engagement of the forward/reverse driven gears with the forward/reverse driving
gears is achieved by sliding the forward/reverse driven gears on the output shaft
120
using a
shifter fork 130. The shifter fork 130 is coupled with a
gear lever
(not shown
in
figures)
via a shifter rod 125
.
More specifically, t
o provide first forward motion to
20
the
tractor
, i.e., when the
tractor
is
subjected to
1st gear
transmission
,
a first forward
driving gear 105 mounted on the countershaft
115
is engaged with a first forwa
rd
driven gear 110 mounted on the output shaft 120. Further, to provide reverse motion
to the
tractor
, i.e., when the
tractor
is in reverse gear, the first forward driven gear 110
8
is engaged with an idler gear 135. The idler gear 135 is
coupled
with the fi
rst forward
driving gear 105. Therefore, to achieve first forward motion and reverse motion, the
first
forward
driven gear 110 needs to be displaced in order to engage the same either
with the first forward driving gear 105 directly
or through the idler ge
ar 135.
In some
agricultural operations, particularly in puddling operation, the transmission of the
5
tractor is frequently shifted from forward drive to reverse drive and vice versa.
However, an operator has a tendency not to reduce speed of the tractor wh
ile doing
such shifting. The frequent shifting of transmission from forward drive to reverse
drive and vice versa at higher speeds causes improper or partial engagement of first
forward driven gear 110 and first forward driving gear 105 which may damage to
oth
10
of both the gears
and idler cluster
. Further, improper or partial engagement of driven
and driving gears generates unpleasant noise, and adversely affects
the
functioning of
the gearbox.
The present disclosure envisages a transmission system for a
trac
tor
that
facilitates
smooth transmission of power
,
requires lesser efforts for gear shifting
, and
does not
15
generate unpleasant sound while shifting gears
.
The transmission system
for a
tractor
, of the present disclosure, is now described with
reference to
figure 2 through figure 4.
Figure 2 illustrates a cross
-
sectional view of a transmission system 200, in
accordance with an embodiment of the present disclosure. Figure 3 illustrates a
20
sectional view of the transmission system 200, in accordance with anothe
r
embodiment of the present disclosure. Figure 4 illustrates another cross
-
sectional
view of the transmission system 200 depicting an arrangement of a dog clutch
assembly 270, in accordance with an embodiment of the present disclosure.
The
transmission sys
tem 200
comprises a housing 202, an input shaft 285, a
25
countershaft 215, and an output shaft 220. The input shaft 285, the countershaft 215,
9
and the output shaft 220 are disposed within the housing 202. The input shaft 285 is
coupled
to
the
countershaft 21
5
, and configured to receive power from the engine of
the
tractor
.
More specifically, a drive shaft is concentrically mounted on the input
shaft 285. The drive shaft is engaged with the countershaft via a drive gear.
The
countershaft 215 is coupled to the
output shaft 220
, and
transfers
power from the
5
input shaft 285
to the countershaft 215
.
The transmission system 200 comprises a
plurality
of driving gears mounted on the
countershaft 215. More specifically, a first forward driving gear 205 and a second
f
orward driving gear 275 are rotatably mounted on the countershaft 215. Apart from
the first forward driving gear 205 and the second forward driving gear 275, other
10
driving
gears can also be mounted on the countershaft 215 as per the speed
requirement of th
e
tractor
.
A plurality of countershaft spacers 230 is mounted on the countershaft 215 between
the plurality of driving gears mounted on the countershaft 215.
The transmission system 200 further comprises a
first
idler gear 290 disposed within
15
the housing
202
, and
coupled
with the first forward driving gear 205.
In an
embodiment, the first idler gear 290
is
mounted on a first shaft 295. A second idler
gear 298 is mounted on the first shaft 295 which is constantly engaged with the first
forward driving gear
205.
The output shaft 220 is disposed within the housing
202
parallel to the countershaft
20
215. The output shaft 220 is coupled to a transmission member, i.e., wheels, of the
tractor
. The output shaft 220 is coupled to the countershaft 215 to receive powe
r
therefrom. The
coupling between the output shaft 220 and the countershaft 215 is
achieved by selectively engaging the plurality of driving gears with a plurality of
driven gears mounted on the output shaft 220.
25
10
In an embodiment, the output shaft 220 is
arranged in line with the input shaft 285
within the housing 202.
In
another embodiment, the input shaft 285, the countershaft 215 and the output shaft
220 are splined shafts to facilitate mounting of gears thereon.
Further, t
he transmission system 200 com
prises
a first forward driven gear 210, a
5
second forward driven gear 280, a reverse driven gear 240, and a dog clutch assembly
270.
The
first forward
driven gear 210
is
rotatably mounted on the output shaft 220 via a
first
bush
245a. The first
bush
245a fa
cilitates rotational motion of the
first forward
driven gear 210
on
the output shaft 220.
The first forward driven gear 210
is
10
configured to engage
with
the first forward driving gear 205. In an embodiment, t
he
first forward driven gear 210
is constantly e
ngaged with
the first forward driving gear
205.
The second forward driven gear 280 is
rotatably mounted on
the
output shaft
220.
The second forward driven gear 280 is
configured to selectively
engage
s
with the
15
second forward driving gear 275 mounted on the
countershaft 215. Both the
first
forward
driven gear 210 and the second forward driven gear 280 provide forward
motion to the
tractor
when engaged with
the
respective driving gears on the
countershaft 215.
The reverse driven gear 240 is rotatably mounted
on the output shaft 220 via a second
20
bush
245b. The second
bush
245b facilitates rotational motion of the reverse driven
gear 240
on
the output shaft 220.
The reverse driven gear 240 is configured to engage
with the first idler gear 290. In an embodiment,
t
he reverse driven gear 240 is
constantly engaged with the
first
idler gear 290.
11
Apart from the
first forward
driven gear 210, the second forward driven gear 280 and
the reverse driven gear 240,
other driven gears can also be mounted on the output
shaft 22
0 which can be selectively engaged with respective driving gears on the
countershaft 215 as per the speed requirement of the
tractor
.
In an
embodiment, the length of
each of
the first
bush
245a and the second
bush
245b
5
is 0.25 mm m
ore than the length of th
e respective driven gears.
The dog cutch assembly 270 is mounted on the output shaft 220 operatively between
the first forward driven gear 210 and the reverse driven gear 240. The dog clutch
assembly 270 is configured to selectively connect the first forw
ard driven gear 210 or
the reverse driven gear 240 to the output shaft 220. More specifically, to provide first
10
forward motion to the
tractor
, i.e., when the
tractor
is
subjected to
1
st
gear
transmission
, the dog clutch assembly 270 connects the first forw
ard driven gear 210
to the output shaft 220. On the other hand, to provide reverse motion to the
tractor
,
i.e., when the
tractor
is in reverse gear, the dog clutch assembly 270 connects the
reverse driven gear 240 to the output shaft 220.
The constant enga
gement of the first
15
forward driven gear 210
with
the first forward driving gear 205
and the reverse
driven gear 240 with
the idler gear 290
eliminates the possibility of partial
engagement of gears while shifting from 1
st
gear to reverse gear or vice vers
a.
The transmission system 200 further comprises a shifter fork 255. The shifter fork
255 is operatively coupled to a gear lever
(not shown in figures)
of the
tractor
via a
20
shifter rod 225. The shifter fork 255 abuts a shifting sleeve 250 of the dog clutch
assembly 270 such that the shifter fork
255 displaces the shifting sleeve 250 when the
gear lever is displaced in a predetermined direction, thereby connecting the first
forward driven gear 210 or the reverse driven gear 240 to the output shaft 220. When
the gear lever is displaced to
facilitate
1
st
gear transmission, the shifter
fork
255
25
displaces the shifting sleeve 250 towards the
first forward driven gear 210
to connect
the first forward driven gear 210
with the output shaft 220. Further, when the gear
12
lever is
displaced to
facilitate
reverse
gear transmission
, the
shifter
fork
255 displaces
the shifting sleeve 250 towards the reverse driven gear 240
to connect
the
reverse
driven gear 240 with the output shaft 220.
In an embodiment, a
n assembly of the f
irst forward driven gear 210, the dog clutch
assembly
270 and the reverse driven gear 240 is axially secured on the output shaft
5
220 via a circlip
2
65. The assembly
is secured at one end by a wall of the housing
202, and at the opposite end
by the circlip
2
65. A first spacer 235 is
mounted on the
output shaft 220 between the
circlip 2
65 and the first forward driven gear 210. A
second spacer 260 is mounted on the output shaft 220 proximal to the reverse driven
gear 240, more specifically
,
between the
bearing
on the output shaft 220 in
housing
10
202 and the reverse driven gear 240.
In an embodiment, the circlip 265 is a heavy duty circlip. In another embodiment, the
first spacer 235
is
a graded spacer
.
The circlip 265 prevents the axial slippage of the assembly
on the countershaft 215.
Further, the
first
spacer 235
reduces the play between the output shaft 220 and driven
15
gears. It was observed that, in conventional gearboxes, the play
of
the output shaft
and
the
driven gears was 0.7 mm, while in the transmission
system 200, the
play
in
stack of gears and hub of dog clutch
between the output shaft 220 and the
driven
gears
(
first forward driven gear 210 and the reverse driven gear 240
)
was 0.2 mm
.
An operator requires lesser efforts for shifting gears in the transmi
ssion system 200
as
20
compared to the conventional gearboxes
. In conventional gearboxes,
typically
the
gear lever is required to be displaced by
26
mm to
facilitate
1
st
gear transmission, and
by 20
.5
mm to
facilitate
a reverse gear transmission. In the trans
mission system 200,
the gear lever is required to be displaced by 9.5 mm to
facilitate
1
st
gear transmission,
and by 9.5 mm to
facilitate
a reverse gear transmission

WE CLAIM
1.A transmission system (200) for a tractor, said system (200) comprising:
an input shaft (285) configured to receive power from an engine of said tractor;
a countershaft (215) coupled to said input shaft (285), and configured to receive power from said input shaft (285);
a first forward driving gear (205) rotatably mounted on said countershaft (215);
a second forward driving gear (275) rotatably mounted on said countershaft (215);
a first idler gear (290) coupled to said first forward driving gear (205);
an output shaft (220) disposed parallel to said countershaft (215), and coupled to a transmission member of said tractor;
characterized in that,
a first forward driven gear (210) is rotatably mounted on said output shaft (220) via a first bush (245a), wherein said first forward driven gear (210) is configured to engage with said first forward driving gear (205);
a second forward driven gear (280) is rotatably mounted on said output shaft (220), wherein said second forward driven gear (280) is configured to selectively engage with said second forward driving gear (275);
a reverse driven gear (240) is rotatably mounted on said output shaft (220) via a second bush (245b), wherein said reverse driven gear (240) is configured to engage with said first idler gear (290); and
a dog clutch assembly (270) is mounted on said output shaft (220) between said first forward driven gear (210) and said reverse driven gear (240), said dog clutch assembly (270) is configured to selectively connect said first forward driven gear (210) or said reverse driven gear (240) to said output shaft (220).
2. The transmission system (200) as claimed in claim 1, wherein an assembly of said first forward driven gear (210), said dog clutch assembly (270) and said reverse driven gear (240) is axially secured on said output shaft (220) via a circlip (265).
3. The transmission system (200) as claimed in claim 2, wherein a first spacer (235) is mounted on said output shaft (220) between said circlip (265) and said first forward driven gear (210), and a second spacer (260) is mounted on said output shaft (220) proximal to said reverse driven gear (240).
4. The transmission system (200) as claimed in claim 1, which includes a shifter fork (255) operatively coupled to a gear lever of said tractor, said shifter fork (255) is configured to displace a shifting sleeve (250) of said dog clutch assembly (270) when said gear lever is displaced in a predetermined direction, thereby connecting said first forward driven gear (210) or said reverse driven gear (240) to said output shaft (220).
5. The transmission system (200) as claimed in claim 1, wherein said output shaft (220) is arranged in line with said input shaft (285).
6. The transmission system (200) as claimed in claim 1, wherein said input shaft (285), said countershaft (215) and said output shaft (220) are splined shafts.
, Description:FIELD
The present disclosure relates to the field of transmission systems for tractors.
BACKGROUND
A sliding mesh gearbox is used in tractors for transmitting power from an engine to wheels of the tractor. A conventional sliding mesh gearbox comprises an input shaft that receives power from an engine of the tractor. The input shaft is coupled to an output shaft of the gearbox via a countershaft. Forward/reverse driving gears, which are mounted on the countershaft, are engaged with respective forward/reverse driven gears that are mounted on the output shaft. The engagement of the forward/reverse driven gears with the forward/reverse driving gears is achieved by sliding the forward/reverse driven gears on the output shaft using a gear lever. This gear mechanism facilitates transmission of power from the countershaft to the output shaft. To provide first forward motion to the tractor, i.e., when the tractor is subjected to 1st gear transmission, a first driven gear mounted on the output shaft is engaged with a first driving gear mounted on the countershaft. Further, to provide reverse motion to the tractor, the same first driven gear mounted on the output shaft is coupled to the first driving gear mounted on the countershaft via an idler gear. Thus, the same first driven gear is displaced on the output shaft to engage it with the first driving gear either directly or via an idler gear to achieve the initial forward motion or the reverse motion. In some of the agricultural operations, particularly in puddling operation, the transmission of the tractor is frequently shifted from forward drive to reverse drive and vice versa. An operator has a tendency not to reduce speed of or to bring to halt the tractor while doing such shifting. The frequent shifting of transmission from forward drive to reverse drive and vice versa at higher speeds causes improper or partial engagement of driven gears and driving gears which may damage tooth of both the gears. Further, improper or partial engagement of driven and driving gears generates unpleasant noise and adversely affects functioning of the gearbox.
Therefore, there is felt a need of a transmission system for a tractor that alleviates the abovementioned drawbacks of the conventional gearboxes and provides a smooth power transmission in tractors.
OBJECTS
Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows:
An object of the present disclosure is to provide a transmission system for a tractor that facilitates smooth transmission of power from engine to the wheels of the tractor.
An object of the present disclosure is to provide a transmission system for a tractor in which improper engagement of gears is prevented.
Another object of the present disclosure is to provide a transmission system for a tractor that requires lesser efforts for gear shifting.
Another object of the present disclosure is to provide a transmission system for a tractor that does not generate an unpleasant sound while shifting the gears.
Other objects and advantages of the present disclosure will be more apparent from the following description, which is not intended to limit the scope of the present disclosure.
SUMMARY
The present disclosure envisages a transmission system for a tractor. The transmission system comprises an input shaft, a countershaft, a first forward driving gear rotatably mounted on the countershaft, a second forward driving gear rotatably mounted on the countershaft, a first idler gear, and an output shaft. The input shaft is configured to receive power from an engine of the tractor. The countershaft is coupled to the input shaft, and is configured to receive power from the input shaft. The first idler gear is coupled to the first forward driving gear. The output shaft is disposed parallel to the countershaft, and is coupled to a transmission member of the tractor. The transmission system further comprises a first forward driven gear, a second forward driven gear, a reverse driven gear, and a dog clutch assembly. The first forward driven gear is rotatably mounted on the output shaft via a first bush. Further, the first forward driven gear is configured to engage with the first forward driving gear. The second forward driven gear is rotatably mounted on the output shaft. The second forward driven gear is configured to selectively engage with the second forward driving gear. A reverse driven gear is rotatably mounted on the output shaft via a second bush. The reverse driven gear is configured to engage with the first idler gear. The dog clutch assembly is mounted on the output shaft between the first forward driven gear and the reverse driven gear. The dog clutch assembly is configured to selectively connect the first forward driven gear or the reverse driven gear to the output shaft.
An assembly of the first forward driven gear, the dog clutch and the reverse driven gear is axially secured on the output shaft via a circlip.
A first spacer (to control vertical moment of gears) is mounted on the output shaft between the circlip and the first forward driven gear. A second spacer is mounted on the output shaft proximal to the reverse driven gear.
The system further comprises a shifter fork operatively coupled to a gear lever of the tractor. The shifter fork is configured to displace a shifting sleeve of the dog clutch assembly when the gear lever is displaced in a predetermined direction, thereby connecting the first forward driven gear or the reverse driven gear to the output shaft.
In yet another embodiment, the output shaft is arranged in line with the input shaft. In yet another embodiment, the input shaft, the countershaft and the output shaft are splined shafts.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
A transmission system for a tractor, of the present disclosure, will now be described with the help of the accompanying drawing, in which:
Figure 1 illustrates a cross-sectional view of a conventional sliding mesh gearbox;
Figure 2 illustrates a cross-sectional view of a transmission system, in accordance with an embodiment of the present disclosure;
Figure 3 illustrates a sectional view of the transmission system, in accordance with another embodiment of the present disclosure; and
Figure 4 illustrates another cross-sectional view of the transmission system depicting an arrangement of a dog clutch assembly, in accordance with an embodiment of the present disclosure.
LIST OF REFERENCE NUMERALS
100 – Conventional arrangement
105 – First forward driving gear
110 – First forward driven gear
115 – Countershaft
120 – Output shaft
125 – Shifter rod
130 – Shifter fork
135 – Idler gear
200 – Transmission system
202 – Housing
205 – First forward driving gear
210 – First forward driven gear
215 – Countershaft
220 – Output shaft
225 – Shifter rod
230 – Countershaft spacer
235 – First spacer
240 – Reverse driven gear
245a – First bush
245b – Second bush
250 – Shifting sleeve
255 – Shifter fork
260 – Second spacer
265 – Circlip
270 – Dog clutch assembly
275 – Second forward driving gear
280 – Second forward driven gear
285 – Input shaft
290 – First idler gear
295 – First shaft
298 – Second idler gear
DETAILED DESCRIPTION
Figure 1 illustrates a cross-sectional view of a conventional sliding mesh gearbox 100 (hereinafter also referred to as gearbox 100). Typically, the gearbox 100 is used in tractors. The gearbox 100 comprises an input shaft (not shown in figures), a countershaft 115, and an output shaft 120. The input shaft receives power from an engine of a tractor. Further, the input shaft is coupled with the countershaft 115. Forward/reverse driving gears, which are mounted on the countershaft 115, are selectively engaged with the respective forward/reverse driven gears that are mounted on the output shaft 120 to transfer power from the input shaft to the output shaft 120. The engagement of the forward/reverse driven gears with the forward/reverse driving gears is achieved by sliding the forward/reverse driven gears on the output shaft 120 using a shifter fork 130. The shifter fork 130 is coupled with a gear lever (not shown in figures) via a shifter rod 125. More specifically, to provide first forward motion to the tractor, i.e., when the tractor is subjected to 1st gear transmission, a first forward driving gear 105 mounted on the countershaft 115 is engaged with a first forward driven gear 110 mounted on the output shaft 120. Further, to provide reverse motion to the tractor, i.e., when the tractor is in reverse gear, the first forward driven gear 110 is engaged with an idler gear 135. The idler gear 135 is coupled with the first forward driving gear 105. Therefore, to achieve first forward motion and reverse motion, the first forward driven gear 110 needs to be displaced in order to engage the same either with the first forward driving gear 105 directly or through the idler gear 135. In some agricultural operations, particularly in puddling operation, the transmission of the tractor is frequently shifted from forward drive to reverse drive and vice versa. However, an operator has a tendency not to reduce speed of the tractor while doing such shifting. The frequent shifting of transmission from forward drive to reverse drive and vice versa at higher speeds causes improper or partial engagement of first forward driven gear 110 and first forward driving gear 105 which may damage tooth of both the gears and idler cluster. Further, improper or partial engagement of driven and driving gears generates unpleasant noise, and adversely affects the functioning of the gearbox.
The present disclosure envisages a transmission system for a tractor that facilitates smooth transmission of power, requires lesser efforts for gear shifting, and does not generate unpleasant sound while shifting gears.
The transmission system for a tractor, of the present disclosure, is now described with reference to figure 2 through figure 4.
Figure 2 illustrates a cross-sectional view of a transmission system 200, in accordance with an embodiment of the present disclosure. Figure 3 illustrates a sectional view of the transmission system 200, in accordance with another embodiment of the present disclosure. Figure 4 illustrates another cross-sectional view of the transmission system 200 depicting an arrangement of a dog clutch assembly 270, in accordance with an embodiment of the present disclosure.
The transmission system 200 comprises a housing 202, an input shaft 285, a countershaft 215, and an output shaft 220. The input shaft 285, the countershaft 215, and the output shaft 220 are disposed within the housing 202. The input shaft 285 is coupled to the countershaft 215, and configured to receive power from the engine of the tractor. More specifically, a drive shaft is concentrically mounted on the input shaft 285. The drive shaft is engaged with the countershaft via a drive gear. The countershaft 215 is coupled to the output shaft 220, and transfers power from the input shaft 285 to the countershaft 215.
The transmission system 200 comprises a plurality of driving gears mounted on the countershaft 215. More specifically, a first forward driving gear 205 and a second forward driving gear 275 are rotatably mounted on the countershaft 215. Apart from the first forward driving gear 205 and the second forward driving gear 275, other driving gears can also be mounted on the countershaft 215 as per the speed requirement of the tractor.
A plurality of countershaft spacers 230 is mounted on the countershaft 215 between the plurality of driving gears mounted on the countershaft 215.
The transmission system 200 further comprises a first idler gear 290 disposed within the housing 202, and coupled with the first forward driving gear 205. In an embodiment, the first idler gear 290 is mounted on a first shaft 295. A second idler gear 298 is mounted on the first shaft 295 which is constantly engaged with the first forward driving gear 205.
The output shaft 220 is disposed within the housing 202 parallel to the countershaft 215. The output shaft 220 is coupled to a transmission member, i.e., wheels, of the tractor. The output shaft 220 is coupled to the countershaft 215 to receive power therefrom. The coupling between the output shaft 220 and the countershaft 215 is achieved by selectively engaging the plurality of driving gears with a plurality of driven gears mounted on the output shaft 220.
In an embodiment, the output shaft 220 is arranged in line with the input shaft 285 within the housing 202.
In another embodiment, the input shaft 285, the countershaft 215 and the output shaft 220 are splined shafts to facilitate mounting of gears thereon.
Further, the transmission system 200 comprises a first forward driven gear 210, a second forward driven gear 280, a reverse driven gear 240, and a dog clutch assembly 270.
The first forward driven gear 210 is rotatably mounted on the output shaft 220 via a first bush 245a. The first bush 245a facilitates rotational motion of the first forward driven gear 210 on the output shaft 220. The first forward driven gear 210 is configured to engage with the first forward driving gear 205. In an embodiment, the first forward driven gear 210 is constantly engaged with the first forward driving gear 205.
The second forward driven gear 280 is rotatably mounted on the output shaft 220. The second forward driven gear 280 is configured to selectively engages with the second forward driving gear 275 mounted on the countershaft 215. Both the first forward driven gear 210 and the second forward driven gear 280 provide forward motion to the tractor when engaged with the respective driving gears on the countershaft 215.
The reverse driven gear 240 is rotatably mounted on the output shaft 220 via a second bush 245b. The second bush 245b facilitates rotational motion of the reverse driven gear 240 on the output shaft 220. The reverse driven gear 240 is configured to engage with the first idler gear 290. In an embodiment, the reverse driven gear 240 is constantly engaged with the first idler gear 290.
Apart from the first forward driven gear 210, the second forward driven gear 280 and the reverse driven gear 240, other driven gears can also be mounted on the output shaft 220 which can be selectively engaged with respective driving gears on the countershaft 215 as per the speed requirement of the tractor.
In an embodiment, the length of each of the first bush 245a and the second bush 245b is 0.25 mm more than the length of the respective driven gears.
The dog cutch assembly 270 is mounted on the output shaft 220 operatively between the first forward driven gear 210 and the reverse driven gear 240. The dog clutch assembly 270 is configured to selectively connect the first forward driven gear 210 or the reverse driven gear 240 to the output shaft 220. More specifically, to provide first forward motion to the tractor, i.e., when the tractor is subjected to 1st gear transmission, the dog clutch assembly 270 connects the first forward driven gear 210 to the output shaft 220. On the other hand, to provide reverse motion to the tractor, i.e., when the tractor is in reverse gear, the dog clutch assembly 270 connects the reverse driven gear 240 to the output shaft 220. The constant engagement of the first forward driven gear 210 with the first forward driving gear 205 and the reverse driven gear 240 with the idler gear 290 eliminates the possibility of partial engagement of gears while shifting from 1st gear to reverse gear or vice versa.
The transmission system 200 further comprises a shifter fork 255. The shifter fork 255 is operatively coupled to a gear lever (not shown in figures) of the tractor via a shifter rod 225. The shifter fork 255 abuts a shifting sleeve 250 of the dog clutch assembly 270 such that the shifter fork 255 displaces the shifting sleeve 250 when the gear lever is displaced in a predetermined direction, thereby connecting the first forward driven gear 210 or the reverse driven gear 240 to the output shaft 220. When the gear lever is displaced to facilitate 1st gear transmission, the shifter fork 255 displaces the shifting sleeve 250 towards the first forward driven gear 210 to connect the first forward driven gear 210 with the output shaft 220. Further, when the gear lever is displaced to facilitate reverse gear transmission, the shifter fork 255 displaces the shifting sleeve 250 towards the reverse driven gear 240 to connect the reverse driven gear 240 with the output shaft 220.
In an embodiment, an assembly of the first forward driven gear 210, the dog clutch assembly 270 and the reverse driven gear 240 is axially secured on the output shaft 220 via a circlip 265. The assembly is secured at one end by a wall of the housing 202, and at the opposite end by the circlip 265. A first spacer 235 is mounted on the output shaft 220 between the circlip 265 and the first forward driven gear 210. A second spacer 260 is mounted on the output shaft 220 proximal to the reverse driven gear 240, more specifically, between the bearing on the output shaft 220 in housing 202 and the reverse driven gear 240.
In an embodiment, the circlip 265 is a heavy duty circlip. In another embodiment, the first spacer 235 is a graded spacer.
The circlip 265 prevents the axial slippage of the assembly on the countershaft 215. Further, the first spacer 235 reduces the play between the output shaft 220 and driven gears. It was observed that, in conventional gearboxes, the play of the output shaft and the driven gears was 0.7 mm, while in the transmission system 200, the play in stack of gears and hub of dog clutch between the output shaft 220 and the driven gears (first forward driven gear 210 and the reverse driven gear 240) was 0.2 mm.
An operator requires lesser efforts for shifting gears in the transmission system 200 as compared to the conventional gearboxes. In conventional gearboxes, typically the gear lever is required to be displaced by 26 mm to facilitate 1st gear transmission, and by 20.5 mm to facilitate a reverse gear transmission. In the transmission system 200, the gear lever is required to be displaced by 9.5 mm to facilitate 1st gear transmission, and by 9.5 mm to facilitate a reverse gear transmission.
Further, the dog clutch assembly 270 is configured to smoothly shift reverse drive to forward drive or vice versa at speed upto 5 km/hr.
In an operative configuration, to facilitate 1st gear transmission, the gear lever is displaced in first predetermined direction such that the shifter fork 255 displaces the shifter sleeve 250 towards the first forward driven gear 210 to connect the first forward driven gear 210 to the output shaft 220. Similarly, to facilitate reverse gear transmission, the gear lever is displaced in second predetermined direction such that the shifter fork 255 displaces the shifter sleeve 250 towards the reverse driven gear 240 to connect the reverse driven gear 240 to the output shaft 220.
The transmission system 200 facilitates smooth transmission of power from engine to wheels as partial engagement of gears is prevented. Further, there is no noise generation while shifting gears in the transmission system 200.
Although the transmission system 200 is described with reference to a tractor, the transmission system of the present disclosure can be fitted in any type of vehicle with appropriate changes.
TECHNICAL ADVANCEMENTS
The present disclosure described herein above has several technical advantages including, but not limited to, the realization of a transmission system for a tractor:
• that facilitates smooth transmission of power from the engine to the wheels of the tractor;
• in which improper engagement of gears is prevented;
• that requires lesser efforts for gear shifting; and
• that does not generate an unpleasant sound while shifting the gears.
The foregoing disclosure has been described with reference to the accompanying embodiments which do not limit the scope and ambit of the disclosure. The description provided is purely by way of example and illustration.
The embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
The foregoing description of the specific embodiments so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.
Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.
The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results.
Any discussion of documents, acts, materials, devices, articles or the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.
The numerical values mentioned for the various physical parameters, dimensions or quantities are only approximations and it is envisaged that the values higher/lower than the numerical values assigned to the parameters, dimensions or quantities fall within the scope of the disclosure, unless there is a statement in the specification specific to the contrary.
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 disclosure. These and other changes in the preferred embodiment as well as other embodiments of the disclosure 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 disclosure and not as a limitation