Note: Descriptions are shown in the official language in which they were submitted.
A METHOD OF CHANGING Tl-IE NUMBER OF
SPEED RATIOS WITHIN A TRANSMISSION
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Technical Field
The present invention relates generally to
transmissions for frameless tractors and the like, and
more particularly to a method of changing the number of
speed ratios within a transmission housing after the
initial buildup of the trac-tor.
Background Art
I-t may be sometimes desireable -to change the
number of speed ratios within -the driveline of the vehicle
after the vehicle has been initially built. In some
vehicles this is possible by simply adding a further
transmission either before or after the initial trans-
mission whereby -the number of speed ratios can be
increased. However, while this is possible in vehicles
having a separate frame, this has not been possible in
frameless tractors wherein the transmission housing along
with the rear or center housing and the engine block form
the tractor frame.
It is known from U.S. Patent 3,382,735 issued
14 May, 1968 to provide a transmission housing for a
frameless tractor wherein the transmission housing can be
provided with a first change gear mechanism, or alterna-
tively first and second change gear mechanisms, the second
change gear mechanism being designed for industrial appli-
cations and including a torque converter and a hydrauli-
cally operated reversing mechanism.
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Disclosure of Invention
The present invention relates to a method of
converting a transmission from a first number of speed
ratios to another. This method is accornplished by provid-
ing a transmission with a first change gear mechanism andinterchangeable second change gear mechanisms. The first
change gear mechanism is common to all transmissions and
does not include the forward/reverse mechanism as this is
included in the interchangeable second gear change mecha-
nisms. Thus, according to this invention, a transmissionis provided inc].uding a housing provided with an inwardly
e~tending annular flange, a fi.rst change gear mechanism
mounted within the housing to one side of the annular
flange, and an initial second change gear mechanism which
is removably mounted on the inwardLy extending annular
flange, the initial second change gear mechanism including
a forward/reverse change gear mechanism. In addition, a
further second change gear mechanism is provided which also
includes a forward/reverse chancle gear mechanism and a
number of speed ratios in one direc-tion different than
the initial second change gear mechanism. When changing
the number of speed ratios, the initial second change gear
mechanism is removed from the transmission housing and the
further second change gear mechanism is installed within
the housing. I'he initial second change gear mechanism may
include only the forward/reverse mechanism. It may also
include a two-speed planetary gear change mechanism in
addition to a forward/reverse mechanism. In the embodi-
ments described above, the second gear change mechanism
will include a shift rail connec-table to a shif-ting mecha-
nism carried by a shift cover mounted on one side of the
transmission housing. It will also be necessary when
performing the method oE this invention to initially
remove the shift cover before removing the ini-tial second
change gear mechanism, and, after installing -the further
change gear mechanism to reinstall the shift cover to
couple the shift rail with the shifting mechanism.
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Brief Description of Drawings
Figure 1 is a sicle view of a frameless tractor
in which the principles of the present invention are
incorporated.
Figure 2 is a sectional view of one -transmission
option.
Figure 3 is an enlarged view of a portion of the
transmission shown in Figure 2.
F~igure 4 is a section taken generally along the
line 4-4 in Figure 3.
Figure 5 is a section taken generally along the
line 5-5 in Figure 4.
Figure 6 is a view similar to Figure 3 showing
a second transmission option.
Detailed Description
Referring first to Fi.gure 1, a frameless trac-tor
is il].ustrated, the tractor being indicated generally at
10 and including an engine 12, a transmission indicated
generally at 14, the transmission including a housing 16,
a rear or center housing 18, and an axle housing 20.
Front and rear wheels 22,24 are mounted on the tractor in
a conventional manner. As can be seen from Fig. 1 the
engine 12, transmission housing 16 and center housing 20
form s-tructural support members for the tractor and there-
fore this type of tractor is generally referred -to as a
frameless tractor.
In accordance with the principles of -this inven-
tion first and second change gear mechanisms, indicated
generally at 26 and 28, (Fig. 2) are coupled to each other
within the transmission housing. The first change gear
mechanism as illustrated is of a type giving eigh-t differ-
ing speed ratios between the input side and tile output
shaft. The second change gear mechanism is of a type
including a forward/reverse mechanism, and it may include
additional speed ratios. Thus, in the embodiment
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illustrated in Figure 2 -the second change gear mechallism
includes a forward/reverse mechanism as well as mechanism
for providing two addi-tional speed ratios to the input of
the first change gear mechanism 26, thereby provid:ing a
transmission having 16 speeds. Differing second change
gear mechanisms may be employed and a second version is
illustrated in Fig. 6. In order to provide for the sub-
stitution of one change gear mechanism for another it has
been necessary to design -the first and second change gear
mechanisms and the housing in a special manner.
To this end the first change gear mechanism 26
is provided with a fi.rst hollow shaft 30 and a second two
piece shaft 34, the rear end o:E the first shaf-t 30 being
rotatably journaled in the rear end wal.l 32 of the housing
16, and the rear end of the second shaf-t assembly 34 being
rotatably journaled in a bearing plate 35 which i.s in turn
carried by the rear wall 32. ~ p].urality o:E intermeshing
gear sets 36 are carri.ed by the first and second shafts
30,34 and are selectively interconnectable to transmit
power from one shaft to the other. One manner in which
the gears 36 may be mounted on the shafts 30,34 is illu
strated in my earlier U.K. Patent 1,391,854. The second
shaft assembly 34 is divided into forward and rear por-
tions 38,40, respectively, the forward end of the rear
portion 40 being journaled by bearings 42 carried within
a cylindrical recess on the rear end of the forward
portion 38. The forward porti.on 38 may be reEerred to as
a counter shaft, and the rear portion 40 as an ou-tput
shaft. The output shaft 40 is coupled to a driven member
(not shown). The forward end of the counter shaft 38 is
carried by a beariny 44 which is in turn supported by a
first flange 46 which extends inwardly from the generally
cyli.ndrical side walls 48 of the housing 16. An addi-
tional flange 50 is provided between the first flange 46
and the rear wall 32, the additional f]ange 50 carrying A
further bearing 52 which rotatably supports a rear portion
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of the counter shaEt 38.
In order to removably moun-t a second chanc~e gear
mechanism within the housing, the housing 16 is provided
with an inwardly extending annular flan~e 59. A support
member indicated generally at 56 is removably secured -to
-the second flange 54. In the embodimen-t illus-trated in
Figs. 2 and 3 the support member 56 is formed of two parts
which shall be referred to as the front cover 58 and the
support frame 60. The front cover 58 is provided with a
radially outwardly extendiny circular flange 62 which is
secured -to the annular flange 5~ by bol-ts 64 or the like.
The support Erame 60 has a radius less than that of the
annular suppor-t flange 54 and is secured to the front cover
58 by cap screws 66. The front cover and support frame
58,60 cooperate with the rear wall 32 to form a fluid
reservoir within the housiny 16. In addition, -the support
frame 60, which is rigid].y mounted withirl the housiny, is
utilized to support the :Eorward end of -the main shaft 30.
To this end, a bearing support 68 which carries a bearillg
70 is secured in place by bolts 72. The forward end of
the first shaft 30 is journaled within the bearing 70.
The support frame 60 carries adcli-tional bearings
74 and 76 in which is journaled a hollow third shaEt 78.
Rotatably mounted on the third shaft are spaced apart
forward and reverse gears 80,82. A shi.ftable coupler 8~
is keyed to the shaft 78 and may be shifted axially of the
sha:Et to drivi.nyly interconnec-t either -the Eorw~rd gear 80
with the shaft 78 or the reverse year 82 with the shaft
78. Tile coupler is caused to be sllifted by a shift rail 83
and fork 85. The shift rail is carried by the support
member 56 for axial slidiny movement. The gear 80 is at
all times in constant mesh with a year 86 carried by the
forward end of the counter shaft 38. The suppor-t member
56 additionally carries a stub shaft 88 (Figs. ~ and 5)
upon which is moun-ted a reverse idler 90 having a Ei.rst
toothed portion 92 which is cons-tantly in mesh with the
teeth on gear 82, and a second too-thed portion 9~ which is
constantly in mesh with the teeth on gear 86.
Mounted forwardly of the Eorward/reverse gear
mechanism is a 2-speed planetary gear se-t indicated
generally at 96, which gear set along with -the Eorward/
reverse mechanism completes the second challge gear mecha-
nism 26. The planetary gear se-t includes a hollow input
shaft 98 the forward end of which is coupled to a drive
member such as a tractor clu-tch plate (not shown). The
rear end of the input shaft 98 is supported by a bearing
100 disposed wi-thin an aperture of the clutch release
bearing carrier 102 which is in turn secured to the fron-t
cover 58 by fasteners 104. A ring gear 106 is secured -to
the input shaft 98 by bolts 108. A hydraulically operated
clutch pack 110 may be utilized -to couple the ring gear
106 to a planet carrier 112. Thus, when fluid is intro-
duced into the chamber 114 behind the piStOIl 116, the
clutch pack 110 will be enqaged thereby locking the plane-t
carrier 112 to the ring gear 106. The planet carrier is
provided with a plurality of axially extending stub shafts
118 on which are mounted planet gears 120. The teeth 122
on the ring gear 106 and the teeth 124 on a sun qear 126
are in constant mesh with the tee-th on the planet gears
120. The planet carrier 112 is coupled directly to the
third shaft 78 upon which the forward/reverse gear mecha-
nism is mounted, and the sun gear 126 is journaled for
rotation about the shaft 78. A clutch disc l28 is secured
to the sun gear, which clutch disc may be utilized to hold
the sun gear from rotation. To this end compression
springs 130 are disposed in sui-table recesses in -the front
cover 58, the springs 130 ac-ting against a pressure plate
132 to normally bias the clutch disc 128 into engagement
with a flat surface on the support frame 60. The clutch
disc 128 may be disengaged by introclucing fluid under
35 pressure into chamber 134 to cause piStOIl 136 to engage
the pressure plate 132 and move the plate 132 away from the
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clutch disc 128 and flat surface. The fluid circuit for
operating the planetary gear set 96 is lllustra-ted somewhat
schematically in Fig. 2 and includes a pump 138, fluid
reservoir 140, valve 142, and manual control lever 144.
When the valve is in the posi-tion illustrated in Fig. 2
fluid from the pump 138 will be re-turned directly to the
reservoir through line 146. In this position the springs
130 will hold the clu-tch disc 128 agains-t the flat surface
of the housing 60. When the manual control lever 144 is
shifted to its other position (not illustrated) fluid from
the pump 138 will be introduced into line 148 and thence
into chambers 114 and 134 to cause the pis-ton 136 to disen-
gage the pressure plate 132 and piston 116 to engage the
hydraulically operated clutch pack 110. The preload of
springs 130 is so designed that when 1uid is introduced
i.nto the chambers 13~ and 11~ the hydraulically operated
clutch pack 110 will be partially engagecl prior to the full
disengagement of the first clutch 128. In the even-t tha-t
the clutch 128 became disengaged beEore -the clu-tch 110
became enyaged it would be possible for power flow to be
interrupted from the shaft 98 to the sha~t 78. By
employing springs 130 having a certain preload charac-
teristic it is possible -to insure con-tinuous power flow
as the plane-tary gear se-t is being shifted from its high
speed ratio when clutch 128 is engaged to its low speed
ratio when clutch pack 110 is engaged, and vice versa.
In -the embodiment shown in Figures 2 through S
the transmission 14 has 16-speed ratios. In the embodiment
illus-trated in E`ig. 6, which will now be described, the
2-speed plane-tary input portion of the second change gear
mechanism is eliminated and therefore the transmission 14
is capable of only eight forward speeds. Before describing
Fig. 6 in detail it should be observed -that some of the
components of the second change gear mechanism illustrated
in Fig. 6 and indicated generally at 150 are identical to
components illus-trated in Figures 2 through 5, and these
components will be indicated by the same reEerence numer-
als. In addition, while a first change gear mecllanism is
illustrated having 8-speeds, other first chan~e gear
mechanisms could be employed having a differing number of
speeds/ such as 4, 6, etc..
The second change gear mechanism 150 of the -type
illustrated in Figure 6 includes a combined front cover and
support frame 152 provided with an annu:Lar flange 154 which
may be sec~red to the annular second flange 54 of the
transmission housing 16 by bol-ts 64. A bearing 70 is
carried by a rear portion of the support 152 and is secured
in place by screws 156 and a bearing retainer 158. The
forward end of the main shaft 30 is journaled within the
hearing 70. ~n input shaft 160, whose forward end is
coupled to a drive member such as a tractor clutch, has
its rear end coupled directly to -the third shaf-t 78. The
forward end oE the hollow third shaft 78 is supported by
a spacer 162 which is in turn suppor-ted hy a bearing 164
carried by -the support frame 152. The rear end of the shaft
78 is also supported by a bearing 166 carried by the
support frame 152. A forward/reverse mechanism including
forward and reverse gears 80,82 and coupler 84 are mounted
about the shaft 78, the gear 80 being in constant mesh
with gear 86 on the forward end of counter shaft 38 and
25- the gear 82 being in constant mesh wi-th a reverse idler 90.
A fork 85 engages the coupler 84 and is shiEted by a shift
rail (not shown) which is carried by -the support frame 152.
By design~ng -the transmission in -the manner indi-
cated above it is possible to u-tilize -the same basic or
first change gear mechanism 26 with a varie-ty of second
change gear mechanisms which may provlde, for example, only
a forward/reverse gear mechanism of the type illustrated
at 150 in Fig. ~, a 2-speed forward/reverse mechanism of
the type illustrated at 28 in Figs. 2 through 5, or by
other input mechanisms such as, for example, a 3 speed
- forward/reverse mechanism of the type illustrated in
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U.K. Patent 1,399,373. The manner of converting a tractor
from the 16-speed transmission of the type illustrated in
Fig. 2 to the 8-speed transmission of the type illustrated
in Fig. 6 will now he described.
It is first necessary to separate the trans-
mission housing 16 from the engine 12 and to move these
parts apart. To this end, it would be necessary to dis-
connect all lines, controls, etc. which extend between the
engine 12 and housing 16. After this has been done bolts
168 (Fig. 1) which secure the housing 16 to the engine
must be removed to permit the front and rear halves of
the tractor to be moved apart. The power takeoff shaft
170 which extends through the hollow shafts 98,78 and 30
is then removed. (The front end of the PTO shaft is
lS connected to the engine flywheel by a spline.~ After this
has been done it is necessary to remove various lubrica-
tions lines ~not illustrated) and to then remove the
clutch release bearing carrier 102, the saddle assembly
172, the clutch release lever 174, and the clutch cross
shaft 176. As the shift rail 83 and fork 85 for the
forward/reverse mechanism are carried by the front member
56 it is necessary that the shift cover 182 be removed from
the right side of the transmission housing in order to
disengage the reverse actuator 184 from the forward reverse
saddle 186 carried at the rear end of the shift rail 83.
While the mechanism for operating the reverse actuator 184
is not illustrated it should be observed that the reverse
actuator 184 may be carried at one end of a rock arm, the
other end of which i5 connected to a rock shaft which ma~
be rotatably mounted in the shift cover 182. ~he shift
column and controls for the other shift rails 188, as well
as the mechanism for operating the reverse astuator 184,
may be of the type illustrated in U.S. Patent 3,975,970.
When the assembly 28 is being removed it is essential that
it be pulled out axially approximately two inches to cause
the fxont ends of shift rails 188 and the rear end of the
lubrication tube 19~ to be disconnected from their
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associated recesses. The assembly is now rotated countex-
clockwise approximately 1/8 of a turn and is then pulled
from the transmission housing 16. To install -the assembly
150 in the housing 16 the procedure outlined above is
followed in reverse order.
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