Note: Descriptions are shown in the official language in which they were submitted.
I EAT 0130 PUS 21 2 5 7 6 6 93-rTRN-021
TRANSMISSION OUTPllT SHAFI DRIVE ASSEl~/IBLY
Technical Field
The present invention relates to compound
transmissions having an auxiliary transmission section
connected in series with a multispeed main transmission
section and, more particularly, to an improved auxiliary
transmission section including an internally toothed
range gear driven by externally toothed auxiliary
countershaft gears providing an output drive arrangement
for transmitting high torque therethrough.
Background Art
Compound change gear transmissions of the type
having one or more auxiliary sections connected in
series with a main transmission section are well known
in the prior art. 8riefly, by utilizing main and
auxiliary transmission sections connected in series,
assuming proper sizing of the ratio steps, the total of
available transmission ratios is equal to the product of
the main and auxiliary section ratios. By way of
example, at least in theory, a compound change gear
transmission comprising a four (4) speed main section
connected in series with a three (3) speed auxiliary
section will provide twelve (4x3=12) available ratios.
Auxiliary transmission sections are of three
general types: range type, splitter type or combined
range/splitter type.
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In compound transmissions having a range type
auxiliary section, the ratio step or steps may ~e
greater, equal or less than the total ratio coverage of
the main transmission section and the main section is
shifted progressively throu~h its ratios in each range.
Examples of compound transmissions ~aving range type
auxiliary sections may be seen by reference to U.S.
Patent Nos. 3,105,39r.; 2,637,222 and
2,637,221.
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In compound transmissions having a splitter
type auxiliary section, the ratio steps of the splitter
auxiliary section are less than the ratio steps of the
main transmission section and each main section ratio is
split, or subdivided, by the splitter section. Examples
of compound change gear transmissions having spl$tter
type auxiliary sectionæ may be seen by reference to U.S.
Patent Nos. 4,290,515; 3,799,002; 4,440,037 and
4,527,447.
In a combined range and splitter type
auxiliary section, or sections, both range and splitter
type ratios are provided allowing the main section to be
progressively shifted through its ratios in at least two
ranges and also allowing the main section ratios to be
~ split in at least one range.
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One example of ~ compound transmission having
a single combined range~splitter type auxiliary section
may be seen by reference to U.S. Patent Nos. 3,2$3,61
3,648,546, and to publication Small Scale
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Print No. 016-AD; Fuller~ Transmissions;
Models T-14613, RT0-14613, RT00-14613,
published March 1981 by Eaton Corporation,
assignee of this invention. Another example
is the "Ecosplit"~ model of transmission
sold by Zahnradfabrik Friedri~hshafen
Aktiengeseushaft of Friedrichshafen, Federal
Republic of Germany which utilizes a
separate splitter auxiliary section in front
of, and a separate range auxiliary section
behind, the main transmission section.~
It should be noted that the terms main and
auxiliary sections are relative and that if the
designations of the main and auxiliary sections are
reversed, the type of auxiliary section (either range or
splitter) will also be reversed. In other words, given
what is conventionally considered a four-speed main
section with two-speed range type auxiliary section, if
the normally designated auxiliary is considered the main
section, the normally designated main section would be
considered a four-speed splitter type auxiliary section
therefor. By generally accepted transmission industry
convention, and as used in this description of the
invention, the main transmission section of a compound
transmission is that section which contains the largest
(or at least no less) number of forward speed ratios,
which allows selection of a neutral position, which
contains the reverse ratio(s) and/or which is shifted
(in manual or semiautomàtic transmissions) by
manipulation of a shift bar or shift rail or shift
shaft/shift finger assembly as opposed to master/slave
valve/cylinder arrangements or the like.
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A conventional auxiliary transmission section
such as that disclosed in U.S. Patent No. 4,754,665
includes an auxiliary section input shaft and an output
shaft cooperably forming a mainshaft assembly, and an
auxiliary countershaft assembly. The auxiliary
transmission section includes three gear layers,
combined range and splitter geaxing and four distinct
selectable auxiliary section ratios. Auxiliary section
countershaft gears drive externally toothed range gears
to provide an output torque flow path.
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Disclosure Of Invention
..
An object of the present invention is to
provide a new and improved compound change gear
transmission that utilizes an internally toothed range
gear in the output torque flow path to increase the
torque capacity of the output torque flow path.
Another objective of the present invention is
to provide a new and improved compound gear transmission
having longer life gearing because of the internal mesh
of the internally toothed range gear which reduces
pitting and bending stresses.
Another object of the present invention is to
provide a new and improved compound change gear
transmission having balanced load sharing between main
and auxiliary countershafts because of the internally
toothed range gear and its ability to deflect and align
deshing gear teeth.
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In carrying out the above object, the compound
transmission includes an auxiliary transmission section
in series with a main transmission section wherein the
auxiliary transmission sectlon includes an improved
output shaft drive arrangement. The output shaft drive
arrangement comprises a synchronizer mounted for
rotation with an auxiliary transmission section output
shaft, and an internally toothed range qear coaxial with
and rotatable relative to the output shagt. The
internally toothed range gear is in torque flow
communication with the synchronizer and a pluralit~ of
auxiliary countershaft assemblies. Each auxiliary
countershaft assembly includes an auxiliary countershaft
and a first auxiliary countershaft gear rotationally
fixed to the auxiliary countershaft. Each auxiliary
countershaft gear is constantly meshed with the
internally toothed range gear for driving engagement
thereby.
Preferably, two auxiliary countershaft drive
gear assemblies are on diametrically opposed sides of
the output shaft and each has an externally toothed
auxiliary countershaft gear that drives the internally
toothed range gear. Such an arrangement allows the
transmission of high torque values through the output
shaft drive arrangement.
The above object and other objects, features,
and advantages of the present invention are readily
apparent from the following detailed description of the
best mode for carrying out the invention when taken in
connection with the accompanying drawings.
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Brief Description Of The Drawin~s
FIGURE 1 is a schematic illustration of a
prior art compound transmission section having a
multispeed main transmission section connected in series
with an auxiliary transmission section;
FIGURE 2 is a schematic illustration of the
prior art compound transmission of FIGURE 1 including
and illustrating an improved output shaft dr-ive
arrangement constructed in accordance with the present
invention; and
FIGURE 3 is a schematic illustration of an
improved compound transmission constructed in accordance
with the present invention including the improved output
shaft drive arrangement.
Best Mode For Carrying Out The Invention
Certain terminology will be used in the
following description for convenience only and will not
be limiting. The words "upwardly", "downwardly",
"rightwardly", and "leftwardly" will designate
directions in the drawings to which reference is made.
~he words "forward" and "rearward" will refer
respectively to the front and rear ends of the
transmission as conventionally mounted in the vehicle,
being respectively to the left and right sides of the
prior art main transmission section illustrated in
Figure 1.
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The term "compound transmission" is used to
designate a change speed or change gear transmission
having a main transmission section and an auxiliary
transmission section connected in series whereby the
5selected gear reduction in the main transmission section
may be compounded by further selected gear reduction in
the auxiliary transmission section. The term "upshift"
as used herein shall mean the speed gear ratio is
changed from a lower value to a higher value. The term
10"downshift" as used herein shall means the shifting from
a higher speed gear ratio to a lower speed gear ratio.
The terms "low speed gear" or "low gear" as used herein
shall designate a gear ratio utilized ~or relatively
lower forward sp~ed operation in a transmission, i.e. a
15set of gears having a higher ratio of reduction of
output shaft speed relative to the speed of the input
shaft. "Synchronized clutch assembly" and words of
similar import shall designate a clutch assembly
utilized to non-rotatably couple a selected gear to a
20shaft ~y means of a positive clutch in which attempted
engagement of said clutch is prevented until the members
of the clutch are at substantially synchronous rotation
and relative large capacity friction means are
associated with the clutch members and are sufficient,
25upon initiation of a clutch engagement, to cause the
clutch members and all members rotating theréwith to
rotate at a substantially synchronous speed.
Referring now to Figure 1, there is
¦ schematicall~ illustrated a well known and highly
¦ 30commercially successful eighteen forward speed compound
transmission 10. Transmission 10 comprises a main
transmission section 12 connected in series with an
auxiliary transmission section 14. Typically, the
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EAT 0130 PUS -8- 93-r~RN-021
transmission 10 is housed in a single housing and
includes an input shaft 16 driven by a prime mover such
as diesel engine E through a selectively disengaged,
normally engaged friction master clutch C having an
input or driving section 18 drivingly connected to the
engine crankshaft 20 and a driven portion 22 rotatably
fixed to the transmission input shaft.
In the main transmission section 12, the input
shaft 16 carries an input gear 24 for simultaneously
driving a plurality of substantially identical main
section countershaft assemblies 26 and 26a at
substantially identical rotational speeds. In the
transmission 10 illustrated, two substantially identical
main section countershaft assemblies are provided on
diametrically opposite sides of a mainshaft 28, which
mainshaft is generally coaxially aligned with the input
shaft 16. Each of the main section countershaft
assemblies 26 and 26a comprises a main section
countershaft 30 supported by bearings 32 and 34 in
housing H, only a portion of which is schematically
illustrated.
Each of the main section countershafts 30 is
provided with an identical grouping of main section
countershaft gears 38, 40, 42, 44, 46 and 48, fixed for
rotation therewith. A plurality of main section drive
or mainshaft gears 50, 52, 54, 56 and 58 surround the
mainshaft 28 and are selectively clutchable, one at a
time, to the mainshaft 28 for rotation therewith by
sliding clutch collars 60, 62 and 64 as is well known in
the art. Clutch collar 60 may also be utilized to
clutch input gear 24 to mainshaft 28 to provide a direct
drive relationship between input shaft 16 and mainshaft
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28. Preferably, each of the main section mainshaft
gears encircles the mainshaft 28 and is in continuous
meshing engagement with and is floatingly supported by
the associated countershaft gear group.
S Typically, clutch collars 60, 62 and 64 are
axially positioned by means of shift forks (not
illustrated) associated with a shift bar housing
assembly (not illustrated) as well known in the prior
art. Clutch collars 60, 62 and 64 are of the well known
non-synchronized double acting jaw clutch type.
With continued reference to Figure 1, main
section mainshaft gear 58 is the reverse gear and is in
continuous meshing engagement with countershaft gears 48
by means of conventional intermediate idler gears (not
shown). It should also be noted that while main
transmission section 12 does provide five selectable
forward speed ratios, the lowest forward speed ratio -~
namely, that ratio provided by drivingly connected
mainshaft drive gear 56 to mainshaft 28 is often of such
a high gear reduction as to be considered a low or -~
"creeper" gear which is utilized only for starting of a -~
vehicle under severe conditions and is usually not
utilized in the high transmission range and/or may not
be split in the low transmission range.
ZS Jaw clutches 60, 62 and 64 are three-position
clutches in that they may be positioned in a centered,
non-engaged position as illustrated or in a fully ~ -
rightwardly engaged or fully leftwardly engaged
posltion.
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EAT 0130 PUS -10- 93-rTRN-021
Auxiliary transmission section 14 includes two
substantially identical auxiliary countershaft
assemblies 68 and 68A, each comprising an auxiliary
countershaft 70 supported by bearings 72 and 74 in
housing H and carrying three auxiliary section
countershaft gears 76, 78 and 80 fixed for rotation
therewith. Auxiliary countershaft gears 76 are
constantly meshed with and support auxiliary section
splitter gear 82 which surrounds mainshaft 28.
Auxiliary countershaft gears 78 are constantly meshed
with and support auxiliary section splitter/range gear
84 which surrounds the output shaft 86 at the end
thereof adjacent the coaxial end of mainshaft 28.
Auxiliary section countershaft gears 80 constantly mesh
and support auxiliary section range gear 88, which
surrounds the output shaft 86. Accordingly, auxiliary
section countershaft gears 76 and splitter gear 82
define a first gear layer, auxiliary section
countershaft gears 78 and splitter/range gear 84 define
a second gear layer and auxiliary section countershaft
gears 80 and range gear 88 define a third layer, or gear
group of the combined splitter and range type auxiliary
transmission section 14.
A sliding two position jaw clutch collar 90 is
utilized to selectively couple either the splitter gear
82 or the splitter/range gear 84 to the mainshaft 28,
while a two position synchronized assembly 92 is
utilized to selectively couple the splitter/range gear
84 or the range gear 88 to the output shaft 86.
FIGURE 2 illustrates the hereinabove described
prior art compound transmission of FIGURE 1 having an
improved output drive arrangement. With continuing
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reference to FI¢URE 2, an internally toothed range gear
112 has been substituted for the externally toothed
range gear 88 seen in FIGURE 1 with the result that
range gear 112 provides superior torque transmission
capacity over the externally toothed range gearing and
improves gear life because of the internal mesh which
reduces stresses.
Immediately following, and by way of example,
is a detailed description of the output shaft drive
arrangement applied to a novel compound transmission ~-
illustrated in FIGURE 3.
With reference to FIGURE 3, the multiple ratio
transmission lOA shown therein is a fourteen-forward
speed, two-reverse speed, compound manually operated
transmission wherein main transmission section 12A is
connected in series to the auxiliary section 14A. The
main transmission section 12A includes a two-speed input
splitter section and auxiliary section 14A includes a
three speed range section. Typically transmission lOA
is housed within a single housing (not shown) and
includes an input shaft 122 driven by a prime mover (not
shown) such as a well known diesel engine or the like.
In the main transmission section 12A input
shaft 122 drives a two position clutch collar 126.
Clutch collar 126 is actuated by an actuator 128 such as
a two-position piston, or the like, and has a first
position for engaging torque input splitter gear 132 to
the input shaft and a second position for engaging the
second splitter gear 134 to the input shaft. The input
splitter s~ction thus defines the first clutch S1 and
second clutch S2 which are mutually exclusively
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engageable to couple torque input splitter gear 132 or
second splitter gear 134 to the input shaft 122.
~orque input splitter gear 132 and second
splitter gear 134 simultaneously drive a pair of
substantially identical main section countershaft
assemblies 138 and 138A at substantially identical
rotation speeds. In the transmission illustrated, two
substantially identical main section countershaft
assemblies are provided on diametrically sides of an
intermediate shaft which is generally coaxially aligned
with the input shaft 122 and output shaft 124. Each of
the main section countershaft assemblies 138 and 138A,
comprise a main section countershaft 142 supported by
bearings and provided with an identical grouping of main
lS section countershaft gears 144,146,148,150 and 152,
fixed for rotation therewith. Main section drive gears
154,156 and 158 surround the intermediate shaft 140 and
are selectively clutchable, one at a time, to the
intermediate shaft 140 for rotation therewith by sliding
clutch collars 160 and 162 as is well known in the prior
art. Clutch collar 160 may also be utilized to clutch
second splitter gear 134 directly to intermediate shaft
140 to provide a direct driving relationship
therebetween. Of course, with clutch S2 engaged, second
splitter gear 134 will rotate with input shaft 122.
Main section drive gears 154,156 are in
continuous meshing engagement with and floatingly
supported by the associated main section countershaft
gears 148,150 and main section intermediate shaft gear
lS8 is the reverse gear and is in continuous meshing
engagement with countershaft gear 152 by means of
conventional intermediate idler gears 164.
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Main section clutch collars 160 and 162 are
axially positioned by shift forks 166 and 168,
respectively, and are typically manually controlled by
means of a shift lever or the like. The rlutch collars
160 and 162 are of the well known nonsynchronizing type
of the well known double acting jaw clutch type.
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It may be seen, that the manually controlled
main section 12A defines six clutches Sl,S2,Jl,J2,J3 and
JR, respectively, which are mutually exclusively
engageable to drivingly couple either torque input
second splitter gears 132,134, main section drive gears
154,156, or reverse intermediate section drive gear 158,
respectively, to the input or intermediate shafts
122,140.
lS The combined range auxiliary section 14A
includes two substantially identical auxiliary
countershaft assemblies 170 and 170A, each comprising an
auxiliary countershaft 172 supported by bearings in a
housing and carrying two auxiliary section countershaft
gears 174 and 176 fixed for rotation therewith.
Auxiliary section countershaft gears 176 are constantly
meshed with in support of intermediate shaft output gear
178. Auxiliary countershaft gears 174 are constantly
meshed with and support auxiliary internally toothed
range gear 180 which surrounds the output shaft 124.
A sliding two-position jaw clutch collar 184
is utilized to selectively couple the main countershaft
142 to the auxiliary countershaft 172, thus defining a
clutch J4. Clutch collar 184 is actuated by an actuator
188 such as a two position piston, or the like, and has
a first position for engaging main countershaft 142 to
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EAT 0130 PUS -14- 93-rTRN-021
auxiliary countershaft 172 and a second position wherein
the countershafts are disengaged.
Synchronized clutch assembly 186 defines two
mutually exclusively engageable range torque flow paths
H and L, respectively. In low range, clutch assembly
186 is engageable to couple range gear 180 to the output
shaft 124 and in high range, clutch assembly 186 is
engageable to couple intermediate shaft output gear 178
to the output shaft 124. Actuator 190 is a two-position
fluid actuated piston for actuating selection of the
desired torque flow path H,L.
With continued reference to FIGURE 3, the
auxiliary transmission section 14A includes the improved
output shaft drive arrangement wherein the output shaft
124 includes internally toothed output shaft range gear
180 coaxial with and rotatable relative to the output
shaft. The first auxiliary countershaft gears are
externally toothed and constantly meshed with the
internally toothed range gear 180. Load sharing between
main and auxiliary countershafts 142,172 is improved
because of the internally toothed range gear and its
ability to deflect and align meshing gear teeth. The
internal tooth construction of the range gear 180
provides a superior torque transmission capacity over
the conventional externally toothed gearing.
While the best mode for carrying out the
invention has been described in detail, those familiar
with the art to which this invention relates will
recognize various alternative designs and embodiments
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for practicing the invention as defined by the following
claims.
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