Multiple identical countershaft powershift transmission

A multiple substantially identical countershaft powershift transmission is provided. The transmission (10) comprises an input shaft (12) and preferably three (16, 18 and 20) input gears and an output gear (22) concentric and rotatable relative thereto. A plurality of substantially identical countershaft assemblies (42, 42A) carrying countershaft gears (54, 56, 58 and 60) constantly meshed with the input gears and output gear surround the input shaft and an output shaft (24) generally coaxial with input shaft (12) and carrying the output gear (22) rotationally fixed thereto are provided. A first double acting friction clutch mechanism (26) for selectively frictionally coupling first speed input gear (16) or third speed input gear (18) to the input shaft and a second double acting friction clutch mechanism (28) for selectively coupling second speed input gear (20) or fourth speed output gear (22) are provided and are concentric and driven by the input shaft (12). Means (V, C) are provided for selectively actuating the clutch portions (30, 32, 36 and 38) of the double acting clutch assemblies with overlapping engagement of the clutch portion being released and the clutch portion being applied.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to powershift transmissions, or transmission 
sections, utilizing multiple identical, or substantially identical, 
countershaft assemblies. 
2. Description of the Prior Art 
Change gear transmissions, or transmission sections, utilizing multiple 
substantially identical countershaft assemblies normally driven by an 
input shaft or input gear and driving an output shaft are well known and 
widely used, especially for heavy duty vehicles such as trucks and the 
like. Such transmissions, especially when provided with floating output 
shafts or mainshafts and/or floating output or mainshaft gears, are highly 
advantageous as each countershaft is required to carry only an equal 
portion of the torque load. Examples of such transmissions and a more 
detailed discusison of the structure and advantages thereof may be seen by 
reference to U.S. Pat. Nos. 3,105,395 and 3,500,695, both hereby 
incorporated by reference. 
Powershift change gear transmissions are known in the prior art as may be 
seen by reference to U.S. Pat. Nos. 3,802,293; 3,362,245 and 3,675,508, 
all hereby incorporated by reference. The advantages of powershifting 
transmissions, i.e. transmissions providing continuous power from the 
input to the output thereof during a ratio shifting operation, for certain 
situations is well known in the art. 
Overlapping clutch engagement, as is often a feature of powershifting 
transmissions, is also well known in the art as may be seen by reference 
to U.S. Pat. Nos. 3,762,518 and 3,783,985, both hereby incorporated by 
reference. 
While the powershifting transmissions of the prior art have been generally 
satisfactory, the designs thereof are subject to improvement as structure 
providing the use of torque sharing substantially identical multiple 
countershafts in known powershift transmission designs is not seen. 
SUMMARY OF THE INVENTION 
In accordance with the present invention, the drawbacks of the prior art 
have been overcome by the provision of a powershift change gear 
transmission, or transmission section, which utilizes a plurality of 
substantially identical countershafts, each of which carry a substantially 
equal torque load for each selectable ratio in the transmission or 
transmission section. Additionally, as a preferred feature, the 
transmission is provided with end and intermediate wall configurations, 
and gearing configurations, allowing the same case, input shaft, output or 
mainshaft, output or mainshaft gears, clutches, countershafts and 
countershaft gears to be utilized for both a two (twin) or three (triplet) 
countershaft transmission. 
The above is accomplished by providing a transmission, or transmission 
section, having an input shaft on or about which three input gears are 
rotationally supported, an output shaft coaxial with the input shaft and 
carrying an output gear rotationally fixed thereto, and a plurality of 
substantially identical countershafts, each countershaft carrying 
countershaft gears fixed thereto which are constantly meshed with the 
input gears and the output gear. Friction clutches are provided for 
rotationaly coupling a selected input gear or the output gear to the input 
shaft. Of course, coupling of the output gear to the input shaft will 
provide direct drive relationship between the input and output shafts. In 
the preferred form, double acting friction clutches are provided for the 
known cost, weight and axial space saving advantages thereof. When double 
acting clutches are utilized, the first and third highest ratio clutchable 
gears are axially adjacent with a conventional double acting friction 
clutch therebetween for selectively coupling the first or third highest 
ratio clutchable gear to the input shaft. The second and fourth highest 
ratio clutchable gears are axially adjacent with a second double acting 
friction clutch interposed therebetween for selectively coupling the 
second or fourth highest ratio clutchable gear to the input shaft. 
Controls and valving are provided for overlapping engagement of the 
friction clutches as one side of one double acting clutch is engaged and 
one side of the other double acting clutch is disengaged as is well known 
in powershaft transmissions. 
As is well known, in a direct drive type transmission, the fourth highest 
ratio clutchable gear will be the output gear which will provide a 1:1 
drive ratio when clutched to the input shaft. In an overdrive type 
transmission, the output gear will be the third highest ratio clutchable 
gear. Although only a direct drive type transmission is illustrated 
herein, it is understood the present invention is also applicable to 
overdrive type transmissions. 
Preferably, the end walls and intermediate walls of the transmission are 
provided with four bores, all equidistant from the centerline or axis of 
the input shaft, for supporting countershaft bearings and/or providing 
countershaft passage. The second bore is displaced 120.degree. from the 
first bore, the third bore is displaced 60.degree. from the second bore 
and the fourth is displaced 60.degree. from the third bore, all in the 
same direction of rotation. Additionally, the input shaft mainshaft gears 
are provided with a number of teeth evenly divisible by both two and 
three. For a twin countershaft transmission, or transmission section, 
countershafts are supported by bearings in the first and third bores, for 
a triplet countershaft transmission, countershafts are supported by 
bearings provided in the first, second and fourth bores. 
Accordingly, it is an object of the present invention to provide a new and 
improved powershift transmission, or transmission section, utilizing 
multiple substantially identical countershaft assemblies. 
Another object of the present invention is to provide a transmission casing 
having bearing supporting and/or intermediate walls provided with four 
bearing support bores and/or countershaft passage bores allowing the 
casing to be utilized for either a twin or a triplet countershaft 
transmission. 
These and other objects and advantages of the present invention will become 
apparent from a reading of the detailed description of the preferred 
embodiment taken in view of the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Certain terminology will be used in the following description for 
convenience in reference only and will not be limiting. The words 
"upwardly," "downwardly," "rightwardly" and "leftwardly" will designate 
directions in the drawings to which reference is made. The words "forward" 
and "rearward" will refer, respectively, to front and rear ends of the 
transmission as same are conventionally mounted in a vehicle, being 
respectively the left and right sides of the transmission as illustrated 
in FIG. 1. The words "inwardly" and "outwardly" will refer to directions 
toward and away from, respectively, the geometric center of the device and 
designated parts thereof. Said terminology will include the words above 
specifically mentioned, derivatives thereof and words of similar import. 
The term "simple transmission" is use to designate a change speed 
transmission wherein the operator may select one of a plurality of single 
gear reductions. The term "compound transmission" is used to designate a 
change speed transmission having a main transmission portion or section 
and an auxiliary transmission portion or section connected in series 
thereto whereby the selected gear reduction the main transmission portion 
may be compounded by a further selected gear reduction in the auxiliary 
transmission portion. The term "transmission" as used herein shall 
designate a simple or compound transmission or a secion of a compound 
transmission. The term "upshift" as used herein shall mean the shifting 
from a lower speed gear ratio to a higher speed gear ratio. The term 
"downshift" as used herein shall mean the shifting from a higher speed 
gear ratio to a lower speed gear ratio. The terms "low speed gear", "low 
gear" and/or "first gear" as used herein shall all designate the gear 
ratio having the lowest forward speed operation in a transmission or 
transmission section, i.e. that set of gears having the highest ratio of 
reduction from the input shaft to the output shaft of the transmission. 
The terms "high speed gear" and/or "high gear" as used herein shall all 
designate the gear ratio utilized for the highest forward speed operation 
in a transmission or transmission section, i.e. that set of gears 
providing the lowest ratio of reduction from the input shaft to the output 
shaft of the transmission or transmission section. 
While the present invention is especially well suited for transmissions 
having forward speeds only, such as transmissions that would typically be 
utilized in industrial applications for driving pumps and the like, it is 
understood that a reversed mode of operation could be provided in the 
transmission section illustrated, in an auxiliary transmission section or 
in an auxiliary device as is well known in the art. 
Referring now to FIGS. 1 and 2, there is schematically illustrated a four 
forward speed simple powershift transmission (or transmission section) 10. 
Transmission 10 comprises an input shaft 12 which may be supported by 
suitable bearings or which may be mounted in a floating and/or pivoted 
manner as is well known in the prior art. Input shaft 12 is preferably 
driven by a one way prime mover (not shown) such as a diesel engine or the 
like, and preferably drives a conventional gear pump 14 for supplying 
pressurized hydraulic fluid for lubrication and cooling of the 
transmission and for providing pressurized fluid for clutch actuation as 
will be described in greater detail below. Three input gears, 16, 18 and 
20 are mounted generally concentric with and rotatable relative to input 
shaft 12. Input gear 16 is the low speed input gear, input gear 20 is the 
second speed or next higher speed input gear and input gear 18 is the 
third speed or second highest speed gear. An output gear 22 is mounted to 
output shaft 24, as by a spline connection, for rotation therewith. It is 
noted that output shaft 24 is generally coaxial with input shaft 12. 
Output gear 22 is the highest speed, or direct drive, gear. 
A first selectively actuated, hydraulically operated double acting friction 
clutch 26 is mounted to the input shaft 12 axially interposed input gears 
16 and 18 for selectively rotationally coupling either input gear 16 or 
input gear 18 to the input shaft 12. A second selectively actuated, 
hydraulically operated double acting friction clutch 28 is mounted to the 
input shaft 12 axially interposed input gear 20 and output gear 22 for 
selectively rotationally coupling either input gear 20 or output gear 22 
to the input shaft 12. The structure and function of double acting 
friction clutches 26 and 28 is convention and is well known in the art as 
may be seen by reference to U.S. Pat. Nos. 3,802,293; 3,465,609 and 
3,619,714, all of which are hereby incorporated by reference. Briefly, 
clutch 26 comprises two frictional clutch portions or halves 30 and 32, 
each of which comprise interdigitated frictional clutch disks, and an 
axially movable clutch slider 34. Similarly, double acting clutch 28 
comprises two clutch portions or halves 36 and 38, and an axially movable 
clutch slider 40. Clutch sliders 34 and 40 are shown schematically as 
being a single unit but it is understood that the actual structure of the 
clutch sliders may include two separately axially movable members such as 
hydraulic pistons or the like as is known in the art. As may be seen, 
movement of clutch slider 34 to the left will engage clutch 30 to 
rotationally fix input gear 16 to input shaft 12, movement of clutch 
slider 34 to the right will cause engagement of clutch 32 to rotationally 
fix input gear 18 to input shaft 2, movement of clutch slider 40 to the 
left will cause engagement of clutch 36 to rotationally fix input gear 20 
to input shaft 12 and movement of clutch slider 40 to the right will cause 
engagement of clutch 38 to rotationally fix output gear 22 to input shaft 
12. As output gear 22 is rotationally fixed to output shaft 24, engagement 
of clutch 38 will result in a direct driving connection between input 
shaft 12 and output shaft 24. Of course, less than full engagement of the 
friction clutches will permit slippage between the clutchable gears and 
input shaft. 
Of course, double acting clutches 26 and 28 could be hydraulically 
actuated, air actuated, electrically actuated and/or mechanically 
actuated. 
Transmission 10 is also provided with a plurality of substantially 
identical countershaft assemblies 42 and 42A, equally circumferentially 
spaced about input shaft 12. Each of the countershaft assemblies may be 
provided with a forward countershaft portion, 44 and 44A, and a rearward 
countershaft portion, 46 and 46A, fixed for rotation, as by a splined 
connection or the like, with the forward portion. Bearings 48, 50 and 52 
are provided for supporting the countershafts. It is understood, that if a 
single piece countershaft is provided, it is preferable that only bearings 
48 and 50 be utilized. Each of the countershafts carry countershaft gears 
54, 56, 58 and 60 rotationally fixed thereto. Countershaft gears 54 are 
constantly meshed with input gear 16, countershaft gears 56 are constantly 
meshed with input gear 18, countershaft gears 58 are constantly meshed 
with input gear 20 and countershaft gears 60 are constantly meshed with 
output gear 22. 
For first speed operation of transmission 10, clutch 30 is engaged and 
torque from input shaft 12 is transmitted via countershaft gears 54 and 
countershafts 42 and 42A to countershaft gears 60 which are constantly 
meshed with output gear 22 on output shaft 24. Similarly, second speed 
operation is through input gear 56 by engagement of clutch 32, third speed 
operation is through input gear 20 by engagement of clutch 36 and fourth 
or direct drive is through direct connection of input shaft 12 to output 
shaft 24 by engagement of clutch 38. Reference to FIG. 2 will illustrate 
the clutches engaged for each selected gear ratio of transmission 10. 
Preferably, to better assure that the two countershaft assemblies 42 and 
42A substantially share an equal torque transmitting capacity, input shaft 
12 and/or input gears 16, 18 and 20 and/or output gear 22 are provided 
with a degree of radial movement or float as is well known in the art. 
Pump 14, preferably a well known gear pump or the like, provides 
pressurized fluid to regulator R which supplies a valve V with a regulated 
supply of hydraulic fluid. Valve V, which may be automatically or manually 
controlled by a control C, will provide pressurized fluid for actuation of 
clutches 30, 32, 36 and/or 38. As is well known in the powershift 
transmission technology, and as may be seen in greater detail by reference 
to U.S. Pat. No. 3,762,518 which is hereby incorporated by reference, 
valve V will provide overlapping engagement of various of the friction 
clutches. For example, during a gear ratio shift from first gear, gear 16, 
to second gear, gear 20, clutch 30 will remain at least partially engaged 
as clutch 36 comes into engagement thereby providing a power path from the 
input shaft 12 to the output shaft 24 during the change in gear ratios as 
is well known in the powershift transmission art. 
FIG. 8 graphically illustrates a typical overlapping engagement of the 
on-going and off-going powershift clutches during a gear change operation. 
To provide for powershifting of transmission 10, when utilizing double 
acting clutches which may not be engaged on both sides simultaneously, 
while also providing for multiple substantially identical countershafts, 
each of which countershafts carry a substantially equal torque load in 
each selected gear ratio and during each gear change, it is important that 
neither of the double acting clutch mechanisms, 26 and 28, is utilized to 
selectively engage any two sequentially engaged gear ratios. Accordingly, 
double acting clutch 26 with its clutch portions 30 and 32 is utilized to 
engage first and third gear speed ratios while double acting clutch 28 
with its clutch portions or halves 36 and 38 is utilized to engage second 
and fourth gear ratios. 
The transmission 10 illustrated in FIG. 1 utilizes two substantially 
identical countershaft assemblies 42 and 42A and is usually referred to as 
a twin countershaft transmission. To increase the torque carrying capacity 
of such a transmission it is often desirable to provide a third 
substantially identical countershaft assembly, i.e. to provide a triplet 
countershaft transmission. To provide a family of transmissions comprising 
a twin countershaft version and a triplet countershaft version, while 
utilizing a maximum of substantially identical components and common 
housings or casings, the bore pattern of the transmission housing end 
walls which support the countershaft bearings 48 and 52 and the 
transmission intermediate wall (if any) which will support the 
countershaft bearings 50 (if any) is illustrated schematically in FIG. 7. 
End wall 60 is provided with a centrally located bore 62 through which the 
input shaft 12 or output shaft 24 passes and in which bearings may be 
provided. Four bores, 64, 66, 68 and 70, which may be blind bores in the 
case of end walls or through bores in the case of intermediate walls, are 
provided. The centers of bores 64, 66, 68 and 70 are equal distance from 
the centerline of bore 62. This distance 72 is generally referred to as 
the centerline distance of the transmission. Moving in the clockwise 
direction, second bore 66 is rotationally displaced by 120.degree. from 
first bore 64. Third bore 68 is rotationally displaced from second bore 66 
by an angular displacement of 60.degree.. Fourth bore 70 is rotationally 
displaced from third bore 68 by a rotational displacement of 60.degree.. 
First bore 64 is rotationally displaced from fourth bore 70 by an angular 
displacement of 120.degree.. If wall 60 is to be utilized for a twin 
countershaft transmission, first bore 64 and third bore 68 which are 
angularly displaced by 180.degree. will be utilized for receiving and 
retaining the countershaft support bearings and/or allowing passage of 
countershafts therethrough. If a triplet countershaft transmission is to 
be provided, first bore 64, second bore 66 and fourth bore 70 will be 
utilized for receiving and supporting countershaft bearings and/or 
allowing the passage of countershafts therethrough. First bore 64, second 
bore 66 and fourth bore 70 are angularly displaced by 120.degree.. 
Accordingly, a transmission casing having side walls, and an intermediate 
wall if necessary, each of which are provided with four bores surrounding 
the centrally located bore 62 in the manner shown in FIG. 7, may be 
utilized for either a twin countershaft or a triplet countershaft 
transmission. Additionally, by providing input gears having a number of 
teeth which are evenly divisible by both two and by three, substantially 
identical countershaft assemblies may be utilized in connection with both 
the twin countershaft and triplet countershaft transmission. Although the 
optional feature schematically illustrated in FIG. 7 is shown in 
connection with a multiple substantially identical powershift 
transmission, it is understood, that this feature is equally applicable to 
any substantially identical countershaft transmissions wherein it may be 
desirable to provide either a twin or triplet countershaft version thereof 
utilizing common components in a common casing, such as the transmissions 
illustrated in the above mentioned U.S. Pat. Nos. 3,105,395 and 3,500,695. 
An alternate embodiment of the present invention may be seen by reference 
to FIGS. 3, 4 and 5. In FIG. 3, a compound transmission 100 having a 
powershift twin countershaft four speed main transmission section 102 and 
a twin countershaft auxiliary range section 104 is illustrated. Auxiliary 
section 104 is connected in series with main section 102 as is well known 
in the art. The main transmission section 102 is substantially identical 
to transmission 10 described above and similar elements thereof will be 
assigned like reference numerals and will be only briefly redescribed 
below. 
Transmission 100 includes an input shaft 12 driven by an unshown prime 
mover and preferably drives a pump 14 which is preferably a gear pump or 
the like. Input gears 16, 18 and 20 are concentric with the input shaft 12 
and normally rotatably thereto. Main section output gear 22 is 
rotationally fixed to an intermediate shaft 106 which provides an input to 
the auxiliary transmission section 104. Double acting frictional clutch 
assemblies 26 and 28 comprising clutch halves 30 and 32, and 36 and 38, 
respectively, are provided for selectively frictionally coupling the input 
gears and the main section output gear to the input shaft. Substantially 
identical countershaft assemblies 42 and 42A, which may include forward 
countershaft portions 44 and 44A and rearward portions 46 and 46A, are 
supported by bearings 48, 50 and 52 and carry countershaft gears 54, 56, 
58 and 60 which are constantly meshed with input gears 16, 18 and 20 and 
main section output gear 22, respectively. Intermediate gear 108 and 
output gear 110 are concentric with intermediate shaft 106 and normally 
rotatable relative thereto. Output gear 110 is fixed to output shaft 118 
for rotation therewith. Double acting friction clutch assembly 112 is 
mounted to intermediate shaft 106 interposed intermediate gear 108 and 
output gear 110 and is rotatable with intermediate shaft 106. Double 
acting clutch assembly 112 is similar in operation and structure to 
clutches 26 and 28 discussed above but is preferably of a larger torque 
transmitting capacity. Double acting clutch 112 includes a first clutch 
half 114 for frictionally coupling intermediate gear 108 to intermediate 
shaft 106 and a second clutch half 116 for coupling output gear 110 to 
intermediate shaft 106. Of course, engagement of clutch half 116 to couple 
output gear 110 to intermediate shaft 106 will couple output shaft 118 
directly to intermediate shaft 106. Output shaft 118 and intermediate 
shaft 106 are generally concentric with input shaft 12. Double acting 
clutch is provided with a clutch slider member 120 which is schematically 
illustrated as a single member but may in fact comprise two independently 
operable pistons or the like, one for each clutch half 114 and 116. 
The intermediate portion 104 is also provided with a pair of substantially 
identical intermediate countershafts 122 and 122A supported by bearings 
124 and 126. Each of the auxiliary countershaft assemblies 122 and 122A 
carries intermediate countershaft gears 128 and 130 which are constantly 
meshed with intermediate gear 108 and output gear 110, respectively. 
As may be seen by reference to FIG. 4, to operate in the low range (speeds 
1-4), clutch 114 is engaged and torque from the intermediate shaft 106 
passes through intermediate gear 108 through intermediate countershaft 
gear 128 intermediate countershaft 122, intermediate countershaft gear 
130, output gear 110 and through output shaft 118. To operate in the high 
or direct range (speeds 5-8), clutch 116 is engaged coupling intermediate 
shaft 106 directly to intermediate shaft 118. 
Appropriate valving and controls are provided for operation of the clutches 
30, 32, 36, 38, 114 and 116 as is known in the art. It is noted that 
operation in the low range, that is operation in first through fourth 
speeds is powershift operation and operation in the high range, that is 
fifth through eighth speed operation, is powershift operation. However, 
during a so called "double swap shift", wherein shifting is between fourth 
and fifth speed requiring a shifting of both the auxiliary and the main 
transmission sections, a break in power does exist. Accordingly, 
transmission 100 is not a powershift transmission during fourth to fifth 
speed shifts nor during fifth to fourth speed downshifts. 
Transmission 100 may be seen in an elevational view, partially in section, 
by reference to FIG. 5. As may be seen, transmission 100 is enclosed in a 
suitable casing or housing 132 which may comprise portions 132A, 132B and 
132C all of which are bolted together in a conventional manner. Flywheel F 
is driven by a prime mover, such as a diesel engine (not shown), and 
preferably drives the input shaft 12 through a flex-plate assembly 134 
comprising a plurality of flexible steel disks 136 and a central hub 
portion 138 splined to the input shaft 12 at splines 140 and 142. The 
flywheel F may be supported on the input shaft at bearing 144. The forward 
end of input shaft 12 may be supported by bearings 146 while the rearward 
end of input shaft 12 is provided with a cavity 148 which receives a pilot 
portion 150 of the intermediate shaft 106. The rearward end of the 
intermediate shaft 106 is provided with a pilot portion 152 which is 
received in a cavity 154 in the forward end of the output shaft 118. 
Output shaft 118 is preferably supported by a bearing assembly 156. Input 
shaft may be a one piece structure or may be formed in two portions, 12A 
and 12B, which are directly splined or are joined by a splined connector 
12C which is supported by a bearing 12D. 
It is noted that input gear 16 is provided with 42 teeth (42T); input gear 
18 is provided with 66 teeth (66T); input gear 20 is provided with 54 
teeth (54T); main section output gear 22 is provided with 42 teeth (42T); 
intermediate gear 108 is provided with 36 teeth (36T) and output gear 110 
is provided 42 teeth (42T), all of which numbers of teeth are evenly 
divisible by both two and three. Accordingly, by utilization of end walls 
and intermediate walls as illustrated in FIG. 7 and discussed above, 
transmission 100 may be provided in either a twin countershaft or triplet 
countershaft configuration utilizing the same housing 132, the same input 
gears and input shaft, the same intermediate gear intermediate shaft, the 
same clutch structure and the same output shaft. Of course, a third 
countershaft assembly, substantially identical to countershaft assemblies 
42 and 42A, will be required for a triplet countershaft transmission. 
Countershaft gear 54 is provided with 51 teeth (51T), countershaft gear 56 
with 54 teeth (54T), countershaft gear 58 with 54 teeth (54T), 
countershaft gear 60 with 28 teeth (28T), intermediate countershaft gear 
128 with 36 teeth (36T) and intermediate countershaft gear 130 with 19 
teeth (19T). The gear ratios and percent steps for a transmission having 
the gear structure illustrated is shown in FIG. 6. 
As may be seen, countershaft portions 44 and 46 are joined at a splined 
connection 158. Preferably, splined connection 158 will allow for slight 
noncoaxial alignment of the countershaft portions as is necessary for a 
three bearing support of the countershaft assemblies. Countershaft gears 
56 and 58 are provided with an equal number of gear teeth, 54 teeth (54T), 
and the splined coupling 158 between the forward, 44 and 44A, and 
rearward, 46 and 46A, countershaft portions is also provided with 54 teeth 
(54T). Accordingly, if the alignment of the teeth of gears 58 and 60 
relative to the splines is identical on both rearward countershaft 
portions, 46 and 46A, and if the alignment of the teeth of gears 54 and 56 
relative to the splines is identical on both forward countershaft 
portions, 44 and 44A, the countershafts 42 and 42A will automatically be 
properly timed when assembled. A more detailed discussion of this 
structure may be seen by reference to U.S. application Ser. No. 165,833, 
filed Jul. 3, 1980 and assigned to the Assignee of this invention. 
Various fluid passages, seals and the like (not shown) are provided in the 
intermediate wall portion 162 of housing 132 and the input shaft 12 for 
supplying lubricating fluid and clutch actuation fluid. Various thrust 
bearings, rings and the like (not shown) are provided on the shafts as is 
known in the art. 
It may thus be seen that a change gear powershift transmission, or 
powershift transmission section, is provided which utilizes substantially 
identical countershaft assemblies, which countershaft assemblies carry a 
substantially equal portion of the torque load in each engaged gear and 
during each powershift. By utilizing specially configured end walls and/or 
intermediate walls, a common transmission case, common input shaft, common 
input gears and common countershaft assembly may be utilized for providing 
twin and/or triplet countershaft powershift transmission or transmission 
sections. 
Although this invention has been described in its preferred form with a 
certain degree of particularity, it is understood that the present 
disclosure of the preferred form is for descriptive purposes only and that 
various modifications and changes of the detailed construction and 
arrangement of the parts may be resorted to without departing from the 
spirit and the scope of the invention as claimed.