CA1231556A - Countershaft transmission - Google Patents

Abstract

Abstract of the Disclosure Countershaft Transmission A countershaft transmission provides at least three forward and three reverse speeds and includes a first countershaft having a second gear secured thereto, a third gear rotatable thereon, and a first clutch for connecting the third gear thereto. A second countershaft has a fourth gear secured thereto which is intermeshed with the second gear, a fifth gear rotatable thereon, a sixth gear rotatable thereon, a seventh gear secured thereto, a second clutch for connecting the fifth gear thereto, and a third clutch for connecting the sixth gear thereto. A first gear is adapted to drive one of the side-by-side third and fifth gears, and a third countershaft is disposed elevationally below them. The third countershaft has an eighth gear secured thereto which is intermeshed with the sixth gear. Ninth and tenth gears are rotatable on the third countershaft and are selectively connected thereto by a fourth clutch and a fifth clutch respectively. The five rotating clutches are of the interleaved plate type, are hydraulically engaged and mechanically disengaged, and are generally internested between the walls of the housing for compactness. Up to eight forward and four reverse speeds can be obtained with but minor alterations.

Description

I

on Counter shaft Transmission Technical Field This invention relates generally to a counter shaft transmission for a vehicle or the like, and more particularly to a counter shaft transmission having a plurality of forward and reverse speeds using lo constant mesh gearing and a plurality of fluid actuated, rotating clutches of the interleaved multiple plate and disc type.

Background Art Counter shaft transmissions having a plurality of speed ratios in each direction of operation are particularly useful in the drive line of vehicles such as earth moving wheel loaders, rubber tired log skidders, track-type tractors, and other off-highway heavy duty vehicles. Such transmissions are advantageous in that a plurality of rotating clutches and associated gears can be so positioned on the usual parallel shafts as to allow considerable flexibility in adapting them to different vehicle space requirements.
A considerable number of speed ratios can also be obtained with but minor changes to the translation, while permitting a substantial number of similar parts to be used for manufacturing economy.
For example, the following United States counter shaft transmission patents are of general interest to the art: Patent No. 3,064,488 issued November 20, 1962 to AWL. Lee et at; Patent No.
3,080,767 issued March 12, 1963 to SO Price, Jr.;
Patent No. 3,425,293 issued February 4, 1969 to HIS. Krawczyk et at; Patent No. 3,465,609 issued .

September 9, 1969 to JOE'. Fisher et at; Patent No.
3,710,637 issued January 16, 1973 to JO Fisher et at;
Patent No. 3,~58,455 issued January 7, 1975 to AL is son et at; Patent No. 3,913,411 issued October 21, 1975 to JO James on; and Patent No.
4,341,127 issued July 27, 1982 to E. Stout.
Ilhile such counter shaft transmissions have a considerable number of desirable features they are deficient in several other respects. One of the major problems with them is that if they are connected to the output member of the engine and/or optional torque converter assembly of the vehicle they require excessive space above the axis of the input shaft.
Specifically, in some vehicular applications it would be necessary to raise the floor plates and elevate the entire operator station in order to obtain sufficient clearance above the input shaft's axis to accommodate large diameter components such as a rotating clutch thereat.
Another factor of significance is that some of these available transmissions have an excessive axial length and/or an excessive transverse width so that they cannot fit into the limited space available in a vehicle.
Furthermore, a family of counter shaft transmissions is needed which can effectively match various vehicular speed requirements with the elevation Al drop requirements between the input and output axes. In other words, the transmission should preferably be conveniently convertible to provide one or more additional speed ratios with but minor modification. In addition to such flexibility of construction, and the need to provide both a short drop and large drop capability, the transmission should be able to provide various PRO options at the desired elevation Al level.

I

Still further, the construction of many of the prior art counter shaft transmissions is excessively complex and costly. Moreover, they have other less noticeable deficiencies such as having excessive bearing speeds and/or clutch plate engagement speeds under certain operating conditions, and these deficiencies reduce the overall service life of the transmissiolls.
Accordingly, what is needed is a family of economical and compact counter shaft transmissions that can provide at least three forward speeds and three reverse speeds, and that can maximize parts commonality and minimize the number of gears, clutches, shafts and bearings that are required. In addition to having a long service life by virtue of designing the bearings and rotating clutches such that they do not function at undesirably high operating speeds, the family of transmissions should be capable of convenient modification so that the individual transmissions can satisfy different drop height requirements as well as different numbers of speeds and speed ratio requirements and thus be adaptable to a wide variety of vehicular applications. In connection with such vehicular use, each of the transmissions should preferably be axially compact and of narrow width while having a minimum elevation Al clearance above the upper input axis in alignment with the engine output.

Disclosure of the Invention The present invention is directed to overcoming one or more of the above problems.
In one aspect of the invention there is provided a counter shaft transmission having an input first gear, a first counter shaft having a second gear secured thereto and a third gear rotatable thereon, a I I

first clutch for connecting the third gear to the first counter shaft, a second counter shaft having a fourth gear secured thereto and a fifth gear rotatable thereon, a second clutch for connecting the fifth gear to the second counter shaft, and the first gear being in inter meshing engagement with the third and fifth gears. Advantageously, a sixth gear is rotatable on the second countershaftt a third clutch is used for connecting the sixth gear to the second counter shaft, and a seventh gear is secured to the second counter shaft. A third counter shaft having an eighth gear connected thereto which is inter meshed with the sixth gear is provided as are coupling means for selectively connecting one of the fourth and seventh gears to the third counter shaft for driving it.
In accordance with another aspect of the invention, a counter shaft transmission includes an input first gear disposed on an upper axis, a first counter shaft having a second gear secured thereto, a third gear connected to the first gear and being rotatable thereon, and first clutch means for connecting the third gear to the first counter shaft. A
second counter shaft is provided having a fourth gear connected to the second gear secured thereto, a fifth gear connected to the first gear and being rotatable thereon, second clutch means for connecting the fifth gear to the second counter shaft, a sixth gear rotatable thereon, third clutch means for connecting the sixth gear to the second counter shaft, and a seventh gear secured thereto. An elevation ally lower third counter shaft is also included which has an eighth gear convected to the sixth gear secured thereto, a ninth gear connected to the fourth gear rotatable thereon, a tenth gear rotatable thereon and connected to the seventh gear, fourth clutch means for connecting the ~31~

ninth gear to the third counter shaft, and filth clutch means for connecting the tenth gear to the third counter shaft.
More specifically, the counter shaft transmission of the present invention as described above provides at least three forward speeds and three reverse speeds with the input shaft being elevation ally directly above the third counter shaft, and with the first and second counter shafts being disposed in generally side-by-side relation elevation ally between the input shaft and the third counter shaft. In one modification thereof, another gear can be added to the input shaft, and a further gear and splitter clutch added to the first counter shaft to provide three more forward speed ratios. In a further modification an additional high speed clutch and two gears are effective with the splitter clutch and gears to provide eight forward and four reverse speeds. Moreover, the third counter shaft can serve as the output shaft and I provide a relatively short drop height or can be geared to an elevation ally lower output shaft to provide a greater drop height in order to match various vehicle requirements.

Brief Description of the Ryan Fig. 1 is a diagrammatic, developed, but substantially side elevation Al sectionalized view of a three-speed forward and three-speed reverse counter shaft transmission constructed in accordance with an embodiment of the present invention;
Fig. 2 is a diagrammatic, enlarged cross sectional view of a portion of Fig. 1 showing details of construction of the first rotating clutch by way of example;

Sue Fig. 3 is a diayra~nmatic, end elevation Al view o-f the counter shaft transmission of Fig. l showing the relationship of the various shaft axes and the constantly meshing gearing associated therewith and the cutting plane of developed Fig. l;
Fig. 4 is a speed char for the transmission of Fig. l showing the clutches which are engaged in each of the forward and reverse speeds;
Fig. 5 is a diagrammatic, single line drawing lo of thy major elements of the counter shaft transmission of Fig. l in solid lines, and illustrating two alternate embodiments in broken lines including additional components for respectively providing six forward and three reverse speeds and eight forward and four reverse speeds and Fly. 6 is a fragmentary, sectional view showing another alternate embodiment of the counter shaft transmission of Fig. l involving a foreshortened construction of the upper input shaft.
Best Mode for Carrying Out the Invention Referring to Fig. l, there is shown a counter shaft transmission lo having a housing or drop box 12~ and an upper input shaft 14 and a lower output shaft 16 rotatable supported in the housing along an input axis 18 and an output axis 20 respectively. In addition, first, second and third counter shafts Of intermediate shafts 22, 24 and 26 are rotatable mounted within the housing respectively along axes 28, 30 and 32 which are parallel to each other and to the input and output axes, and are disposed elevation ally between the input and output axes as may be noted by reference to Fig. 3.
The housing 12 is advantageously constructed of two major pieces; namely, a front case portion or front cover 34 disposed at the left when viewing Fig. l ~q~3~
I

and a rear case portion or main body 36 located at the right. In regard to the general orientation of the counter shaft transmission 10 it is contemplated that when it is placed in a vehicle, not shown, the axes of all of the shafts will normally be oriented parallel to the vehicle's longitudinal centerline or along a straight travel direction. Preferably, the input axis 18 will be in coaxial alignment with the output axis of the vehicle's engine, not shown.
A stepped cylindrical bore 38 and a plurality of blind cylindrically shaped stepped pockets 40, 42 and 44 are integrally defined in a front wall 46 of the front case portion 34 along the axes 18, 28, 30 and 32 respectively. The front case portion also defines a peripheral wall 48 that extends rearwardly from the front wall and terminates with a rearwardly facing coupling surface 50 located in a plane 52 normal to the axes of the shafts 14,22,24,~6 and I In a like manner a cylindrical bore 54, a plurality of blind cylindrically shaped pockets 56 and 58t and a stepped cylindrical bore 60 are integrally defined in a rear wall 62 of the rear case portion 36. An encircling peripheral wall 64 extends forwardly from the rear wall and is provided with a mounting flange 66 which defines a forwardly facing coupling surface 68. A first plurality of threaded fasteners 70 extend through the mounting flange of the rear case portion and are screwthreadably received in the front case portion, and a second plurality of threaded fasteners 71 extend through the front wall 46 of the front case portion 34 and are screwthreadably received in the rear case portion in order to secure them positively together and to define an internal chamber 72.
The bottom of the rear case portion 36 includes a front wall 74 having a conically inwardly tapering integral tube portion 76 defining a stepped cylindrical bore I symmetrically arranged along the lower axes 20 of the output shaft 16. The rear case portion also defines a cylindrical bore 80 and a rear face 82 encircling the bore, which are adapted to releasable receive a service brake assembly 84.
Specifically, the service brake assembly 84 includes a flanged brake body 86 which palatably extends forwardly into the bore 80, and a rear cover 88 defining a stepped cylindrical bore 90. A plurality of threaded lo fasteners 92 extend through the cover and the brake body and are screwthreadably received in the rear case portion to positively secure the parts in place and to define with the rear case portion an oil sup region identified generally by the reference numeral 94 in the lower part of the internal chamber 72. A partition 96 extends upwardly from the bottom of the rear case portion 36 and a sheet metal baffle 98 is releasable secured thereto. This baffle has a flat annular body 100 with a cylindrical opening 102 there through and a JO U-shaped rearwardly extending flange 104 which serve to divide the sup region 94 into a front or main oil reservoir 106 and a slightly elevated rear cavity 108 having an oil level below that of the main reservoir therein during operation of the transmission as will be later explained In the embodiment illustrated in Fig. 1, the counter shaft transmission 10 has an upper rear, flanged extension tube 110 which is piloted in the bore 54 and releasable secured to the rear wall 62 by a plurality of threaded fasteners 112. A first bearing assembly 113 is disposed in the extension tube for rotatable supporting the rear end of the input shaft 14, and a second bearing assembly 114 is disposed in the stepped bore 38 for rotatable supporting the front end of the input shaft. An input gear or first gear 118 is ~3~5~
I

connected to rotate with the input shaft near the front end thereof, while a power take off (PT0) flange 120 is connected to it at the rear end This PT0 flange is particularly useful for driving auxiliary equipment such as a winch on the vehicle, not shown.
As is illustrated best in Fig. 2, the front end of the first counter shaft 22 is supported in the stepped pocket 40 of the front case portion 34 by a straight roller or needle bearing assembly 1220 And, as shown in Fig. 1, the rear end of the first counter shaft is supported in the pocket 56 of the rear case portion 36 by a straight roller or needle bearing assembly 124. A second gear 126 is mounted on the first counter shaft in abutment with an annular shoulder 127 formed on the counter shaft and is preferably connected for conjoint rotation therewith by an annular fillet weld 128 as is illustrated in Fig. 2. A third gear 130 is freely rotatable mounted on the first counter shaft through an intermediate hub assembly 132 and is continually inter meshed with and driven by the input gear 118. The hub assembly 132 has a hub or an annular body 134 defining first and second external splints 136 and 137, a distal end 13~, and an enlarged proximal end 139 having an internal bore 140 in which is mounted a flanged bushing or sleeve bearing 141~
The third Lear 130 has an internal splint 142 which is intermeshingly engaged with the external splint 136 on the hub 134, and the third gear is axially entrapped between a shoulder 144 on the hub at the inner end of the splint and a releasable retaining ring 146.
A first hydraulically engaged and spring disengaged rotating clutch 152 can be selectively engaged to connect the third gear 130 to the first counter shaft 22 for conjoint rotation through the second gear 126 in order to achieve a forward mode of -10- it operation. Gore particularly, the first clutch 152 has a first plurality of annular plates 154 and a second plurality of interleaved annular plates or friction discs 156 connected respectively to an internal splint 158 formed on a drum 160 and to the external splint 137 on the hub 134. The drum 160 is secured to the second gear 126 by any suitable means and defines a cylindrical bore 163 within it that is disposed over a cylindrical pilot surface 164 formed on the second gear. An annular reaction plate 166 having a cylindrical bore 168 and an external splint 170 connected to the internal splint 158 of the drum 160 rotates with the first counter shaft 22 and is limited in its axial movement by a releasable retaining ring 15 172.
The first clutch 152 further has an actuating piston 174 having an external splint 176 connected to the internal splint 158 on the drum 160 so that it rotates with the first eountershaft 22. An axially outwardly opening pocket 178 having an inner cylindrical surface 180 is defined in the piston in order to telescopically receive the distal end 138 of the hub assembly 132. In this connection a cooling fluid passage 186 is provided in the first counter shaft 22 which is in communication with the loft or outermost end of the pocket 40. In this way cooling fluid can be directed through the front case portion 34 into the pocket, axially along the passage 186 and radially outwardly into an annular cooling fluid chamber 188. A
plurality of radially oriented passages 190 are formed in the distal end 138 of the hub assembly 132 for controllable directing the cooling fluid radially outwardly to the interleaved plates 154 and discs 156.
An actuating chamber 192 is defined between 35 the piston 174, the first countershaEt 22, the drum 160, and the second gear 126, and can be supplied with pressurized fluid via a passage 193 in a conventional manner. With such pressurization the piston it urged to the left when viewing Fig. 2 so that it presses the interleaved plates 154 and discs 156 axially together and against the reaction plate 166. Thus the third Jo gear 130 is caused to rotate with the first counter shaft. A plurality of compression springs 194 acting against annular seat means 195 on the first counter shaft serve to positively disengage the first lo clutch 152 by moving the piston to the right when viewing Fig. 2 when pressure is reduced in the actuating chamber.
Any forces tending to urge either the first counter shaft 22 or the hub assembly 132 forwardly or to the left when viewing Fig. 2 will be transmitted to the housing 12 substantially independently of the straight roller bearing assemblies 122,124 through a front thrust washer 197 located between the housing and hub assembly. Any forces tending to move these same elements to the right when viewing Fig. 1 will be transmitted to the housing through a rear thrust washer 199 located between the housing and a shoulder 201 formed on the first counter shaft.
Turning now to the second counter shaft 24 shown in Fig. 1, it can be noted to have a fourth gear 196 secured thereto which is continually meshing with the second gear 126 so that the second counter shaft always rotates in a direction opposite to the first counter shaft 22. Fifth and sixth gears 198 and 200 are freely rotatable mounted on the second counter shaft, and with the fifth gear 198 being continually inter meshed with and driven by the input gear 118 as can best be visualized by reference to Fig. 3. A
second clutch 202 is used to connect the fifth gear 198 US to the second counter shaft for a reverse drive, and a ~L~3~S16 third clutch 204 is used to connect the sixth gear 200 to the second counter shaft for a second speed condition. Although illustrated only diagrammatically in Fig. 1, the clutches 202 and 204 are of the multiple plate and disc type and are similar in construction to the first speed clutch 152 described immediately above as can be appreciated by reference to the drawings. It can be further seen that the second counter shaft 24 is rotatable supported in the pockets 42 and 58 through lo straight roller or needle bearing assemblies 206 and 208 respectively, and that a seventh gear 210 is releasable connected for conjoint rotation therewith as by a splint joint 212.
The third counter shaft 26 is advantageously displaced axially rearwardly a preselected distance with respect to the first and second counter shafts 22 and 24 for optimized compactness, and is rotatable mounted in the front stepped pocket 44 via a straight roller or needle bearing assembly 214. The rear portion of the third counter shaft is supported in a somewhat larger capacity straight roller bearing assembly 216 in the stepped bore 60, and is releasable connected to a splinted steering pump drive shaft 218.
A steering pump 220 is releasable secured to the rear case portion 36 by any suitable means and is continually driven by the third counter shaft via the drive shaft.
An eighth gear 222 is preferably weldable secured to the third counter shaft 26 in the same manner as the gears 126 and 196 are secured to their respective counter shafts 22 and 24. A ninth gear 228 is mounted for free rotation on the third counter shaft 26, and is selectively connected whereto by a fourth clutch 230 which can provide a third speed condition.
A tenth gear 232 is also freely mounted on the third counter shaft, and is connectable thereto by hydraulic actuation of a fifth clutch 234 which can provide a first speed condition. Because of the axially rearwardly displaced, but nested relationship of the third counter shaft 26 to the second counter shaft 24, the gears 228, 222 and 232 are disposed in aligned and continually inter Meshing engagement with the gears 196, 200 and 210 respectively. The fourth and fifth clutches 230 and 234 are preferably like the first lo clutch 152 described in detail earlier.
While it may be desirable to use the third counter shaft 26 as the output shaft in those vehicles having less elevation Al distance between the input and output axes, the embodiment of Fig. 1 has an eleventh gear 235 that is releasable secured to the third counter shaft by a splint joint 236. This eleventh gear serves to drive a relatively large diameter twelfth gear 237 conjointly coupled to the output shaft 16 by a shaft splint 238. A hub 240 forming part of the service brake assembly 84 is connected to the same shaft splint, so that when the service brake assembly is actuated by release of pressure fluid from a chamber 242 an actuating piston 244 will be moved leftwardly when viewing Fig. 1 by a Belleville compression spring 246. This will axially compress a plurality of alternately interleaved plates and discs 248 together in a well known manner, as is only diagrammatically indicated, so that the hub 240 can be frictionally connected to the rear case portion 36. this brakes the output shaft 16 and the front and rear wheels, not shown, which can be respectively driven through a front connecting flange 250 and a rear connecting flange 252. Advantageously, the flange 250 is nestable received within the tube portion 76 of the housing 12 and this permits a compact connection with the associated axle of the vehicle, not shown.

-14- ~X3~

The output shaft 16 is rotatable supported by a pair of opposed tapered bearing assemblies 254 and 256 in the stepped bores 78 and 90 respectively, and when it rotates the twelfth gear 237 is disposed in relatively close proximity to the flange 104 of the baffle 9B. Accordingly, the teeth of the twelfth gear urge cooling fluid upwardly and forwardly over the edges of the U-shaped flange 104 of the baffle 98 into the reservoir 106 in order to decrease the fluid level lo in the cavity 108. In this regard it is to be noted that the flange 104 relatively tightly encircles or conforms with the lower periphery of the flanged brake body 86 and provides minimal clearance there between so that only a small amount of fluid from the reservoir 15 can enter the cavity 108 from the reservoir 106 because of the reservoir's elevation ally greater fluid level.
This minimizes horsepower losses in cavity 108 that would otherwise occur due to fluid churning and aeration problems.
Industrial Applicability In operation, the input shaft 14 of the counter shaft transmission 10 shown in Figs. 1 and 5 can - be driven by the engine of the vehicle Andre by the output member of an optional torque converter mechanism as is well known in the art, although not illustrated.
This will simultaneously drive the third gear 130 and the fifth gear 198 because the input gear 118 on the input shaft is inter meshed with both of them. Assuming that a first forward speed is desired, the operator so controls the vehicle as to cause the first clutch 152 and fifth clutch 234 to be hydraulically actuated so as to engage the interleaved plates thereof together.
This respectively connects the third gear 130 for conjoint rotation with the first counters hat 22, and the tenth gear 232 for conjoint rotation with the third counter shaft 26. Accordingly, the output shaft 16 is driven at a relatively low speed ratio by way ox gear pairs 118-130, 126-196, 210-232 and 235-237. Note is made that counter shafts 22 and 24 always rotate in opposite directions because the gears 126 and 196 rotate respectively therewith and yet are continually inter meshed. Also, since the fifth clutch 234 is subject to greater torque loading due to its higher lo speed reduction ratio it is preferably larger in diameter than the other rotating clutches 152, 202, 204 an 230, which can advantageously be of the same lesser diameter for parts commonality.
As indicated by the speed chart of Fig. 4, it is only necessary to disengage the fifth clutch 234 and to engage the third clutch 204 in order to shift the transmission 10 from first to second forward speed. In this mode, the speed reduction ratio is reduced and the output shaft is driven at a higher speed by way of gear 20 pairs 118-130, 126-196, 200-222, and 235-237.
In order to shift from second to third speed forward, the third clutch 204 is disengaged and the fourth clutch 230 is engaged. Hence, only one clutch need be engaged from first to second, or from second to third which is advantageous from both the torque loading and control standpoints. In third gear forward the drive is by way of gear pairs 118-130, 126-196, the gear 228 driven by the year 196 and to the third counter shaft 26, and by the gear pair 235-237.
In first reverse, as shown by the chart of Fig 4, the low speed clutch 234 is engaged as it is in first forward. However, in the reverse mode of operation the second clutch 202 is always engaged Torque is thereby transmitted to the output shaft 16 35 via gear pairs 118-198, 210-232, and 235-237.

Lo To achieve second reverse, the low speed clutch 234 is disengaged and the third clutch 204 is engaged. Output shaft 16 is driven by gear pairs 118-198, 200-222, and 235-237.
Lastly, to shift to third speed reverse, the third clutch 204 is disengaged while the fourth clutch 230 is engaged. Again, as in forward, it is only necessary to engage a single clutch to change reverse speeds. Torque is transmitted in third speed reverse lo through gear pairs 118-198 and 196-228 to the third counters hat 26, and from there to gear pairs 235-237.
Referring now to Fig. 5, and to a first alternate embodiment of the counter shaft transmission 10 which includes some additional components as is diagrammatically shown by the broken lines at the upper right portion thereof. Specifically, a thirteenth gear

2~8 can be secured to the input shaft 14 rearwardly of the first gear 118, a fourteenth gear 260 can be rotatable mounted on the first counter shaft 22, and a sixth or splitter clutch 262 can be used to selectively connect the fourteenth gear 260 for conjoint rotation with the first counter shaft. This will enable the second gear 126 to be driven at either one of two speeds as determined by the ratio of gear pair 118-130 25 or gear pair 258-260. With such construction the counter shaft transmission 10 can provide from four to six forward speeds in addition to the three reverse speeds discussed heretofore.
A second alternate embodiment of the counter shaft transmission 10 includes some additional members over those described with respect to the first alternate embodiment. Such new members are illustrated in broken lines at the lower left portion of Fig. 5 and include a fifteenth gear 264 freely rotatable mounted on the output shaft 16 and continually inter meshed with

3~ilrj~

the ninth gear 228 on the third countershaFt 26.
seventh clutch or high speed clutch 266 can then be used to selectively connect the fiEteeilth gear 264 for conjoint rotation with the output shaft. This is effective to provide up to eight forward speeds and four reverse speeds. For example, the first clutch 152 can be used progressively with the fifth clutch 234, the third clutch 204, the fourth clutch 230, and the seventh clutch 266 to provide the first to the fourth lo forward speed ratios. Then the sixth clutch 262 can be used progressively with the same clutches 234, 204, 230 and 266 to provide the fifth through eighth forward speed ratios. In reverse the highest speed would be provided by the engagement of the reverse clutch 202 with the seventh clutch 266.
Another alternate embodiment is shown by the auxiliary view ox Fig. 6, wherein the input shaft 14' is foreshortened in comparison with the input shaft 14 where no power take-off is required along the upper 20 axis 18. In this instance an end cap 268 is palatably disposed in the bore 54 and releasable secured to the rear case portion 36 by the fasteners 112. A stepped pocket 270 is defined in the end cap and a tapered roller bearing assembly 272 is seated in the pocket and against a shoulder 274 formed on the input shaft I
for rotatable supporting the rear end of the input shaft 14' in paired thrust absorbing relation to the facing tapered roller bearing assembly 114 shown in Fig. 1. With such alternative construction, all of the 30 shafts 14', 22 and 24 would be relatively short and define a particularly axially compact construction at the upper portion of the transmission 10.
As can be visualized with reference to Fig. 3, an upright or vertical plane 276 preferably passes through the input axis 18, the axis 32 of the third counter shaft 26, and the axis 20 of the output shaft 16. The axes I and 30 of the first and second counter shafts 22 and 24 respectively are substantially symmetrically arranged on the opposite sides of the vertical plane and elevation ally between the upper axis 18 and the intermediate axis 32 of the third counter shaft 26. The third counter shaft could clearly serve as the transmission output, if desired, by merely removing the steering pump 220 from the location 10 illustrated in Fig. 1. Moreover, the axes 28 and 30 are so located relative to a horizontal plane 278 passing through the input axis 18 that the relatively large diameter gears 126 and 196 do not extend to any substantial degree above such horizontal plane. Since the input gear 118 is desirably relatively small in diameter, the instant transmission requires only a minimal vertical clearance height pa above the input axis 18 as is indicated in Fig. 3. This is a significant feature in many vehicle applications. Note 20 that the overall width OW" of the gears 126 and 196 as indicated in the drawing is also minimal. Still further, the overall drop can be tailored from the minimum distance illustrated between axes 18 and 32 to a maximum distance corresponding to the distance between axes 18 and 20. end, the overall speed reduction ratios can also be conveniently changed by modifying only the output gears 235 and 237 and/or by modifying the input gears 118, 130 and 198.
In view of the foregoing, it is apparent that I the counter shaft transmission 10 is simple and rugged in its construction, and is of light weight. Moreover, it is adaptable to a large number of vehicular applications since the output shaft drop height from the input centerline can be conveniently varied and the number of speed ratios varied as explained heretofore.

I

The first and second clutches 152 and 202 are laterally in longitudinal alignment, and the third and fourth clutches 204 and 230 are elevation ally in longitudinal alignment in order to conserve space. Furthermore, the S longitudinally offset and elevation ally nested nature of the second and third clutches 202 and 204 on the second counter shaft 24 and the fourth and fifth clutches 230 and 234 on the third counter shaft 26 is particularly advantageous from an overall compactness lo standpoint. Also, the construction of the region of the input shaft 14 minimizes transmission height and provides a highly desirable PRO location.
Another feature of the counter shaft transmission 10 is that the physical location of the first or low speed providing clutch 234 is such as to minimize high speed rotation of other elements of the transmission under normal operating conditions. In certain prior art transmissions it is understood that bearing speeds considerably above about 5,000 rum, for example 8~0~0 rum, are experienced by the inactive gears. Whereas in the counter shaft transmission 10 the bearing speeds of the inactive gears during roaring of the vehicle are generally limited to a maximum of about 5,000 rum with an assumed speed of 2400 rum for the I input shaft 140 Thus the bearings will live substantially longer and/or can be of somewhat less sophisticated and more economical design.
Other aspects, objects and advantages of this invention can be obtained from a study of the drawings, the disclosure and the appended claims.

Claims (14)

Claims

1. In a countershaft transmission of the type having an input first gear, a first countershaft having a second gear connected for joint rotation therewith and a third gear mounted for free rotation thereon, a first clutch for selectively connecting the third gear to the first countershaft, a second countershaft having a fourth gear connected for joint rotation therewith and a fifth gear mounted for free rotation thereon, the second and fourth gears being intermeshed, and a second clutch for selectively connecting the fifth gear to the second countershaft, the improvement comprising:
a sixth gear mounted for free rotation on the second countershaft;
a third clutch for selectively connecting the sixth gear to the second countershaft;
a seventh gear mounted for joint rotation with the second countershaft;
a third countershaft and an eighth gear connected for joint rotation therewith and being intermeshed with the sixth gear;
the input first gear being drivingly intermeshed with the third gear and the fifth gear such that selective actuation of one of the first clutch and the second clutch provides forward and reverse operation of the second countershaft; and coupling means for selectively drivingly connecting one of the fourth and seventh gears to the third countershaft for driving operation thereof, selective actuation of the third clutch and the coupling means providing three output speeds of the third countershaft with simultaneous actuation of one of the first clutch and the second clutch.

2. The countershaft transmission of claim 1 wherein the coupling means includes a ninth gear mounted for free rotation on the third countershaft and continually intermeshing with the fourth gear, and a fourth clutch for selectively connecting the ninth gear to the third countershaft.

3. The countershaft transmission of claim 2 wherein the coupling means includes a tenth gear mounted for free rotation on the third countershaft and continually intermeshing with the seventh gear, and a fifth clutch for selectively connecting the tenth gear to the third countershaft.

4. The countershaft transmission of claim 1 including an output shaft, means for drivingly connecting the third countershaft and the output shaft, another gear mounted for free rotation on the output shaft and another clutch for selectively connecting the another gear to the output shaft, the coupling means including a ninth gear coaxially mounted on the third countershaft and intermeshing the another gear.

5. The countershaft transmission for claim 1 including an input shaft connected to the first gear, another gear secured to the input shaft, a further gear mounted for free rotation on the first countershaft and directly intermeshing with the another gear, and another clutch for selectively connecting the further gear to the first countershaft.

6. The countershaft transmission of claim 1 wherein the coupling means includes a fourth clutch and a fifth clutch coaxial with the third countershaft, the fifth clutch having an engaged position effective to provide the lowest speed ratio.

7. The countershaft transmission of claim 6 wherein the first, second, third and fourth clutches are of the interleaved multiple plate and disc type and have a common preselected diameter for parts commonality.

8. The countershaft transmission of claim 7 wherein the fifth clutch is of the interleaved multiple plate and disc type and has a diameter larger than the preselected diameter of the remaining clutches.

9. The countershaft transmission of claim 1 wherein the coupling means includes a fourth clutch and a fifth clutch, all of the clutches being of the interleaved multiple plate and disc type.

10. A countershaft transmission comprising:
an input first gear disposed on an upper first axis;
a first countershaft having a second axis, a second gear secured thereto, and a third gear rotatable thereon and intermeshingly connected directly to the first gear;
first clutch means for connecting the third gear to the first countershaft;

a second countershaft having a third axis, a fourth gear secured thereto and connected to the second gear, a fifth gear rotatable thereon and intermeshingly connected directly to the first gear, a sixth gear rotatable thereon, and a seventh gear secured thereto;
second clutch means for connecting the fifth gear to the second countershaft;
third clutch means for connecting the sixth gear to the second countershaft;
a third countershaft having a lower fourth axis, an eighth gear secured thereto and connected to the sixth gear, a ninth gear rotatable thereon and connected to the fourth gear, and a tenth gear rotatable thereon and connected to the seventh gear;
fourth clutch means for connecting the ninth gear to the third countershaft; and fifth clutch means for connecting the tenth gear to the third countershaft, and wherein selective actuation of one of the first clutch means and the second clutch means provides forward and reverse operation of the third countershaft, and selective actuation of one of the third, fourth and fifth clutch means provides three output speeds of the third countershaft.

11. The countershaft transmission of claim 10 including another gear secured to rotate with the first gear on the first axis, a further gear rotatable on the first countershaft and directly intermeshing with the another gear, and sixth clutch means for connecting the further gear with the first countershaft.

12. The countershaft transmission of claim 10 including an output shaft, another gear intermeshed with the ninth gear and being mounted for free rotation on the output shaft, and another clutch means for selectively connecting the another gear to the output shaft.

13. The countershaft transmission of claim 10 wherein actuation of the fifth clutch means is effective to provide the lowest speed ratio.

14. The countershaft transmission of claim 10 wherein the first, second, third and fourth clutch means are of the interleaved multiple plate and disc type having a common diameter, and the fifth clutch means is also of the interleaved multiple plate and disc type having a diameter larger than the common diameter.