CA1126539A

CA1126539A - Four speed tractor transmission

Info

Publication number: CA1126539A
Application number: CA336,383A
Authority: CA
Inventors: Rudolf Beim
Original assignee: Ford Motor Company of Canada Ltd
Current assignee: Ford Motor Company of Canada Ltd
Priority date: 1978-11-21
Filing date: 1979-09-26
Publication date: 1982-06-29
Also published as: GB2036208A; GB2036208B; DE2941062A1

Abstract

ABSTRACT OF THE DISCLOSURE

A multiple-ratio, manually-controlled, synch-ronized power transmission for an agricultural tractor wherein provision is made for reducing the rotating iner-tia mass of the torque delivery elements of the power transmission mechanism during speed ratio changes thereby simplifying the transmission ratio shifting sequence and improving the shift quality.

Description

FOUR SPEED TRACTOR TRANSMISSION
The present inventionrelates to improv~ts in tractor t:ransmissions of the txpe shown in U.S. patents Nos.
3,293,933; 3,542,176; 3,115,047 and 3,173,303, which are S assigned to Ford Motor Company. It is an improvement also in trac~or transmissions of the type shown in U.S. patent No, 3,886,815.
Tractor transmissions normally include a main shaft and a countershaft arranged in parallel disposition.
The countershaft is connected to an output shaft through drive range gearing so that the multiple ratio transmission gearing can operate either in a high drive range or a low drive range depending upon the output torque that is required. The input shaft is connected to th~ tractor engine through a neutr-al clutch. A power gear for estab-lishing a further speed reduction or a 1:1 driving ratio can be introduced between the torque output element of the neutral clutch and the i~put gear element of the multiple ratio transmission to provide an additional drive range.
The ratio shifts of my improved transmission are fully synchronized. This is achieved by the use of a double acting synchronizer mounted concentrically on the power input shaft and a companion synchronizer mounted conce~trically about the countershaft. The synchronizers are arranged strategically so that during a ratio changefrom the second ratio to the third ratio, the power input gear and the neutral clutch are disengaged from the rotat-ing gear elements, and the rotating mass inertia is reduced accordingly. The same ls true on a downshift from a third ratio to the second ratio. This synchronizer clutch arrangement and its shift pattern is distinguished from prior art designs in which the rotating mass is connected to the power input shaft and forms a part of the power delivery path at the instant the ratio change is made or prior to the ratio change thereby making shifting much more difficult if not impossible to achieve while the vehicle is moving.

The synchronizer clutching arrangement of the improved multiple ratio gearing improves shift quality and drivability. Unlike many tractor transmissions of known design, the design makes it unnecessary for the tractor 5 operator to bring the tractor to a stop prior to shifting from one ratio to another.
Accordingly, the present invention provides a multiple ratio transmission assembly comprising a power input shaft and a countershaft arranged in parallel disposition, lO a first input gear journalled for rotation about the input shaft, second and third input gears connected together and mounted for rotation about the input shaft, first, second and third driving gears mounted for rotation about the counter-shaft, the first and second driving gears being connected 15 together, first synchronizer clutch means connected drivably to the input shaft for connecting together selectively the input shaft and the first and second input gears, second synchronizer clutch means carried by the countershaft for connecting together selectively the countershaft and the 20 second and third driving gears, an output shaft and final drive means for connecting the countershaft to the output shaft, the first input gear being connected to the input shaft by the first clutch means during first and third speed ratio operation and the second input gear being connected 25 to the input shaft by the first clutch means during second and fourth speed ratio operation, the third driving gear being connected to the countershaft by the second synchronizer clutch means during first and second speed operation and the second driving gear being connected to the countershaft 30 by the second synchronizer clutch means during third and fourth speed operation, the second synchronizer clutch means being engaged before the first synchronizer clutch means whenever the positions of the synchronizer clutch means are both changed to shift from one gear ratio to the other.
The invention is described further, by way of illustration with reference to the accompanying drawings, A~ wherein:
~.

~Z.~i5;;~
4 ~
Figure l is a cross-sectional assembly view of the main elements of the gear system of my improved trac-tor transmission.
Figure 2 is a diagram showing the shift pattern that is followed by the manually controlled gearshift linkage as the synchronizers shown in Figure l are operatçd.
Figure 3 is a cross-sectional view of a power sear which may be used betiween the tractor neutral clutch and the input element of ~he gear system of Figure 1.
Figure 4 is a cross-sectional assem~ly view of a neutral clutch used to connect the tractor engine to the torque input side o~ the power gear of Figure 3.
Referring to the drawings, in Figure 4, reference numeral 10 shows one end of the crankshaft of an internal combustion tractor engine. Crankshaft end 10 is connected to flywheel 12. A neutral clutch 14 is adapted to connect respectively the flywheel 12 to power sleeve shaft 16. Clutch 14 comprises a clutch 20 disc 18 carried by clutch disc hub 20 which, in turn, is splined to the shaft 16 at 22. A clutch housing 24 supports clutch release levers 26 which, when rotated in a counter-clock~ise direction as seen in Figure 4, cause the clutch pressure plate 28 to disengage the disc 18. Pressure 25 plate 28 normally is pressed against the clutch disc by clutch apply springs 30.
The clutch is applied and released by the opera-tor as he moves the clutch throw-out bearing hub 32 in one . ~ _.
dir0ction or the other. Upon movement in a left-hand 30direction the clutch throw-out bearing 32 engages clutch release ring 34 which engages the operating ring of the clutch relea~e levers 26.
The driver operated clutch operating mechanism for moving the clutch throw-out bearing is shown generally 35at 36. ~ever 36 is pivoted on the transmission housing, and the driver controlled clutch pedal is connected to the operating end of the lever 36 as shown at 38. The end 40 o~ the lever 36 is connected to the clutch throw-out bear-ing sleeve 42.

iS.,3~

A power takeoff shaft 44 is splined at 45 to the engine crankshaft to pro~ide a direct driving connection betw~en the engine and the output end of the PTO shaft, which will be described with reference to Figure 1.
Figure 3 shows a power gear which may be used between the neutral clutch of Figure 4 and the gearing system of Figure 1. ~.he power gear is enclosed within a gear housing 46 which forms a part of the main transmis-sion housing or which is bolted or otherwise connected 10 directly to it. A forward stationary support wall 48, which is bolted at its margin to power gear housing sup-port 50, forms a support for clutch throw-out bearing support sleeve 52.
The power gear housing support S0 is bolted to 15 the housing 46. A planetary reduction gear assembly 54 is located within the support 50. It includes a ring gear 56 ,~
-connected to the neutral clutch output sleeve 16, a- sun gear 58, which is splined to disc clutch cylinder 60, and pl net pinions 62 which mesh wlth ring gear 56 and ~ gear 58.
20 Pinions 62 are carried by carrier 64 which is splined to power gear output shaft 66.
The clutch cylinder 60 and sun gear 58 can be braked by multiple disc brakes 68. This includes brake discs carried by the clutch member 60 which are clamped 25 into braking engagement with brake ring 70 when fluid pres-sure is applied behind annular piston 72. The end of the piston 72 cooper~tes with the housing support 50 to define ~, , " ,~, a pressure chamber 74 to which pressure may be admitted when brake application is desired.
A multiple disc clutch assembly 76 is adapted to connect the clutch cylinder 60 with the carrier ~
when fluid pressure is admitted behind annular piston 78.
This piston cooperates with cylinder 60 to define a pres-sure cavity 80 to which pressure may be admitted when clutch application is desired. The clutch piston 78 nor-mally is urged to a clutch release position by clutch pis-ton return spring 82.
When the brake shown in part at 68 is applied,the planetary reduction gear unit provides an increased torque ratio as the sun gear 58 serves as a reaction mem-ber. When the brake 68 is released and the clutch shown in part at 76 is applied, the elements of the planetary gear system 54 are locked together and a 1 1 driving relationship exists between sleeve 16 and power gear out-put sleeve 66.
As seen in Figure 1, power input sleeve shaft 86 serves as a torque input element for the multiple ratio gear system. Sleeve shaft 86 is splined by means of inter-nal spline teeth 88 to external spline teeth on the sleeve shaft 66. A power takeoff shaft 44 extends through the sleeve 86, and its right-hand end is journalled in bearing 90 in a bearing opening forme~ in end plate 92 secured to the main transmission housing 94. The end of the power takeoff shaft 44 extends outwardly, as shown at 96, to permit a driving connection with tractor power implements.
Sleeve shaft 86 is journalled at its right-hand end by needle bearings 98 which are supported by bearing race 100 which, in turn, is journalled by bearings 102 and bearing suppor~ wall 104 of the housing 94. The left-hand end of the sleeve shaft 86 is journalled by tapered roller thrust bearings 106 in bearing wall 108 carried by another internal bearing support wall 110 of the housing 94. A first torque input gear 112 is supported on the sleeve shaft 86. A second torque input gear 114 is formed on or supported by sleeve 116. Gear 114 is part of a '~` ~,.~.. 21~;~5~e?.1~9 cluster gear which includes also gear 118. Sleeve 116 is supported on the sleeve 86 by needle bearings 120 and 122.
A double acting synchronizer clutch assembly 124 is adapted to connect selectively sleeve shaft 86 with either one or the other of the gears 112 or 114. The clutch assembly 124 includes a hub 126 which is externally splined to an axially movable internally splined clutch actuator 128. When the actuator 128 is moved in a left-hand direction, the internal spline teeth formed in it drivably engage external spline teeth 130 formed on the gear 112. When it is shifted in a right-hand direction, as seen in Figure 1, it drivably engages external splines 132 formed on the gear 114. Cone clutch elements 134 and 136 are carried respectively by the gears 112 and 114 and rotate with them. Internal cone clutch surfaces are formed in clutch elements 134 and 136 which are adapted to engage external co~e clutch surfaces formed on clutch elements 138 and 140. Elements 138 and 140 are connected together by cross shafts 142. The shafts 142 are formed with cam grooves which register with openings 144 in the clutch actuator 128 ~hen the rotation of the hub 126 is out of synchronism with one gear or the other depending upon the direction of movement of the actuator 128. The cammed edges of the groove in the shafts 142 will register with corresponding cam surfaces on the margins of the openings 144 thereby creating a cone clutch engaging rorce that tends to force one gear or the other to rotate in synchronism with the hub 126. After synchronism is esta~-lished, the actuator 128 can be moved in a right-hand direction or a left-hand direction depending upon the speed ratio that is desired.
A countershaft 146 is mounted in the transmission assembly in parallel disposition with respect to the shaft 44 and is journalled at its left-hand end in bearing 148 formed in a bearing opening in a bearing support wall 150 which is joined to the transmission housing 94. The right-hand end of the shaft 146 is supported by bearing 152 in a , ,, 3~

bearing opening formed in the previously described trans-mission bearing support wall 104.
A cluster gear assembly 154 is journalled on the countershaft 146 by bearings 156 and 158. It includes the first gear element 160 and a second gear element 162 which respectively engage the gears 112 and 114. Also supported by the countershaft 146 is drive gear 164 which meshes with gear 118.
The countershaft 146 and the hub 166 are splined at 168. Hub 166 forms a part of a second synchroni2er clutch assembly 170, which is substantially the same - construction as the previously described synchronizer clutch assembly 124. The synchronizer clutch assembly 170 includes an actuator 172 which can be shifted in the left-hand direction or the right-hand direction depending upon the ratio that is desired. When it is shifted in the left-hand direction, clutching engagement occurs between the internal splines of the actuator 172 and external splines 174 carried by the cluster gear assembly 154.
When the actuator 174 is shifted in the right-hand direc-tion, it engages drivably external splines 176 carried by the gear 164.
Countershaft 146 carries at its right-hand end drive gear 178 which meshes with larger diameter drive gear 180. This gear 180 forms a part of an output cluster gear assembly 182, which is journalled at its right-hand end by bearing 184 supported in the bearing opening formed in bearing support 92. The left-hand end is supported by the bearing 102 previously described, the bearing race 100 being formed as a part of the cluster gear assembly 182.
Cluster gear assembly 182 includes also the reverse drive gear 186 and a low drive range gear 188, the latter meshing with low drive.range output gear 190 rotatably supported on output shaft 192. The shaft 192 is journalled at its right-hand end by bearing 194 positioned in bearing support 196, and its left-hand end is journalled in bearing 198 in bearing recess formed in the right-hand end of the countershaft 146.

. .J

?J~

.

A reverse drive range gear 200 is rotatably supported on the shaft 192. It i~ adapted to engage a reverse drive p~nion, not shown, which in turn engages the reverse gear 186. A reverse-and-low clutch sleeve 202 is slidably supported and drivably connected to clutch hub 204 on the output shaft 192. It may be shifted in a right-hand airection to drivably engage external clutch teeth 206 carried by the gear 190 to establish a low drive range. It can be shifted in a left-hand direction to drivably engage external clutch teeth 208 formed on reverse drive range gear 200.
Clutch hub 210 carries a second internally splined clutch sleeve 212 whlch i5 adapted to drivably engage external clutch teeth 214 on gear 178 when it is shifted in a left-hand direction thereby establishing a direct connection between shaft 146 and output shaft 192.
Thi~ would correspond to the high drive range position.
When the sleeve 212 L~ moved to the position shown in Figure 1, the transmission may be conditioned for low drive range operation provided the sleeve 202 also is shifted in a right-hand direction.
In Figure 2, there is shownthe gear shift linkage motion pattern for a shift linkage that would be adapted for controlling the synchronizer clutches of Fisure 1.
It forms generally an "H" pattern. The line 216 is the line ~f motion for the actuator 128 for the synchronizer assembly 124. Line 218 is the line of motion for actuatsr 172 of the synchronizer clutch assembly 170.
To establish low speed ratio operation the actuator 128 is shifted in a left-hand direction, and the actuator 172 of the clutch assembly 170 is shifted in a right-hand direction. Both synchronizers must be engaged to effect a complete torque flow path through the gearing.
When the synchronizers are engaged in this fashion, torque is delivered from the output element of the power drive unit of Figure 3 and through the synchronizer clutch hub 128 and then is distributed to gear 112. This drives the cluster gear assembly 154. Torque then is transferred directly from the cluster gear assembly 154 through the engaged clutch splines 176 and the actuator 172 to the countershaft 146. If it is assumed that the sleeve 212 is shifted in a lef~-hand direction, torque is distributed then directly to the output.shat 192 from the counter~
shaft 146.
A ratio change from the first speed ratio to the second speed ratio requires actuation only of one synchronizer clutch assembly; namely, synchronizer clutch assembIy 124. The other synchronizer clutch assembly remains in the position it assumed during first speed ratio operation. Actuator 12 a is shifted in a right-hand ,direction thereby establishing a driving co~nection bet- . -ween the hub 126 and the gear 114. The same torque flow path exists although the driving gear now is sear 114 rather than gear.112. Thus the overall ratio is increased ,~
because of the larger pitch diameter of the gear 114.
A speed ratio change from the second speed ratio to the third speed ratio requires actuation of both synch-ronizer clutches. A~ter initiation of this speed change,synchronizer clutch assembly 124 is moved to the neutral position shown in Figure 1, and synchronizer clutch assembly 170 is shifted in a left-hand direction thereby establishing a cvnnection between the countershaft 146 and the gear 162. After this shift is completed, synchronizer clutc~ assembly 124 is shifted in a left-hand direction thereby again connecting drivably gear 112 to the torque input sleeve shaft 86. During that ratio change the synchronizer clutch assembly 170 establishes synchronism in the torque delivery elements while the mass associated with the power gear and the input clutch of ~igure 4 is d~sconnected from the rotating mass. Thus synchronization occurs relatively easily. The same reduced inertia shift occurs when the transmission mechanism shifts to a lower ratio; namely, from the third ratio to the second ratio.
In that case the synchroni7er clutch assembly 124 is moved initially to the neutral position, thereby disconnecting 53~9 -the rotating masses on the torque input side of the ~leeve shaft 86 as..the synchronizer clutch 170 again establishes a synchronized driving connection between the counter-shaft 146 and the cluster gear assembly 154.
A ratio change from a third ratio to a high-speed, fourth driving ratio is achieved by maintaining the synchronizer clutch assembly 170 in a left-hand posi-tion, which it assumes during third-speed ratio operation.
Thus it is necessary to actuate only one synchronizer clutch assembly; namely,synchronizer clutch assembly 12~.
This is done by moving the actuator ring 128 in a right-hand direction to establish a driving connection between the sleeve shaft 86 and the gear 114. Torque is then delivered from the input shaft to the gear 114 and hence to the gear 162.. Torque is delivered then to the engaged clutch 170 to the countershaft 146 and then to the output shaft.
The final drive gear assembly found in the pre-viously described patent to Foxwell, for example, is capable of establishing either a high drive range or a low drive range depending upon the position of the sleeves 212 and 202. During the previous description it has been assumed that the final drive gearing assembly of Figure 1 is in the high speed drive range. However, if the sleeve 212 is shifted in a right-hand direction and the sleeve 202 is shifted in a right-hand direction, an additional torque multiplication occurs because the gear 178 now becomes connected to the cluster gear assembly 182 of which gear 188 is a part. Gear 188 drives gear 190 which, in turn, is connected throu~h the sleeYe 202 to the output shaft 192.
.i ;h Reverse drive is achieved by moving the sleeve 202 ~ a left-hand direction to establish a driving connec-tion between the reverse gear 200 and the output shaft 192 as the low speed drive gear is connected.

,

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A multiple ratio transmission assembly comprising a power input shaft and a countershaft arranged in parallel disposition, a first input gear journalled for rotation about the input shaft, second and third input gears connected together and mounted for rotation about the input shaft, first, second and third driving gears mounted for rotation about the countershaft,said first and second driving gears being connected together, first synchronizer clutch means connected drivably to said input shaft for connecting together selectively said input shaft and said first and second input gears, second synchronizer clutch means carried by said countershaft for connecting together selectively said countershaft and said second and third driving gears, an output shaft and final drive means for connecting said countershaft to said output shaft, said first input gear being connected to said input shaft by said first clutch means during first and third speed ratio operation and said second input gear being connected to said input shaft by said first clutch means during second and fourth speed ratio operation, said third driving gear being connected to said countershaft by said second synchronizer clutch means during first and second speed operation and said second driving gear being connected to said countershaft by said second synchronizer clutch means during third and fourth speed operation, the second synchronizer clutch means being engaged before said first synchronizer clutch means whenever the positions of said synchronizer clutch means are both changed to shift from one gear ratio to the other.

2. The combination as set forth in Claim 1 wherein said second and third input gears form a first cluster gear assembly and said first and second driving gears form a second cluster gear assembly, said first synchronizer clutch means being disposed between said first gear and said second input gears and said second synchronizer clutch means being disposed between said second driving gear and said third driving gear.

3. The combination as set forth in Claim 1 wherein said final drive means comprises a third cluster gear assembly mounted for rotation about the axis of said input shaft, a reverse drive output gear mounted for rotation about the axis of said countershaft and first and second final drive output gears, said first and second final drive output gear being selectively connected to said countershaft, each final drive output gear meshing drivably with a separate gear element of said third cluster gear assembly.

4. The combination as set forth in Claim 2 wherein said final drive means comprises a third cluster gear assembly mounted for rotation about the axis of said input shaft, a reverse drive output gear mounted for rotation about the axis of said countershaft and first and second final drive output gears, said first and second final drive output gear being selectively connected to said countershaft, each final drive output gear meshing drivably with a separate gear element of said third cluster gear assembly.