Transmission system for a work vehicle

A powershift transmission for a work vehicle includes a speed section. Within the speed section, a speed C clutch is engageable to transfer rotational power from a speed input shaft to a speed countershaft via first and second speed gears, a speed A clutch is engageable to transfer rotational power from the speed input shaft to the speed countershaft via third and fourth speed gears, and a speed B clutch is engageable to transfer rotational power from the speed input shaft to the speed countershaft via fifth and sixth speed gears. A first gear ratio between the first and second speed gears is greater than a second gear ratio between the third and fourth speed gears and a third gear ratio between the fifth and sixth speed gears.

BACKGROUND

Transmissions are used in agricultural and construction equipment to transmit power from power sources, such as internal combustion engines, to equipment for accomplishing a desired task. For example, transmissions are used to transmit power to wheels and/or tracks of a work vehicle. A powershift transmission is a transmission that controls the engagement and release of multiple clutches to switch between speeds/gears while maintaining a torque path through the transmission. Gear switching changes the speed of the work vehicle as well as the available torque. For example, switching to progressively higher gears my increase a work vehicle's speed while decreasing the available torque. Unfortunately, operating a work vehicle at a maximum speed may involve operating the engine at a maximum engine speed, which may increase noise and fuel consumption.

BRIEF DESCRIPTION

In certain embodiments, a powershift transmission for a work vehicle includes a speed section having a speed input shaft configured to be driven in rotation by an input. The speed section also includes a speed countershaft and a speed A clutch coupled to the speed input shaft. In addition, the speed section includes a speed B clutch coupled to the speed input shaft and a speed C clutch coupled to the speed countershaft. Furthermore, the speed section includes a first speed gear coupled to the speed input shaft and configured to rotate with the speed input shaft, and the speed section includes a second speed gear coupled to the speed C clutch and engaged with the first speed gear. In addition, the speed section includes a third speed gear coupled to the speed A clutch, and the speed section includes a fourth speed gear coupled to the speed countershaft and configured to rotate with the speed countershaft. The fourth speed gear is engaged with the third speed gear. The speed section also includes a fifth speed gear coupled to the speed B clutch, and the speed section includes a sixth speed gear coupled to the speed countershaft and configured to rotate with the speed countershaft. The sixth speed gear is engaged with the fifth speed gear. In addition, the speed A clutch is engageable to transfer rotational power from the speed input shaft to the speed countershaft via the third and fourth speed gears, the speed B clutch is engageable to transfer rotational power from the speed input shaft to the speed countershaft via the fifth and sixth speed gears, and the speed C clutch is engageable to transfer rotational power from the speed input shaft to the speed countershaft via the first and second speed gears. Furthermore, a first gear ratio between the first and second speed gears is greater than a second gear ratio between the third and fourth speed gears and a third gear ratio between the fifth and sixth speed gears.

DETAILED DESCRIPTION

As used herein, the term “coupled” or “coupled to” may indicate establishing either a direct or indirect connection, and is not limited to either unless expressly referenced as such. The term “set” may refer to one or more items. Wherever possible, like or identical reference numerals are used in the figures to identify common or the same elements. The figures are not necessarily to scale and certain features and certain views of the figures may be shown exaggerated in scale for purposes of clarification.

Certain transmissions include multiple gears and clutches configured to facilitate a change in the output speed of the transmission relative to the input speed. Changes in the output speed of the transmission change the speed of the work vehicle or other devices that receive power from the transmission. The transmission described below includes twenty-one forward speeds/gears and five reverse speeds/gears. Due to the gears of the transmission and a selection of engaged clutches, the work vehicle may travel at a maximum vehicle speed without operating the engine at a maximum engine speed. The work vehicle may, therefore, use less fuel and provide a quieter ride during operation (e.g., while the transmission is in the highest speed/gear, such as a road economy speed/gear).

With the foregoing in mind,FIG.1is a side view of an embodiment of a work vehicle10that may employ a transmission system. The work vehicle10may be any suitable type of loader, tractor, grader, backhoe, forklift, agricultural vehicle, or any other suitable work vehicle that utilizes a transmission. The work vehicle10has a body12that may house an engine, transmission, and power train. Further, the work vehicle10has a cabin14where an operator may sit or stand to operate the work vehicle10. The work vehicle10has front wheels16and rear wheels18that rotate along the ground. The engine of the work vehicle10may drive the front wheels16and/or the back wheels18using the transmission. For example, a full powershift transmission system may transfer power from the engine to the front wheels16and/or the rear wheels18. While the work vehicle10includes two front wheels16and two rear wheels18in the illustrated embodiment, in other embodiments, the work vehicle may include any suitable number of front wheels (e.g., 2, 4, etc.) and any suitable number of rear wheels (e.g., 2, 4, etc.). Furthermore, in certain embodiments, the work vehicle may include one or more sets of tracks driven by the transmission. For example, the work vehicle may include rear tracks instead of the rear wheel.

FIG.2is a block diagram of an embodiment of a transmission system20that may be used in the work vehicle ofFIG.1. An engine22(e.g., an internal combustion engine) provides power to drive a transmission24of the transmission system20. The transmission24(e.g., powershift transmission) may include a hydraulic system, a planetary gear unit, seals and gaskets, a torque converter, a modulator, sensor(s), other suitable components, or a combination thereof. Output from the transmission24drives a load26, such as the wheels of the work vehicle. The transmission system20further includes a controller28configured to control various systems and units within the transmission24. As illustrated, the controller28includes one or more memory devices30and one or more processors32. For example, the one or more memory devices30may include volatile memory, such as random access memory (RAM), and/or non-volatile memory, such as read-only memory (ROM), optical drives, hard disc drives, solid-state drives, or a combination thereof. Additionally, the one or more processors32may include one or more application specific integrated circuits (ASICs), one or more field programmable gate arrays (FPGAs), one or more general purpose processors, or any combination thereof. Furthermore, the term processor is not limited to just those integrated circuits referred to in the art as processors, but broadly refers to computers, processors, microcontrollers, microcomputers, programmable logic controllers, ASICs, and other programmable circuits. The one or more memory devices30(e.g., non-transitory computer-readable medium/memory circuitry) may store one or more sets of instructions (e.g., processor-executable instructions) to operate the transmission24. In operation, the controller28uses the one or more processors32to execute instructions stored in the one or more memory devices30to control the transmission24. For example, the controller28may receive instructions to cause various clutches to be engaged/disengaged to cause gear ratio changes while the work vehicle10is moving (e.g., at different speeds).

FIG.3is a schematic diagram of an embodiment of a transmission24(e.g., powershift transmission) that may be used within the transmission system ofFIG.2. In the following description, an axial direction40pointing toward an input42is referred to as “a forward direction”, and an axial direction44pointing toward a load or output (e.g., the rear wheels18) is referred to as “a rearward direction”. The input42may be a motor or the engine of the work vehicle, and the load or output may include the rear wheels18. The input42couples to and drives rotation of a driveshaft48, thereby enabling the transmission24to receive rotational power from the input42.

As illustrated, the driveshaft48is an element of a dropbox50. The dropbox50includes multiple gears. In the illustrated embodiment, the dropbox50includes a first dropbox gear52, a second dropbox gear54, and a third dropbox gear56. The first dropbox gear52is coupled directly to the driveshaft48and configured to rotate with the driveshaft48, and the third dropbox gear56is coupled directly to a speed input shaft58and configured to rotate with the speed input shaft58. In addition, the first dropbox gear52is engaged with the second dropbox gear54, and the second dropbox gear54is engaged with the third dropbox gear56. In operation, the gears of the dropbox50drive the speed input shaft58at a speed greater than the speed of the driveshaft48. In other words, the gears of the dropbox50establish a gear ratio that causes the speed input shaft58to rotate at a speed greater than the speed of the driveshaft48. By way of example, the gears of the dropbox50may establish a gear ratio between the driveshaft48and the speed input shaft58of 0.706. In certain embodiments, the first dropbox gear52may have 34 teeth, the second dropbox gear54may have 35 teeth, and the third dropbox gear may have 24 teeth. Increasing the speed of the speed input shaft58(e.g., as compared to dropbox gears that establish a higher gear ratio between the driveshaft and the speed input shaft, such as 0.909) may reduce torque on clutches in the transmission24, which may enable the transmission24to use smaller clutches, shafts, gears, or a combination thereof. As a result, the size and/or the manufacturing cost of the transmission may be reduced. As used herein, “gear ratio” refers to a torque multiplier between components (e.g., gear(s), shaft(s), etc.). For example, the gear ratio may be determined by dividing the number of teeth of the driven gear by the number of teeth of the driving gear.

As illustrated, the speed input shaft58is coupled directly to a first speed gear60within a speed section61of the transmission24and to a first pump drive gear62. The first speed gear60is configured to rotate with the speed input shaft58, and the first pump drive gear62is configured to rotate with the speed input shaft58. In addition, the speed input shaft58is coupled to a speed A clutch65within the speed section61and to a speed B clutch67within the speed section61. Furthermore, the speed input shaft58is coupled directly to a power take-off (PTO) input shaft64. As illustrated, the first speed gear60is engaged with a second speed gear68, and the second speed gear68is coupled to a speed C clutch69of the speed section61. The speed C clutch69is configured to selectively couple the second speed gear68to a speed countershaft70, thereby enabling power transmission from the speed input shaft58to the speed countershaft70. In certain embodiments, the gear ratio between the first and second speed gears is 2.360. For example, the first speed gear60may have 25 teeth, and the second speed gear68may have 59 teeth. Due to the large gear ratio between the first and second speed gears, engaging the speed C clutch causes the speed countershaft to be driven with high torque and at a low speed (e.g., as compared to a configuration in which the gear ratio between the first and second speed gears is 0.795). As a result, the speed C clutch may be engaged to establish the lowest speeds/gears of the transmission, such as the first three forward speeds/gears and the first reverse speed/gear (e.g., as compared to a configuration in which the gear ratio between the first and second speed gears is less than 1.000, such as 0.795, and the speed C clutch is engaged for a highest speed/gear, such as an overdrive speed/gear).

Furthermore, the speed section61of the transmission24includes a third speed gear72and a fourth speed gear74, in which the third speed gear72is engaged with the fourth speed gear74. As illustrated, the third speed gear72is coupled to the speed A clutch65, and the speed A clutch65is configured to selectively couple the third speed gear72to the speed input shaft58. In addition, the fourth speed gear74is coupled to the speed countershaft70and configured to rotate with the speed countershaft70. In certain embodiments, the gear ratio between the third and fourth speed gears is 1.147. For example, the third speed gear72may have 34 teeth, and the fourth speed gear74may have 39 teeth. In addition, the speed section61of the transmission24includes a fifth speed gear76and a sixth speed gear78, in which the fifth speed gear76is engaged with the sixth speed gear78. As illustrated, the fifth speed gear76is coupled to the speed B clutch67, and the speed B clutch67is configured to selectively couple the fifth speed gear76to the speed input shaft58. Furthermore, the sixth speed gear78is coupled to the speed countershaft70and configured to rotate with the speed countershaft70. In certain embodiments, the gear ratio between the fifth and sixth speed gears is 1.000. For example, the fifth speed gear76may have 37 teeth, and the sixth speed gear78may have 37 teeth.

A selected one of the speed A clutch, the speed B clutch, or the speed C clutch may be engaged to establish a power transfer path from the speed input shaft58to the speed countershaft70. For example, the speed A clutch65may be engaged while the speed B clutch67and the speed C clutch69are disengaged. Accordingly, the power transfer path extends from the speed input shaft58to the speed countershaft70via the third speed gear72and the fourth speed gear74(e.g., establishing a gear ratio of 1.147 between the speed input shaft and the speed countershaft). In addition, the speed B clutch67may be engaged while the speed A clutch65and the speed C clutch69are disengaged. Accordingly, the power transfer path extends from the speed input shaft58to the speed countershaft70via the fifth speed gear76and the sixth speed gear78(e.g., establishing a gear ratio of 1.000 between the speed input shaft and the speed countershaft). Furthermore, the speed C clutch69may be engaged while the speed A clutch65and the speed B clutch67are disengaged. Accordingly, the power transfer path extends from the speed input shaft58to the speed countershaft70via the first speed gear60and the second speed gear68(e.g., establishing a gear ratio of 2.360 between the speed input shaft and the speed countershaft). As such, the rotational speed of the speed countershaft70may be adjusted via engagement of a selected one of the speed A clutch, the speed B clutch, or the speed C clutch.

In the illustrated embodiment, the speed section61of the transmission24includes a seventh speed gear82and an eighth speed gear84. The seventh speed gear82is coupled to the speed countershaft70and configured to rotate with the speed countershaft70, and the eighth speed gear84is coupled to the speed countershaft70and configured to rotate with the speed countershaft70. In addition, the fourth speed gear74is engaged with a ninth speed gear86of the speed section61, the seventh speed gear82is engaged with a tenth speed gear88of the speed section61, the eighth speed gear84is engaged with an eleventh speed gear90of the speed section61, and the fifth speed gear76is engaged with a twelfth speed gear92of the speed section61. In certain embodiments, the gear ratio between the fourth and ninth speed gears is 0.872. For example, the fourth speed gear74may have 39 teeth, and the ninth speed gear86may have 34 teeth. In addition, in certain embodiments, the gear ratio between the seventh and tenth speed gears is 1.147. For example, the seventh speed gear82may have 34 teeth, and the tenth speed gear88may have 39 teeth. Furthermore, in certain embodiments, the gear ratio between the eighth and eleventh speed gears is 1.517. For example, the eighth speed gear84may have 29 teeth, and the eleventh speed gear90may have 44 teeth. In addition, in certain embodiments, the gear ratio between the fifth and twelfth speed gears is 1.054. For example, the fifth speed gear76may have 37 teeth, and the twelfth speed gear92may have 39 teeth.

In the illustrated embodiment, the speed section61of the transmission24includes a speed 1 clutch87coupled to the eleventh speed gear90and to a speed output shaft80, a speed 2 clutch89coupled to the tenth speed gear88and to the speed output shaft80, a speed 3 clutch91coupled to the ninth speed gear86and to the speed output shaft80, and a reverse clutch93coupled to the twelfth speed gear92and to the speed output shaft80. A selected one of the speed 1 clutch, the speed 2 clutch, the speed 3 clutch, or the reverse clutch may be engaged to establish a power transfer path from the speed countershaft70or the speed input shaft58to the speed output shaft80. For example, the speed 1 clutch87may be engaged while the speed 2 clutch89, the speed 3 clutch91, and the reverse clutch93are disengaged. Accordingly, the power transfer path extends from the speed countershaft70to the speed output shaft80via the eighth speed gear84and the eleventh speed gear90(e.g., establishing a gear ratio of 1.517 between the speed countershaft and the speed output shaft). In addition, the speed 2 clutch89may be engaged while the speed 1 clutch87, the speed 3 clutch91, and the reverse clutch93are disengaged. Accordingly, the power transfer path extends from the speed countershaft70to the speed output shaft80via the seventh speed gear82and the tenth speed gear88(e.g., establishing a gear ratio of 1.147 between the speed countershaft and the speed output shaft). Furthermore, the speed 3 clutch91may be engaged while the speed 1 clutch87, the speed 2 clutch89, and the reverse clutch93are disengaged. Accordingly, the power transfer path extends from the speed countershaft70to the speed output shaft80via the fourth speed gear74and the ninth speed gear86(e.g., establishing a gear ratio of 0.872 between the speed countershaft and the speed output shaft).

In addition, the reverse clutch93may be engaged while the speed 1 clutch87, the speed 2 clutch89, and the speed 3 clutch91are disengaged. Accordingly, if one of the speed A clutch or the speed C clutch is engaged, the power transfer path extends from the speed countershaft70to the speed output shaft80via the sixth speed gear78, the fifth speed gear76, and the twelfth speed gear92(e.g., establishing a gear ratio of 1.054 between the speed countershaft and the speed output shaft). As previously discussed, with one of the speed A clutch or the speed C clutch engaged, the speed B clutch is disengaged. Accordingly, the fifth speed gear76may rotate substantially freely about the speed input shaft58. Furthermore, if the speed B clutch is engaged, the power transfer path extends from the speed input shaft58to the speed output shaft80, bypassing the speed countershaft70, via the fifth speed gear76and the twelfth speed gear92(e.g., establishing a gear ratio of 1.054 between the speed input shaft and the speed output shaft). By selectively engaging one of the speed 1 clutch, the speed 2 clutch, the speed 3 clutch, or the reverse clutch, the rotational speed/direction of the speed output shaft may be adjusted.

The speed output shaft80selectively couples to a range input shaft94of a range section63of the transmission24via a master clutch95. In certain embodiments, the master clutch95is configured to vary a degree of engagement to control power flow through the transmission (e.g., during initiation of movement of the work vehicle, during shuttle shifting, etc.). In the illustrated embodiment, the range section63of the transmission24includes a first range gear96coupled to the range input shaft94and configured to rotate with the range input shaft94. In addition, the range section63of the transmission24includes a range low clutch97coupled to a range countershaft98. Furthermore, the range section63of the transmission24includes a second range gear99coupled to the range low clutch97and engaged with the first range gear96. In certain embodiments, the gear ratio between the first and second range gears is 2.455. For example, the first range gear96may have 22 teeth, and the second range gear99may have 54 teeth. In addition, the range section63of the transmission24includes a third range gear100and a fourth range gear102. The third range gear100is coupled to a range mid clutch101of the range section63, and the range mid clutch101is coupled to the range input shaft94. Furthermore, the fourth range gear102is coupled to the range countershaft98and configured to rotate with the range countershaft98, and the fourth range gear102is engaged with the third range gear100. In certain embodiments, the gear ratio between the third and fourth range gears is 1.054. For example, the third range gear100may have 37 teeth, and the fourth range gear102may have 39 teeth. Furthermore, the range section63of the transmission24includes a fifth range gear104and a sixth range gear106. The fifth range gear104is coupled to a range high clutch103of the range section63, and the range high clutch103is coupled to the range input shaft94. Furthermore, the sixth range gear106is coupled to the range countershaft98and configured to rotate with the range countershaft98, and the sixth range gear106is engaged with the fifth range gear104. In certain embodiments, the gear ratio between the fifth and sixth range gears is 0.424. For example, the fifth range gear104may have 59 teeth, and the sixth range gear106may have 25 teeth.

A selected one of the range low clutch, the range mid clutch, or the range high clutch may be engaged to establish a power transfer path from the range input shaft94to the range countershaft98. For example, the range low clutch97may be engaged while the range mid clutch101and the range high clutch103are disengaged. Accordingly, the power transfer path extends from the range input shaft94to the range countershaft98via the first range gear96and the second range gear99(e.g., establishing a gear ratio of 2.455 between the range input shaft and the range countershaft). In addition, the range mid clutch101may be engaged while the range low clutch97and the range high clutch103are disengaged. Accordingly, the power transfer path extends from the range input shaft94to the range countershaft98via the third range gear100and the fourth range gear102(e.g., establishing a gear ratio of 1.054 between the range input shaft and the range countershaft). Furthermore, the range high clutch103may be engaged while the range low clutch97and the range mid clutch101are disengaged. Accordingly, the power transfer path extends from the range input shaft94to the range countershaft98via the fifth range gear104and the sixth range gear106(e.g., establishing a gear ratio of 0.424 between the range input shaft and the range countershaft). As such, the rotational speed of the range countershaft may be adjusted via engagement of a selected one of the range low clutch, the range mid clutch, or the range high clutch.

In the illustrated embodiment, the range section63of the transmission24includes a seventh range gear108coupled to the range countershaft98and configured to rotate with the range countershaft98. The range section63of the transmission24also includes an eighth range gear110engaged with the seventh range gear108. The eighth range gear110is coupled to a rear axle input shaft112and configured to rotate with the rear axle input shaft112, and the rear axle input shaft112is configured to drive the rear wheels18to rotate. In certain embodiments, the gear ratio between the seventh and eighth range gears is less than 1.900, such as 1.808. For example, the seventh range gear108may have 26 teeth, and the eighth range gear110may have 47 teeth. Due to the gear ratio between the seventh and eighth range gears, the rear axle input shaft112may be driven to rotate at a high speed (e.g., as compared to a transmission in which the seventh and eighth range gears establish a gear ratio of 2.000). As a result, the maximum speed of the work vehicle may be achieved with an engine speed that is less than the maximum engine speed, thereby reducing noise and increasing fuel efficiency. Furthermore, due to the gear ratio between the seventh and eighth range gears, the rear axle input shaft112may be driven to rotate with a lower torque (e.g., as compared to a transmission in which the seventh and eighth range gears establish a gear ratio of 2.000). Due to the lower torque, the transmission may utilize smaller clutches, shafts, gears, or a combination thereof, thereby reducing the size and/or the manufacturing cost of the transmission. In certain embodiments, the rear wheels may be coupled to the rear axle input shaft via bevel gears that establish a suitable gear ratio (e.g., 4.909).

In some situations, it may be desirable to drive the front wheels16to rotate (e.g., while the work vehicle is operating in low traction conditions). To provide power to the front wheels16, the transmission24includes a mechanical front-wheel drive (MFD) system113having an MFD driveshaft114that is coupled to the front wheels16. Power is transferred to the MFD driveshaft114through an MFD gear116and an MFD clutch118. As illustrated, the MFD gear116is engaged with the eighth range gear110, and the MFD clutch118is coupled to the MFD gear116and to the MFD driveshaft114. Accordingly, while the MFD clutch118is engaged, power is transferred from the MFD gear116to the front wheels16. In certain embodiments, the gear ratio between the eighth range gear110and the MFD gear116is 1.000. For example, the eighth range gear110may have 47 teeth, and the MFD gear116may have 47 teeth. In certain embodiments, the front wheels16may be coupled to the MFD driveshaft114via bevel gears that establish a suitable gear ratio (e.g., 3.083).

Additional systems may couple to and receive power from the transmission24. These systems may include a pump drive120and a PTO output136. In the illustrated embodiment, the first pump drive gear62, which is coupled to the speed input shaft58and configured to rotate with the speed input shaft58, is engaged with a second pump drive gear124. In addition, the second pump drive gear124is engaged with a third pump drive gear126, and the third pump drive gear126is coupled to the pump drive120. In certain embodiments, the gear ratio between the first pump drive gear62and the third pump drive gear126is 0.981. For example, the first pump drive gear62may have 54 teeth, the second pump drive gear124may have 61 teeth, and the third pump drive gear126may have 53 teeth. Accordingly, the pump drive may be driven to rotate by the pump drive gears faster than the speed input shaft58. In addition, in certain embodiments, the gear ratio between the first dropbox gear52and the third pump drive gear126is 0.693. As a result, the pump drive may be driven at a high speed (e.g., as compared to a transmission in which the gear ratio between the first dropbox gear and the third pump drive gear is 0.707). While the transmission includes three pump drive gears in the illustrated embodiment, in other embodiments, the transmission may include more or fewer pump drive gears (e.g., 1, 2, 3, 4, etc.).

Power is also transferred from the speed input shaft58to the PTO output136. In the illustrated embodiment, the PTO input shaft64is coupled to the speed input shaft58. The PTO input shaft64is also coupled to a PTO clutch128, and the PTO clutch128is coupled to a first PTO gear130. In addition, the first PTO gear130is engaged with a second PTO gear132, and the second PTO gear132is coupled to a PTO output shaft134and configured to rotate with the PTO output shaft134. In certain embodiments, the gear ratio between the first and second PTO gears is 2.452. For example, the first PTO gear130may have 42 teeth, and the second PTO gear132may have 103 teeth. Furthermore, the PTO output shaft134is coupled to the PTO output136. Accordingly, while the PTO clutch128is engaged, rotational power is transferred from the speed input shaft58to the PTO output136.

In certain embodiments, a two-speed system may be coupled to the PTO output shaft. The two-speed system may include a series of gears configured to increase the gear ratio between the PTO output shaft and the PTO output. For example, in certain embodiments, the two-speed system includes a first gear coupled to the PTO output shaft and configured to rotate with the PTO output shaft. In addition, the first gear is engaged with a second gear, and the second gear is coupled to an intermediate shaft and configured to rotate with the intermediate shaft. A third gear is coupled to the intermediate shaft and configured to rotate with the intermediate shaft. The third gear is engaged with a fourth gear, and the fourth gear is coupled to a second PTO output shaft and configured to rotate with the second PTO output shaft. In certain embodiments, the gear ratio between the first and second gears is 1.172, and the gear ratio between the third and fourth gears is 1.583. Because the gear ratio between the PTO input shaft and the first PTO output shaft is 2.452 in certain embodiments, the total gear ratio between the PTO input shaft and the second PTO output shaft may be 4.549. For example, the first gear of the two-speed system may have 29 teeth, the second gear of the two-speed system may have 34 teeth, the third gear of the two-speed system may have 24 teeth, and the fourth gear of the two-speed system may have 38 teeth. The two-speed system may also include a selector assembly configured to selectively couple the first PTO output shaft to the PTO output or the second PTO output shaft to the PTO output. Accordingly, the rotation rate/torque at the PTO output may be controlled by selectively coupling the PTO output to a selected PTO output shaft.

In some embodiments, the transmission24ofFIG.3may include one or more speed sensors, each configured to output a respective signal indicative of the rotational speed of a respective shaft. The speed sensor(s) may include reflective sensor(s), interrupter sensor(s), optical sensor(s), magnetic sensor(s), Hall-effect sensor(s), other suitable type(s) of sensor(s), or a combination thereof. The speed sensor(s) may continuously, periodically, or upon receiving an instruction from the controller output signal(s) indicative of rotational speed(s) of respective shaft(s) to the controller. Based on the signal(s) from the speed sensor(s), the controller may determine the rotational speed of respective shaft(s) of the transmission24and may determine whether respective clutch(es) of the transmission24are engaged.

The clutches described herein may be any suitable type(s) of clutch(es), including dry clutch(es), wet clutch(es), single/multi plate clutch(es), centrifugal clutch(es), pneumatic or hydraulic clutch(es), electromagnetic clutch(es), or any combination thereof. Each of the clutches may be configured to selectively couple a gear to a shaft or selectively couple a shaft to another shaft upon receiving a control signal from the controller (e.g., the controller28).

Rotation of the various gears and shafts described above is controlled with the clutches (e.g., the speed A clutch, the speed B clutch, the speed C clutch, the speed 1 clutch, the speed 2 clutch, the speed 3 clutch, the reverse clutch, the master clutch, the range low clutch, the range mid clutch, the range high clutch, the MFD clutch, and the PTO clutch), such as to achieve different gear ratios (e.g., speeds) between the driveshaft48and the respective outputs (e.g., the rear axle input shaft, the MFD driveshaft, the third pump drive gear, and the PTO output shaft). For example, the clutches may be controlled (e.g., via the controller) to establish different power flow paths through the transmission, thereby achieving different speeds/gears in forward and reverse directions, as discussed in detail below.

Examples of the number of teeth on certain gears are disclosed above. However, in certain embodiments, at least one gear may have more or fewer teeth. For example, if a gear ratio between gears is disclosed, each gear may have any suitable number of teeth to achieve the disclosed gear ratio. Furthermore, any of the gear ratios disclosed above may be particularly selected for a desired transmission configuration (e.g., such that the gear ratio is different than the disclosed gear ratio). In addition, while the transmission is configured to output rotational power to the PTO output, the rear wheels, the pump drive, and the front wheel in the illustrated embodiment, in other embodiments, the transmission may be configured to output rotational power to more or fewer outputs/elements.

FIG.4is an embodiment of a shift diagram corresponding to gear ratio changes within the transmission ofFIG.3. As illustrated, the transmission is configured to provide twenty-one forward speeds/gears, from speeds/gears 1 to 21, and five reverse speeds/gears, from speeds/gears 1 to 5. The forward and reverse speeds/gears are illustrated in successive rows, with each speed/gear achievable via a power flow path through the transmission ofFIG.3. For each respective speed/gear, each clutch of the speed A, speed B, speed C, reverse, speed 1, speed 2, speed 3, range low, range mid, and range high clutches that is not indicated/described as being engaged is disengaged. Forward speed/gear 1 is achieved by engaging the speed C clutch, the speed 1 clutch, and the range low clutch. In certain embodiments, with the transmission in the forward speed/gear 1, the gear ratio through the transmission is 11.215. Forward speed/gear 2 is achieved by engaging the speed C clutch, the speed 2 clutch, and the range low clutch. In certain embodiments, with the transmission in the forward speed/gear 2, the gear ratio through the transmission is 8.479. Forward speed/gear 3 is achieved by engaging the speed C clutch, the speed 3 clutch, and the range low clutch. In certain embodiments, with the transmission in the forward speed/gear 3, the gear ratio through the transmission is 6.444.

Furthermore, forward speed/gear 4 is achieved by engaging the speed A clutch, the speed 1 clutch, and the range low clutch. In certain embodiments, with the transmission in the forward speed/gear 4, the gear ratio through the transmission is 5.451. Forward speed/gear 5 is achieved by engaging the speed B clutch, the speed 1 clutch, and the range low clutch. In certain embodiments, with the transmission in the forward speed/gear 5, the gear ratio through the transmission is 4.752. Forward speed/gear 6 is achieved by engaging the speed A clutch, the speed 2 clutch, and the range low clutch. In certain embodiments, with the transmission in the forward speed/gear 6, the gear ratio through the transmission is 4.121. Forward speed/gear 7 is achieved by engaging the speed B clutch, the speed 2 clutch, and the range low clutch. In certain embodiments, with the transmission in the forward speed/gear 7, the gear ratio through the transmission is 3.593. Forward speed/gear 8 is achieved by engaging the speed A clutch, the speed 3 clutch, and the range low clutch. In certain embodiments, with the transmission in the forward speed/gear 8, the gear ratio through the transmission is 3.132. Forward speed/gear 9 is achieved by engaging the speed B clutch, the speed 3 clutch, and the range low clutch. In certain embodiments, with the transmission in the forward speed/gear 9, the gear ratio through the transmission is 2.731.

In addition, forward speed/gear 10 is achieved by engaging the speed A clutch, the speed 1 clutch, and the range mid clutch. In certain embodiments, with the transmission in the forward speed/gear 10, the gear ratio through the transmission is 2.341. Forward speed/gear 11 is achieved by engaging the speed B clutch, the speed 1 clutch, and the range mid clutch. In certain embodiments, with the transmission in the forward speed/gear 11, the gear ratio through the transmission is 2.041. Forward speed/gear 12 is achieved by engaging the speed A clutch, the speed 2 clutch, and the range mid clutch. In certain embodiments, with the transmission in the forward speed/gear 12, the gear ratio through the transmission is 1.770. Forward speed/gear 13 is achieved by engaging the speed B clutch, the speed 2 clutch, and the range mid clutch. In certain embodiments, with the transmission in the forward speed/gear 13, the gear ratio through the transmission is 1.543. Forward speed/gear 14 is achieved by engaging the speed A clutch, the speed 3 clutch, and the range mid clutch. In certain embodiments, with the transmission in the forward speed/gear 14, the gear ratio through the transmission is 1.345. Forward speed/gear 15 is achieved by engaging the speed B clutch, the speed 3 clutch, and the range mid clutch. In certain embodiments, with the transmission in the forward speed/gear 15, the gear ratio through the transmission is 1.173.

Furthermore, forward speed/gear 16 is achieved by engaging the speed A clutch, the speed 1 clutch, and the range high clutch. In certain embodiments, with the transmission in the forward speed/gear 16, the gear ratio through the transmission is 0.941. Forward speed/gear 17 is achieved by engaging the speed B clutch, the speed 1 clutch, and the range high clutch. In certain embodiments, with the transmission in the forward speed/gear 17, the gear ratio through the transmission is 0.820. Forward speed/gear 18 is achieved by engaging the speed A clutch, the speed 2 clutch, and the range high clutch. In certain embodiments, with the transmission in the forward speed/gear 18, the gear ratio through the transmission is 0.711. Forward speed/gear 19 is achieved by engaging the speed B clutch, the speed 2 clutch, and the range high clutch. In certain embodiments, with the transmission in the forward speed/gear 19, the gear ratio through the transmission is 0.620. Forward speed/gear 20 is achieved by engaging the speed A clutch, the speed 3 clutch, and the range high clutch. In certain embodiments, with the transmission in the forward speed/gear 20, the gear ratio through the transmission is 0.541. Forward speed/gear 21 is achieved by engaging the speed B clutch, the speed 3 clutch, and the range high clutch. In certain embodiments, with the transmission in the forward speed/gear 21, the gear ratio through the transmission is 0.471.

In addition, with regard to the reverse speeds/gears, reverse speed/gear 1 is achieved by engaging the speed C clutch, the reverse clutch, and the range low clutch. In certain embodiments, with the transmission in the reverse speed/gear 1, the gear ratio through the transmission is 7.79. Reverse speed/gear 2 is achieved by engaging the speed A clutch, the reverse clutch, and the range low clutch. In certain embodiments, with the transmission in the reverse speed/gear 2, the gear ratio through the transmission is 3.79. Reverse speed/gear 3 is achieved by engaging the speed B clutch, the reverse clutch, and the range low clutch. In certain embodiments, with the transmission in the reverse speed/gear 3, the gear ratio through the transmission is 3.30. Reverse speed/gear 4 is achieved by engaging the speed A clutch, the reverse clutch, and the range mid clutch. In certain embodiments, with the transmission in the reverse speed/gear 4, the gear ratio through the transmission is 1.63. Reverse speed/gear 5 is achieved by engaging the speed B clutch, the reverse clutch, and the range mid clutch. In certain embodiments, with the transmission in the reverse speed/gear 5, the gear ratio through the transmission is 1.42.

As previously discussed, the controller may control engagement and disengagement of each clutch to achieve a desired speed/gear. For example, the controller may be communicatively coupled to an actuator of each clutch, and the controller may output a control signal to each actuator indicative of instructions to engaged or disengage the respective clutch. For example, the controller may cause the transmission to establish the first speed/gear by outputting signals indicative of instructions to engage the speed C clutch, the speed 1 clutch, and the range low clutch, and to disengage the speed A clutch, the speed B clutch, the reverse clutch, the speed 2 clutch, the speed 3 clutch, the range mid clutch, and the range high clutch.

Technical effects include a twenty-one forward speed/gear and a five reverse speed/gear transmission. The transmission enables the work vehicle to travel at a maximum vehicle speed while the engine operates below the maximum engine speed. The work vehicle may, therefore, use less fuel and provide a quieter ride during operation (e.g., while the transmission is in the highest speed/gear, such as a road economy speed/gear).

As used herein, the terms “inner” and “outer”; “up” and “down”; “upper” and “lower”; “upward” and “downward”; “above” and “below”; “inward” and “outward”; and other like terms as used herein refer to relative positions to one another and are not intended to denote a particular direction or spatial orientation. The terms “couple,” “coupled,” “connect,” “connection,” “connected,” “in connection with,” and “connecting” refer to “in direct connection with” or “in connection with via one or more intermediate elements or members.”

The foregoing description, for purpose of explanation, has been described with reference to specific embodiments. However, the illustrative discussions above are not intended to be exhaustive or to limit the disclosure to the precise forms disclosed. Many modifications and variations are possible in view of the above teachings. Moreover, the order in which the elements of the methods described herein are illustrated and described may be re-arranged, and/or two or more elements may occur simultaneously.