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| Illustration 1 | g00886406 |
(1) Input shaft (2) Torque Converter (3) Gear (4) Gear (5) Fan drive shaft (6) Gear (7) Gear (8) Pump drive shaft (9) Gear (10) Gear (11) Forward/Reverse shaft (12) Input drive gear (13) Forward clutch (14) Forward primary gear (15) Reverse clutch (16) Reverse primary gear (17) Reverse idler shaft (18) Gear (19) Gear (20) Countershaft (21) Fourth gear (22) Synchronizer ( fifth speed) (23) Fifth gear (24) Output shaft (25) First gear (26) First gear (27) Second gear (28) Second gear (29) Third gear (30) Third gear (31) Fourth gear (32) Fifth gear (33) Synchronizer ( first/second speeds) (34) Synchronizer ( third speed and fourth speed) | |
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| Illustration 2 | g00886748 |
Reverse Idler Shaft (Shown Outside of the Transmission for Clarity) | |
Note: The transmission that is shown in Illustration 1 is a transmission with five speeds. The fifth gear (23) is removed when the machine has only four speeds. Also, synchronizer (22) is replaced by a spacer, and fifth gear (32) is replaced by a spacer.
The transmission consists of the following main components:
Input shaft (1) - Power from torque converter (2) is transferred to the input shaft which causes the input shaft to rotate. Gear (3) is splined to the input shaft, and gear (4) rotates freely on the input shaft at the engine speed.
Fan drive shaft (5) - The fan drive shaft is splined to gear (6) which meshes with gear (4) on the input shaft. Power is transferred from gear (4) to gear (6) in order to cause the fan drive shaft to rotate. Gear (7) meshes with gear (3) on the input shaft. Power is transferred from gear (3) to gear (7) in order to cause gear (7) to rotate on the fan drive shaft. A needle bearing is located between gear (7) and the fan drive shaft in order to allow the gear to rotate independently of the fan drive shaft.
Pump drive shaft (8) - Gear (9) that is on the pump drive shaft for the implement pump is driven by gear (6) on the fan drive shaft. Gear (9) is splined to the pump drive shaft in order to provide drive to the pump drive shaft. Power is transferred from gear (7) to gear (10) that rotates on the pump drive shaft. The pump drive shaft rotates at engine speed. A needle bearing is located between gear (10) and the pump drive shaft in order to allow the gear to rotate independently of the pump drive shaft.
Forward/Reverse shaft (11) - Input drive gear (12) that is splined to the forward/reverse shaft meshes with gear (10) on the pump drive shaft. Power is transferred from gear (10) to the forward/reverse shaft via input drive gear (12) .
Forward clutch (13) - When the forward clutch is engaged, forward primary gear (14) is locked to the forward/reverse shaft. When the forward clutch is not engaged, forward primary gear (14) can rotate freely on two needle bearings on the forward/reverse shaft. Refer to "Clutch Operation" for more information on the operation of the forward clutch.
Reverse clutch (15) - When the reverse clutch is engaged, reverse primary gear (16) is locked to the forward/reverse shaft. When the reverse clutch is not engaged, reverse primary gear (16) can rotate freely on two needle bearings on the forward/reverse shaft. Refer to "Clutch Operation" for more information on the operation of the reverse clutch.
Reverse idler shaft (17) - Gear (18) on the reverse idler shaft meshes with reverse primary gear (16). When reverse clutch (15) is engaged, power from the reverse primary gear is transferred to the reverse idler shaft via gear (18). The power in the reverse idler shaft is transferred to gear (19) .
Countershaft (20) - Forward primary gear (14) and gear (19) mesh with fourth gear (21) on the countershaft. If the forward clutch is engaged, power is transferred from the forward primary gear to the fourth gear on the countershaft. The reverse idler shaft will rotate freely in this case. If the reverse clutch is engaged, power is transferred from gear (19) to the fourth gear on the countershaft. Forward primary gear will rotate freely in this case. The countershaft has four gears that are integral to the shaft, a fifth gear (if equipped) that rotates on two needle bearings, and a synchronizer (if equipped). When the synchronizer (22) is engaged, fifth gear (23) is locked to the countershaft.
Output shaft (24) - The countershaft and the output shaft have the following gear sets that are in constant mesh:
- First gear (25) on the countershaft with first gear (26) on the output shaft
- Second gear (27) on the countershaft with second gear (28) on the output shaft
- Third gear (29) on the countershaft with third gear (30) on the output shaft
- Fourth gear (21) on the countershaft with fourth gear (31) on the output shaft
- Fifth gear (23) (if equipped) on the countershaft with fifth gear (32) (if equipped) on the output shaft
The required gear ratio is selected by locking the specific gear sets to the respective shafts by engaging one of the following synchronizers:
- Synchronizer (33) for the first/second speed that is on the output shaft
- Synchronizer (34) for the third/fourth speed that is on the output shaft
- Synchronizer (22) (if equipped) for the fifth speed that is on the countershaft
Refer to Systems Operation/Testing and Adjusting, "Transmission Power Flow" for information on the clutches and the synchronizers that are engaged for each speed.
Clutch Operation
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| Illustration 3 | g00886075 |
(11) Forward/reverse shaft (14) Forward primary gear (16) Reverse primary gear (35) Seal rings (36) Control oil passage (37) Drum shaft assembly (38) Clutch piston (39) Clutch pack (40) Outer discs (41) Inner discs (42) Backing plate (43) Snap ring (44) Needle bearings (45) Spring (46) Needle bearings (47) Spring retainer (48) Circlip | |
The two clutches on the forward/reverse shaft operate in an identical manner. The forward clutch and the reverse clutch have the following main components:
Seal rings (35) - Three seal rings are located on the end of forward/reverse shaft (11). Control oil is connected to each clutch through a series of passages which are formed in the housings of the torque converter and the transmission. Control oil is connected to a control oil passage (36) in the forward/reverse shaft. The control oil is prevented from leaking by seal rings (35) .
Drum shaft assembly (37) - Each clutch pack is installed in a drum shaft assembly which has internal splines. A section of the bore of drum shaft assembly is smooth in order to allow operation of clutch piston (38) .
Clutch pack (39) - The clutch packs consist of outer discs (40) with external splines on the outer diameter and inner discs (41) with internal splines on the inner diameter. The outer discs are made from steel and the inner discs (friction) are made from steel and a paper based material. An outer disc is installed first against clutch piston (38), and an inner disc is then installed. The external splines on the outer disc engage with corresponding splines in drum shaft assembly (37). The discs are stacked alternately until six inner discs and six outer discs are installed. The discs are held in position by backing plate (42) and snap ring (43) .
The hub of forward primary gear (14) and the hub of reverse primary gear (16) have external splines which engage with the internal splines of inner discs (41). The inner discs and the primary gears which run on needle bearings (44) are free to increase in speed and free to rotate in the opposite direction to the outer discs provided that there is no oil pressure in that specific clutch.
Clutch piston (38) - When the clutch is engaged, control oil pressure is transmitted into the area behind the clutch piston. The oil pressure forces the clutch piston and clutch discs (40) and (41) against backing plate (42) in order to form a solid connection. The drive can then be transmitted from drum shaft assembly (37) to the hub of forward primary gear (14) or reverse primary gear (16) .
Spring (45) - The spring is located on spring guide (46) between spring retainer (47) and clutch piston (38). The spring is held under compression by circlip (48). The spring force is used to move clutch piston (38) away from clutch discs (40) and (41) in order to disengage the clutch. Oil from behind the clutch piston flows back through control oil passage (36) when the clutch is disengaged.
When pressure is relieved from the clutch, drum shaft assembly (37) can rotate with outer discs (40) at a different speed to the forward primary gear (14) or reverse primary gear (16) and inner discs (41). Also, when pressure is relieved from the clutch, the drum shaft assembly can rotate with the outer discs in the opposite direction to the forward primary gear or reverse primary gear and the inner discs.
Operation of the Synchronizers
The synchronizer for the first speed and second speed, and the synchronizer for the third speed and fourth speed are two-way synchronizers. The synchronizer assemblies and the shift rails can be operated manually or the synchronizer assemblies and the shift rails can be operated by solenoids. The operation of the synchronizer assemblies and the shift rails depends on the type of transmission on the machine. Each of these synchronizers can lock one of two output gears to the output shaft at a time. The synchronizer for the fifth speed can only lock the fifth gear to the countershaft. All three of the synchronizers are actuated with forks and a shift rail. The shift rails have a steel ball and spring detents in order to hold the NEUTRAL position and the GEAR positions. The first/second synchronizer use a double clutch. The third/forth synchronizer and the fifth synchronizer use a single cone clutch. The synchronizer assemblies are all strut type. The following text explains the operation of the synchronizer assemblies.
Synchronizer for the First Speed and Second Speed
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| Illustration 4 | g00886407 |
Synchronizer for the First/Second speed (24) Output shaft (26) First gear (28) Second gear (49) Hub (50) Sleeve (53) Connecting block (54) Strut (55) Spring (56) Detent pin (57) Outer cone (58) Friction ring (59) Inner cone (60) Plate | |
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| Illustration 5 | g00887427 |
Output Shaft (Shown Outside of the Transmission for Clarity) (51) Fork (52) Shift rail | |
The synchronizer contains the following main components:
Hub (49) - The hub is splined to output shaft (24). The outer radius of the hub also has splines.
Sleeve (50) - Splines on the internal radius of the sleeve are interlocked with the splines on the outer radius of hub (49). A groove around the circumference of the sleeve provides a location for fork (51) which is attached to shift rail (52) .
Connecting blocks (53) - Three connecting blocks are located between hub (49) and sleeve (50). The connecting blocks are positioned around the sleeve at 120 degree intervals. The connecting blocks connect the inner cone to the outer cone.
Struts (54) - Three struts are also located between hub (49) and sleeve (50). Each strut is positioned directly opposite one of the connecting blocks (53). Each of the three struts have a spring (55) and detent pin (56). The head of the detent pin sits in a groove on the inside of sleeve (50) .
Two outer cones (57) - Each outer cone sits in a circular channel on the side of hub (49). The outer cones are driven by lugs which engage in slots in the hub. The outer cones also have teeth on the circumference which can engage with the internal teeth of the sleeve.
Two friction rings (58) - Each friction ring which sits between the inner cone and the outer cone (57) can rotate independently of the cones. The friction ring drives the plate (60) via lugs.
Two inner cones (59) - Each inner cone sits inside friction ring (58) and interlocks with connecting blocks (53) to the outer cones.
Two Plates (60) - Each plate (60) fits over an inner cone (59), a friction ring (58) and an outer cone (57). The location lugs of friction rings (58) are interlocked with the alignment slots of the adjacent plate (60). Each plate (60) is also splined with an output gear that is on the output shaft.
When the synchronizer is not engaged, the following components rotate with the output gear:
- Plate (60)
- Friction ring (58)
When the synchronizer is not engaged, the following components rotate with the output shaft:
- Hub (49)
- Inner cone (59)
- Outer cone (57)
- Connecting blocks (53)
- Strut (54)
- Detent pins (56)
- Springs (55)
- Sleeve (50)
When a transmission speed is selected the solenoid on the gear valve is switched on. Oil flows into the actuator at the opposite end of the shift rail. The shift rail (52) moves in a direction that is parallel to the output shaft. Fork (51), which is attached to the shift rail, exerts a force on sleeve (50) and the sleeve begins to move toward the output gear. As sleeve (50) moves toward output gear detent pins (56) are dragged by the groove in sleeve (50). This causes struts (54) to move until the struts contact outer cone (57). The modulating valve drops the pressure initially. The pressure then ramps up to a predetermined level. When the surfaces of the struts and the surfaces of the cones come together outer cone (57) will rotate by half a tooth. The chamfers of the teeth on sleeve (50) contact the chamfers of the teeth on outer cone (57). The force on sleeve (50) is now transmitted to the cones by these tooth chamfers. Further movement of sleeve (50) is blocked by the interaction of the synchronising torque and the indexing torque of the chamfers on the tooth. The friction that is created causes the speed of the output gear and the speed of output shaft (24) to become equal. Zero synchronising torque will result if the speed of the output gear is equal to the speed of the output shaft. The chamfers on the teeth are now able to rotate outer cone (57) by half a tooth. Sleeve (50) will then move up over the teeth on the outer cone and up to plate (60). The teeth on sleeve (50) will engage with the teeth on plate (60). This action will fix the output gear to output shaft (24). Sleeve (50) rides over the top of detent pins (56) so that no force is transmitted to struts (54) .
The pressure to the clutch is controlled by a proportional pressure reducing valve. When the synchronizer is engaged, the output gear is locked to the output shaft. Power flows through the system components in the following order:
- Output gear
- Synchronizer
- Output shaft
Synchronizer for the Third Speed and Fourth Speed
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| Illustration 6 | g00888146 |
Synchronizer for the Third/Fourth Speed (24) Output shaft (30) Third gear (31) Fourth gear (49) Hub (50) Sleeve (54) Strut (55) Spring (57) Outer cone (61) Plate (62) Steel ball | |
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| Illustration 7 | g00888421 |
Output Shaft (Shown Outside of the Transmission for Clarity) (63) Shift rail (64) Fork | |
The synchronizer for the third/fourth speed operates on the same principles as the synchronizer for the first/second speed, but it does not include all of the same components. The components that are not used in the synchronizer for the third/fourth speed are the friction rings and the connecting blocks.
The synchronizer for the third/fourth speed has the following components that operate in the same way as the synchronizer for the first/second speed:
- Sleeve (50)
- Strut (54)
- Springs (55)
- Outer cone (57)
- Hub (49)
The synchronizer for the third/fourth speed has the following components that operate in a different way to the synchronizer for the first/second speed:
Plates (61) - The plate (61) for the third speed is splined to third gear (30) on output shaft (24). The plate (61) for the fourth speed is splined to fourth gear (31) on output shaft (24). The plates (61) have an inner cone that is machined into the inner circumference of the plates (61). The plates (61) also have teeth around the outer circumference.
When third speed or fourth speed is selected, shift rail (62) moves in a direction that is parallel to the output shaft. Fork (63), which is attached to the shift rail, exerts a force on sleeve (50) in order to initiate the engagement of the synchronizer. The synchronizer for the third speed and fourth speed operates in the same way as the synchronizer for the first/second speed. The frictional force that is required to equalize the speed of the output shaft and the speed of the output gear is produced between outer cone (57) and the inner cone on plate (61) .
Steel balls (62) - The three steel balls will operate in the same way as the detent pins on the synchronizer for the first/second speed. The steel balls sit in a groove on the inside of outer ring (50). This action causes the struts to move.
Synchronizer for the Fifth Speed (If Equipped)
The synchronizer for the fifth speed operates on the same principles as the synchronizer for the third/fourth speed. However, the synchronizer for the fifth speed has the following differences to the synchronizer for the third/fourth speed:
- The fifth speed cannot be selected manually.
- The fifth gear is engaged and disengaged automatically when the transmission is in fourth gear.
- The synchronizer for the fifth speed operates on one side instead of two sides.
- The synchronizer operates on the countershaft instead of the output shaft.
- The actuator is held hydraulically in the DISENGAGED position.
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| Illustration 8 | g00886408 |
Synchronizer for the Fifth Speed (20) Countershaft (32) Fifth gear (49) Hub (50) Sleeve (54) Strut (55) Spring (57) Outer cone (61) Plate (62) Steel ball | |
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| Illustration 9 | g00888072 |
(65) Shift rail (66) Fork | |
The synchronizer for the fifth speed operates in the same way as the top half of the synchronizer for the third/fourth speed. The synchronizer for the fifth speed is only able to lock the fifth gear to the shaft.
The fifth speed is automatically selected by the machine when the output shaft reaches a set speed. Shift rail (65) and forks (66) move outer ring (50) in order to engage the synchronizer, and the fifth gear is then locked to the countershaft. Power is transferred through the system components in the following order:
- Countershaft
- Synchronizer for the fifth speed
- Fifth gear on the countershaft
- Fifth gear on the output shaft
- Output shaft
Limits
Several limits have been incorporated into the control system of the transmission. The limits prevent damage to the power train. The limits also prevent overspeed of the engine.
- Transmission shifting through the gears will be prevented when the torque converter has stalled.
- When a direction change from fourth gear forward or fifth gear forward is received, this will be limited. The ECM will change down the gears to third gear in order to reach a suitable speed before changing direction.
- Shifting down causing engine overspeed will be limited. Once the speed drops the shift will be allowed.
- The ECM will allow directional changes at any speed in third gear. Excessive numbers of directional changes at any speed in third gear is limited. Excessive numbers of directional changes at any speed in third gear could damage the integrity of the system.
- The machine has a downshift inhibitor in order to prevent the engine from over-speeding. The ECM will detect the current speed. The ECM will stop the operator from selecting a lower gear while the machine is coasting down a hill.
- The machine has a inhibitor on shifting for protection from rollback in order to prevent the machine from rolling back between shifts on a slope if the torque converter is near a stall. If the transmission output speed and the torque converter ratio fall below the limit, the ECM will not allow a downshift. The ECM will shift to the requested gear when the limit has passed.