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| Illustration 1 | g02731000 |
Five Transmission Shafts (1) Planetary carrier (2) Gear (3) Clutch pack (4) Planetary carrier | |
Note: Gear (4) meshes only with gear (2). The configuration of the five transmission shafts in Illustration 1 is only for illustrative purposes.
There are seven similar clutch packs (3) that are located on four shafts. There are two identical planetary clutch packs that fit to planetary carriers (1) and (5). The planetary clutch packs are fastened to the front and rear transmission cases. See Illustrations 2 and 3.
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| Illustration 2 | g02731015 |
Front Transmission Case (6) Planetary clutch pack | |
One planetary clutch pack (6) is located in the front transmission case. This planetary clutch pack fits to planetary carrier (1). See Illustration 1.
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| Illustration 3 | g02731020 |
Rear Transmission Case (7) Planetary clutch pack | |
One planetary clutch pack (7) is located in the rear transmission case. This planetary clutch pack fits to planetary carrier (4). See Illustration 1.
Each clutch pack and each planetary clutch packs controlled by a corresponding modulating valve (transmission). There are nine modulating valves for the nine clutch assemblies.
ReferenceSee Systems Operation/Testing and Adjusting, "Transmission Power Flow" for additional information.
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| Illustration 4 | g02731052 |
Transmission Shafts (8) Input shaft (9) Intermediate shaft (10) Output shaft (11) Transfer gear shaft | |
The following shafts contain clutch packs and planetary clutch packs that control the FORWARD speeds:
- Input shaft (8)
- Intermediate shaft (9)
- Output shaft (10)
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| Illustration 5 | g02731057 |
Transmission Shafts (2) Gear (4) Gear (8) Input shaft (9) Intermediate shaft (10) Output shaft (11) Transfer gear shaft (12) Reverse shaft | |
Note: Gear (4) meshes only with gear (2). The configuration of the five transmission shafts in Illustration 5 is only for illustrative purposes.
The following shafts contain clutch packs and planetary clutch packs that control the REVERSE speeds:
- Input shaft (8)
- Intermediate shaft (9)
- Output shaft (10)
- Reverse shaft (12)
ReferenceSee Systems Operation/Testing and Adjusting, "Transmission Power Flow" for additional information.
Oil Flow and Rotational Power Flow
Regular Clutch Pack
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| Illustration 6 | g02731129 |
(3) Clutch pack (13) Gear (14) Spring (15) Clutch lubrication passage (16) Friction discs (17) Clutch plates (18) Balance piston (19) Piston (20) Clutch pressure oil passage (21) Lube pressure oil passage (22) Cylinder | |
Oil flows from the modulating valve through clutch pressure oil passage (20) in the transmission shaft. Oil fills the chamber behind piston (19) .
Piston (19) is used for the following functions:
- The piston will compress clutch plates (17) against friction discs (16) .
- The piston will control lube flow to the friction discs and the clutch plates.
Note: Illustration 6 shows the clutch in the disengaged position.
Clutch Engagement
As pressure builds up behind the piston, the piston will start to move toward the friction discs and clutch plates. This will eventually overcome the spring and the lubrication oil pressure in front of the piston. At maximum pressure, the piston will completely compress the friction discs and clutch plates.
The clutch plates are engaged to cylinder (22) by the use of spline teeth. Because the cylinder is rotating with the transmission shaft, the clutch plates will cause the friction discs to rotate.
Because the friction discs are engaged to gear (13) by the use of spline teeth, the gear will rotate. Consequently, rotational power flow will be transferred through the transmission shaft to the gear.
Balance Piston Operation
The piston will block clutch lubrication passage (15) when the clutch is disengaged. This will prevent viscous friction between the lubrication oil and the rotating friction discs and clutch plates. This friction could cause increased load to the engine.
Centrifugal pressure will build up behind the piston when the transmission shaft is turning and the clutch is disengaged. This will cause the piston to move toward the friction discs and the clutch plates. This movement is sufficient enough to slightly engage the clutch. If the piston is not properly retracted away from the friction discs and clutch plates, excess heat could build up in the hydraulic oil system. Also, unnecessary wear to the friction discs and clutch plates could occur. Consequently, it is necessary to assist spring (14) by using lubrication oil to help balance the centrifugal pressure and to prevent piston movement when the clutch is disengaged.
The piston contains oil holes in order to allow lubrication oil to flow in front of the piston. The lubrication oil flows from lube pressure oil passage (21) through the holes in the piston. This lubrication oil pressure assists the spring in retracting the piston away from the friction discs and clutch plates. This passage is always open.
Planetary Clutch Pack
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| Illustration 7 | g02689496 |
(20) Clutch pressure oil passage (21) Lube pressure oil passage (22) Clutch housing | |
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| Illustration 8 | g02731160 |
Intermediate Shaft, Output Shaft, and Transfer Output Shaft (1) Planetary Carrier (5) Planetary Carrier (24) Gear (25) Gear (35) Clutch housing | |
There are two planetary clutch packs that control planetary carriers (1) and (5).
Gear (25) drives gear (24) in the explanation of the operation of the planetary clutch pack. The operation of the other planetary clutch pack is identical.
Illustration 9 and the following text uses the planetary clutch pack that controls planetary carrier (1) as an example.
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| Illustration 9 | g02887593 |
Planetary Clutch Pack (25) Friction discs (26) Clutch plates (27) Oil holes (28) Piston (29) Spring (30) Ring gear (31) Gear (32) Drive tube (33) Sun gear (34) Planetary gears | |
Unlike the regular clutch pack, lubrication oil flows through the planetary clutch pack continuously. The lubrication oil flows through an oil passage in the shaft and through the planetary carrier. The oil is dispersed to friction discs (25) and clutch plates (26) through oil holes (27) .
Because the friction discs and the clutch plates do not rotate with the transmission shaft, the viscous drag within the clutch assembly is not significant. Also, the lubrication oil is better able to disperse from the planetary clutch pack.
Oil flows from the modulating valve (transmission), through the transmission case, and to one of the oil passages in the clutch housing. Oil flows through the clutch housing to the front of piston (28) .
As pressure builds up behind the piston, the piston will start to move toward the friction discs and clutch plates. This will eventually overcome six springs (29). At maximum pressure, the piston will completely compress the friction discs and clutch plates. At this point, the clutch will be completely engaged.
When the clutch is engaged, the friction discs will not rotate. Because ring gear (30) is engaged to the friction discs by the use of spline teeth, the ring gear will not rotate.
Gear (31) turns drive tube (32). The drive tube turns sun gear (33). The sun gear turns planetary gears (34) .
Because the ring gear is held stationary by the friction discs, the planetary gears are forced to travel around the ring gear. The planetary gears are pinned to the planetary carrier. As a result, the planetary carrier will rotate.
The planetary carrier is splined to the output shaft. Consequently, the planetary carrier will cause the output shaft to rotate.
ReferenceRefer to Special Publication, SEBV0533, "The Gear Book" for additional information about the basic operation of gears.