Design and Function

Design and function

Updates in automatic transmission TF80-SC Generation 2








1. Tapered bearings - To reduce the inner friction losses, some of the tapered bearings now have bigger diameter and shorter length of bearing rollers. This change gives fewer rollers and thus less friction.
2. Torque converter - To reduce noise/sound when locking at lower engine rpms, the LTD (Long Travel Damper) has been provided with an inner circle of damping springs
3. TCM ( Transmission Control Module) - TCM has the same hardware as before but the software has been changed.
4. Solenoids - Faster shifting has been achieved by making all linear solenoids that control the clutch systems more effective. This change has been achieved by removing the hydraulic part of the solenoids. Further, the magnetic flow in the solenoid has been increased and gap between thrust piston and magnetic coil has been reduced to increase power.
5. Seal rings - New seal rings with smaller sealing surface contributes to reducing the inner friction. By tapering the seal, the sealing surface is reduced as is the pressure on the sealing surface.
6. Friction pads - The new friction pads on the discs reduce the impact of drag losses between the friction pads. This has been achieved by optimizing the oil flow channels between the friction surfaces.

Transmission components










Torque converter with lock-up









The torque converter is between the engine and the automatic transmission. It consists of a round metal casing which contains three impellers. The torque converter is filled with oil. The first impeller, pump rotor, is secured in the torque converter casing, which is connected to the engine's crankshaft via a carrier plate. The pump rotor rotates with the crankshaft.
The second impeller, the turbine rotor, is connected to the transmission's input shaft and is driven by the oil that is circulated by the pump rotor.
The third impeller, the stator, is located between the pump rotor and the turbine rotor.
There is a hydraulically controlled lock-up clutch with a friction plate in the torque converter. The turbine rotor can connect with the torque converter housing via the lock-up clutch. This reduces fuel consumption.
The torque converter functions like a hydraulic automatic clutch. At idle, the pump action is too weak to drive the turbine rotor and thus the vehicle is stationary. When the engine speed is increased the turbine rotor starts to drive in a smooth way. Thanks to the stator rotor, the torque converter can also reinforce the engine's torque when starting and low driving speed.
The rotating impellers and the oil in the torque converter "slip" slightly. This gives a certain power loss, which slightly increases fuel consumption.
When the vehicle is moving the torque converter's reinforcement of the engine's torque is not needed. In this situation the lock-up function is activated and, at a certain speed, mechanically connects the transmission's input shaft with the engine. This is automatic and cannot be affected by the driver. The engine speed drops and, since the torque converter's slipping disappears, fuel consumption is also reduced.

Planetary train




X = locked





Unique to the TF-80SC is a Ravigneaux planetary gear connected in series to a conventional planetary gear. The conventional planetary gear creates a reduction in RPM in the Ravigneaux planetary gear for 1st gear up to 5th gear and reverse.
The planetary gear's ratios are controlled by 3 clutches (C1, C2, C3) and 2 brakes (B1, B2).
The number of planetary gears depends on the engine's cylinder displacement and can therefore differ from what is shown here.

Planetary train, Ravigneaux









The characteristic of a Ravigneaux planetary train is that several gears can be used in comparison to a conventional planetary train. It is compact (takes up little room) in relation to the number of possible ratios. The Ravigneaux planetary train has two sun gears of different diameters and sets of two planetary gears, an inner and outer set. The inner planetary gears are constantly connected to the outer planetary gears and the small sun gear. The outer planetary gears are constantly connected to the ring gear and large sun gear.
The planetary train has a common planetary gear carrier for both sets of planetary gears.

Principles of function









The ratios are obtained through different combinations of locked and/or connected components. The table displays the principle for how the ratios are obtained from large ratio, 1, to small ratio, 6, and counter rotation (i.e. reverse with large ratio).






Oil pump




The oil pump is of "non-crescent" type and is located after the torque converter. It is driven by the engine's crankshaft via the torque converter housing.
The oil pump supplies the hydraulics with oil and supplies the other components of the transmission with oil for lubrication and cooling. Excess oil is routed back to the oil sump.

Oil cooler
The oil is routed in/out in separate lines to the external oil cooler.

The hydraulic system









The transmission's hydraulic system consists of oil pump, torque converter, hydraulic control system and oil cooler.
The solenoids, which control the hydraulic valves, are located in the transmission's control system, which are mounted on the front edge of the transmission. The solenoids are activated by the Transmission control module (TCM). For information about the Transmission control module (TCM), solenoids and sensors, see Design and Function, Transmission control module (TCM).
The oil pump supplies the hydraulics with oil and supplies the other components of the transmission with oil for lubrication and cooling. Excess oil is routed back to the oil sump.

Caution! The transmission oil differs from conventional ATF oil properties. Always use transmission oil that is specified for this transmission. Otherwise the function of the transmission will be damaged.

The oil level is checked though a level pipe (transmission does not have conventional oil dipstick).









Shifting occurs by the oil pump building up hydraulic pressure. The hydraulic valves, which are controlled by their respective solenoids, send the hydraulic pressure to the relevant clutch, brake or lock-up depending on which signals come from the Transmission control module (TCM).
Information about how the Transmission control module (TCM) controls the solenoids is available in Design and Function, Transmission control module (TCM).

Hydraulic pressure chamber




A = Piston's hydraulic pressure chamber
B = Counter acting hydraulic pressure chamber
When the rotation of the clutch increases, the centrifugal force affects the oil inside the clutch. The hydraulic pressure increases and the clutch engages. The centrifugal force means that a difference occurs in the rotation between the input and output shafts, which can mean a shift judder. To solve this, there is an extra pressure chamber opposite the piston's hydraulic pressure chamber. This extra pressure chamber means that the centrifugal force also works in the opposite direction and therefore affects the pressure from the piston's hydraulic pressure chamber. In addition, the clutch does not engage too soon.

Gear selector assembly




The gear selector assembly is in the tunnel console. It is mechanically connected to the transmission by a cable which moves the gear valve. The gear valve is integrated in the Transmission control module (TCM). The gear selected is indicated by a row of LEDs in the top panel on the gear selector assembly.
Gear selector assemblies with Geartronic, in addition to P/R/N/D modes, have a manual (M) shifting mode. The manual gear positions can be selected at any point while driving. The engaged gear is locked until the driver selects another gear. The automatic transmission only down shifts if the vehicle slows down to very low speed. To downshift the gear selector must be moved to minus (-). To upshift the gear selector must be moved to plus (+). At start, 3rd is the highest possible gear.
The engine can only be started in position P or N.






Power flow

Clutches, brakes and freewheel










Position D, 1st gear









X = activated
- = not activated
* B2 is only active during engine braking.





The input shaft rotates clockwise, the same direction as the torque converter's turbine rotor.
The front planetary train's ring gear rotates clockwise.
The front planetary train's planetary gear rotates clockwise on its shafts. Because the front planetary train's sun gear is locked by the oil pump, the planetary train's planetary gear presses against the front planetary train's ring gear, and therefore rotates around the sun gear. Because the front planetary train's ring gear has inner teeth, the direction of rotation does not change.
The front planetary gear carrier rotates clockwise.
Clutch C1 rotates clockwise and connects the front planetary gear carrier with the rear planetary train's small sun gear.
Rear planetary train's sun gear rotates clockwise.
The rear planetary train's inner planetary gear rotates counter-clockwise on its shaft. The rear planetary gear carrier attempts to rotate counter-clockwise but is prevented by freewheel F1.
The rear planetary train's outer planetary gear rotates clockwise on its shafts. The rear planetary train's small sun gear rotates counter-clockwise, at idle.
The rear planetary train's ring gear rotates clockwise using the rear planetary train's outer planetary gear. Because the rear planetary train's ring gear has inner teeth, the direction of rotation does not change.
The driven gear rotates clockwise. Because the rear planetary train's ring gear is on the driven gear, the driven gear rotates in the same direction as the rear planetary train's ring gear.
The counter-rotating gear rotates counter-clockwise.
The differential's ring gear rotates clockwise.

Position D, 2nd gear









X = activated
- = not activated





The input shaft rotates clockwise, the same direction as the torque converter's turbine rotor.
The front planetary train's ring gear rotates clockwise.
The front planetary train's planetary gear rotates clockwise on its shafts. Because the front planetary train's sun gear is locked by the oil pump, the planetary train's planetary gear presses against the front planetary train's ring gear, and therefore rotates around the sun gear. Because the front planetary train's ring gear has inner teeth, the direction of rotation does not change.
The front planetary gear carrier rotates clockwise.
Clutch C1 rotates clockwise and connects the front planetary gear carrier with the rear planetary train's small sun gear.
Rear planetary train's sun gear rotates clockwise.
The rear planetary train's large sun gear is locked by brake B1.
The rear planetary train's inner planetary gear rotates counter-clockwise on its shaft.
The rear planetary train's outer planetary gear rotates clockwise on its shafts.
The rear planetary train's ring gear rotates clockwise using the rear planetary train's outer planetary gear. Because the rear planetary train's ring gear has inner teeth, the direction of rotation does not change.
The driven gear rotates clockwise. Because the rear planetary train's ring gear is on the driven gear, the driven gear rotates in the same direction as the rear planetary train's ring gear.
The counter-rotating gear rotates counter-clockwise.
The differential's ring gear rotates clockwise.

Engine brake
When the engine brake works, the driven force is transferred from the tires.

Position D, 3rd gear









X = activated
- = not activated





The input shaft rotates clockwise, the same direction as the torque converter's turbine rotor.
The front planetary train's ring gear rotates clockwise.
The front planetary train's planetary gear rotates clockwise on its shafts. Because the front planetary train's sun gear is locked by the oil pump, the planetary train's planetary gear presses against the front planetary train's ring gear, and therefore rotates around the sun gear. Because the front planetary train's ring gear has inner teeth, the direction of rotation does not change.
The front planetary gear carrier rotates clockwise.
Clutch C1 rotates clockwise and connects the front planetary gear carrier with the rear planetary train's small sun gear.
Clutch C3 rotates clockwise and connects the front planetary gear carrier with the rear planetary train's large sun gear.
The rear planetary train rotates clockwise. Because the rear planetary train's inner and outer planetary gears are in constant engagement with each other, they are kinetically locked in relation to each other. The kinetic energy from both the rear planetary train's sun gears is therefore transferred to the rear planetary train's ring gear.
The rear planetary train's ring gear rotates clockwise.
The driven gear rotates clockwise. Because the rear planetary train's ring gear is on the driven gear, the driven gear rotates in the same direction as the rear planetary train's ring gear.
The counter-rotating gear rotates counter-clockwise.
The differential's ring gear rotates clockwise.

Engine brake
When the engine brake works, the driven force is transferred from the tires.

Position D, 4th gear









X = activated
- = not activated





The input shaft rotates clockwise, the same direction as the torque converter's turbine rotor.
The front planetary train's ring gear rotates clockwise.
The front planetary train's planetary gear rotates clockwise on its shafts. Because the front planetary train's sun gear is locked by the oil pump, the planetary train's planetary gear presses against the front planetary train's ring gear, and therefore rotates around the sun gear. Because the front planetary train's ring gear has inner teeth, the direction of rotation does not change.
The front planetary gear carrier rotates clockwise.
Clutch C1 rotates clockwise and connects the front planetary gear carrier with the rear planetary train's small sun gear.
The intermediate shaft rotates clockwise, the same direction as the input shaft.
Clutch C2 rotates clockwise.
The rear planetary gear carrier rotates clockwise.
The rear planetary train's inner planetary gear rotates clockwise on its shafts.
The rear planetary train's outer planetary gear rotates counter-clockwise on its shafts.
The rear planetary train's ring gear rotates clockwise. Because the rear planetary train's outer planetary gear rotation pulls away from the rear planetary gear carrier's rotation, the ring gear's speed is lower than the speed at the planetary carrier.
The driven gear rotates clockwise. Because the rear planetary train's ring gear is on the driven gear, the driven gear rotates in the same direction as the rear planetary train's ring gear.
The counter-rotating gear rotates counter-clockwise.
The differential's ring gear rotates clockwise.

Engine brake
When the engine brake works, the driven force is transferred from the tires.

Position D, 5th gear









X = activated
- = not activated





The input shaft rotates clockwise, the same direction as the torque converter's turbine rotor.
The front planetary train's ring gear rotates clockwise.
The front planetary train's planetary gear rotates clockwise on its shafts. Because the front planetary train's sun gear is locked by the oil pump, the planetary train's planetary gear presses against the front planetary train's ring gear, and therefore rotates around the sun gear. Because the front planetary train's ring gear has inner teeth, the direction of rotation does not change.
The front planetary gear carrier rotates clockwise.
Clutch C3 rotates clockwise and connects the front planetary gear carrier with the rear planetary train's large sun gear.
The rear planetary train's large sun gear rotated clockwise. Its speed is reduced by the front planetary train so that the speed becomes lower than the speed of the input shaft.
The intermediate shaft rotates clockwise, the same direction as the input shaft.
Clutch C2 rotates clockwise.
The rear planetary gear carrier rotates clockwise.
The rear planetary train's outer planetary gear rotates clockwise. Because the rear planetary gear carrier rotates faster than the rear planetary train's large sun gear, the inner planetary gears are pressed outwards by the speed difference and rotate clockwise on their shafts.
The rear planetary train's ring gear rotates clockwise. Because the rear planetary train's outer planetary gear rotation is added to the rear planetary gear carrier's rotation, the ring gear's speed is greater than the speed at the planetary carrier.
The driven gear rotates clockwise. Because the rear planetary train's ring gear is on the driven gear, the driven gear rotates in the same direction as the rear planetary train's ring gear.
The counter-rotating gear rotates counter-clockwise.
The differential's ring gear rotates clockwise.

Engine brake
When the engine brake works, the driven force is transferred from the tires.

Position D, 6th gear









X = activated
- = not activated





The input shaft rotates clockwise, the same direction as the torque converter's turbine rotor.
The intermediate shaft rotates clockwise, the same direction as the torque converter's turbine rotor
Brake B1 locks the rear planetary train's large sun gear.
Clutch C2 connects the intermediate shaft with the rear planetary gear carrier.
The rear planetary gear carrier rotates clockwise.
The rear planetary train's outer planetary gear rotates clockwise on its shafts. Because the rear planetary train's large sun gear is locked, the planetary train's outer planetary gear can always increase the speed.
The rear planetary train's ring gear rotates clockwise. Because the rear planetary train's outer planetary gear rotation is added to the rear planetary gear carrier's rotation, the ring gear's speed is greater than the speed at the planetary carrier.
The driven gear rotates clockwise. Because the rear planetary train's ring gear is on the driven gear, the driven gear rotates in the same direction as the rear planetary train's ring gear.
The counter-rotating gear rotates counter-clockwise.
The differential's ring gear rotates clockwise.

Engine brake
When the engine brake works, the driven force is transferred from the tires.

Position R, reverse gear









X = activated
- = not activated





The input shaft rotates clockwise, the same direction as the torque converter's turbine rotor.
The front planetary train's ring gear rotates clockwise.
The front planetary train's planetary gear rotates clockwise on its shafts. Because the front planetary train's sun gear is locked by the oil pump, the planetary train's planetary gear presses against the front planetary train's ring gear, and therefore rotates around the sun gear. Because the front planetary train's ring gear has inner teeth, the direction of rotation does not change.
The front planetary gear carrier rotates clockwise.
Clutch C3 rotates clockwise and connects the front planetary gear carrier with the rear planetary train's large sun gear.
The rear planetary train's large sun gear rotates clockwise.
Brake B2 locks the rear planetary gear carrier.
The rear planetary train's outer planetary gear rotates counter-clockwise.
The rear planetary train's ring gear rotates counter-clockwise using the rear planetary train's outer planetary gear. Because the rear planetary train's ring gear has inner teeth, the direction of rotation does not change.
The driven gear rotates counter-clockwise. Because the rear planetary train's ring gear is on the driven gear, the driven gear rotates in the same direction as the rear planetary train's ring gear.
The counter-rotating gear rotates clockwise.
The differential's ring gear rotates counter-clockwise.

Engine brake
When the engine brake works, the driven force is transferred from the tires.

Differential




The differential consists of the differential housing, large and small differential gears, shaft journals and thrust washers. The differential housing is completely sealed so that if a drive shaft is removed no dirt can penetrate and no oil can run out.
The differential distributes power equally between the drive wheels, even if they are rotating at different speeds. When driving straight ahead, the ring gear and differential housing rotate at the same speed as the drive shafts and the driving wheels. When cornering, the differential gears rotate to compensate for the different speeds of the wheels. Because the small differential gears are rotating on the shaft journal, the drive shafts can rotate at different speeds. Power is transferred from the differential housing to the drive shafts via the small differential gears in the same way as when driving straight ahead. Both drive wheels still have the same driven power.

AWD
Cars with four wheel drive have a splined pin on the differential housing. The sleeve on the pin connects the differential housing with the bevel gear. This transfers the power to the rear wheels.

Test plugs





Identification plate




A. Model number ( Transverse Fwd, Slipping lock-up, integrated Computer)
B. Serial number
1. Production year (04 indicates 2004)
2. Production month (C indicates March, see table below)
3. Transmission model (38 indicates TF-80SC)
4. Sequence number