The torque converter housing is fastened to the flywheel housing. A pump and two valves attached to the torque converter housing. The flange of the output shaft of the torque converter is connected to the drive shaft.
The transmission is driven by the torque converter in NEUTRAL and in REVERSE. In FIRST speed, torque converter drive is used at lower ground speeds. In FIRST speed, direct drive is used at higher ground speeds. The lockup clutch is activated in FIRST speed by the Electronic Programmable Transmission Control (EPTC II) according to the ground speed. During shifts from FIRST speed through SIXTH speed, torque converter drive is momentarily activated in order to provide smoother shifts. When the transmission clutches are engaged, the lockup clutch engages and the transmission is in direct drive.
| Operation of the Torque Converter For Transmission Speed | ||
| Transmission Speed | Torque Converter Drive | Direct Drive with an Engaged Lockup Clutch |
| Reverse | X | |
| Neutral | X | |
| First | X | X |
| Second | X | |
| Third | X | |
| Fourth | X | |
| Fifth | X | |
| Sixth | X | |
Torque Converter Drive
 | |
| Illustration 1 | g00348312 |
Torque converter that is in torque converter drive (1) Rotating housing (2) Turbine (3) Impeller (4) Drive gear for the torque converter and parking brake release gear pump (5) Inlet passage for converter oil (6) Stator (7) Hub (8) Lockup clutch (9) One-way clutch (10) Outlet passage for converter oil (11) Carrier (12) Output shaft | |
The engine flywheel turns rotating housing (1) which turns impeller (3). The impeller directs the oil to the blades of turbine (2). This will cause the turbine to turn. The turbine directs the oil to stator (6). This causes the stator to try to turn in the opposite direction of the turbine. The movement of the stator causes the rollers of one-way clutch (9) to move between stator (6) and the carrier for the stator. The action of the one-way clutch keeps the stator from rotation. The stator now directs most of the oil back to impeller (3). The remainder of the oil goes out of the torque converter through outlet passage (10). The oil, that goes back to impeller (3) from stator (6), moves in the same direction as the rotation of the impeller.
Turbine (2) turns hub (7). Hub (7) turns output shaft (12). Power is sent through the output yoke to the drive shaft and the transfer gears of the transmission.
One-Way Clutch
 | |
| Illustration 2 | g00479227 |
(6) Stator (13) Race (14) Cam for the one-way clutch (15) Rollers (16) Cage (17) Springs (18) Slot (19) Cam surface | |
The one-way clutch functions in order to keep the stator stationary up to higher torque converter output speeds. Stator (6) is connected to the cam (14) through splines. As a result, stator (6) rotates with cam (14), and race (13) is stationary. Roller cage (16) is located between cam (14) and race (13). Spring (17) is partially inserted in a tab at the top and at the bottom of cage (16). At lower turbine speeds, spring (17) forces the tab of cage (16) to the right in slot (18). This forces roller cage (16) to rotate clockwise. Then, rollers (15) move against the surfaces (19) of cam (14). The rollers wedge between cam (14) and race (13). This action locks stator (6) to race (13) which is stationary. The stator then returns oil to the impeller which multiplies the torque output of the torque converter.
As the speed of turbine (2) approaches the speed of impeller (3), the force of hydraulic oil overcomes the force of the rollers (15) that are wedged. The hydraulic oil acts in a clockwise direction on stator (6). The stator (6) then free wheels in the same direction as the impeller (3) and turbine (2). The stator (6) also free wheels when the speed of turbine (2) exceeds the speed of impeller (3). This occurs during downhill coasting when the transmission is engaged.
Direct Drive
 | |
| Illustration 3 | g00348313 |
Torque converter that is in direct drive (1) Rotating housing (2) Turbine (3) Impeller (4) Drive gear for the torque converter and parking brake release gear pump (6) Stator (7) Hub (8) Lockup clutch (9) One-way clutch (12) Output shaft (20) Inlet passage for lockup clutch oil (21) Distributor (22) Plates (23) Discs (24) Piston | |
Lockup Clutch
Lockup clutch (8) is part of the torque converter. The lockup clutch (8) is located between the engine flywheel and the turbine (2). The lockup clutch is engaged when the transmission is in SECOND through SIXTH speeds. The lockup clutch will engage in FIRST speed as the output speed of the transmission increases. When the lockup clutch is engaged, impeller (3) and turbine (2) turn at the same speed as the engine and there is no loss of power in the torque converter. The connection between the engine and the transmission is now direct.
The main components of lockup clutch (8) are piston (24), plates (22), and discs (23) .
Operation
Rotating housing (1) is connected to the engine flywheel by splines. Rotating housing (1) is fastened to impeller (3) by bolts. Piston (24) and plates (22) are also connected to rotating housing (1) by splines. Discs (23) and output shaft (12) are connected to hub (7) by splines. Turbine (2) is fastened to hub (7) .
The EPTC II activates the lockup clutch solenoid. The torque converter lockup clutch and synchronizing valve sends pressure oil through inlet passage (20) in distributor (21). The oil goes through a passage in the center of output shaft (12). The oil then goes through a passage in rotating housing (1) to piston (24). The pressure of the oil causes piston (24) to move toward disc (23). This causes plates (22) and discs (23) to be held together. Plates (22) and discs (23) will now turn at the same speed. The clutch becomes a direct connection between rotating housing (1) through hub (7) to output shaft (12) .
This causes turbine (2) and impeller (3) to turn at the same speed. Stator (6) turns freely. At this time, the torque converter is not in operation and the machine is in direct drive.
The flow of power is from rotating housing (1), through lockup clutch (8), hub (7), output shaft (12), and the yoke. The power goes directly through the torque converter to the drive shaft. The drive shaft sends the power to the transfer gears of the transmission.
When the lockup clutch is not engaged, the operation of the torque converter is normal.