Twin Disc TA-90-8501, Operator'S Manual

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Twin Disc, Incorporated
Operation
Power Shift Transmission System Operator’s Manual #1020510
Power Flow Through Transmission System
The torque converter driving ring bolts directly onto the engine flywheel. The
internal teeth of the driving ring mesh with the gear teeth on the rotating housing.
The rotating housing provides input power to the impeller wheel of the torque
converter. Power flow system components and their functions are as follows:
Converter Drive
When in converter drive, converter fluid is moved by the impeller blades and
directed against the turbine wheel blades, driving the turbine wheel assembly.
Since the turbine wheel assembly is spline connected to the output shaft, the
output shaft is driven.
After the fluid passes through the turbine wheel blades, it is redirected to the
impeller wheel blades by the stator blades. When output torque requirements
exceed input torque, the freewheel unit on the stator is locked up. However,
when output torque requirements are equal to, or less than, input torque, the
stator freewheels.
The pumps run at engine speed.
Lockup Clutch Drive
The lockup clutch is controlled automatically through the electronic control
system.
When the lockup clutch is engaged, power is transmitted from the rotating
housing, through the steel driving plates which are spline connected to the
rotating housing, and to the friction clutch plates by clamping action of the
engaged clutch. The friction clutch plates are spline connected to the turbine
hub. The turbine hub is spline connected to the output shaft. Thus, the lockup
clutch provides direct mechanical drive.