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Automatic Transmission/Transaxle – Vehicles With: 307-01-5 307-01-5 6-Speed Automatic Transaxle - 6R80 DESCRIPTION AND OPERATION torque converter, 1 solenoid valve and 6 pressure regulators. Gear selection is achieved by the control of automatic transmission fluid flow to operate various internal clutches. The TCM operates the electrical components and provides for the control of gear selection shift pressure, which increases refinement and torque converter slip. In the event of a system fault, the TCM also provides for Failure Mode Effect Management to maintain maximum functional operation of the transmission with a minimum reduction in driver, passenger or vehicle safety. In the event of a total loss of control or electrical power, the basic transmission functions P, R, N and D are retained. Also 3rd or 5th gear is retained by the hydraulic system. The gear retained is dependent upon the gear selected at the time of the failure. Major Components This transmission has the following major components: ‡ Transmission case with integral torque converter housing and extension housing ‡ Torque converter ‡ Fluid pump ‡ Three drive clutches: œ Forward clutch (A) œ Direct clutch (B) œ Overdrive (O/D) clutch (E) ‡ Two brake clutches: œ Intermediate clutch (C) œ Low/reverse clutch (D) ‡ Two planetary gearsets: œ Front single planetary gearset (1 sun gear, 1 carrier, 1 ring gear) œ Rear Ravigenaux planetary gearset (2 sun gears, 1 carrier with 2 sets of pinion gears and 1 ring gear) ‡ Main control (mechatronic assembly): œ Upper valve body œ Lower valve body œ Transmission Control Module (TCM) œ Transmission Range (TR) sensor œ Turbine Shaft Speed (TSS) sensor œ Output Shaft Speed (OSS) sensor NOTE: Friction and steel plate quantity will vary based on engine displacement. Refer to the Clutch Plate Quantity Chart in the Specifications portion of this section. In addition to the torque converter, the other shift elements are: ‡ three rotating multi-plate clutches: forward (A), direct (B) and overdrive (E). ‡ two fixed multi-disc brakes: intermediate (C) and low/reverse (D). All gear shifts from 1st to 6th or from 6th to 1st are power-on overlapping shifts. That is, during the shift, one of the clutches must continue to transmit the drive at lower main pressure until the other clutch is able to accept the input torque. The shift elements, clutches or brakes are engaged hydraulically. The transmission fluid pressure builds up between the cylinder and the piston, pressing the clutches together. The purpose of these shift elements is to carry out in-load shifts with no interruption to traction. Multi-plate clutches; forward, direct and overdrive, supply power from the engine to the planetary geartrain. Multi-disc brakes, intermediate and low/reverse, press against the transmission housing in order to achieve a torque reaction effect. Multi-Plate Clutch Clutches; O/D (E), forward (A) and direct (B) are balanced in terms of dynamic pressure. That is, their pistons are exposed to the transmission fluid flow on both sides, in order to prevent pressure buildup in the clutch as speed increases. This equalization process is achieved by a baffle plate and pressure-free transmission fluid supply by a lubricating passage, through which the space between piston and baffle plate is filled with transmission fluid. The advantages of this dynamic pressure equalization are: ‡ Reliable clutch engagement and release in all speed ranges. ‡ Improved shift refinement. Shift Overlap Control The electro-hydraulic shift action is obtained by means of various valves in the TCM and main control valve body, actuated by pressure regulators. They engage or disengage the relevant clutches or brakes at the correct moments.