The Hybrid Two-Mode 2ML70 is a fully automatic, variable-speed, rear-wheel drive, electronic-controlled transmission. It consists primarily of a torque dampener assembly, an integral fluid pump and converter housing, 3 planetary gear sets, 2 friction (rotating) and 2 mechanical (stationary) clutch assemblies, and a hydraulic pressurization and control system, and 2 internal concentric 60 KW electric motors.
The torque dampener contains an internal torsional springs, fluid, input shaft. The torque dampener acts as a spring coupling to smoothly transmit power from the engine flexplate to the transmission. The dampener provides a mechanical direct drive coupling of the engine to the transmission.
The planetary gear sets provide 4 fixed gear ratios and the 2 EVT forward modes rations and reverse. Changing gear ratios is fully automatic and is accomplished through the use of a transmission control module (TCM) located inside the transmission and the hybrid powertrain control module (HPCM) located under the hood. Both the TCM and HPCM receives and monitors various electronic sensor inputs and uses this information to shift the transmission at the optimum time.
The TCM commands shift solenoids and variable bleed pressure control solenoids to control shift timing and feel. All the solenoids, including the TCM, are packaged into a self-contained control solenoid valve assembly.
The main hydraulic system primarily consists of a vane-type pump, 2 control valve body assemblies, converter housing and case. The pump maintains the working pressures needed to stroke the clutch pistons that apply or release the friction components. These friction components, when applied or released, support the automatic shifting qualities of the transmission.
The hydraulic system also uses a secondary system and consists of an auxiliary pump attached to the bottom of the transmission. This is a gerotor-type pump, electric 3 phase 12 volt motor, electric harness, and control module. This pump maintains working pressures when the engine is off.
The friction components used in this transmission consist of 4 multiple disc clutches. The multiple disc clutches combine with a planetary gear set and electric motor to deliver the different gear ratios, forward and 1 electric reverse. The gear sets then transfer torque through the output shaft.
The transmission may be operated in any of the following gear ranges:
PARK (P): This position locks the rear wheels and prevents the vehicle from rolling either forward or backward. PARK is the best position to use when starting the vehicle. Because the transmission utilizes a shift lock control system, it is necessary to fully depress the brake pedal before shifting out of PARK. For safety reasons, use the parking brake in addition to the PARK position.