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307-01-7 Automatic Transmission 307-01-7 DESCRIPTION AND OPERATION (Continued) In the case where Reverse is selected inappropriately, Electronic Control solenoids 1 and 3 both have the supply output This system is comprised of various input sensors, a pressure exhausted, the RLO spring biases the RLO PCM and seven solenoids. The PCM simply reads the valve to the B2 band exhausted position, reverse oil is inputs and activates the outputs as per the software prevented from feeding the B2 band. and table values stored in the Read Only Memory (ROM). Mechanical Arrangement The PCM drives the hydraulic valve body via the The mechanical arrangement consists of four clutch seven electromagnetic solenoids. Six of the seven assemblies, two bands, two sprag (or one way) solenoids are ON/OFF solenoids used to: boost the clutches and a planetary gear set. line pressure, operate shift valves and turn on and off Power Flow two regulator valves to control shift feel. The seventh solenoid is the proportional or Variable Pressure First gear is accomplished by applying the C2 clutch Solenoid (VPS). and regulating the front band off, the reaction torque is taken by the 1-2 One Way Clutch (OWC). The C2 Hydraulic Control clutch is applied in all forward gears. The hydraulic control system consists of a primary The 1-2 shift is accomplished by applying the B1 band regulator valve for line pressure, a solenoid supply and overrunning the 1-2 OWC (Only the outer B1 regulator, a lockup clutch regulator valve, a band servo apply area is used). apply regulator valve, a clutch apply regulator valve, a The 2-3 shift is accomplished by applying the C1 servo exhaust valve, C1 bias valve for converter clutch concurrent with releasing the B1 band. lockups, a 4-3 sequence valve, three shift valves, a manual valve and the previously mentioned solenoids. The 3-4 shift is accomplished by applying the B1 band and overrunning the 3-4 OWC. (Both inner and outer All upshifts are accomplished by simultaneously B1 servo apply areas are used). switching: a shift valve or valves, the band and/or clutch regulator valve and controlling the VPS output The C3 clutch and the B2 band are applied to pressure. The event is completed by switching the accomplish Reverse. (Both inner and outer B2 servo regulator off concurrent with sending the VPS to apply areas are used). maximum pressure. The C4 clutch is applied in Sequential Sports All downshifts are accomplished by simultaneously Shift/manual ranges 3, 2 and 1 to provide engine switching on one or both of the regulators and braking. In addition the C4 clutch is applied in controlling the VPS output pressure. The event is Adaptive and Performance mode for 2nd and 3rd completed by concurrently; switching the regulator off, gears to prevent objectionable ‘freewheel’ coasting. switching the shift valve and sending the VPS to Note in Auto 1st the C4 clutch is applied but due to maximum pressure. The exception to this is a the B2 band not being applied the 1-2 OWC is able to downshift to Auto 1st where the VPS is reduced to overrun this enables the vehicle to ‘freewheel’. minimum pressure while switching the shift valve, the B2 band is applied in Sequential Sports Shift/manual regulator remains on while in Auto 1st. range 1 to achieve engine braking shift. The servo is Neutral to ‘D’ shifts while the vehicle speed is below a dual area design which allows smooth overrun shifts approximately 6 km/hr results in a shift to Garage 1st at high vehicle speeds without the addition of a to improve garage shift quality. Above 6 km/hr the regulator valve (i.e. servo is applied with line transmission shifts to Auto 1st. Garage 1st is identical pressure). Only the inner B2 area is used for manual to Auto 1st hydraulically except solenoid 1 is 1st. energised, this results in the C4 clutch not being The B1 servo is also a dual area design to provide supplied with oil. additional clamping force on the B1 band in fourth Downshifts to Manual 1st gear state are accomplished gear. in the same manner as other downshifts, however the The mechanical arrangement utilizes non-asbestos gear state is achieved by exhausting the output friction materials for all members. These paper pressures of solenoids 1, 2 & 3. This results in the 1-2 composites were selected based upon their Shift Valve toggling to the Manual 1st position performance with a specially formulated Automatic supplying oil to the C4 clutch and B2 band. Transmission Fluid. The Reverse gear state is accomplished by the driver Converter Lockup Clutch positioning the manual valve into the reverse position, the manual valve supplies oil to the C3 clutch and to The Converter Lockup Clutch is a conventional clutch the reverse lockout valve (RLO). To obtain Reverse with a spring damper arrangement to reduce engine gear state either solenoids 1 or 3 supply output torsional disturbances. Located in the torque pressure to the RLO valve, this biases the valve to the converter, its function is to couple the turbine (driven B2 Band applied position where reverse oil is fed to member) to the impeller (drive member) to eliminate the B2 band. slippage. It is generally functional in 3rd gear and 4th G73081 en |