| Description and Operation General The 5F31J automatic transmission has been developed by the Japanese automatic transmission manufacturer Jatco TransTechnology. 5F31J stands for: - 5- 5 forward drive gears
- F- front-wheel drive
- 31- maximum input torque of 310 Nm
- J- Jatco TransTechnology
The transmission is fully-automatic and electronically controlled. The transmission ratios are achieved with three planetary gearsets on two shafts. The individual components are driven or held by means of four clutches, three brakes and two roller-type one-way clutches. A torque converter lock-up clutch (TCC) ensures that fuel consumption is optimised. It is engaged by the transmission control unit depending on the vehicle speed and the engine load. If the vehicle is stopped while a gear is engaged, then the transmission control system ensures that the transmission is shifted into neutral (currently only available on vehicles with a diesel engine). This results in improved NVH characteristics, reduced fuel consumption and reduced emissions. The transmission control unit calculates the gearshift timing according to the personal driving style of the driver. The current driving resistance, such resistance due to towing a trailer or driving uphill/downhill in mountains or steep hills, is also taken into account when calculating the gearshift timing. Gears can be selected either automatically (selector lever position "D") or by the driver (Select-Shift-Mode). The transmission range or selected gear (Select-Shift-Mode) is indicated to the driver in the instrument panel. In the event of failure of key electronic components a hydraulic emergency running programme provides restricted operation of the transmission. For one year initially no repairs are planned on the transmission, apart from the replacement of various oil seals, the main control body, individual solenoid valves, the torque converter and the transmission range (TR) sensor. Under normal operating conditions the transmission fluid is filled for service life of the transmission and does not need to be changed. At a glance Transmission layout - 5-speed automatic transmission for FWD
- Three simple planetary gearsets on two shafts
- Transmission ratios achieved by means of four multi-plate clutches, two multi-plate brakes, one brake band and two one-way clutches
- The final drive is integrated into the transmission housing.
- Electronically controlled, hydraulically activatedTCC
Transmission ratios in the individual gears: | Gear | Transmission ratio | | 1st gear | 3.801 | | 2nd gear | 2.131 | | 3rd gear | 1.364 | | 4th gear | 0.935 | | 5th gear | 0.685 | | Reverse gear | 2.970 | Transmission control - Gearshift timing is calculated by the transmission control unit according to the individual driving style of the driver and the current driving resistance.
- Automatic gear selection by the transmission control unit or manual gear selection by the driver in Select-Shift-Mode
- Automatic engagement of neutral when the vehicle is stationary to stabilise idling and reduce fuel consumption and emissions (only on vehicles with a diesel engine)
Transmission cross-section 8 - 1st gear one-way clutch 9 - Driven gear of 1st and 2nd planetary gearset 13 - Transmission input shaft 15 - Driven gear of reduction planetary gearset 17 - Drive gear for reduction planetary gearset 18 - Reduction planetary gearset 21 - Reduction one-way clutch Torque converter with TCC 1 - Torque converter housing and impeller 3 - Stator with roller-type one-way clutch 5 - Transmission input shaft NOTE:Three different torque converters are used, depending on the engine variant. The torque converter hydraulically transmits the output torque from the engine to the input shaft of the transmission. The stator increases the torque up to the clutch point (approx. 90% speed difference between the impeller and the turbine). In order to increase the efficiency of the automatic transmission, the torque converter is also equipped with a hydraulically activated TCC The torque converter lock-up clutch (is applied with controlled slip to ensure soft engagement.) When the TCC is engaged, the torque is transmitted directly from the crankshaft via the torque converter housing to the transmission input shaft. Under normal operating conditions, the TCC can be activated in selector lever position "D" in 3rd, 4th and 5th gear, as well as in 2nd gear if the temperature of the transmission fluid is too high. When Select-Shift-Mode is activated the TCC can be activated in all forward drive gears. Oil pump The oil pump is a G-rotor oil pump. It sucks up transmission fluid from the sump, builds up the oil pressure and then supplies it under high pressure to the main control body. The oil pump is driven by the crankshaft via the torque converter housing. 1. and 2nd planetary gearset 2 - Planetary gear carrier (1st set) 3 - Ring gear (1st set) and planetary gear carrier (2nd set) 7 - Transmission input shaft The 1st and 2nd planetary gearsets are located on the level of the transmission input shaft. They are two simple planetary gearsets, whereby the ring gear (1st set) and the planetary gear carrier (2nd set) form a single component. Through actuation of various clutches and brakes, certain components of the planetary gearsets are driven while others are held still. The different combinations of driven/held components result in different transmission ratios. Drive is output via the ring gear (1st set) and the planetary gear carrier (2nd set) to the driven gear. Reduction planetary gearset 4 - Drive gear for reduction planetary gearset 5 - Driven gear of reduction planetary gearset The reduction planetary gearset is a simple planetary gearset. The ring gear of the reduction planetary gearset is driven by the driven gear of the 1st and 2nd planetary gearset via the drive gear of the reduction planetary gearset. Drive is always output via the planetary gear carrier to the driven gear of the reduction planetary gearset, and thereby to the differential. Clutches and brakes 6 - 1st gear one-way clutch 9 - Reduction one-way clutch The transmission is equipped with four clutches and five brakes. The clutches are laid out as multi-plate clutches. The brakes are made up of two multi-plate brakes (2nd/4th/5th gear brake and reverse gear brake), two one-way clutches (1st gear one-way clutch and reduction one-way clutch) and one brake band (reduction brake band). The torque is transmitted via the clutches to certain components in the planetary gearsets. Other components in the planetary gearsets are held with the brakes. These combinations result in the different transmission ratios for the individual gears. Differential assembly 2 - Driven gear of reduction planetary gearset 4 - Planetary gear carrier for reduction planetary gearset The planetary gear carrier for the reduction planetary gearset is rigidly linked via the intermediate shaft to the driven gear of the reduction planetary gearset and drives the differential. The differential assembly transmits the torque via the drive halfshafts to the front wheels. Any differences in rotational speed between the two drive halfshafts are compensated by the differential. Control housing The hydraulic pressure is distributed to the individual clutches and brakes in the main control body. The hydraulic lines and pressures are electronically regulated by four pulse-width modulated (PWM) solenoid valves and five shift solenoid valves. In addition, the manual selector lever in the main control body provides a hydraulic emergency running programme, which allows the vehicle to drive in 4th gear with the selector lever in position "D" and in reverse gear with the selector lever in position "R". | 
