Transaxle Description
Transaxle DescriptionThe automatic transmission used in the vehicle is a new development.
It is a fully automatic, electronically controlled four-speed transmission designed for front wheel drive vehicles.
Its abbreviated designation 4F27E means:
- 4 - 4-four-speed transmission
- F - front wheel drive
- 27 - maximum input torque after torque converter: 365 Nm (270 ft. lbs.)
- E - fully electronic control
It is produced by Ford in Sterling Heights, Michigan (USA)
The individual ratios are achieved through two planetary gear sets connected one behind the other.
The individual components of the planetary gear sets are driven or held by means of three multiplate clutches, a multiplate brake, a brake band and a roller one-way clutch.
The torque is transmitted to the final drive assembly through an intermediate gear stage.
Mercon V is the fluid specified for the 4F27E transmission. The fluid is changed as directed by the Scheduled Maintenance Guide that is supplied with the vehicle.
The electrical and hydraulic functions are carried out by a 104-pin EEC V powertrain control module.
The manual selector lever gives the driver a choice of"P","R","N","1","2" and"D".
In drive range"Do it is also possible to operate an O/D switch on the manual selector lever to prevent the transmission shifting into 4th gear or to shift down to 3rd gear.
To minimize fuel consumption, the torque converter lock-up clutch is closed by the PCM in 3rd and 4th gears depending on the throttle position and vehicle speed.
The transmission has Electronic Synchronous Shift Control (ESSC) which guarantees extremely smooth gear shifting over the entire life of the transmission.
A hydraulic emergency operating program maintains limited operation in the event of failure of important electrical components.
The transmission can be tested using FDS2000 or WDS through the Data Link Connector (DLC), in the passenger compartment.
- 1st gear: 2.816: 1
- 2nd gear: 1.498: 1
- 3rd gear: 1.000: 1
- 4th gear: 0.726: 1
- Reverse gear: 2.649: 1
Converter housing with converter assembly and fluid pump assembly
Forward clutch
Differential assembly and final drive input
Clutches and planet gears
Clutches and band
Main control assembly
Case assembly
Seals rings and gaskets
Snap rings
Bearings, bushings and thrust washers
Range Selection
The transaxle range selector has six positions: P, R, N, D, 2, 1.
Manual selector lever position"P"
In manual selector lever position"P" no gear is selected. The parking pawl is engaged manually by the manual selector lever cable and the shift shaft.
For safety reasons always apply the parking brake whenever the vehicle is parked.
Manual selector lever position"R"
In manual selector lever position"R" reverse gear is selected. REVERSE allows the vehicle to be operated in a rearward direction, at a reduced gear ratio.
Manual selector lever position"N"
In manual selector lever position"N" no gear is selected. The drive line is not locked, so the wheels are free to rotate. The vehicle may be started in NEUTRAL.
Manual selector lever position"D"
In manual selector lever position"D" and when the O/D switch is not pressed, the transmission control allows all the gears to be selected. When the O/D switch is pressed, shifting into 4th gear is prevented or the transmission shifts down to 3rd gear.
Manual selector lever position"1"
In manual selector lever position"1" only first gear is selected. In addition to the 1st gear one-way clutch the transmission control closes the reverse gear brake to produce engine braking effect in overrun.
If the manual selector lever is moved to position"1" at an excessive vehicle speed for 1st gear, the transmission control only allows the downshift to take place when the corresponding vehicle speed has been reached.
Manual selector lever position"2"
In manual selector lever position"2" only 2nd gear is selected. The transmission control does not allow shifting into 1st gear.
If the manual selector lever is moved to position"2" at an excessive vehicle speed for 2nd gear, the transmission control only allows the downshift to take place when the corresponding vehicle speed has been reached.
Overview of construction and function
Torque converter and torque converter lock-up clutch
The torque converter transmits engine torque hydraulically to the transmission input shaft.
The stator boosts the torque to the input shaft (approximately 85% difference in speed between the impeller and the turbine).
The stator is made of synthetic resin to reduce weight.
To increase the efficiency of the automatic transmission, the torque converter has an apply clutch. When the torque converter lock-up clutch is closed, the torque is transmitted directly from the crankshaft through the torque converter housing to the transmission input shaft.
The torque converter clutch is applied hydraulically by the PCM by means of the solenoid valves in the valve body in 3rd and 4th gears. Apply is dependent on the throttle position, vehicle speed and manual selector lever position.
Oil pump and stator support
The fluid pump is a crescent gear pump and is driven directly from the crankshaft by means of drivers on the converter impeller hub. The fluid pump is bolted to the transmission housing.
The stator support is part of the fluid pump. Splines on the support locate and hold the converters stator.
Planetary gear sets
The individual gears are shifted by means of two planetary gear sets connected one behind the other.
Clutches and bands
The individual ratios are selected by means of four multiplate clutches, a brake band and a roller one-way clutch.
The components are controlled by the PCM through Pulse Width Modulation (PWM) solenoid valves.
Valve body
The valve body contains six solenoid valves:
- three PWM solenoid valves (pulse width modulation solenoid valves,
- two shift solenoid (on/off) valves,
- one main regulating valve (variable force solenoid).
The individual clutches and bands are supplied pressure from the PWM solenoid valves and the shift solenoid (on/off) valves and thus the gears are shifted.
The PWM solenoid valves allow direct actuation of the clutches and bands to ensure extremely smooth gear shifting through precise pressure regulation.
The shift solenoid (on/off) valves switch the hydraulic path to the clutches and bands, reducing the number of required modulating valves.
The main regulating valve (variable force solenoid) ensures that sufficient hydraulic pressure is available in all operating conditions.
PWM solenoid valves 1-3
PWM solenoid valves 1, 2 and 3 control the pressure to the bands and clutches.
Shift solenoid (on/off) valves 1 and 2
The shift solenoid (on/off) valves switch the different oil passages in the valve body to direct the pressure to the individual clutches and bands.
The use of the shift solenoid valves are needed for direct actuation of the individual clutches and bands.
Main regulating valve
The main regulating valve (variable force solenoid) controls the required main line pressure for the individual transmission ranges.
The main line pressure is controlled dependent on the current engine load.
Internal shift mechanism
The shift lever is secured on a square on the manual shaft. Axial movement of the selector lever cable is changed into rotation of the manual shaft.
In the transmission the manual shaft operates the parking pawl engaging lever and the actuating lever of the manual valve.
The manual valve, a valve operated entirely manually, is moved by means of the manual valve actuating lever in the valve body.
The manual valve guarantees the functions during hydraulic emergency operation.
External shut mechanism
The transmission end of the manual selector lever cable is attached to a ball on the lever on the manual shaft.
The cable abutments are secured to the transmission housing, and then to the bracket of the manual selector lever.
The adjuster for the manual selector lever cable is located at the transmission side of the sheath.
At the manual selector lever end the cable is clipped onto a ball.
Intermediate gear stage and final drive assembly
The final drive input gear is splined to the planet carrier of the front planetary gear set and drives the transfer shaft input gear of the intermediate gear stage.
The transfer shaft output gear of the intermediate gear stage drives the final drive assembly.
The torque is transmitted to the halfshafts through the final drive assembly.
The differential offsets differences in speed of rotation of the halfshafts.
The intermediate gear stage is designed so that the final drive ratio can be adapted to requirements when the automatic transmission is used in conjunction with different engines.
Overview transmission control
Powertrain control module (PCM)
The PCM is located under the trim panel on the right-hand A-pillar.
On vehicles with automatic transmission the EEC V PCM controls the transmission in addition to the engine management system. In this case a module with 104 pins is used.
The PCM evaluates the incoming signals from the individual sensors and actuates the solenoid valves in the valve body of the transmission directly according to the operating state.
Diagnostic checks can be carried out on the transmission through the Data Link Connector (DLC) above the Central Junction Box (CJB).
Emergency operating program
If correct gear shifting can no longer be guaranteed due to failure of certain signals, the PCM changes to an emergency operating program. The driver is informed of the operation of the emergency operating program by the illumination of the powertrain warning indicator in the instrument cluster. Continued motoring is guaranteed in the following limited conditions:
- maximum main line pressure.
- 3rd gear in manual selector lever positions"D","2" and"1" without the torque converter lock-up clutch.
- reverse gear in manual selector lever position