Automatic Transmission: Overview Ford Focus I рестайлинг

SOLENOID OPERATION CHART - CONVERTER ENGAGED

SOLENOID OPERATION CHART - CONVERTER ENGAGED

SOLENOID OPERATION CHART - CONVERTER DISENGAGED

SOLENOID OPERATION CHART - CONVERTER DISENGAGED

Transaxle Description

The 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

Scheme 12

1. 4 - 4-four-speed transmission
2. F - front wheel drive
3. 27 - originally designed for maximum input torque after torque converter: 365 Nm (270 lb-ft)
4. E - fully electronic control

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 manual selector lever gives the driver a choice of "P", "R", "N", "1", "2" and "D".

In drive range "D" it is also possible to operate an O/D switch on the manual selector lever to prevent the transmission from shifting into fourth gear. The default gear for this transmission is third 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, NGS or WDS through the data link connector (DLC) in the passenger compartment.

GEAR RATIO

Identification Tags

When servicing the automatic transaxle, refer to the identification tag located on the case.

Scheme 13

Control Of Shift Operations

During a shift operation certain elements are released while others are actuated. Ideally, this process takes place simultaneously (synchronously) to avoid jerky gear shifting.

The time for the shift operation should remain within the time limits provided.

When the shift operation is controlled conventionally, the pressure buildup and reduction at the shift elements are set and defined for ideal conditions (synchronous shifting).

As there is no way of influencing the control in the event of different levels of wear in the shift elements, when the transmission has been used for a fairly high mileage it is possible that the pressure buildup and reduction may no longer be synchronous.

The result or premature pressure reduction at the element to be switched off is an unwanted rise in the turbine shaft speed as the element to be switched on cannot transmit the input torque.

The result of delayed pressure reduction at the element to be switched off is an unwanted decrease in the turbine shaft speed as both shift elements transmit the input torque. In the process the torque is transmitted to the transmission housing through internal locking.

In both cases a jerk will be felt during the shift operation.

In addition, wear in the shift elements leads to a lengthening of the shift operation. Therefore, shifting takes longer when the transmission has accumulated a higher mileage.

Control Of Shift Operations With ESSC

In the automatic transmission, electronic synchronous shift control (ESSC) is used.

ESSC monitors the shift operations and is able to adapt to the wear in the shift elements over the life of the transmission.

This is possible since the shift elements are actuated by modulating valves.

The system monitors the shift time whether the shift operation is synchronous.

If the PCM detects a deviation from the stored values for the shift time and synchronization of the shift operation, the pressure buildup or reduction is adapted accordingly.

SOLENOID OPERATION CHART - CONVERTER DISENGAGED

SOLENOID OPERATION CHART - CONVERTER ENGAGED