Ford Workshop Service and Repair Manuals

Torque converter with Torque Converter Clutch (TCC)

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. 85 % 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 TCC is applied with controlled slip to ensure soft engagement.

When the TCC is engaged, the engine torque is transmitted directly from the crankshaft via the torque converter housing to the transmission input shaft.

Fluid pump

The fluid pump is a high-pressure radial piston pump which offers a high degree of efficiency.

It operates in accordance with the displacement principle.

It is driven by the crankshaft via the torque converter housing, which engages in the eccentric sleeve of the radial piston pump.

Eight radially arranged pistons are driven by the eccentric sleeve.

In order to limit the amount of power drawn by the pump, the volume flow on the suction side is limited to approximately 22 l/min.

The pump sucks in the fluid from the oil pan through a filter and delivers compressed fluid to the main pressure valve in the main control body.

There the main pressure is adjusted, the transmission components are supplied with oil for cooling and lubrication, and any excess fluid is returned to the suction side of the pump.

Planetary gearset

The planetary gearset is a single planetary gearset with additional intermediate planet gears.

The drive is delivered via the transmission input shaft with the planet gear carrier.

The sun gear is splined on the variable speed input gear.

The forward clutch connects the planet gear carrier to the variable speed input gear.

The reverse gear brake connects the ring gear with the transmission housing.

Forward clutch and reverse gear brake

The forward clutch and the reverse gear brake are both laid out as a multi-plate clutch/brake and are engaged hydraulically.

The forward clutch is a centrifugal equalisation clutch.

This means that the piston of the clutch is subjected to oil pressure on both sides in order to prevent a speed dependent build-up of pressure in the clutch.

Idling

During idling neither the forward clutch nor the reverse gear brake are engaged, so no torque is transmitted to the variable speed input gear.

Forward drive

When the forward clutch is engaged it connects the planet gear carrier with the variable speed input gear.

The planetary gearset turns as a complete unit and has no effect on the transmission ratio.

Reverse drive

When the reverse gear brake is engaged it connects the ring gear with the transmission housing. The ring gear is then held in place.

As a result, the planet gears run on the fixed ring gear and drive the sun gear in the opposite direction of rotation to the output from the engine.

The sun gear is splined on the shaft of the variable speed input gear and drives it in the opposite direction to the output from the engine, thus providing reverse drive.

Variable speed gear

The variable speed gear is at the heart of the continuously variable automatic transmission.

It comprises two opposing pairs of pulley halves, with a steel belt running around the two pairs of pulleys like a V-belt in accordance with the Van-Doorne principle.

Two pulley halves are fixedly attached to each corresponding shaft.

The other two pulley halves can be displaced in the same direction as each other by applying hydraulic pressure.

This sets a certain transmission ratio.

The cylinder spaces of the adjusting hydraulics for the variable speed input and output gears are pressurised separately.

The steel belt is pressed onto the pairs of pulley halves in accordance with the torque that is to be transmitted.

The force with which the steel belt is pressed on is controlled so that slippage is prevented.

The direction of the adjustment, the adjustment travel and the pressing force are determined by the transmission control unit via the solenoid valves.

When the engine is switched off, a spring provides a certain amount of pressing force for the steel belt to prevent the steel belt from slipping when the vehicle is being towed.

Intermediate shaft

The torque is transmitted from the output wheel of the variable speed output gear via the variable speed output gear onto the input wheel of the intermediate shaft.

The intermediate shaft with output gear drives the differential assembly.

Differential assembly

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.

Mechanical parking lock

The mechanical parking lock secures the vehicle against rolling away.

When the vehicle is stationary it is engaged purely mechanically via the selector lever when the selector lever position "P" is engaged.

The movement of the selector lever is transmitted via the selector lever cable to the selector shaft lever.

The movement is then transferred via the selector shaft to the engaging plate.

A connecting rod with a cone is hooked into the engaging plate.

This cone displaces the parking pawl when the selector lever position "P" is engaged.

The parking pawl engages in the teeth on the variable speed output gear and thus blocks it.

Accordingly, the differential is blocked via the intermediate shaft, and the vehicle is secured and cannot roll away.

Valve housing for the manual selector lever

The manual selector lever is located in its own separate housing rather than in the main control body like in a conventional automatic transmission.

It is connected to the main control body via two hydraulic lines.

The engaging plate engages in the manual selector lever via a pin.

When the driver moves the selector lever, this movement is transferred via the selector lever cable, the selector shaft and the engaging plate onto the manual selector lever.

Hydraulic emergency running mode is provided by means of the manual selector lever.

The manual selector lever engages via a pin into the TR sensor. If the manual selector lever is moved via the engaging plate, then this movement is transferred to the TR sensor.

Transmission control unit and main hydraulic control body

The transmission control unit and the main hydraulic control body form a single component and are located inside the transmission housing.

Both are matched to each other at the factory in terms of tolerances and pressure regulation.

The transmission control unit evaluates the incoming signals and controls the solenoid valves.

The solenoid valves determine the pressure which is applied via the main hydraulic control body to the corresponding components.

The electrical connector to the vehicle wiring harness provides the transmission control unit with a supply voltage and connects it to the CAN databus. It is also used to receive and send various signals.