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Home >> Ford >> 2017 >> Fiesta Titanium, 4D Hatchback, Automatic DCT Trans >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 4 (Manual Transmission - 5-Speed Manual Transmission - B5/IB5) >> Description And Operation >> Manual Transmission - System Operation and Component Description >> 5th Gear Synchronizer

5th Gear Synchronizer

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GFD140509Courtesy of FORD MOTOR COMPANY
Item Description
1 Shift collar (5th gear)
2 Synchronizer (5th gear)
3 Spring washer
4 C-washer
5 Synchronizer ring (5th gear)
GFD140510Courtesy of FORD MOTOR COMPANY
Item Description
F Axial force
1 5th gear synchronizer assembly
2 Shift collar (5th gear)
3 Synchronizer ring (5th gear)
4 C-washer abutment points
5 C-washer
6 Direction of rotation - output shaft
7 C-washer seating point
8 Synchronizer ring seating point

Function Of The 5th Gear Synchronizer 

The axial force of the selector rod moves the shift collar in the direction of 5th gear.

With the movement of the shift collar, the C-washer is pressed against the synchronizer ring  (upper abutment point  ). At the same time, the C-washer is supported on the synchronizer clutch  (lower abutment point  ).

Because of the pressure of the C-washer on the synchronizer ring, this is pressed against the conical friction surface of the gearwheel and thus the pre-synchronization  starts.

As long as the shift collar and gearwheel rotate at different speeds, a turning torque is generated. This twists the synchronizer ring until the synchronizer ring abutment point touches the C-washer abutment point (arrow). The pre-synchronization is over.

After the complete synchronization process is finished, the shift collar moves over the splines of the synchronizer ring into the splines of the gearwheel. In the process, the two C-washers are pushed away inwards against the spring effect of the spring washer.

Engaging Reverse Gear 

GFD140511Courtesy of FORD MOTOR COMPANY
Item Description
F Axial force
4 C-washer abutment points
5 C-washer

Because of the shift construction of the transmission, the axial force of the selector rod moves the 5th gear shift collar in the opposite direction  to the 5th gear gearwheel.

As a result of this, the C-washer is pressed against the synchronizer ring  (lower abutment point  ). At the same time, the C-washer is supported on the synchronizer clutch  (upper abutment point  ).

Because of the pressure of the C-washer on the synchronizer ring, this is pressed against the conical friction surface of the gearwheel. The synchronizer ring thereby presses against the conical friction surface of the gearwheel and in doing so slows down the input shaft  .

This ensures that the speed of the transmission shafts is equal to zero while the reverse gear idler gear is inserted. The so-called 'crunch' during rapid engagement of reverse gear is thus prevented. The pre-requirement however is that the vehicle is no longer moving while reverse gear is being engaged.

Function Of Slowing The Input Shaft As Reverse Gear Is Engaged 

The 5th gear synchronizer is firmly connected to the output shaft. The vehicle is stationary during engagement of reverse gear, whereby the output shaft does not turn. On the other hand, the input shaft with the gear for 5th gear and the 5th gear gearwheel on the output shaft rotate at engine speed. During the shift operation into reverse gear, the 5th gear synchronizer ring is briefly pressed against the 5th gear gearwheel and slows it down, whereby in turn the input shaft is slowed down.

Neutral Position 

In the neutral position of the 5th gear synchronizer clutch, the C-washers are exactly perpendicular to the Y-axis. Consequently, there is also no pressure exerted on the synchronizer ring.