Triple Cone Synchronizer
| ITEM | DESCRIPTION |
|---|---|
| 1 | Hub |
| 2 | Inner balk ring |
| 3 | Selector sleeve |
| 4 | Bearing |
| 5 | Crown wheel shaft |
| 6 | Crown wheel drive gear |
| 7 | Pinion drive gear |
| 8 | Pinion shaft |
| 9 | Seal |
| 10 | Piston |
| 11 | Circlip |
| 12 | Circlip |
| 13 | Detent |
| 14 | Selector fork |
| 15 | Detent spring and ball (3 off) |
| 16 | Detent housing (3 off) |
| 17 | Blocker ring |
| 18 | Inner cone |
| 19 | Outer balk ring |
| 20 | Needle bearing |
| 21 | Intermediate cone |
| 22 | Oil seal |
| 23 | Input shaft |
| 24 | Ball bearing |
| 25 | Circlip |
The triple cone synchronizer has three frictional interfaces. The intermediate cone has friction material on its inner and outer surfaces, the inner cone has friction material on its inner surface. These co-axial surfaces are supplemented by the inner and outer balk rings.
The synchronizers work as brakes. They brake or accelerate the components to align the rotational speed of the input shaft and the crown wheel shaft to allow the synchronizer to engage.
The synchronization process starts with the selector sleeve which is moved by the selector fork towards the engagement ring on the input shaft. While there is a speed difference between the selector hub and the engagement ring, the selector sleeve is blocked by the blocker ring. The synchronizer cones create a friction torque which aligns the rotational speed of the crown wheel shaft to speed of the input shaft. When the speeds of both shafts are synchronized the selector sleeve can be moved further and engages into the engagement ring on the input shaft, providing a positive drive to the crown wheel shaft.
The synchronizer is operated by a double acting piston located in a bore in the PTU casing. Hydraulic pressure lines from the RDU valve block supply hydraulic pressure to the piston. The pressure lines are connected to drillings in the PTU casing marked P3 and P4. P3 and P4 correspond to the markings on the AWD valve block. Connection P3 supplies pressure to engage the synchronizer and P4 supplies pressure to disengage the synchronizer.
The piston is sealed in the bore with two seals and retained with a circlip. An extension on the piston locates in the selector fork and is retained with a circlip. A spring loaded detent ball is fitted in the casing. The spring loaded ball positively retains the selector fork in the required position, until hydraulic pressure is applied to move it in the opposite direction.