Dog Clutch 'F'
| ITEM | DESCRIPTION |
|---|---|
| 1 | ATF pressure supply - open |
| 2 | Spur pinion |
| 3 | Angular contact ball bearing race |
| 4 | ATF pressure supply - close |
| 5 | Pressure sensing leakage hole |
| 6 | Sun gear 3 and 4 |
| 7 | Dog 'F' |
| 8 | Bearing support housing |
Dog clutch 'F' is located between the multiplate clutch 'E' and planetary gear set 4. The dog clutch is controlled by a double acting piston located within the bearing support housing.
Dog 'F' is a sleeve with internal and external splines. Dog 'F' is permanently engaged on the splines with the bearing support housing, which in turn is fixed and static within the transmission casing. When dog 'F' is moved to the closed position, it acts as a brake for sun gears 3 and 4 in planetary gear set 4.
The dog 'F' has two states; open and closed. Dog 'F' employs a more simple sensing system than dog 'A'. Dog 'F' is also the piston itself and does not use a sensing piston. The piston of dog 'F' has a leakage sensing hole which is used to detect its current position via pressure sensing.
Referring to the below illustration, if ATF pressure is applied to the right side of the piston, the piston is pushed to the left. During the movement of the piston, a small amount of ATF pressure is passed through the leakage sensing hole. This leakage pressure is measured at the left side of the piston by the pressure sensor in the sensor unit. When the piston has moved fully to the left and reached its end position, the leakage through the leakage sensing hole is blocked. The pressure drop on the left side of the piston is sensed and the TCM can determine that dog clutch 'F' is fully engaged with sun gears 3 and 4.
If the pressure on the left side of the piston does not drop within a specified shift time, the TCM can determine that the dog 'F' has stopped in an intermediate position.
The dog clutch 'F' has four possible states of operation as follows:
| ITEM | DESCRIPTION |
|---|---|
| A | Dog 'F' open - piston at end position |
| B | Dog 'F' closing - piston at intermediate position |
| C | Dog 'F' closed - piston at end position |
| D | Dog 'F' opening - piston at intermediate position |
| 1 | ATF Pressure applied - dog 'F' open |
| 2 | ATF pressure applied - dog 'F' closed |
| 3 | ATF pressure applied - dog 'F' in intermediate position |
| 4 | Leakage through leakage sensing hole for pressure sensing |
- Dog 'F' Open - ATF pressure is applied to the piston from the right side chamber and the dog clutch 'F' is open. The ATF pressure in the left chamber is almost zero because the piston is pushed to its limit of movement and leakage through the leakage sensing hole is prevented.
- Dog 'F' Closing - ATF pressure is applied from the left side chamber which starts the piston moving to the right into engagement with the sun gears 3 and 4. The piston is now in the intermediate position and leakage pressure is passed through the leakage sensing hole into the right side chamber. Pressure in the right side chamber can be measured and will be approximately 2 bar (29 lbf in3 ).
- Dog 'F' Closed - ATF pressure is applied to the piston from the left side chamber, the dog 'F' is closed and fully engaged with the sun gears 3 and 4. The ATF pressure in the right chamber is almost zero because the piston is pushed to its limit of movement and leakage through the leakage sensing hole is prevented.
- Dog 'F' Opening - ATF pressure is applied to the piston from the right side chamber which starts the piston moving to the left and disengaging from the sun gears 3 and 4. The piston is now in the intermediate position and leakage pressure is passed through the leakage sensing hole into the left side chamber. Pressure in the left side chamber can be measured and will be approximately 2 bar (29 lbf in3 ).