A/T System Description - Clutches and Gears
A/T System Description - Clutches and Gears
Clutches and Gears
The six speed automatic transmission applies hydraulic pressure to the clutches to engage or disengage the gears. When hydraulic pressure is introduced into the clutch drum, the clutch piston moves and presses the steel plates and the clutch discs. Power is then transmitted through the engaged clutch pack to its gear mounted on the shaft. Likewise, when the hydraulic pressure is bled from the clutch drum, the piston releases the steel plates and the clutch discs. Then the steel plates rotate with the clutch drum, and the clutch discs rotate with gear on the shaft. The clutch discs are released from the steel plates. This allows the clutch disc to spin independently, transmitting no power.
1st Clutch
The 1st clutch engages/disengages 1st gear, and is located at the right end of the secondary shaft. The 1st clutch is supplied hydraulic pressure through the secondary shaft by a circuit connected to the internal hydraulic circuit.
2nd Clutch
The 2nd clutch engages/disengages 2nd gear, and is located at the left end of the secondary shaft. The 2nd clutch is joined back-to-back to the 5th clutch. The 2nd clutch is supplied hydraulic pressure through the secondary shaft by a circuit connected to the internal hydraulic circuit.
3rd Clutch
The 3rd clutch engages/disengages 3rd gear, and is located at the left end of the mainshaft. The 3rd clutch is joined back-to-back to the 6th clutch. The 3rd clutch is supplied hydraulic pressure through the mainshaft by a circuit connected to the internal hydraulic circuit.
4th Clutch
The 4th clutch engages/disengages 4th gear, and is located at the right end of the third shaft. The 4th clutch is supplied hydraulic pressure through the third shaft by a circuit connected to the internal hydraulic circuit. The vehicle also moves backward when the 4th clutch is engaged while the reverse selector hub engages with the reverse gear.
5th Clutch
The 5th clutch engages/disengages 5th gear, and is joined back-to-back to the 2nd clutch located at the left end of the secondary shaft. The 5th clutch is supplied hydraulic pressure through the secondary shaft by a circuit connected to the internal hydraulic circuit.
6th Clutch
The 6th clutch engages/disengages 6th gear, and is joined back-to-back to the 3rd clutch located at the left end of the mainshaft. The 6th clutch is supplied hydraulic pressure through the mainshaft by a circuit connected to the internal hydraulic circuit.
One-Way Clutch
The one-way clutch is located between the countershaft 1st gear and the park gear. The park gear is splined with the countershaft. The countershaft 1st gear engages the outer race surface of the one-way clutch, and the park gear engages the inner race surface of the one-way clutch. The one-way clutch locks when power is transmitted from the secondary shaft 1st gear to the countershaft 1st gear. The 1st clutch and 1st gear remain engaged in 1st, 2nd, 3rd, 4th, 5th, and 6th gear ranges in D or S. However, the one-way clutch disengages when the 2nd, 3rd, 4th, 5th, or 6th clutches and gears are applied in D or S. This is because the rotational speed of the countershaft exceeds that of 1st gear, which causes the one-way clutch to free-wheel with the 1st clutch still engaged.
Transmission Cutaway View
Gear operation
Gears on the mainshaft:
- 3rd gear is engaged/disengaged with the mainshaft by the 3rd clutch.
- 6th gear is engaged/disengaged with the mainshaft by the 6th clutch.
- 4th gear is splined with the mainshaft and rotates with the mainshaft.
Gears on the secondary shaft:
- 1st gear is engaged/disengaged with the secondary shaft by the 1st clutch.
- 2nd gear is engaged/disengaged with the secondary shaft by the 2nd clutch.
- 5th gear is engaged/disengaged with the secondary shaft by the 5th clutch.
- Idler gear is splined with the secondary shaft, and rotates with the secondary shaft.
Gears on the third shaft:
- 4th gear is engaged/disengaged with the third shaft by the 4th clutch.
- 6th gear and reverse gear rotate freely from the third shaft. The reverse selector hub engages with 6th gear or reverse gear by the reverse selector. The reverse selector hub is splined to the third shaft so 6th gear or reverse gear engages with the third shaft.
Gears on the countershaft:
- Final drive gear is integral with the countershaft.
- 2nd gear, 5th gear, and park gear are splined with the countershaft, and rotate with the countershaft.
- 1st gear is engaged with the park gear splined to the countershaft by the one-way clutch when accelerating. It is disengaged from the park gear by the one-way clutch when decelerating.
Gears on the idler gear shaft:
Idler gear is press-fitted with the idler gear shaft, and rotates with the idler gear shaft. It is engaged with the 4th gear splined with the mainshaft, and transmits the mainshaft rotation to the secondary shaft.