MTX-75
Function
Clutch, general
The main tasks of the clutch system are disengagement during shifting, torque transfer and making a comfortable start possible.
Disengaging the clutch plate during shifting is an important part of the functionality. When the driver depresses the clutch pedal, the release bearing moves toward the fan a specific distance and releases the plate. The lift in the clutch is received by the lifting springs, which are riveted to the pressure plate and hold it in place.
Complete disengagement does not occur until the last quarter of clutch pedal travel.
The plate is pinched between the flywheel and pressure plate in order to transfer torque. Torque is transferred to the input shaft via the clutch.
Torque goes across the crankshaft via the flywheel to the clutch plate. Half of the torque is led via the clutch screw across the clutch housing through the lifting spring over to the pressure plate and on to the clutch plate. The clutch plate then transfers the torque via the clutch plate hub and spline to the input shaft.
During shift manoeuvres, the clutch plate speed is increased (when downshifting) or decreased (when upshifting). Engine speed is then synchronized with vehicle speed when the clutch is released. If there were no disengagement when shifting, there would be abnormal wear on the synchronizer ring in the gearbox.
Pretensioned lifting springs connect the clutch housing and the pressure plate.
The clutch is defined by 3 characteristic forces:
1. pressure plate force on the clutch plate
2. fan force on the release bearing
3. pressure plate lift.
Pressure plate force increases as the clutch plate is subjected to wear. Due to this increase in force, fan force and thereby pedal force increase in conjunction with increased wear on the clutch plate. The fan position moves rearward in a degree corresponding to clutch plate wear and the gear ratio in the clutch. The clutch is designed to handle 1.5 mm of lining wear. This means that the clutch cover has an 8-9 mm wear capacity for rearward release bearing movement.
An auxiliary spring at the pedal reduces the amount of force required for disengagement. When the pedal is in its upper position, the auxiliary spring works to expand, which presses the pedal upward. When the pedal starts to be pushed down and the resistance from the clutch is small, the spring compresses at first by the pedal force until it has reached its breakpoint. It then expands while turning upward, thus helping to press the pedal down, which makes the clutch easier to depress.
The clutch pedal requires no lubrication. All joints of the pedal system are low-friction.
Concentric slave cylinder
In order to shift, the gearbox must be disengaged from the engine, which is done with the clutch pedal. When the clutch pedal is depressed, fluid is transferred through pipes from the master cylinder to the slave cylinder housed in the clutch cover. This then presses on the clutch, which releases the clutch plate. Noise and vibrations are also sent from the engine. To reduce this, the pipe and hose are designed to absorb vibration. Diesel-engine vehicles also employ a damping unit, a volume of fluid enclosed between two membrane discs that are adjusted to the correct degree of rigidity.
Self-adjusting clutch (XTend) (D4164T only)
When the lining on a clutch plate is worn, the normal work position of the pressure plate changes and disengagement pressure increases.
On the self-adjusting clutch, an adjuster ring is affected by clutch plate wear. If there is wear, the adjuster ring automatically moves a bit during the next disengagement and adjusts the bearing point of the fan. This keeps the work area of the pressure plate and thereby the disengagement pressure constant.
The path of the force
Engine torque is transferred from the clutch to the gearbox input shaft and then onward via various drive gear sets and driving final drive pinion, depending on which gear is engaged, to the final drive/differential, drive shafts and out to the front wheels.
1st gear
1. Input shaft
2. Output shaft
3. Final drive rack
4. 1st gear impeller
5. 1st and 2nd gear synchronizationn
6. 1st gear rack
2nd gear
1. Input shaft
2. Output shaft
3. Final drive rack
4. 1st and 2nd gear synchronization
5. 2nd gear impeller
6. 2nd gear rack
3rd gear
1. Input shaft
2. Output shaft
3. Final drive rack
4. 3rd gear gearwheel
5. 3rd and 4th gear synchronization
6. 3rd gear impeller
4th gear
1. Input shaft
2. Output shaft
3. Final drive rack
4. 4th gear gearwheel
5. 4th gear impeller
6. 3rd and 4th gear synchronization
5th gear
1. Input shaft
2. Output shaft
3. Final drive rack
4. 5th gear impeller
5. 5th and reverse gear synchronization
6. 5th gear gearwheel
Reverse gear
1. Input shaft
2. Output shaft
3. Final drive rack
4. 5th and reverse gear synchronization
5. Reverse gear impeller
6. Reverse intermediate gear
7. Reverse gear rack
Shift mechanism
When the gear level is moved laterally toward the 1st gear position, a pressing force is exerted on the cable that turns the lever for lateral travel.
When the gear lever is moved forward toward the 1st gear position, a pressing force is exerted on the cable that turns the lever for longitudinal travel.
This is executed in a similar manner when other gears are engaged.
Differential
The differential distributes the force between the drive wheels.
Torque is transferred from the ring gear to the two conical differential pinions on the differential shaft and then on to the conical gearwheels on the drive shafts. When taking curves, the drive wheels need to move at different speeds since the wheels are moving different distances. This is made possible by the differential gears that rotate on their own shaft.