MTX-75

Design

Clutch, general




The main tasks of the clutch system are:
- torque transfer
- disengagement during shifting
- making a comfortable start possible
- be an effective vibration damper to eliminate noise and vibrations in the chassis and drive train.
The clutch is located between the engine and the gearbox. It consists primarily of a pressure plate and a disc. The clutch connects the torque from the engine to and from the gearbox and thereby to driving of the wheels.
The clutch is a single plate dry disc clutch. The disc is connected to the input shaft of the gearbox.
For vehicles with engine D4164T, a self-adjust clutch is used to obtain low clutch forces.

Hydraulic clutch control




1. Dual mass flywheel
2. Bleed nipple
3. Hydraulic hose
4. Master cylinder
5. Control cylinder
6. Pressure plate
The clutch control is based on a system with hydraulic power transmission.

Clutch plate




The clutch plate is the component that transfers the torque to the input shaft and into the gearbox. The clutch plate is also used to produce a gentle, comfortable vehicle start.
The plate has no damping or friction elements. These functions are instead integrated in the dual mass flywheel.
The plate has an adjustable hub that adjusts the centering between the gearbox primary shaft and the engine crankshaft. This is known as a radially travelling hub.
The inside of the plate center is greased when the plate is fitted at the factory. This reduces the amount of friction between the plate and the input shaft to make shifting easier.
If the plate is replaced, the input shaft should be lubricated. See the instructions for clutch replacement.

Concentric slave cylinder




Clutch control is completely hydraulic, meaning that the slave cylinder sits within the clutch cover. There is no mechanic transfer (fork) in the clutch cover from an external slave cylinder.
The slave cylinder is concentric because it is integrated in the release bearing.
The concentric slave cylinder is highly efficient, centres the release bearing well and is reliable.
The unit is mounted with two screws in the cover of the gearbox. The bearings and sliding surfaces do not require lubrication. The bearing on the concentric slave cylinder is self-centering to the clutch fan.
The hydraulic line from the master cylinder is connected to the concentric slave cylinder via an adapter. The adapter houses a bleed nipple.
To reduce the force required for torque transfer, several reductions are incorporated into the system:
- pedal reduction
- hydraulic reduction
- clutch finger reduction.
Force is reduced from approx. 7800 N force on the clutch to approx. 80 N pedal force.

Shock load limiter




If the clutch pedal returns to its original position too quickly, the high torque could damage the drive train. To avoid such damage, the clutch is equipped with a shock load limiter, which restricts the flow between the concentric slave cylinder and the master cylinder if there is a risk that the torque will become too great. The shock load limiter is housed in the angle adapter beneath the bleed nipple.

Self-adjusting clutch ( XTend) (only D4164T)




1. Spring
2. Adjuster ring
3. Wear detector
The size of the clutch has increased as more powerful engines have been introduced.
A self-adjusting clutch ( XTend) eliminates problems with both wear capacity on the pressure plate and clutch plate and the increase in pedal force when the lining is worn. The self-adjusting clutch eliminates the increased load caused by increased wear. The advantages of a self-adjusting clutch are as follows:
- Constant load throughout the entire service life of the clutch.
- Increased service life of the clutch plate.
- Reduced stroke for the release bearing.
A self-adjusting clutch XTend detects the wear on the clutch plate and adjusts the wear using a adjustment mechanism between the sun spring and the clutch housing. The adjustment mechanism maintains the position of the sun spring and ensures that the pedal effort required remains constant throughout the service life of the vehicle.

Pressure plate (D4164T only)




1. Compression springs
2. Pressure plate (housing)
3. Ramp
4. Ramp ring
The clutch is a single plate dry disc clutch. Pretensioned lifting springs connect the clutch housing and the pressure plate.
Because self-adjusting clutches cannot be reset when the clutch plate has been replaced, the pressure plate must also be replaced.
The pressure plate is fan-shaped. This differs from a traditional type in that the pressure plate contains an adjuster ring that is made of plastic or steel. When wear begins to show, the adjuster ring is automatically moved slightly so that the work mode of the clutch remains constant.
The following advantages stem from the compression springs not moving rearward:
- the wear capacity can be increased
- the clutch cover can be made shorter since space is not needed for the fan to move rearward.

Dual mass flywheel (DMF)




The dual mass flywheel reduces noise from the gearbox and improves driveability.
The dual mass flywheel also contributes to reducing the load on the engine crankshaft bearing and improving shift quality since the flywheel mass of the clutch plate is less.
The components of the dual mass flywheel can rotate in relation to one another. This twisting depends on the load from the engine. Twisting of the dual mass flywheel is up to 60 degrees in both directions. You can feel a certain twisting between the components if you turn a dual mass flywheel.

Gearbox, general




1. Clutch cover
2. Input shaft
3. Differential
4. Output shaft
5. Reverse idler gear
6. Gear case
7. Outer shift mechanism
MTX-75 is a five-speed manual gearbox. The gearbox and differential are integrated in the same housing. The two cast aluminium housing halves are called the gear case and clutch cover. A floating seal sits between the two housing halves. The gearcase has been equipped with an extra reinforcement rib, which reduces noise and vibrations.
The gearbox has two parallel shafts. All gearwheels are in constant mesh. The different gear ratios are obtained with a gearwheel pair for each gear.
When reverse gear is engaged, an idler gear reverses the output shaft's direction of rotation.
The output shaft is in constant mesh with the final drive.
All impellers, including the reverse gearwheel, have bevelled cogs and are mounted on needle bearings.
In neutral, no impellers are connected to the input or output shaft via the synchromesh unit. No torque is transferred to the differential.
The input and output shaft are mounted in the gearbox, each with a roller bearing in the clutch cover (1) and a roller bearing in the gearcase (6).
The final drive rack is in constant mesh with the crown wheel of the differential.
Gear lever movements are transferred to the gearbox via two thick cables. This generates low shift forces and distinct positions.
All gears are synchronized. 1st and 2nd gears have double synchronization. 3rd, 4th, 5th and reverse gears have single synchronization.
The gearbox oil is synthetic and normally does not require changing. The oil is heat resistant and can handle high loads. The oil level is checked and topped up via the level plug. Oil is drained through the drain plug at the bottom of the gearbox. For more information on oil and capacity, see Specifications, Gearbox.

Inner gearbox components









All impellers and gearwheels have bevelled cogs, which make the cogs extend over a longer distance without changing the width between the impeller and gearwheel. This results in better contact between the wheels, which leads to higher forces being transmitted. The noise level is also lower.
Reverse gear also has bevelled cogs and thus works as quietly as other gear in the gearbox.
The ring gear with final drive rack is found in the differential housing, which contains a differential gear (with and without drive shaft splines) and planetary gear with lock.

Input shaft, primary shaft









The input shaft is mounted on conical roller bearings - one in each cover.
The 3rd and 4th gear impellers sit on the input shaft.

Shift fork for 3rd and 4th gears




The input shaft is positioned above the output shaft in the gearbox. To provide lubrication to 3rd and 4th gear synchromesh units, the shift forks are equipped with a guide plate which provides oil to the synchromesh units.

Output shaft, secondary shaft









The output shaft is mounted on conical roller bearings - one in each cover.
The 1st, 2nd, 5th and reverse gear impellers sit on the output shaft.
The final drive rack is an integrated component of the output shaft.

Reverse idler gear




1. Reverse shaft mounting
2. Thrust washer
3. Reverse idler gear (small collar down)
4. Needle bearing
5. Thrust washer
The reverse idler gear is driven by the input shaft. Its function is to change the output shaft's direction of rotation when reverse gear is engaged. The reverse idler gear runs on a needle bearing on the idler gear shaft.

Shifter




The gearbox has four shifting rods, three of which house shift forks.
The shifting motion is transferred from the gear lever to the gearbox via double cables.
The torsion pin mounted on the shaft for shift travel executes the longitudinal shift movement. The shift fork and gate are located on the input shifting rod, which is connected to the lever for lateral travel.
The lateral travel cable can be adjusted, but the longitudinal cable cannot. If either wire has a fault or is damaged, both cables must be replaced together.
The inner shifter in the gearbox is mounted in bearings lubricated with gearbox oil.

Reverse detent
A spring-loaded reverse detent, which is located in connection to the gear selector gate, prevents the gear lever from being unintentionally shifted from the 5th gear position to reverse. The reverse detent usually rests in a recess on the gear selector gate.

Differential




The main components of the differential are:
- ring gear
- differential shaft
- four conical gearwheels positioned at right angles to one another
- differential housing with two roller bearings.
The gearbox and differential are mounted in a two-component aluminium housing that is mounted on the engine with a flange.
The drive shafts have splines and are locked with a lock ring.
The differential is pretensioned via shims that sit between the gearcase and the conical roller bearing.

Synchronization
The synchronizer hub assembly consists of a coupling sleeve, drive piece and synchronizer hub. Each synchronizer hub is connected to its shaft via splines and rotates with it.
An impeller that can rotate freely on the shaft sits on each side of each synchronizer hub. Each impeller is in constant mesh with its respective gearwheel. The synchronization kit is located between the synchronizer hub and the impeller.
The synchromesh units have the following positions on the shafts in the gearbox:
- The 1st, 2nd, 5th and reverse gear synchromesh units sit on the output shaft
- The 3rd and 4th gear sychromesh unit sits on the input shaft.
The following have single synchronization:
- reverse gear
- 3rd gear
- 4th gear
- 5th gear.
The following have double synchronization:
- 1st gear
- 2nd gear.