The principle of operation of a manual gearbox
Pic. 6.4. Sectional view of a five-speed manual gearbox: 1 - dual-mass flywheel; 2 - driven disk; 3 - clutch pressure plate; 4 - clutch release bearing; 5 – a forward cover of a mechanical gear box; 6 – the case of a mechanical gear box; 7 – a back cover of a mechanical box of a gear change; 8 - output shaft flange; 9 - secondary shaft; 10 - input shaft
Torque from the engine is transmitted through the driven disk 2 (pic. 6.4) on the input shaft 10 of the gearbox. It contains the forward gears and the reverse gear. These gears are engaged with the gears located on the output shaft 9. The reverse gear is engaged through the intermediate gear, which reverses the direction of rotation.
Gears and shafts
If the gear is not engaged at all, the input shaft gears rotate without transmitting torque. When the gear is engaged, one of the gears of the input shaft is connected to the gear of the secondary shaft, and the torque with the corresponding gear ratio is transmitted to the secondary shaft of the gearbox. The ratio of the number of teeth of a pair of gears forms the gear ratio. All transmissions are synchronized. Thanks to the synchronizers, the speeds of the shaft and the gear located on this shaft are aligned, after which the synchronizer clutch is connected to the gear without shock. As a result, transmissions are switched on easily and silently. The rubbing elements, slowing down the faster rotating parts, ensure the alignment of the contacting parts. Synchronization occurs within fractions of a second, so when shifting gears, it is important to move the lever smoothly, with some exposure.
Re-gassing when operating a fully synchronized gearbox is usually not required. Only at low temperatures and thick gear oil can it help when downshifting.
Forward and reverse gears
Pic. 6.5. The location of the gearshift rods for a five-speed manual gearbox
The first three forward gears increase torque. The 4th, the so-called direct gear, transmits torque at a ratio of approximately 1:1. In 5th gear, the driven shaft speed is higher than the engine speed. In order for the car to move in reverse, there is an additional gear that changes the direction of rotation of the wheels to the opposite. When you select the desired gear with the shift lever, the movement of the lever through the rods (pic. 6.5) transmitted to the shift mechanism in the gearbox.
Sequence of work
1. Move the shift lever to neutral position.
2. Place the car on stands and remove the lower engine protection.
Pic. 6.6. Fixing the intermediate levers of a manual gearbox with a drill (arrow) diameter 5.9 mm
3. Fix the intermediate levers (under the shift lever), inserting a 5.9 mm drill bit into the holes of the shifter support and intermediate levers (fig 6.6). At the service station, a special fixing pin with a diameter of 5.9 mm is used for this.
Pic. 6.7. To adjust the rods, loosen the bolts shown by the arrows and move the rods to the set position
4. If the length of each rod is correct, the rods without additional displacement must fit the intermediate levers of the shift mechanism. Otherwise, loosen the bolts (pic. 6.7, arrows) fastening the rods to the gearbox and move the rods to the set position.
5. Move the shift lever on the gearbox to neutral position and tighten the bolts in this position.
6. Remove the drill and check the gear change with the engine running.