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Pic. 17: 1. Primary shaft. 2. Secondary shaft. 3. Gear wheel of constant engagement of the input shaft. 4. Breather. 5. Fourth gear synchronizer ring gear. 6. Sliding clutch of the synchronizer of the third and fourth gears. 7. Shift fork for third and fourth gears. 8. Gear box. 9. Gear wheel and ring gear of the third gear synchronizer. 10. Gear wheel and ring gear of the synchronizer of the second gear. 11. Fork of switching of the first and second transfers. 12. Clutch hub of the synchronizer of the first and second gears. 13. Sliding clutch of the synchronizer of the first and second gears. 14. Gear wheel and ring gear of the synchronizer of the first gear. 15. Reverse gear. 16. Gearshift lever. 17. Speedometer drive gear. 18. Flexible coupling flange. 19. Reverse fork. 20. Reverse fork rod. 21. The rod of the fork of inclusion of the third and fourth gears. 22. The rod of the fork of inclusion of the first and second gears. 23. Restrictive screw of inclusion of the first and second transfers. 24. Intermediate shaft. 25. Reverse gear wheel of the intermediate shaft. 26. Axis of an intermediate gear wheel of a backing. 27. Intermediate reverse gear. 28. Speedometer driven gear. 29. The rear cover of the gearbox. 30. Bushing of the gear wheel of the first gear. 31. The gear wheel of the first gear of the intermediate shaft. 32. Blocking ring of the synchronizer of the first. 33. Drain plug. 34. Blocking ring of the synchronizer of the second transfer. 35. The gear wheel of the second gear of the intermediate shaft. 36. Gear wheel of the third gear of the intermediate shaft. 37. The blocking ring of the synchronizer of the third transfer. 38. Third and fourth gear synchronizer clutch hub. 39. Fourth gear synchronizer blocking ring. 40. Gear wheel of constant meshing of the intermediate shaft. 41. Clutch housing. 42. Synchronizer blocking ring spring. 43. Spring thrust washer. 44. Belleville spring. 45. Retaining ring of the synchronizer hub. 46. A lock ring of a blocking ring of the synchronizer. I - Neutral position. II - The beginning of the inclusion of the third gear. III - Full engagement of third gear.
The principle of operation of a gear gearbox is based on changing the engagement of those pairs of gears that are involved in the transmission of torque from the primary (leading) shaft 1 to secondary (slave) shaft 2. This is achieved by moving the sliding clutches 6 and 13 of the synchronizers or the intermediate gear 27 of the reverse gear using the gear lever. In this case, the gear ratios of the gears change, and hence the magnitude of the transmitted torque. In direct fourth gear, the torque transmitted to the driving wheels of the car is almost equal to the torque on the engine crankshaft. In first gear, the torque increases by 3.67 times, in second gear by 2.10 times, in third gear by 1.36 times, and when reverse gear is engaged, by 3.53 times.
Since 1987, on all manufactured VAZ vehicles, gearboxes have been unified in terms of gear ratios and differ from each other in speedometer drives. Each speedometer drive corresponds to its final gear ratio. For external distinction, a mark is applied to the speedometer drive with paint: blue for the final gear ratio of 3.9; red for 4.1; not colored for 4.3. In addition, on the clutch housing (opposite the breather) a marking is applied indicating which model it is installed on. For example, for a VAZ-2106 car it is marked with the number 6, for a VAZ-2105 - 5.
Torque transmission schemes when all gears are engaged are shown by arrows in the figure.
When the gear lever is in neutral position, no torque is transmitted to the output shaft. But since the engine is running and the clutch is engaged, the rotation from the input shaft 1 is transmitted to the intermediate shaft through the gear 3 and the gear wheel 40 of constant mesh. From the gears 31, 35 and 36 of the intermediate shaft, the rotation is transmitted to the gears 14, 10 and 9 of the secondary shaft. Since these gears are not directly connected to shaft 2, they will rotate freely on the output shaft. These wheels are connected to shaft 2 through synchronizers.
When the first gear is engaged, the force from the gear lever through the rod and fork 11 is transmitted to the sliding clutch 13. Moving along the splines of its hub 12, the clutch engages with the spur ring of the wheel 14. Thus, the synchronizer clutch will connect the hub 12 and the wheel 14.
And since the hub 12 is rigidly connected to the shaft 2, the torque from the wheel 14 through the clutch 13 is transmitted to the hub 12 and from it to the output shaft of the gearbox. When the second gear is engaged, the clutch 13 will connect the hub 12 with the spur rim of the wheel 10, and the torque is transmitted from the wheel 10 to the hub 12 and to the output shaft. The third and fourth gears are switched on by a different synchronizer. When the third gear is engaged, the torque from the input shaft 1 through the wheels 36 and 9 is transmitted through the clutch 6 to the hub 38 and then to the secondary shaft.
The fourth gear is called direct, when the torque is transmitted directly from the input shaft 1 to the secondary shaft 2, bypassing the gears of the intermediate shaft. In this case, the clutch 6 connects the toothed rim 5 of the input shaft with the hub 38. The speed of rotation of both shafts will be the same, and the amount of torque transmitted from the engine to the drive wheels does not change.
When the reverse gear is engaged, the force from the gear lever through the rod 20 and the fork 19 is transmitted to the intermediate gear wheel 27. Moving on the axis 26, it connects the reverse gears 25 and 15, and the torque is transmitted from the input shaft through the gear 5 and gear wheel 40 to the intermediate shaft and then through gear wheels 25, 27 and 15 to the secondary shaft. In this case, the latter will rotate in the opposite direction, providing the reverse rotation of the driving wheels of the car.
As can be seen from the gearbox operation diagram, all forward gears are synchronized. The principle of operation of the synchronizer when the third gear is engaged is shown in diagrams a, b, c. When the gear lever is in neutral position (see diagram a) there is a gap between the sliding sleeve 6 and the blocking rings 37. The locking rings are pressed by springs 42 against the locking rings 46. In this position, the teeth of the locking rings are in the cavities of the gear rims 5 and 9. Due to the gap between the clutch 6 and the locking rings 37, the torque from the gear rim 9 through the locking ring is not transmitted.
At the start of third gear (see diagram b) the sliding sleeve 6, moving along the splines of the hub 38, is pressed against the conical surface of the blocking ring. Semi-dry friction occurs between the conical surfaces of the coupling and the ring, as a result of which the blocking ring is braked and rotated through a small angle (circumferential travel from 2.5 to 5 mm). In this case, the side bevels of the teeth of the blocking ring abut against the side bevels of the teeth of the crown 9, and further turning of the blocking ring stops. At the same time, resistance is created to further axial movement of the clutch 6. This occurs until the speeds of rotation of the secondary and intermediate shafts of the gearbox are equalized. As soon as such a moment comes, the friction force between the conical surfaces of the coupling and the ring decreases. Under the action of the axial force transmitted from the rod to the sliding sleeve of the synchronizer, the blocking ring begins to slide along the bevels of the teeth of the crown 9 and, together with the clutch, moves along the teeth of the crown. Thus, the clutch will connect the hub 38 and the ring gear 9. The third gear is fully engaged (see diagram in). In this position, the synchronizer sleeve together with the stem is held by a ball detent.
Clear and complete engagement and gear shifting is ensured by the good technical condition of the gearbox itself, as well as the clutch. Sometimes gears are switched with some difficulty. This can occur when the shift forks are deformed, when the rods or spherical joint of the lever are jammed, and also when the clutch is not fully disengaged. When the blocking rings, teeth of the synchronizer couplings and detents are worn out, spontaneous disengagement or fuzzy engagement of gears occurs. When the gears, bearings and synchronizers are worn, noise occurs in the gearbox, and when the seals are worn or the covers are loosened, oil leaks. These malfunctions during proper operation of the car may occur only with very long use of the car.