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Pic. 16. Scheme of operation of a four-speed gearbox.
1. Primary shaft; 2. Secondary shaft; 3. Gear wheel of constant engagement of the input shaft; 4. Breather; 5. Synchronizer ring of IV gear; 6. Sliding clutch of the synchronizer of III and IV gears; 7. Switching fork III and IV gears; 8. Gearbox housing; 9. Gear and ring gear of the synchronizer of the III gear; 10. Gear and ring gear synchronizer II gear; 11. Switching fork of I and II gears; 12. Synchronizer coupling hub for I and II gears; 13. Sliding clutch of the synchronizer of I and II gears; 14. Gear and ring gear of the synchronizer of the 1st gear; 15. Reverse gear; 16. Gearshift lever; 17. Speedometer drive gear; 18. Flexible coupling flange; 19. Reverse fork; 20. Reverse fork rod; 21. Rod of the fork of inclusion of III and IV gears; 22. The rod of the fork of inclusion of I and II gears; 23. Limiting screw for switching on I and II gears; 24. Intermediate shaft; 25. Countershaft reverse gear; 26. The axis of the intermediate reverse gear; 27. Intermediate reverse gear; 28. Speedometer driven gear; 29. Rear cover of the gearbox; 30. Bushing gear 1st gear; 31. Gear wheel of the 1st gear of the intermediate shaft; 32. The blocking ring of the synchronizer of the I transfer; 33. Drain plug; 34. The blocking ring of the synchronizer of the II transfer; 35. Gear wheel of the second gear of the intermediate shaft; 36. Gear wheel of the III gear of the intermediate shaft; 37. The blocking ring of the synchronizer of III transfer; 38. Synchronizer hub III and IV gears; 39. The blocking ring of the synchronizer of IV transfer; 40. Pinion of constant engagement 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. Retaining ring of the blocking ring of the synchronizer; I. Neutral position; II. The beginning of the inclusion of the third gear; III. Full third gear.
1. Primary shaft; 2. Secondary shaft; 3. Gear wheel of constant engagement of the input shaft; 4. Breather; 5. Synchronizer ring of IV gear; 6. Sliding clutch of the synchronizer of III and IV gears; 7. Switching fork III and IV gears; 8. Gearbox housing; 9. Gear and ring gear of the synchronizer of the III gear; 10. Gear and ring gear synchronizer II gear; 11. Switching fork of I and II gears; 12. Synchronizer coupling hub for I and II gears; 13. Sliding clutch of the synchronizer of I and II gears; 14. Gear and ring gear of the synchronizer of the 1st gear; 15. Reverse gear; 16. Gearshift lever; 17. Speedometer drive gear; 18. Flexible coupling flange; 19. Reverse fork; 20. Reverse fork rod; 21. Rod of the fork of inclusion of III and IV gears; 22. The rod of the fork of inclusion of I and II gears; 23. Limiting screw for switching on I and II gears; 24. Intermediate shaft; 25. Countershaft reverse gear; 26. The axis of the intermediate reverse gear; 27. Intermediate reverse gear; 28. Speedometer driven gear; 29. Rear cover of the gearbox; 30. Bushing gear 1st gear; 31. Gear wheel of the 1st gear of the intermediate shaft; 32. The blocking ring of the synchronizer of the I transfer; 33. Drain plug; 34. The blocking ring of the synchronizer of the II transfer; 35. Gear wheel of the second gear of the intermediate shaft; 36. Gear wheel of the III gear of the intermediate shaft; 37. The blocking ring of the synchronizer of III transfer; 38. Synchronizer hub III and IV gears; 39. The blocking ring of the synchronizer of IV transfer; 40. Pinion of constant engagement 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. Retaining ring of the blocking ring of the synchronizer; I. Neutral position; II. The beginning of the inclusion of the third gear; III. Full 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 input shaft 1 to the secondary shaft 2. This is achieved by moving the sliding clutches 6 and 13 of the synchronizers or the reverse gear 27 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 the first gear, the moment increases by 3.75 times, in the second - by 2.30 times, in the third - by 1.49 times, and when the reverse gear is engaged, by 3.87 times.
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 gears 3 and 40 of constant engagement. 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. The connection of these gears with shaft 2 is carried out 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 gear rim 14. Thus, the synchronizer clutch will connect the hub 12 and the gear 14 And since the hub 12 is rigidly connected to the shaft 2, the torque from the gear 14 through the clutch 13 is transmitted to the hub 12 and from it to the secondary shaft of the gearbox.
When the second gear is engaged, the clutch 13 will connect the hub 12 with the spur gear 10, and the torque is transmitted from the gear 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 through the gears 36 and 9 is transmitted through the clutch 6 to the hub 38 and then to the output shaft.
The fourth gear is called direct, since 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 ring gear 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 will 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 27. Moving on the axis 26, it will connect the reverse gears 25 and 15, and the torque is transmitted from the input shaft through the gears 5 and 40 to intermediate shaft and further through gears 25, 27 and 15 to the output 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 I, II, III. When the gear lever is in neutral position (see diagram I) there is a gap between the sliding sleeve 6 and the blocking rings 37. The blocking rings are pressed by springs 42 against the circlips 46. In this position, the teeth of the blocking rings are in the cavities of the gear rims 5 and 9. Due to the gap between the clutch 6 and the blocking rings 37, the torque from the ring gear 9 through the blocking ring is not transmitted.
At the start of third gear (see diagram II) 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 the further axial movement of the coupling 6. This occurs until the speeds of rotation of the secondary and intermediate shafts 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 connects the hub 38 and the ring gear 9. The third gear is fully engaged (see diagram III). IN» In this position, the synchronizer sleeve together with the stem is held by a ball detent.
Selected gear ratios provide intensive acceleration, high average vehicle speed and economical engine operation. And constant mesh helical gears ensure quiet and durable transmission operation.