Gear box device

The gearbox converts the torque transmitted from the engine in magnitude and direction. This is necessary to ensure optimal speed and flotation of the vehicle, as well as for the most economical operation of the engine and reversing of the vehicle. In addition, the gearbox decouples the engine from the transmission when the vehicle is stopped and when it coasts with the engine running.

Due to the small number of gears, the gearbox is compact and simple in design. Selected gear ratios provide intensive acceleration, high average speed and economical engine operation. Constant mesh helical gears and synchronizers in all forward gears ensure quiet operation and durability of the transmission.

Depending on the vehicle configuration, a four- or five-speed gearbox can be installed, combined with the main gear, the gear ratio of which can have several values: 3.94 for the VAZ-2108; 4.13 - for VAZ-21081; 3.7 or 3.94 for VAZ-21083 or VAZ-2109 and its modifications. On VAZ-21081 cars, a four-speed gearbox is installed, and on other models and their modifications, both gearboxes can be installed.

The four-speed gearbox consists of a primary 23 (pic. 59) and secondary 33 shafts with gears and synchronizers, an axle with an intermediate reverse gear, a differential and a gear shift drive. The shafts and gears of the gearbox and final drive, as well as the differential, are located in the aluminum crankcase 1.

Gearbox housing

The gearbox housing is connected by studs to the clutch housing 29 during the assembly of the gearbox and together they form a single unit. On the other hand, the back cover 17 is attached to the gearbox housing, into which the breather 19 is pressed, which communicates the crankcase cavity with the atmosphere. This prevents pressure build-up in the crankcase and oil leakage through the seals. In the crankcase there are sockets for the bearings of the primary and secondary shafts, as well as for the retainers of the gearshift rods. The latches are closed with a common cover 8 (see fig. 62), and the reverse lock - with a plug 12. To fill the gearbox with oil, there is an opening closed by a plug 2 (see fig. 59), and for draining the oil, the hole is closed with a plug 3. The oil level should reach the lower edge of the filler hole.

Input shaft

The input shaft 23 rotates in two bearings. Cylindrical roller bearing 26 is installed in the socket of the clutch housing, ball - in the seat of the gearbox housing. The front end of the shaft at the outlet of the crankcase is sealed with an oil seal, which is closed by the flange of the guide sleeve of the clutch release bearing coupling. This flange is attached to the clutch housing with three bolts. On the sleeve there is a bearing clutch 31 for disengaging the clutch. The rear bearing 18 is fixed on the shaft with a nut and from axial displacement in the crankcase seat is held by an adjusting ring, which is pressed by cover 17 to the gearbox housing. The nut is fixed by caulking its girdle into the groove of the shaft.


The primary shaft is made in the form of a block of driving gears of I, II, III, IV gears and reverse gear. The clutch disc is located on the splined end of the shaft.

Output shaft

The output shaft 33 is made in one piece with the final drive gear. The front end of the shaft rests on a cylindrical roller bearing 32, the rear end on a ball bearing 16. The front bearing is located in the clutch housing housing, into which a rubber plug is pressed for sealing. The rear bearing is mounted on the shaft with a nut, which is fixed in the same way as on the input shaft. From axial displacement, the secondary shaft is held together with the rear bearing by its adjusting ring.

On the secondary shaft on needle bearings with plastic cages, driven gears of I, II, III and IV gears and two synchronizers are installed. Needle bearings «bracelet» type, which facilitates the installation of gears on the shaft. The installation of gears on needle bearings reduces friction losses and increases the efficiency of the gearbox. The gear 6 of the first gear is clamped between the thrust washer and the retaining ring of the synchronizer hub of I, II gears and reverse gear, the gear 8 of the second gear is between the second retaining ring of the same synchronizer hub and the thrust half rings 10 of the secondary shaft. The half rings are fixed on the shaft with a ball and a retaining ring 9, put on the half rings. Similarly mounted on the shaft and gears III and IV gears. Only the needle bearing of the gear 13 of the fourth gear is put on the bushing and a spacer ring is located between the bearing and the foot, and a thrust washer 15 is located between the bushing and the ball bearing.

Synchronizer

The synchronizer consists of a hub 5 (pic. 60), rigidly connected to the secondary shaft using splines, a sliding clutch 2, two blocking rings 1, three crackers 4 with latches 3 and springs, as well as gear rims of synchronizers. Sliding clutch 7 (see fig. 59) The synchronizer of I to II gears has an external crown for engaging the reverse gear.



The hub of the synchronizer of I and II gears is mounted on the splines of the secondary shaft and is fixed on the shaft from axial displacement with two retaining rings. There are six longitudinal grooves in the hub, three of which have sockets for the retainer springs. Crackers 4 are installed in the same grooves (see fig. 60) with retainer balls. The springs press the retainers against the annular grooves of the coupling. On both sides of the hub there are bronze blocking rings I with gear rims, the pitch of which is equal to the pitch of the internal teeth of the sliding clutch and the gear rims of the gears of I and II gears. The blocking rings have six protrusions that go into the grooves of the hub, while three short protrusions go into the grooves in which the latches are located, and longer and wider ones go into other grooves. These protrusions are installed in grooves with a side clearance equal to half the thickness of the coupling tooth (hubs), and limit the angle of rotation of the blocking ring relative to the hub. Thus, the hub rotates together with the blocking rings. With their conical surface, the blocking rings come into contact at the moment the gear is engaged with the conical belts of the gear of the 1st or 2nd gear. To break the oil film at the point of contact and increase the friction forces, especially fine threads and longitudinal grooves are cut on the conical surface of the ring.


The sliding clutch with its inner crown is seated on the outer ring gear of the hub and can move along the hub. To do this, a gear shift fork enters the annular groove of the clutch. The ends of the coupling teeth are beveled at the same angle as the teeth of the blocking rings and synchronizer rims.

Idler gear

Intermediate gear 5 (pic. 61) reverse gear spur. A bushing is pressed into its hole, through which axle 4 passes. It is installed in the holes of the clutch and gearbox housings. Fork 6 for reverse gear enters the gear groove.

Differential

The differential is two-satellite. His box is 36 (see fig. 59) rotates in two tapered bearings 35, the preload in which is regulated by selecting the thickness of the ring 4. The driven gear 34 of the main gear is attached to the flange of the differential box, and the plastic gear 40 of the speedometer drive 42 is pressed onto the differential box. The gear 34 is in constant engagement with the main drive gear secondary shaft transmission.

Satellites 37 and side gears 39 have spherical bearing surfaces. The use of a solid sphere in the differential box, coupled with gears and satellites, made it possible to eliminate the support washers of side gears.

The satellites are located on the axle 43, which is held in the holes of the differential box by retaining rings 44. Grooves are made on the landing journals of the axle to retain lubricant. The holes of the semi-axial gears have internal splines, into which the splined shanks of the housings of the internal hinges of the front wheel drives enter.