Description of components and mechanisms of the gearbox

Section of the RKPP

Final Drive Assembly Components

Gear shift mechanism

Hinged assembly of the gear shift mechanism drive

Carter

The section of the gearbox is shown in the illustration.

The cast aluminum crankcase of the box consists of three interconnected parts: the crankcase (domes) clutch and main gear, the manual transmission housing itself and the cover. A flange is provided on the outer side of the cover for mounting the power unit support. The cover is attached to the gearbox housing with six long M8x80 bolts and three short M8x35 bolts.

A hole is provided in the lower part of the gearbox housing, into which the sensor-switch of the reversing lights is screwed. The drain plug has an M22 thread and its seat is sealed by an aluminum sealing washer with an outer diameter of 27 mm and an inner diameter of 22 mm.

A magnet is fixed inside the crankcase, designed to remove metal particles from the gear oil, which are formed during the operation of the internal components of the manual transmission.

Input shaft

The input shaft is installed in the gearbox housing on two tapered roller bearings: type 30205 AC6 and type 32005 AC6.

The shaft is supplied complete with helical gears 1÷4 gears and spur gear reverse gear. In this case, the gears of the 1st and 2nd and reverse gears are one with the shaft, and the 3rd and 4th gears are pressed. The 5th gear gear is mounted on a PLC 43-18 type needle bearing on the shaft.

In front of the 5th gear gear, its synchronizer is located, then the M22x1.5 nut is screwed (12) .

Output shaft

The output shaft is made integral with the final drive gear and installed in the manual transmission on two bearings: a single-row ball bearing of the PLC 05-12 type and a special bearing of the PLC 44-17 type. Between the first bearing and the final drive gear are the 4th gears, the 3/4 synchronizer, the 3rd gear, then the 2nd, then the 1/2 gear, and finally the 1st gear. Ahead of the ball bearing is a 5th gear gear, fixed with a M22x1.5 nut. The 1/2 gear synchronizer sleeve is equipped with a ring gear designed to engage reverse gear.


Helical gears of 1÷4 gears are equipped with additional gear rims for pairing them with synchronizers.

Gears

All listed gears of both shafts are in constant engagement with each other. When the engine is running and the gear is in neutral, the gears of the output shaft rotate freely on it (the exception is the 5th gear), while the shaft itself remains stationary. At the same time, when the clutch is engaged, the input shaft gears rotate with it, with the exception of the 5th gear, which, while turning, remains stationary.

The use of helical gears in the gearbox has significantly reduced the noise level.

Synchronizers provide shockless introduction of the shaft into engagement with the gear corresponding to the selected gear, only after equalizing the frequencies of their rotation, which guarantees smooth shifting.

The intermediate gear is designed to connect the reverse gears of the primary and secondary shafts. When the reverse gear is off, the gears of the shafts are disengaged (unlike other gears). When reverse is engaged, the intermediate gear simultaneously engages with the reverse gears of both shafts. This double engagement causes the output shaft to rotate in the same direction as the primary shaft, while the vehicle's drive wheels also begin to rotate in the opposite direction, ensuring the forward movement of the vehicle in reverse. Due to the fact that all the gears considered in this case are spur gears, the synchronizer is not provided here and the reverse gear should be engaged only after the car has completely stopped.

Lubrication system

The lubrication supply to the internal components of the manual transmission is carried out by the driven gear of the final drive, which is partially immersed in oil and, when rotated, transfers it upwards. From above, the oil flows down the main system into the output shaft channel and lubricates the gears and synchronizers.

There is a small oil drain inside the gearbox housing (33), through which the oil sprayed by the gears is supplied to the bearing of the 5th gear.

At the top of the crankcase there is a vent hole that is sealed with a plastic plug. On the cylindrical part of the plug there are coils that impede the passage of oil, however, freely passing air.

Main gear

The final drive components are shown in the illustration. The assembly is designed to transmit torque from the secondary shaft of the manual transmission to the drive shafts of the driving front wheels of the car, as well as to increase this torque.

The increase in torque is achieved through a constant gear ratio (see specs).

The main components of the reverse gear are: the drive gear, the teeth of which are cut directly on the body of the output shaft of the gearbox, the crown driven gear, to the end of which the differential box is attached with eight bolts. The main gear of this design is called cylindrical and differs from others in that it does not change the direction of torque transmission. The main drive gear has 19 teeth, the driven gear has 74.

The combination of the driven gear with the differential box made it possible to use the case of the latter as support pins for fitting the assembly into the bearings.

The differential provides the ability to rotate the driving wheels of the car at different speeds. When cornering, the inner wheel moves along a smaller radius than the outer one, and if the speeds of rotation of the wheels are the same, slippage will inevitably occur, leading to rapid wear of the wheels. A similar situation can also occur in a straight-line motion of a car, when the tires of the right and left driving wheels are worn out to varying degrees, or inflated with different pressures. In order to prevent slippage and reduce the load on the transmission, each of the driving wheels of the car is driven by a separate shaft connected to the manual transmission through a differential mechanism.

The differential consists of a housing (boxes), put on the axis of satellites and bevel side gears mated with the drive shafts of the drive wheels of the car. The differential case is one-piece. It has cutouts for installing internal components. In the horizontal plane, the differential housing ends with trunnions, on which bearings of the PLC 64-7 type are pressed. The outer bearing races, in turn, are pressed into the holes in the gearbox housing.

Bearings are installed without play. Preload is achieved by placing a shim of appropriate thickness in the left bearing bore. Washers are available in thicknesses from 2.0 to 2.7 mm in increments of 0.1 mm. An additional gear is installed on the trunnion located closer to the flywheel, designed to drive the speedometer.

The holes for the drive shafts in the crankcase of the manual transmission are sealed with oil seals 40x55x7 mm in size.

The axis of the satellites is made of a steel rod and is prevented from falling out of the differential box by two retaining rings recessed into specially provided grooves at both ends of the axis.

Satellites are bevel gears that rotate freely on their axis. Between the wide ends of the satellites and the walls of the differential box, disc washers are installed that act as bushings.

The bevel side gears of the differential are in constant engagement with the satellites. Longitudinal splines are cut on the walls of their holes, which engage with the splines of the internal pins of the drive shafts.

In a straight line (and identical wheel parameters) the satellites, and the side gears that are in constant engagement with them, remain motionless relative to their axis and housing. In this case, the differential represents, as it were, a monolithic assembly, rotating both drive shafts at the same speed. When the car moves along a curve, or various characteristics of wheel assemblies, one of the wheels (internal along the turning radius, or larger diameter) encounters greater resistance, which is rigidly transmitted to the corresponding side gear of the differential, forcing it to slow down due to the relative movement of the planetary assembly with the satellites starting to rotate. Despite the difference in the frequency of rotation of the driving wheels of the car, the amount of torque transmitted to them remains the same. At the same time, if one wheel hits a surface area with a reduced grip component (ice, snow, sand, etc.), and the second remains on a hard surface, then the first wheel will rotate with increased (up to double) speed, the second can stop rotating altogether.

During the operation of the car, you should monitor the same characteristics of the right and left driving wheels of the car (tire inflation pressure, tread wear, geometry, etc.), because otherwise the differential will continue to function even in a straight line, creating additional resistance associated with an increase in fuel consumption.

Gear shift mechanism

The gear change mechanism consists of a gear selection rod, two shift fork rods and a device that prevents the simultaneous engagement of two gears.

The gear selection rod is connected at one end to the gearshift drive rod, and at its other end a three-arm control lever for the shift fork rods is fixed. The exit point of the gear selection rod from the gearbox housing is protected from dust by a rubber boot.

On one of the shift rods, 1/2 and 3/4 gear forks are planted. On the other is the 5th gear fork and the reverse gear lever.

The ends of the forks are placed in the grooves of the outer rings of the corresponding synchronizers. The movement of the fork leads to the displacement of the synchronizer and the engagement of the driving and driven gears of the corresponding gear.

Gearshift drive

The reaction rod, located under the bottom of the body, is attached to the gearbox and the bottom. An M6x20 bolt is screwed into the gearbox, passing through a rubber bushing planted in the tip of a specially shaped jet rod. The rear end of the rod is installed in a rubber stop, pressed from below with a mounting clamp, attracted by two M8x40 bolts. Bushings are planted in the holes of the rubber stop, protecting the assembly from excessive compression. The manual transmission control lever is slightly curved and is equipped with a spherical joint at the bottom. The lower end of the lever ends with a transverse axial sleeve, and the upper end is provided with a handle.

The hinge of the lever is placed in a cavity formed by two bushings of a special shape planted in the support. On the outer surfaces of both bushings, a groove is provided in which rubber rings are seated. The entire assembly is fixed from above in the support using a retaining ring, under which a spacer washer is placed. The assembly is protected from contamination by a rubber boot.

The transverse bushing, located at the lower end of the manual transmission control lever, is designed to connect the lever to the linkage fork of the shift mechanism drive using an M8 bolt and nut. The second end of the rod ends with a transverse sleeve, with the help of which it is connected to the cardan joint, connecting the rod to the gear selection bar. At the end of the gear selection bar there is an 8x20 mm coupling, fixed with a cylindrical pin.