3.2. Gearbox and its drive. Device.

On MAZ vehicles, an eight-speed dual-range gearbox YaMZ-238A is installed with synchronizers in all gears, except reverse. The gearbox consists of a main two-stage gearbox and a two-stage additional gearbox (downshift).
The gearbox device is shown in Fig.44. Installation of all parts of the gearbox is carried out in the crankcases of the main and additional boxes, which are interconnected, and then assembled to the clutch housing; a single power unit is formed as part of the engine, clutch and gearbox.
The primary shaft 1 of the main box is mounted on two ball bearings; driven clutch discs are installed on the front splined end, and the rear end is made in the form of a ring gear of the constant mesh gear of the main box.
The output shaft 5 of the main box in front rests on a cylindrical roller bearing mounted in the bore of the gear rim of the drive shaft, and at the rear - on a ball bearing mounted in the front wall of the crankcase of the additional box. The rear end of the secondary shaft is made in the form of a ring gear, which is a gear of constant engagement of the additional box.
The gears of the second and fourth gears of the output shaft of the main box are mounted on plain bearings made in the form of steel bushings with a special coating and impregnation, and the gears of the first gear and reverse gear are mounted on roller bearings.
The intermediate shaft 26 of the main box in front rests on a roller bearing mounted in the front wall of the main box crankcase, and at the back - on a double-row spherical bearing placed in a cup installed in the rear wall of the main box crankcase. In the tides of the crankcase of the main box, an additional axle is installed for the reverse intermediate gear. The reverse gear is switched on by moving the reverse carriage 24 forward until it is connected to the ring gear of the reverse gear 25, which is in constant engagement with the reverse intermediate gear.
The secondary shaft 15 of the additional box in front rests on a cylindrical roller bearing located in the bore of the gear rim of the secondary shaft of the main box, at the back - on two bearings: a cylindrical roller bearing and a ball bearing, installed respectively in the rear wall of the crankcase of the additional box and the bearing cover of the secondary shaft.
On the splines of the middle part of the secondary shaft of the additional box, gear shift synchronizers are installed, and on the rear splined end there is a flange for fastening the cardan shaft. On the middle cylindrical part of the shaft, on roller cylindrical bearings, gear 11 of the additional box is installed.
The intermediate shaft 19 of the additional box in front rests on a cylindrical roller bearing installed in the front wall of the additional box crankcase, and at the rear - on a double-row spherical bearing placed in a glass mounted in the rear wall of the additional box crankcase. Downshift gear 22 is installed on the front splined end of the intermediate shaft of the additional box. At the rear of the intermediate shaft, a ring gear is made, coupled with the downshift gear of the secondary shaft of the additional box.
To switch gears in the main box, inertial synchronizers with conical friction rings are used, and in the additional box - with friction discs.
Gear shifting in the main box is carried out using a mechanical remote drive, and the additional box is controlled using a pneumatic drive.

Remote drive of the main box (Fig. 45).

Telescopic type, consists of a mechanism located directly on the gearbox 13, and a system of rods and levers connected to the 3 gear lever mounted in the cab.
In the tides of the top cover 1 (Fig. 46) of the main box, three rods are mounted: on the extreme right (along the direction of the car) the fork 3 of the reverse gear is fixed, on the middle - the fork 4 of the first and second gears of the main box, and on the third - the fork 8 shifting third to fourth gear of the main box.
Rods 5, 20 and 21 move in the guide supports of the top cover with the help of lever 22. There are heads (11 and 17, respectively) on the reverse gear and the shift rod of the first and second gears of the main gearbox. The lever 22 enters the head 17 directly, and the head 11 through the leash 15 of the reverse gear.
To enable the third and fourth gears of the main gearbox, the lever 22 can enter directly into the groove of the fork 8 for shifting these gears. The position of the reverse rod is fixed in the cover with the help of a fuse 16, which is included in the leash 15 under the action of a spring 12 placed in a special glass 13. Only by overcoming the force of the spring of this fuse, you can turn on the reverse. The rods with the gear engaged and in the neutral position are held by ball clamps. To prevent the possibility of simultaneous engagement of two gears, a special ball-type lock is installed in the rods.
On the top cover of the main box, there is a crankcase 11 (see Fig. 45) of the remote control mechanism of the main box, in which the gear shift shaft 12 is located with the lever 14 fixed on it and the intermediate lever 18 connected with the longitudinal rod 7 of the remote drive.
In the crankcase of the remote mechanism there is a ball lock 9 for gear selection. Longitudinal thrust 7 can perform both longitudinal and angular movement. The angular movement of the rod causes axial movement of the shaft 12, which leads to the connection of the lever 14 sitting on it with a certain slider in the top cover of the main box 13. The movement of the longitudinal rod causes the rotation of the gear shift shaft 12 and the lever 14 sitting on it. moves along with the fork until the appropriate gear is engaged.
The additional box is controlled by means of a pneumatic valve by the switch 1 (see Fig. 45) of the ranges located on the handle of the gear lever 3.

The switching mechanism of the additional box (Fig. 47).

It consists of a pressure reducing valve 12, an air distributor 6, a pneumatic cock 5, an inlet valve 8, a working cylinder 1 and air ducts.
Reducing valve 3 (Fig. 48) serves to reduce the pressure of compressed air supplied from the pneumatic system of the car to 4.75 kgf / cm² - the working pressure of the pneumatic system of the gearbox. The air distributor 23 directs compressed air from the inlet valve 17 into one or another cavity of the working cylinder 25 and bleeds air from its cavities.
Pneumocrane 5 controls the air distributor. With the 6 range switch down, the air distributor spool is set to the position corresponding to the direct transmission in the additional box. With the switch up, to the downshift position.
The inlet valve 17 supplies compressed air through the air distributor 23 to the working cylinder 25 only when the gear in the main box is switched off. When the gear is on in the main box, the valve inlet is closed by the pusher 16 and air does not enter the air distributor and the working cylinder, the unloading hole in the valve body is open, both cavities of the working cylinder are connected to the atmosphere.
When the range switch 1 is raised (see Fig. 45), the cable 6 moves the spool 3 (Fig. 49) to a position in which compressed air supplied from the pressure reducing valve to channel A through the pneumatic valve channel enters channel B and then to the air distributor on downshifting. Channel B at this time is connected to the atmosphere through filter 8.

When the range switch is lowered, the cable moves the spool 3 to a position where compressed air enters channel B through channel A and from there to the air distributor for direct transmission. At this time, channel B is connected to the atmosphere through cover 5.
The gearshift mechanism of the additional box is located in the top cover of its crankcase. Here is the rod 13 (see Fig. 44), connected with the piston of the pneumatic cylinder 14. The direction of movement of the rod with the fork 10 of the gear change of the additional box fixed on it depends on the pressure supplied to the pneumatic cylinder to the left or right of the piston, which causes the large 20 or small 21 synchronizer, i.e., reduction or direct transmission of an additional box.
On the top cover of the additional box there is a synchronizer sensor, downshift engagement. When the rod 13 and the fork 10 of the gear shift of the additional box are moved from one position to another, the control lamp connected to the switch terminal 35 lights up in the driver's cab. The lamp goes out as soon as the selected (direct or downshift) gear is fully engaged.
In addition, there is a locking device on the top cover of the additional box to turn off the additional box when the vehicle is towed. To do this, having set the fork 10 in the neutral position, the locking bolt 9 is screwed all the way into the hole made on the rod, and it is locked in this position with a nut.

Gearbox lubrication system.

It is combined: the gear bearings of the secondary shafts of the main and additional boxes are lubricated under pressure, the gear teeth and shaft bearings are spray lubricated. The oil is sucked in from the oil bath of the crankcase through the intake 29 and the system of channels by a gear oil pump. The pump drive is carried out from the end of the intermediate shaft of the main box. The pump has a pressure reducing valve, which is adjusted to a pressure of 0.78 kgf / cm² and, in case of an excessive increase in oil pressure, connects the pump discharge channel to the suction channel. The oil baths of both crankcases are interconnected by a channel to ensure the same oil level in them. The internal cavity of the gearbox housings communicates with the atmosphere with the help of a breather.
The gearbox has an oil filler hole on the cover of the main box, an oil level control hole on the side wall of the main box, and two drain holes each from the bottom of the crankcases of the main and additional boxes.

2381-3902150 IE

Gearboxes

YaMZ-2381

YaMZ-238VM

YaMZ-238VK

YaMZ-238VU

and their modifications

User manual

This manual applies to KP YaMZ-2381; YaMZ-238VM; YaMZ-238VK; YaMZ-238VU; YaMZ-238VL of all modifications and establishes the basic requirements for the operation of gearboxes.

1 Characteristics

The YaMZ-2381 gearbox is eight-speed mechanical, consists of a main four-speed gearbox and a two-range planetary demultiplier.

Gearboxes YaMZ-238VM; YaMZ-238VK; YaMZ-238VU; YaMZ-238VL differ from the above gearbox in the input shaft, input shaft cover and oil pump.

Gearboxes YaMZ-238VM4 (238VK4; 238VU; 238VU2; 238VU4; 238VL) are designed for installation together with a double-plate clutch of the YaMZ-238 type and a cardan shaft with a “smooth” flange.

YaMZ-238VM5 gearboxes (238VK5; 238VU1; 238VU3; 238VU5; 238VL1; 2381; 2381-30) are designed for installation together with a YaMZ-183 type diaphragm clutch and a cardan shaft with a “smooth” flange.

Gearboxes YaMZ-238VM7 (238VM1; 238VK7; 238VU6; 238VU7; 238VU9; 238VL1; 2381-02; 2381-05; 2381-31; 2381-52) are designed to be installed together with a YaMZ-183 type diaphragm clutch and cardan shaft with " euro” flange.

Gearboxes YaMZ-238VM4; YaMZ-238VM5; YaMZ-238VM7 can be installed instead of discontinued YaMZ-238A gearboxes; YaMZ-238A3; YaMZ-238A5 in accordance with the recommendations (see Appendix).

1.1 Gear shifting is carried out in accordance with

with picture 1.

Figure 1-Scheme of the positions of the gear lever.

Attention!

When controlling the gearbox using a mechanical remote drive, the positions of the gear lever handle may differ from those shown in the diagram and are indicated in the vehicle's operating manual.

When moving the shift lever from neutral to reverse, resistance should be felt from the spring mechanism. Engage reverse gear only after the vehicle has come to a complete stop.

1.1.1 Range switch mechanism

equipped with an automatic low range lockout system (ASBP). The ASPB relay is designed in such a way that it allows the inclusion of the lower range at a speed of rotation of the gearbox output shaft of not more than 920 rpm, which corresponds to a vehicle speed of 25-35 km/h.

1.2 Gear ratios of the gearbox are given in table 1

Table 1

Broadcast	Transfer in the main box	range in demultiplier	Gear ratio
1 2 3 4	1 2 3 4	lower	7,30 4,86 3,50 2,40
5 6 7 8	1 2 3 4	higher	2,09 1,39 1,00 0,71
s.h.	s.h.	lower higher	10,46 2,99

2 Operation of gearboxes.

Change gears from first to fourth and from fifth to eighth by moving the shift lever to the appropriate position.

To turn on the fifth gear, leave the fourth gear engaged and move the range switch button to the higher range (the location of the range controls is indicated in the vehicle manual).

Fifth gear is engaged by moving the shift lever of the main box to the first gear position. At the moment of transition through the neutral position, the highest range in the demultiplier is automatically switched on; at the same time, hold the lever in the neutral position until the range switch switching lamp goes out.

To switch from fifth to fourth gear, switch the range switch button to low range when fifth gear is engaged, while the vehicle speed should not exceed 35 km / h. Then shift the gearshift lever to the neutral position, hold until the indicator lamp goes out and turn on the fourth gear in the main box.

Starting off a loaded car from a place to produce in first gear. Starting the car in second gear is allowed only on paved roads with a partial load of the car.

Reverse movement should be carried out only when the lower range is turned on in the demultiplier.

3 Maintenance.

3.1 Gearbox lubrication

The following oils should be used to lubricate the gearbox:

all-weather gear oil TSp-15k GOST 23652-79

(SAE 85W-90);

all-weather gear oil MT-16p GOST 6360-83 (substitute);

all-weather gear oil TAD-17I GOST 23652-79 (SAE 85W-90);

“YAR. Mark T” TU 0253-019-00219158-95 (SAE 80W-90; GL-3);

Angrol TSp-15k TMZ-18 GOST 23652-79 (SAE 85W-90; GL-3);

a mixture of oil TSp-15k GOST 23652-79 (85%) and diesel fuel grade A or Z GOST 305-82 (15%) (for operation at temperatures below minus 30°C);

grease Litol 24 GOST 21150-87 (for lubricating parts of the clutch release mechanism);

grease No. 158 TU 38.101.320-77 (for lubricating parts of the demultiplier switching mechanism).

Filling capacity of the lubrication system from 7.5 to 8 liters. The oil level below the control hole located on the right side of the spacer is not allowed.

3.2 Maintenance after running the car.

After running in the car, change the oil in the gearbox housing, clean the oil intake grid and the drain plug magnet from the run-in products.

3.3 First maintenance (TO-1).

3.3.1 Check the oil level in the crankcase and top up if necessary in accordance with this manual.

3.4 Second maintenance (TO-2).

3.4.1. Perform all first maintenance operations.

3.4.2. Fill the clutch release clutch with grease, making 3-4 strokes with a syringe.

3.4.3 Lubricate the clutch release fork roller through two grease fittings, making 2 strokes with a syringe.

3.4.4 Check and, if necessary, adjust the rear gearbox support in accordance with the vehicle operation manual.

3.5 Additionally, through one TO-2.

3.5.1 Change the oil in the gearbox with flushing the crankcase, mesh and magnet.

3.5.2 In the absence of a regulated vehicle maintenance system, change the oil depending on the operating conditions according to the following scheme:

cars with an annual mileage of 80,000 km. and more after 50,000 km.

vehicles with an annual mileage of less than 80,000 km. and under severe operating conditions (dirt road, mountainous or hot desert terrain, etc.) - after 30,000-40,000 km.

Attention!

When using a substitute oil, the timing of its change should be halved. Drain the gearbox oil immediately after hot work. Crankcase flushing should be carried out with liquid industrial oils (I-12A or I-20A according to GOST 20799-88). It is forbidden to flush the gearbox with diesel fuel or kerosene, in order to avoid failure of the oil pump.

3.5.3 Clean and lubricate the gearbox air distributor parts (using grease No. 158 according to TU 38.101.320-77; Litol-24 grease can be used according to GOST 21150-87).

3.5.4 Clean and lubricate the piston and the working surface of the switch cylinder of the demultiplier with grease Litol-24 GOST 21150-87.

4 Rules for towing a car.

Towing a car with an idle engine can only be done with the cardan shaft disconnected.

Attention!

Towing the car in violation of the above rules leads to the failure of the gearbox.

5. Possible transmission malfunctions.

5.1. Possible malfunctions of the gearbox and methods for their elimination are given in table 2.

table 2

Possible malfunctions		Elimination Methods
Difficulty shifting gears
incomplete clutch disengagement (clutch “leads”) wear or damage to the synchronizer, teeth of gear couplings are damaged		adjust pedal free play if the defect is due to defective clutch parts, replace the damaged parts replace the faulty synchronizer, replace damaged parts
Increased noise during gearbox operation
not enough oil in the gearbox gear shaft bearing wear increased wear or chipped teeth		fill with oil up to the level of the control hole replace worn gears
Spontaneous disengagement of gears when the car is moving
uneven wear of gear couplings malfunctions of rods and forks of the gear shift mechanism increased wear of gearbox bearings		replace defective parts replace defective parts replace defective bearings
Spontaneous disengagement of gears in the demultiplier
the flow of compressed air into the cylinder cavity opposite to the engaged gear range fork bearing wear			replace the defective O-rings of the spool and the inlet valve of the air distributor replace worn parts, adjust the position of the range cylinder rod
Non-engagement or delayed engagement of gears in the demultiplier with the lever in the neutral position in the main box. The alarm lamp does not go out for a long time, air exits through the air distributor breather
wear of the sealing ring of the inlet valve of the air distributor uneven fit of the intake valve to the body intake valve sticking in the depressed position jamming of the edge of the cuff in the piston groove, wear or loss of elasticity of the cuffs			replace worn out valve replace sealing ring replace defective parts clean and lubricate intake valve stem, polish if necessary to replace cuffs of the cylinder of switching of a demultiplier
Non-engagement or slow shifting of gears in the demultiplier with the lever in the neutral position in the main box. The alarm lamp does not go out for a long time, air exits through the breather of the top cover.
damage to the air diffuser membrane wear or loss of elasticity of the O-rings of the range shifting cylinder rod	replace damaged membrane replace damaged rings
Passing air through the air distributor breather with the gear engaged in the main box
wear of the rubber of the inlet valve of the air distributor loose fit of the pusher to the inlet valve in the air distributor	replace valve replace defective parts

6 Features of the assembly of the gearbox.

6.1 Before installing the demultiplier with a spacer on the crankcase of the main box and the spacer on the crankcase of the demultiplier, apply anaerobic sealant UG-6 TU 6-01-1285-84 on both sides with a continuous strip 2-3 mm wide. along the contour.

6.2 When installing the demultiplier with a spacer on the crankcase of the main box (Figure 2) and the cover of the output shaft of the demultiplier (Figure 3), ensure minimum axial play of the shafts using shims selected as follows:

-measure dimension A with an accuracy of 0.1 mm. from the end face of the outer ring of the bearing of the surface of the crankcase of the main box (Figure 2) or the crankcase of the demultiplier (Figure 3) with the bearing pressed to the stop.

-measure dimension B with an accuracy of 0.1 mm. the depth of the groove for the bearing in the gear coupling (Figure 2) or the output shaft bearing cap (Figure 3), taking into account the thickness of the gasket.

- select the total thickness of the shims, which should be less than the difference B-A by 0.15 ... 0.2 mm

6.3. When installing the input shaft bearing cover (Figure 4), ensure the minimum axial play of the shaft using shims selected as follows:

-measure dimension B with an accuracy of 0.1 mm. the depth of the groove for the bearing in the bearing cap, taking into account the thickness of the gasket

-measure dimension A with an accuracy of 0.1 mm. from the end face of the outer ring of the bearing to the surface of the crankcase wall with a pressed bearing

- select the total thickness of the shims, which should be less than the difference B-A by 0.2-0.3 mm.

6.4. Tighten the nuts for fastening the crankcase of the multiplier in two steps (see table 3). Tightening sequence according to figure 5.

6.5 When repairing the demultiplier with the replacement of synchronizer parts, adjust the required rod stroke when the upper range is turned on, ensuring unloading of the fork bearings, for which:

6.5.1 turn on the highest range in the demultiplier with the adjusting bolt turned out, by supplying air under pressure from 784 to 833 kPa (8 ... 8.5 kgf / cm2) into the pneumatic cylinder. Verify that the high range clutch teeth are fully engaged. When fully engaged, the indicator lamp should go out, the driveshaft mounting flange should not turn by hand.

6.5.2 Screw the adjusting bolt into the piston rod until it stops (when turning the bolt, a noticeable increase in resistance to rotation should be felt) Repeat the operation several times, making sure that the stop is felt at the same position of the bolt head.

6.5.3 Turn the adjusting bolt from the position of its stop to the end by 5…7 faces of the bolt head (5/6…7/6 turns) and, holding it in this position, lock it with a lock nut, tightening it with a torque from 137.29 to 156, 9 Nm (from 14 to 16 kgf/m). After adjustment, the driveshaft mounting flange should turn easily, without jamming by hand. Rotate the flange through an angle of at least 360°.

Attention!

Incorrect adjustment causes an unacceptable overload of the range fork bearings, which leads to their rapid destruction.

7 Tightening torques for the main threaded connections.

7.1 The tightening torques of the main threaded connections are given in table 3.

Table 3

Table 3. Name of fasteners	Tightening torque Nm (kgcm)
Bolts of fastening of a crankcase of coupling to a crankcase of a box	137-157 (14-16)
Bolts for fastening the clutch housing to the flywheel housing	70-80 (7-8)
Bolts for fastening the spacer to the crankcase of the main box	123-157 (12,5-16)
Bolts of fastening of a crankcase of a demultiplicator to a spacer preload final tightening	20-30 (2-3) 79-98 (8-10)
Bolts of fastening of the top cover of a crankcase of the main box	35-49 (3,6-5)
Axes of a fork of switching of a range	118-128 (12-13)
Bolts of fastening of a cover of a primary shaft	23,5-35 (2,4-3,6)
Low range gear coupling to spacer bolts	23,5-35 (2,4-3,6)
Bolt of fastening of a flange of an output shaft	363-422 (37-43)

8 Preparing the gearbox for operation.

8.1 Before installation, the gearbox must be depreserved in accordance with clause 11.3. this manual.

8.2 The bolts securing the gearbox to the engine and the cardan shaft to the gearbox must be securely tightened.

8.3 The gearbox rear support must be adjusted in accordance with the vehicle's operating instructions.

8.4 After mounting on the vehicle, the gearbox must be connected to the pneumatic and electrical systems of the vehicle (see figures 7 and 8).

9 Completeness.

9.1 A longitudinal section of the gearbox is shown in Figure 6.

9.2 The gearbox is delivered fully assembled on a wooden stand with transport parts that protect the gearbox from mechanical damage, dirt and precipitation.

Attention!

To prevent breakage of the contacts of the switch of the range switching signaling lamp, the switch is turned out and tied to the pneumatic pipelines of the gearbox in the package, and the threaded hole is closed with a plug. Before installation, remove the plug and screw in the switch.

10 Transportation and storage.

10.1 Gearboxes can be transported by any mode of transport. The gearbox mounting must ensure its safety from damage during transportation; a protective cover must be installed on the cardan shaft mounting flange.

10.2 Gearboxes must be stored in closed, dry rooms. Acids, alkalis and other chemicals must not be stored in these rooms (storage conditions “C”

GOST 15150-69).

11 Preservation and re-preservation.

11.1 Gearboxes are shipped to the consumer with short-term conservation, ensuring the safety of gearboxes for three months from the date of shipment from the manufacturer, subject to the requirements of clause 10.2.

11.2 At the request of the consumer, gearboxes can be subjected to long-term conservation according to the manufacturer's technology, which provides storage for 36 months. Information about long-term conservation is entered in the “Conservation Act”.

11.3 When depreserving gearboxes, remove the protective casing, paraffin paper, unscrew the drain plug, drain the remaining preservation grease, screw the plug.

Conservation act

Preservation and packaging done

Date______________200

Preservation period up to _______________

12 Acceptance certificate

Transmission___________________

(model)

Serial number ___________________ is manufactured in accordance with the current technical documentation and recognized as fit for use.

OTK stamp _______________________

_________________ _______________________

(personal signature) (signature transcript)

________________

(year, month, days)

13 Warranty.

13.1 The Tutaev Motor Plant guarantees the correct operation of the gearbox subject to the requirements of the “Instructions for the operation of YaMZ-238B engines; YaMZ-238D; YaMZ-238N; YaMZ-238L; YaMZ-238FM” and this manual

13.2 The gearbox must be installed on the vehicle no later than three months from the date of shipment from the manufacturer's factory. Gearboxes that have undergone conservation must be installed on the vehicle no later than the period specified in the Conservation Act.

13.3 The warranty period is 12 months from the date of installation of the gearbox on the vehicle. The warranty mileage for this period should not exceed the value established by the instructions for a specific modification of the car.

Application

Recommendation for the installation of gearboxes of the YaMZ-238VM type instead of gearboxes of the YaMZ 238A type.

This recommendation applies to YaMZ-238VM4 gearboxes; YaMZ-238VM5; YaMZ-238VM7 of all modifications and establishes the basic requirements for the installation of these gearboxes instead of YaMZ-238A gearboxes; YaMZ-238A3; YaMZ-238A5.

1 General information

The YaMZ-238VM4 gearbox is installed instead of the YaMZ-238A gearbox.

The YaMZ-238VM5 gearbox is installed instead of the YaMZ-238A3 gearbox.

The YaMZ-238VM7 gearbox is installed instead of the YaMZ-238A5 gearbox.

2 Preparing for installation

2.1 Purchase the required gearbox YaMZ-238VM-1700003-40 (50 or 70).

2.2 Purchase relay 6312.3747 (manufacturer, Kaluga).

2.3 Purchase cardan shaft (see table 1).

Table 1

Table 1 Model car	Model boxes gear	Designation cardan shaft	Note
MAZ-5432 and modifications	YaMZ-238VM4 YaMZ-238VM5	5551-2201010-02	2 X axle tractor 4x2
	YaMZ-238VM7	5551-2201010-10
MAZ-5516 and modifications	YaMZ-238VM4 YaMZ-238VM5	5516-2205010-20	3 X axle dump truck 4x4
	YaMZ-238VM7	54328-2201010-10
MAZ-6422 and modifications	YaMZ-238VM4 YaMZ-238VM5	64229-2205010-01	3 X axle tractor 6x4
	YaMZ-238VM7	64229-2205010-10

Attention!

For cardan shaft numbers not listed in this table, for other car models, check with the car manufacturer or service centers.

2.4 Release the gearbox from the technological stand by removing the transport plug from the propeller shaft mounting flange, the protective cover of the demultiplier switch indicator switch and the packing paper from the input shaft, remove the plug from the top cover.

2.5 External inspection should make sure the integrity of the speed sensor and air supply pipes.

2.6 Install the demultiplier switching indicator switch (the switch is packed in paper and tied to pipelines), having previously removed the metal transport plug.

2.7 Lubricate the spline part of the input shaft with a thin layer of Litol-24 GOST 21150-87 grease and make sure that the clutch release bearing is filled with the specified grease.

3. Mounting and dismantling.

3.1 To remove the YaMZ-238A gearbox from the car, you should:

- remove the landing gear;

- dismantle the cardan shaft by disconnecting it from the gearbox and drive axle;

- disconnect the air supply pipe from the pressure reducing valve;

- disconnect from the air distributor the air supply pipelines from the pneumatic control valve of the demultiplier;

- disconnect the plug of the clutch release booster valve from the clutch release lever;

- disconnect the air supply pipe from the clutch release cylinder;

- disconnect the electrical wires from the switch of the signal lamp for switching the demultiplier, the switch for the reverse signal lamps and the speedometer drive sensor;

- having unscrewed the four fastening nuts, disconnect the gear shift mechanism together with the control rod or shift lever from the gearbox and take it aside;

- having unscrewed the nuts, remove the rear supporting support of the power unit;

- unscrew the bolts of the bracket with fuel pipes from the gearbox cover;

- unscrew the bolts and remove the brackets of the supporting support of the power unit;

- bring a lifting mechanism under the gearbox;

- unscrew the bolts securing the clutch housing from the flywheel housing, hang out the gearbox and disconnect it from the engine;

- lower the gearbox onto the trolley, raise the rear of the car and roll out the trolley with the gearbox from under the car, then lower the car.

3.2 Before installation, rearrange from the YaMZ-238A gearbox to the YaMZ-238VM gearbox:

-clutch release lever;

- the bracket together with the clutch release cylinder;

- the switch of signal lights of a backing and a ball of Ø14 mm.;

- speedometer drive sensor and replaceable sensor drive gears.

3.3 To install the YaMZ-238VM gearbox on a car, you must:

- raise the rear of the car and roll the trolley with the gearbox under it, then lower the car;

- hang out the gearbox with a lifting mechanism and, avoiding large distortions, attach it to the engine, aligning the splines of the input shaft and the clutch discs;

- tighten the bolts securing the clutch housing to the flywheel housing with a torque of 7 ... 8 kgm, disconnect the lifting mechanism;

- fix the bracket with fuel pipes on the gearbox cover with bolts;

-install the standard rear supporting support on the gearbox bracket;

- place the cross member with the plate downwards over the supporting support on the spars (see Figure 9);

Attention!

The drawings of the cross member were developed in relation to the MAZ-54323 car, before manufacturing the cross member for other car models, it is necessary to measure the distance between the frame side members in the plane of the gearbox support and, if necessary, change the corresponding dimensions of the cross member.

-measure the distance “A” between the cross member and the supporting support (see figure 10);

- select a package of adjusting plates (see Figure 11) of thickness “A”, install it between the cross member and the supporting support and fix the supporting support on the cross member with bolts;

-drill a 13 mm hole in place (coaxially with the holes in the cross member) in the flanges of the side member;

- fix the cross member with bolts;

- fix, by wrapping four nuts, the gear shift mechanism, aligning the shift lever with the groove on the heads of the rods;

- connect the electrical wires to the switch of the signal lamp for switching the demultiplier, the switch of the reverse signal lamps, the speedometer drive sensor;

- connect the air supply pipelines from the demultiplier control valve to the air distributor and the solenoid valve (see Figure 7);

- connect the air supply pipe from the pneumatic system of the car to the air distributor;

- connect the valve plug of the clutch release booster to the clutch release lever;

- connect the air supply pipeline to the clutch release cylinder;

-Install cardan shaft;

- fix the landing gear in place;

- install the relay in the driver's cab in a convenient place;

- connect the relay to the electrical system of the gearbox and the car (see Figure 8);

Attention!

The gearbox is operational in the absence of a relay. However, switching the demultiplier at vehicle speeds above 25 ... 30 km / h will lead to its rapid failure.

The manufacturer's warranty does not apply to a gearbox operated without a relay!

4. Adjustment.

After carrying out the installation work, in accordance with the vehicle operating instructions, adjust:

MAZ vehicles are aggregated with engines manufactured by the Yaroslavl Plant, MMZ, MAN, Deutz, Mercedes-Benz, Cummins. Therefore, each MAZ gearbox installed with these engines has design features.
Most of the gearboxes that the automaker prefers are mechanical. The task of the gearbox is to act as an “intermediary” between the crankshaft of the internal combustion engine and the drive wheels in the transmission of torque, while changing its magnitude and direction. With the help of the gearbox, the driver can perform the separation of the internal combustion engine and transmission.

You can buy a MAZ gearbox at a competitive price on the Sparox website. We offer certified spare parts and components for gearboxes from different manufacturers.

Short description

Mechanical gearbox MAZ structurally consists of shafts (leading, driven and intermediate), gears, synchronizers. Gearbox elements are located in the crankcase.
The shift mechanism is used by the driver to change gear. At this point, the gears are engaged, their combination depends on the selected gear.

The MAZ box with the 236 engine is a 5-speed manual transmission (synchronizers in all gears, starting from the second). With the 238 engine, an 8-speed manual transmission is installed (without a synchronizer, only reverse gear). Manov motors are equipped with 16-speed ZF manual transmissions (synchronization is similar to 8SP YaMZ).

In this article, we will tell you what functions the gearbox performs in the MAZ engine, make several recommendations for repair, and also indicate the MAZ gearshift scheme with a divider, which you can examine and study in detail.

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Appointment of the checkpoint

In the gearbox there is such an element as a gear, usually there are several of them, they are connected to the gear control lever and it is due to them that gear changes occur. Gear changes control the speed of the car.

That is, in other words, gears are gears. They have different sizes and different rotation speeds. In the process of work, one clings to the other. The system of such work is due to the fact that a large gear clings to a smaller one, the rotation increases, and at the same time the speed of the MAZ car. In cases where a small gear clings to a large one, the speed, on the contrary, drops. The box consists of 4 speeds plus reverse. The first is considered the lowest and with the addition of each gear, the car starts to move faster.

The box is located in the MAZ car between the crankshaft and the driveshaft. The first one comes directly from the engine. The second is directly connected to the wheels and drives their work. The list of works that lead to speed adjustment:

1. The motor sets the movement of the drive and crankshaft.
2. Gearbox gears receive a signal and set in motion.
3. Using the gear lever, the driver selects the desired speed.
4. The speed selected by the driver is transmitted to the cardan shaft, which drives the wheels.
5. The vehicle continues to move at the selected speed.

Device diagram

The scheme of the gearshift device for a gearbox with a divider on a MAZ is not simple, but it will help you a lot when making repairs. The step gearbox on the MAZ consists of such elements as the crankcase, shafts, mortar, synchronizers, gears and other equally important elements.

9 speed

Such a unit is installed, in most cases, on trucks or cars that will be subjected to high traffic.

8 speed

This unit, like its predecessor, is popular among machines with high payloads.

5 speed

The most popular among cars.

Want to keep your divider box in good condition for years to come? Then she needs care and elementary checks. It is necessary to monitor the work of such elements as gears, a mortar, the control lever itself, and so on. Has it happened that the breakdown is unavoidable? We will give you the following recommendations for self-repair:

• familiarize yourself with the diagram and instructions for your mechanism in detail;
• in order to carry out repairs, first of all it is necessary to remove the box completely and only after that you can proceed with the repair;
• after you pull it out, do not rush to disassemble it completely, sometimes the problem is on the surface, pay special attention to all the details, if you see suspicious "behavior", then most likely the problem is in this element;
• if you still have to disassemble the box completely, put all the parts in the order of disassembly, so as not to get confused at the moment when you collect it back.

If you are not confident in your abilities, do not have certain skills and knowledge, contact the service center. Is there no such possibility? Well, it's never too late to learn new and useful things. Ask questions in the comments, we will give you open and detailed answers.

In this article, a gearshift scheme for MAZs of all types was considered. We hope that the information was useful to you in the repair. Let your box serve you for many years!

Video "Checkpoint operation"

You can see the principle of operation of a mechanical box in this video.

One of the famous brands of Belarus is MAZ. The produced equipment from the Minsk Automobile Plant (MAZ), which includes tractors, timber trucks, heavy vehicles, is known throughout the world.

Components of the checkpoint MAZ

The vehicle gearbox (MAZ) includes several gears that are connected to the gear lever. Each of the available gears performs its function, rotates at a certain speed, providing efficient control of the machine.

The manufacturer placed the box in the MAZ car between the crankshaft and cardan shaft. The crankshaft is a component part characterized by a complex shape. High demands were placed on the production of this element. The cardan shaft is no less reliable working mechanism, the function of which is to transfer the moment of force between the shafts.

Gearbox drive

In addition to the shafts, the MAZ manual gearbox includes a crankcase, mortar, synchronizers. The speed control on the machine is carried out by changing gears. Interacting with each other, the gears are able to both increase and decrease the speed of the MAZ. The lever with the gear divider works effectively.

MAZ checkpoint scheme

The MAZ gearbox air distributor is designed to switch air flows. The device is located in the top cover of the crankcase.

The MAZ transfer case is a complex mechanism that provides wheel locking and affects gear changes.

Given this, the MAZ transfer case is installed on heavy vehicles that are great for operation on a dirt road, poorly equipped tracks.

The MAZ gearbox with a demultiplier includes an intermediate shaft drive gear, which is equipped with a damper. The damper helps to reduce vibrations. The MAZ pillow helps to suppress noise from the checkpoint while driving.

Scheme of the demultiplier

Gearbox options for heavy vehicles

The 8-speed MAZ gearbox is typical for vehicles that have a high carrying capacity.

9-speed versions are installed not only on powerful trucks, but also on ordinary cars.

5-speed gearboxes are present on the MAZ-500 car with the YaMZ-236 diesel engine.

5 speed gearbox

16-speed versions are found on dump trucks, KamAZ vehicles. The mass of the box in this case exceeds 250 kg. The ZF16S gearbox has an adapter plate that communicates with the engine and gearbox.

The listed versions are distinguished by high reliability, long-term working capacity.

A MAZ car with a ZF gearbox is decided to be purchased by those who want to enjoy a full ride both in urban conditions and on rough terrain. Often this type of gearbox is found on snowplows.

The need for checkpoint maintenance

Contributes to the extension of the resource of the speed box - its timely maintenance. In particular, the car owner must monitor the efficiency of the gears, the control lever, and control the level of oil poured into the MAZ automobile system.

If it is necessary to repair the gearbox at MAZ, it is necessary to dismantle the gearbox from its regular place. The device should be visually inspected for external deformations. It is highly likely that this is the reason that the checkpoint "does not obey" the driver's commands. If there are no deformations, you can proceed to the analysis into the components of the gearbox.

If the MAZ checkpoint circuit fails, then the following symptoms will appear:

• some gears do not work, for example, 4 and 5;
• manual switching is difficult.

To flush the gearbox, about 3 liters of special oil are required. Repair of the MAZ gearbox may consist in the restoration of bridges, washing, fault detection of the box. Also, the crankcase and cover are subject to repair.