Gearbox design
It is necessary to study the design of this important element in more detail. It is a standard mechanical gearbox equipped with 5 stages, which allows you to select the optimal speed. It should be noted that thanks to the presence of 3 movable carriages at once, as well as a reduction gearbox, it is possible to double the number of gears.
As the diagram of the YuMZ gearbox shows, the key elements of such a unit are the following parts:
- shafts - primary, intermediate, secondary, and also gear;
- the housing in which all the parts are located;
- gear mechanisms - driving and driven;
- gear lever;
- gear coupling;
- fasteners, clamps, brackets, latches.
YuMZ gearbox diagram
It should be noted that the housing of such an element is directly connected to the rear axle housing. All moving parts of the gearbox of this model are lubricated to prevent mechanical damage due to friction. Oil is poured into the device using a special hole located in the lid of the box.
In order for the unit to serve for a long time without any problems, it is necessary to change the oil in a timely manner and also monitor its level. For this purpose, 2 control plugs are placed on the gearbox housing - minimum and maximum oil level. To drain the oil, there is another hole located in the lower part of the unit, which is closed with a magnetic plug.
Fig. 1 — Gearbox of the YuMZ-6 tractor
1 – primary shaft 36-1701030-B; 2 – coupling bolt 36-1701031; 3 – driving gear 40-1701324; 4 – pressure plates 40-1701331; 5, 31 – glasses (front 40-1701035 and rear 36-1701398); 6 – intermediate roller; 7 – adjusting gasket; 8 – ball bearing; 9 – gear for engaging second and fourth gears 40-1701117-A; 10 – gear shift rollers; 11 – shift roller clamp 36-1702108-A; 12 – locking roller 45T-1702354; 13 – locking roller clamp 45T-1702373-02; 14 – thrust 45T-1702052; 15 – rocker 45T-1702200; 16 – switch; 17 – stop 45T-1702221; 18 – axle 45T-1702018-B; 19 – lever for engaging the PTO drive clutch lock; 20 – rocker 45T-1702017; 21 – spring-loaded latch 45T-1702022; 22 – rack 45T-1702012-01; 23 – gear shift lever 45T-1702120; 24 – bolt; 25 – gear shift column housing 45T-17022S1; 26 – fork; 27 – lever stop (36-1702053 and 40-1702054); 28 – gear for engaging first gear and reverse gear 36-1701112-A2; 29 – secondary shaft 40-1701105; 30 – roller bearing 2612KM; 32 – third and fifth gear engagement gear 40-1701116-A1; 33 – round nut; 34 – reverse drive gear 40-1701051; 35 – first gear drive gear 40-1701054; 36 – third gear drive gear 40-1701059; 37 – intermediate shaft 40-1701048; 38 – drive gear of fourth and fifth gears 40-1701055; 39 – second gear drive gear 40-1701057; 40 – thrust ring 40-1701088; 41 – oil drain plug; 42 – constant mesh gear 40-1701056; 43 – gearbox housing 40-1701015; 44 – PTO drive shaft.
The shaft (pos. 49) of the gearbox rotates in ball bearings mounted in the bracket (pos. 45). On the cylindrical part of the shaft there is a driven gear (pos. 46) of the gearbox, and on the splined part there is a gear coupling (pos. 47) for engaging the gearbox, as well as a drive gear (pos. 48). The gear coupling is made with an annular groove and can move along the shaft. Turning on the gearbox leads to the engagement of the gear coupling and the gear hub crown (pos. 46). At the same time, the gear (pos. 42) moves, disengaging with the inner ring of the gear (pos. 39) with an additional toothed rim, and engaging with the gear (pos. 46) of the gearbox.
Lubrication of the gearbox parts of the YuMZ-6 tractor is carried out by spraying oil, which is located in the housing of the gearbox itself and the rear axle. Elements that arise during the wear of parts and assemblies, as well as other metal particles, settle on the magnet of the plug (pos. 41), which closes the drain hole in the housing.
Possible faults
Despite the high quality of assembly and the impressive service life of components, the gearbox of tractors of the YuMZ series often requires repair. As a rule, problems occur on units with an impressive mileage, the elements of which have a high degree of wear. Among the most typical breakdowns that occur most often, it is advisable to include:
- increased free play of the gear shift lever or their abrupt shutdown;
- excessive noise when the device operates;
- overheat;
- knocking noise when changing gears.
Such breakdowns can lead to serious problems, including failure of the entire unit, and therefore it is strongly recommended to begin repairing the YuMZ gearbox immediately after they are detected.
The gearbox requires careful care
Diagnosis of malfunctions should be carried out when switching the first reverse and forward gears.
During long-term operation, it is recommended to visually inspect the parts of the disassembled gearbox for defects.
Troubleshooting methods
The following breakdowns are possible:
- If the free play of the gear lever suddenly increases or they turn off spontaneously during operation, there is most likely a lack of proper contact in the gear mechanism. As a rule, this is caused by wear of the shift forks and carriages. In addition, the clamp springs could have failed and will need to be replaced to restore the device to working order.
- If overheating or unusual noise is detected, the condition of the shaft bearings should be checked, since their failure often leads to similar problems. To do this, you will need to dismantle the cabin floor, drain the oil from the gearbox, then open its cover and check the functionality of all shafts. Damaged items found during inspection will need to be replaced.
- A knocking sound when changing gears occurs when the gear mechanism breaks down due to wear of individual elements. To eliminate the malfunction, you will need to dismantle the cover and the dispensing unit, then find the broken part and replace it.
If you study the catalog of gearbox spare parts, you can conclude that servicing and repairing such a unit will not require significant costs, since all consumable items are affordable.
Be sure to read: Steering MTZ 82
Design
Gearbox of tractors YuMZ-6KL and YuMZ-6KM:
- Mechanical
- Five-speed
- No direct transmission
- With three movable carriages and a reduction gearbox that doubles the number of gears.
The following are installed in the front compartment of the common housing of the gearbox and rear axle:
- Primary
- Secondary
- Intermediate shafts
- Gearbox shaft.
The gearbox shaft is mounted on an attached bracket attached to the right side of the housing. The constant mesh drive gear is installed on the splines of the input shaft and secured with a coupling bolt.
The shaft with gear rotates on two roller bearings in a cup installed in the bores of the front wall and partition of the housing.
The outer races of both bearings are fixed at the outer ends between a split spring ring inserted into the annular recess of the cup and two pressure plates, which limits the axial movement of the input shaft assembly.
1 - input shaft; 2 - coupling bolt; 3 - drive gear; 4 — pressure plates; 5 and 31 - glasses; 6 — intermediate roller; 7 — adjusting gasket; 8 — ball bearing; 9 — gear for engaging second and fourth gears; 10 — gear shift rollers; 11 — shift roller clamp; 12 — locking roller; 13 — locking roller lock; 14 - thrust; 15 - drawstring; 16 - switch; 17 — emphasis; 18 - axis; 19 — lever for engaging the PTO drive clutch lock; 20 - rocking chair; 21 - spring-loaded latch; 22 - stand; 23 — gear shift lever; 24 - bolt; 25 — gear shift column housing; 26 - fork; 27 — emphasis; 26 — gear for engaging first gear and reverse gear; 29 — secondary shaft; 30 - roller bearing; 32 — gear for engaging third and fifth gears; 33 — round nut: 34 — reverse drive gear; 35 - first gear drive gear: 36 - third gear drive gear; 37 — intermediate shaft; 38 — drive gear of fourth and fifth gears; 39 — drive gear of the second gear; 40 - thrust ring; 41 — oil drain plug; 42 — constant mesh gear; 43 — gearbox housing; 44 — PTO drive shaft.
The glass simultaneously serves as a seat for the ball bearing, which is the front support of the secondary shaft,
installed coaxially with the primary shaft.
The principle of gear shifting on the YuMZ tractor and their inclusion
To engage the gear on the YuMZ tractor, install the lever against the corresponding sign of the indicator , and then tilt it in the direction of the indicator until it stops.
The latch fixes the position of the lever when selecting a gear, which reduces the possibility of mistakenly engaging it.
To engage the second or fourth gear , move the lever to the right until the latch stops on the right protrusion of the figured surface of the rack, and to engage the third and fifth gears, move it to the left until the latch stops against the left protrusion.
To engage first gear or reverse gear, move the lever to the right further than to engage second or fourth gear, overcoming the resistance of the latch, which at the same time extends beyond the right protrusion of the figured surface of the rack, compressing the spring.
The gearbox is switched by moving the lever and latch to the left behind the protrusion of the rack.
YuMZ gear shift diagram
Gears are changed using a gear shift mechanism.
The main details of this mechanism are:
- four shift rollers with forks,
- stops and clamps,
- rocker and double-hinged column with lever.
The rollers are installed in the upper part of the body and have the ability to move in the longitudinal direction . The rollers are equipped with forks and stops.
The forks with their horns fit into the annular grooves of the corresponding carriages and can therefore move them along the axis of the secondary shaft without interfering with the rotation of the carriage.
To move the rollers, grooves are made on the fork of the third and fifth gear rollers, as well as on the stops of the other three rollers, into which the lower end of the gear shift lever fits .
The lever swings on an axis installed in the rocker, which, in turn, can also swing on two bolts fixed in the gear shift column housing.
When the lever is moved transversely, a gear is selected, and when the lever is moved longitudinally, it is switched.
Gear shift diagram for YuMZ 8070−8280
When selecting a gear, the lever, rotating around an axis,
is installed in the groove of the fork or the stop of one of the rollers.
When changing gears, the lever rotates together with the rocker around the bolts and moves the gear shift shaft.
To prevent the possibility of simultaneous engagement of two gears, a slide is provided, four longitudinal slots that are made strictly against the shift rollers. This makes it impossible to move the lever to engage the next gear without disengaging the previous one.
