Front axle gearbox repair
For repairs, the gearbox of any drive axle is disassembled into several assembly units. In this case, the oil from the center differential and the axles themselves are first drained. The gearbox should be disassembled into the following elements:
- drive bevel gear;
- cross-axle differential (it is important to consider that its bearing caps are not interchangeable, since they are processed together with the gear housing);
- driven bevel gear;
- center differential (if the intermediate axle gearbox is disassembled).
If the front axle gearbox is being repaired, it is imperative to check the play of the assembly units, since the assembly must be carried out with the obligatory preload of the conical bearings. Upon completion of disassembly, all gearbox parts must be washed and checked.
Measuring the oil level
The procedure may seem complicated only at first glance. In fact, everything is much simpler; the whole procedure is reminiscent of checking the oil level in a regular car. First of all, unscrew the plug on the crankcase inspection hole; if the oil does not flow, it means that it needs to be added until it starts to drip.
Changing the oil is a more complicated procedure, however, it is also doable even for a non-professional .
- It is necessary to jack up the rear cart and place a stop under it to prevent it from rolling.
- Next, unscrew the drain, filler and inspection plugs.
- Drain the oil.
- Replace the drain plug.
- Fill the system with five or six liters of gear flush or, in extreme cases, diesel fuel.
- Start the car, engage third gear and let the engine run at 1000 rpm for 3-4 minutes.
- Drain the wash.
- Next, add fresh oil.
As you can see, there is nothing complicated. It’s another matter if the gearbox or one of its components is completely out of order and the part needs to be replaced. Only experienced auto mechanics can handle this task. The procedure is very complex and responsible, and if you make even a minimal mistake, the car will eventually require expensive repairs, so it is better to trust the specialists.
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Repair of the KAMAZ middle axle gearbox
Remove the bolts securing the center differential and remove the differential. Remove the self-locking bolts securing the bevel drive gear bearing housing.
Then you need to unscrew the nut, unscrew it, remove the washer and flange. Unscrew the bolts securing the cover and remove it. Remove the rear shaft.
Oil fasting
One of the common causes of gearbox failure is the lack of the required oil level in the crankcase. The middle gearbox is the most sensitive to this problem. It is equipped with a MOD center differential, which is the first to experience oil starvation when its level is low. Leaks in hub and flange seals or mechanical damage can lead to oil leakage from the axle housing in which the gearbox is installed. Lack of oil leads to overheating of the gearbox and rapid failure.
Repair of KAMAZ rear axle gearbox
To disassemble the rear axle gearbox, it is necessary to unscrew the self-locking bolts used to secure the stoppers in the bearing nuts related to the rear axle differential, and also remove the stoppers.
Then you need to bend the locking plates related to the mounting bolts in the differential bearing caps. These bolts should be removed. Then you need to remove the bearing caps and differential bearing adjustment nuts. After this, remove the differential belonging to the rear axle.
Then you need to unscrew and unscrew the nut securing the flange on the rear axle and remove the flange. After this, the bolts securing the bevel drive gear bearing housing cover are turned out, the cover is removed, as well as the support washer.
Remove the bolts securing the cover and remove the cover. The drive shaft and bevel drive gear are pressed. The bolts holding the covers are removed and the covers are removed. Then you need to loosen the nut, unscrew it, and remove the support washer.
Remove the bearing cup, bearings and outer bearing race. Remove the adjusting washers and take out the bevel gear.
Causes of breakdowns
Oil fasting
One of the common causes of gearbox failure is the lack of the required oil level in the crankcase. The middle gearbox is the most sensitive to this problem. It is equipped with a MOD center differential, which is the first to experience oil starvation when its level is low. The reason is leakage of the hub and flange seals or mechanical damage leading to leakage. Lack of oil leads to overheating of the gearbox and rapid failure.
Entry of foreign objects
When replacing a gearbox, it happens that the axle housing (stocking) is not cleaned well enough of foreign objects (gear fragments, rollers from bearings, etc.) and a gearbox is installed, which almost immediately fails.
Water entering the axle housing
Water may enter the axle housing due to a loose connection with the gearbox, if there are cracks in the axle housing or there is no breather. Oil, when mixed with water, loses its properties, which leads to increased wear of bearings and rubbing parts.
Natural wear and tear
The gearbox's service life between repairs is approximately 300 thousand kilometers. It depends on the operating conditions of the vehicle. First of all, the spline connections of the bevel pair and the spline connections of the axle gears wear out.
Improper use of the vehicle
The gearbox often fails when the driver operates the vehicle incorrectly. As an example, passing a sharp turn with the ICD (inter-wheel lock) turned on or rough operation in difficult road conditions.
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Adjusting the KAMAZ middle gearbox
When installing and adjusting the gearbox gears and bearings, the tapered roller bearings of the shaft belonging to the bevel drive gear must be installed after preloading.
The torque required to rotate the bearing drive gear shaft should be from 0.78 to 1.57 Nm (0.08 to 0.16 kg/cm).
If you are repairing a KAMAZ medium gearbox yourself, you should measure the torque during continuous one-way rotation of the flange after at least 5 shaft revolutions. In this case, the bearings should be lubricated.
When checking the rotation torque of the drive gear belonging to the middle axle gearbox, it is necessary that the bearing cup cover is moved towards the flange so that the centering protrusion leaves the cup socket and the oil seal does not resist the rotation of the gear.
The bearings of the bevel drive gear of the gearbox should be adjusted by selecting shims included in the kit, which is supplied as spare parts.
Malfunctions and their elimination
The gearbox is reliable and rarely fails, provided timely preventive measures are taken.
Determine mechanism failure as follows:
- At a speed of 20 km/h, extraneous noise appears; when it increases to 80 km/h, it disappears.
- When driving at a speed of 80 km/h, turn on neutral and turn off the ignition - if noise appears, then the problem is in the gearbox.
In the operation of the Kamaz unit, 3 types of malfunctions most often occur:
- Main gear overheating. The reasons may be:
- lack or excess of oil in the crankcase;
- increased bearing tension;
- inaccurate tooth settings.
- Increased noise. Causes:
- bearing wear;
- incorrectly adjusted clutch;
- weak bearings.
- An oil leak may result from:
- cuff wear;
- breather contamination.
When problems are identified, technicians perform repairs. Car owners go to a service station or do it themselves.
How to adjust
Adjusting the axle gearbox in KamAZ vehicles involves setting parameters such as:
- tapered roller bearing ring tension;
- differential;
- lateral clearance in the mesh of a pair of gears;
- contact patch.
When repairing the middle gearbox, the technical data must be observed; nominal values of clearances and tolerances are maintained.
To accurately adjust the tension you need to:
- Reduce the dimensions of the washer pack by the amount of axial shift with a tolerance of 0.04-0.06 mm.
- Tighten the fastening nut.
- Check the turning force of the glass.
- Install into the housing.
To adjust the side clearance to a permissible value of 0.2-0.35 mm, shims of different thicknesses are required.
The differential is installed so that the ring gear of the driven wheel is symmetrical to the drive wheel. The adjustment is made by uniformly tightening the adjusting nuts and tightening the connecting bolts.
How to remove, disassemble and reassemble
Stages of disassembling and assembling the middle or rear gearbox:
- Oil drain.
- Dismantling the drive axle assembly.
- Disassembling it into components sequentially:
- driving and driven gears;
- crankcase;
- differential box;
- satellite axes.
- Status check:
- crosspieces;
- necks;
- semi-axial gears;
- drive.
- Replacement of worn-out products.
- Carrying out adjustments.
- Reassemble the bridge in reverse order.
- Testing the assembled bridge for absence of rattles and leaks at the joints.
After all operations have been completed, the assembled mechanism is installed in its working position.
The KamAZ 5320 gearbox is a mechanism that converts and transmits torque from the crankshaft to the wheels. This device experiences serious loads and requires regular inspections, adjustments, and repairs.
Adjusting the KAMAZ rear axle gearbox
The rear axle gearbox needs adjustment when it begins to emit a characteristic hum, audible at speeds of 30 km/h or more. The reasons may be regular heavy overloads of the car, constant driving with trailers and ordinary mechanical damage. Therefore, the next action should be a visual inspection of the unit.
Flanges, bearings, seals, satellites, their axles are removed and inspected; if wear is detected, they are replaced.
You should check the distance between the bolts holding the nuts using a caliper. After this, you need to approach from the opposite side of the plane, then tighten the nuts, preferably by the same amount, for example, by one groove. Then the distance from bolt to bolt is measured again, which should change slightly (from 1.5 to 2 mm). If this is the case, you need to check the gear for play - it should remain the same as it was just set. After this, the adjustment is completed.
Typical gearbox faults
Typical malfunctions of KAMAZ gearboxes
The gearbox for KAMAZ trucks was developed in the early 70s. Since then, their design in most cases has not changed fundamentally, with the exception of cars 6520 and 4308.
Currently, the gearbox model 5320 and its analogues are relatively unreliable and obsolete units. Their design has bevel and cylindrical gears, which contributes to severe wear, unlike modern models.
It is necessary to remember the importance of timely maintenance, which is a set of measures that allows you to prevent almost all causes of gearbox failure.
