Ensuring Reliability of Transfer Gearbox
Irina Makarova
1a
, Larisa Gabsalikhova
1b
, Eduard Mukhametdinov
1c
, Ruslan Kazantsev
2d
,
Polina Buyvol
1e
, Aleksandr Kapitonov
2f
and Alexandr Glushkov
3g
1
Kazan Federal University, Syuyumbike prosp., 10a, 423822 Naberezhnye Chelny, Russia
2
PJSC "KAMAZ", Avtozavodskij str., 2, 423827 Naberezhnye Chelny, Russia
3
South Ural State University, Lenin prospekt, 76, 454080 Chelyabinsk, Russia
Keywords: Intelligent Transport, Reliability, Transfer Gearbox, Failure, Intermediate Shaft Bearing.
Abstract: There is a tendency in the world to create and develop intelligent vehicles. Considering that while smart
vehicles have not conquered the market and potential customers are only thinking about the degree of trust in
them from the point of view of the transportation process safety, the issues of ensuring the reliability of such
vehicles are becoming more urgent. One of the trucks main characteristics that ensure their reliability is
transmission units. The transfer gearbox of KAMAZ 6522 trucks was chosen as the object of the study. The
statistics of the transfer gearbox failures for 2018-2019 were considered. Based on these statistics, the problem
area of the unit and mileage the breakdown occurs were determined. The transfer gearbox main faults include
the shaft bearings wear, the teeth of the included gears wear; the switching mechanism clamps wear. Bench
tests have shown that the countershaft bearing is experiencing overheating due to lubricant lack, which
ultimately leads to failure. In most cases, the cause of these faults is the lubrication system malfunction, as a
result of which the transmission parts overheating occurs. The relevance of the work is due to the fact that it
is necessary to analyze the causes of failures in the transfer gearbox that cause transmission parts overheating
and establish dependencies that cause overheating. This will increase the unit reliability and propose methods
for improving its operation. Based on the data obtained, it was proposed to increase the holes for the lubricant
supply in the seat of the front intermediate bearing of the intermediate shaft by 1.5 mm by changing the milling
parameters. At the end of the work, the transfer gearbox is again subjected to life tests. The scientific novelty
lies in the establishment of the dependence of the intermediate shaft bearing heating temperature on the
operating time by bench tests.
1 INTRODUCTION
The need to increase the efficiency of road transport
usage and ensure the implementation of transport
work’s required volume with minimal costs requires
constant work to improve vehicle reliability. It is one
of the factors affecting the vehicle competitiveness
(Makarova, Pashkevich, Buyvol, Mukhametdinov,
2019). The complexity of the problem lies in the fact
that vehicles are operated in different road and
a
https://orcid.org/0000-0002-6184-9900
b
https://orcid.org/0000-0003-3325-3285
c
https://orcid.org/0000-0003-0824-0001
d
https://orcid.org/0000-0002-4031-5125
e
https://orcid.org/0000-0002-5241-215X
f
https://orcid.org/0000-0002-7665-2510
g
https://orcid.org/0000-0002-6292-7122
climatic conditions with different degrees of their
workload and the driver's staff qualifications
(Makarova, Khabibullin, Belyaev, 2012). And in the
case of autonomous vehicles’ creation, high
reliability can be ensured with an integrated approach
to solving this problem at all stages of the "life cycle"
of a car: during its design, manufacture and operation.
A truck with a high cross-country ability,
equipped with a complex mechanism for transmitting
torque to the axle. Because these vehicles are
Makarova, I., Gabsalikhova, L., Mukhametdinov, E., Kazantsev, R., Buyvol, P., Kapitonov, A. and Glushkov, A.
Ensuring Reliability of Transfer Gearbox.
DOI: 10.5220/0010530607630767
In Proceedings of the 7th International Conference on Vehicle Technology and Intelligent Transport Systems (VEHITS 2021), pages 763-767
ISBN: 978-989-758-513-5
Copyright
c
 2021 by SCITEPRESS – Science and Technology Publications, Lda. All rights reserved
763

designed for long trips on low-grade road surface and
even off-road, they are equipped with several drive
axles at once to increase cross-country ability, but this
in turn complicates the torque transmission system. A
transfer gearbox is used for proper distribution and
coordination in the required proportions of torque
between the front, rear axle and the engine.
During the vehicle operation, it is worth paying
great attention to the transfer gearbox condition and
operability. In order to understand whether the
transfer gearbox needs repair, it is important to
monitor the appearance of the following signs:
constantly or regularly there are knocks, noises and
other sounds while driving, which warn of problems
in normal operating mode; transmissions began to
turn off on their own; there are difficulties in gear
shifting. The task of predicting the transfer gearbox
current state is especially important at the design and
operation stage in order to determine the optimal
frequency of maintenance and repair.
2 METHODS OF ENSURING THE
OF TRANSMISSION UNITS
RELIABILITY: A LITERATURE
REVIEW
One of the trucks main characteristics that ensure
their reliability is transmission units. In keeping with
customers' high expectations and requirements to
vehices, developing reliable products is critical. In
addition, for reasons of competitiveness, it is
necessary to know the product future life as
accurately as possible (Woll, Jacobs, Feldermann,
2017).
Manufacturers divide the methods of ensuring the
automotive equipment reliability into three categories
conditionally corresponding stages of the vehicle life
cycle: structural reliability; improving reliability in
operation; technological reliability assurance.
Monitoring and diagnostics of the vehicle
technical condition are very important at the
operation stage, as this allows eliminating the causes
of possible failures and predicting the vehicle life
(Makarova, Shubenkova, Mukhametdinov,
Giniyatullin, 2020). Diagnosis is an important
component in predicting vehicle reliability
(Gritsenko, Shepelev, Zadorozhnaya, Shubenkova,
2020, Tsybunov, Shubenkova, Buyvol,
Mukhametdinov, 2018). Studies of equipment with
rotating parts (generators, turbines, fans, etc.) for the
development of faults that cause vibration are carried
out by vibration diagnostics (Sait, Sharaf-Eldeen,
2018, Muszynska, 1995). Failure detection using a
vibration signal is considered one of the most
important methods applied to rotating parts (Furch,
Nguyen, Glos, 2017, Gritsenko, Shepelev,
Zadorozhnaya, Almetova, Burzev, 2020). The article
(Makarova, Mukhametdinov, Gabsalikhova,
Garipov, Pashkevich, Shubenkova, K., 2019) justifies
the possibility of improving the trucks reliability by
creating an intelligent system and a method for clutch
diagnostics by controlling changes in vibration levels.
The article (He, Shao, Wang, Lin, Cheng, Yang,
2020) presents a new approach called multi-wavelet
auto-encoder of deep transfer for transmission faults
intelligent diagnostics with a small amount of training
samples. The new type of multi-pulse autoencoder is
designed to study important features of the
transmission collected vibration signals.
Improving the truck transmission units reliability
and durability has been considered in a number of
works (Vasilev, Grigorev, Mardashov, 2019, Wang,
Wu, 2016, Bartholdt, Grundler, Bollmann, Bertsche,
2018). Failures early detection and diagnostics allows
for the correct planning of shutdowns to prevent
catastrophic failures and therefore leads to safer
operation and higher cost savings (Liang, Zuo, Feng,
2018).
In work (Oliveira, Martins, Seabra, Seyfert,
Igartua, 2006), transfer gearbox tests were carried out
to assess wear depending on the oil used. The paper
(Choi, Yang, Hwang, Son, On, Kim, 2010) examines
the distribution of the time of the J79 engine transfer
gearbox failure using the probability method, which
is one of the most convenient methods of reliability
analysis.
Transfer gearbox main faults include: the shaft
bearings wear, the teeth of the included gears wear;
the switching mechanism clamps wear. In most cases,
the cause of these faults is lubrication system
malfunction, as a result of which overheating of the
transmission parts occurs. The relevance of the work
is due to the fact that it is necessary to analyze the
causes of failures in the transfer gearbox that cause
transmission parts overheating and establish
dependencies that cause overheating, which will
increase the reliability of the unit and propose
methods for improving its operation.
3 RESULTS AND DISCUSSION
According to the data obtained from the complaint
acts, a number of the transfer gearbox faults were
revealed (Figure 1). Based on these data, statistics of
the most frequent failures were compiled, among
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which the intermediate shaft bearing is the clear
leader. The statistics of the main faults and their
dependence on the mileage are shown in Figure 2.
These diagrams show that bearing failure occurs
on a mileage from 2,000 to 30,000 km. This is due to
the fact that these bearings overheat excessively, the
lubricating fluid does not flow in the required volume,
there is no lubrication and heat dissipation, which
ultimately leads to heating, and subsequently to the
bearing destruction.
Figure 1: Transfer gearbox failure statistics for 2019.
Figure 2: Failure statistics of the front bearing of the
transfer gearbox intermediate shaft for 2018-2019.
To determine the critical degree, bench tests for
durability are required. The tests were carried out in
bench conditions, in a design and research bureau in
compliance with the requirements for ensuring
normal climatic conditions for testing products in
accordance with GOST (GOST 15150-69), namely:
- ambient temperature - (25 ± 10) ° С;
- relative air humidity - (45-80)%;
- atmospheric pressure - (84 - 106.7) kPa.
Tests to determine the resource of an experimental
transfer gearbox during flexural life tests were carried
out on a stand with a closed power circuit "MTS"
The operating time till failure of any of its
component parts was taken as an estimated parameter
for the transfer gearbox durability.
Criteria for failure of the transfer gearbox:
breakage of the gear teeth; fatigue chipping of the
gear teeth or bearing defects resulting in clearly
audible knocking.
During the tests, clear knocks were noticed in the
transfer gearbox, which characterizes the rollers’
defect. From the beginning of the tests, the
temperature was measured every hour using a thermal
imager on which the overheating zones are clearly
expressed, and the temperature after 9 hours was 132
° C (Figure 3).
Figure 3: Heating curve for the intermediate shaft bearing
zone.
In a durability test, an intense rise in temperature
was noticed within 9 hours, which subsequently led
to the transfer gearbox failure. After a lengthy test,
the transfer gearbox was disassembled. During
disassembly, the following results were made: the
intermediate shaft bearing was destroyed, the bearing
rollers were severely deformed, and a crack was also
found in the transfer gearbox cover. The bearing
destruction occurred due to the spare part
overheating, as a result of which the transfer gearbox
failed.
Figure 4 shows the result of the tests carried out,
which clearly shows that in the first case, the test was
interrupted, due to the transfer gearbox failure at 9
hours of testing, having completed 24% of the total
number of cycles:
9 hours = 24% = 67 200 cycles.
In the second case, the test is completed:
37,2 hours = 100% = 280 000 cycles.
Based on the data obtained, the transfer gearbox
durability is increased by 4 times.
The test results before and after the changes are
shown in Table 1.
Ensuring Reliability of Transfer Gearbox
765

Table 1: Comparative characteristics of data after testing.
Test data
Test time, hour
Number of
cycles, rpm
Limit
temperature, ° с
Before
enlarging the
housing port
9 67 200 132
After enlarging
the housin
g
p
ort
37,2 280 000 113
Figure 4: The graph of the temperature change of the
transfer gearbox intermediate shaft bearing
Upon completion of tests in this mode with a load
of 3.4 V on the transfer gearbox input shaft, the
thermal imager showed the highest temperature of
113 ° C in the studied area of the front intermediate
bearing. The overheating test can be considered
satisfactory since the next test mode is to shift the
transfer gearbox down. In low gear, the shaft speed
and load (load in low gear is 2.7 V) is lower than in
high. Considering these modes, this study on the
overheating of the intermediate shaft front bearing
area is satisfactory, since at the lowest gear the
temperature will decline.
Figure 5 shows the test results before and after
changing the crankcase bore in the form of a
comparative graph of the transfer gearbox
temperatures in the area of the intermediate shaft
bearing.
Figure 5: Heating of the intermediate shaft bearing area
before and after improving the transfer gearbox housing
4 CONCLUSIONS
As a result of a study of the truck transfer gearbox
operation, it was found that the heating of the
intermediate shaft bearing at a certain operating time
exceeds the maximum permissible values, which
negatively affects the lubrication system. The
lubricating fluid does not flow in the required volume,
there is no lubrication and heat dissipation, which
ultimately leads to heating, and subsequently to the
bearing destruction.
In order to eliminate this defect, work to improve
the design of the transfer gearbox housing was carried
out. To increase the hole for the lubricant supply in
the seat of the intermediate shaft front intermediate
bearing by 1.5 mm was taken as the main measure.
Bench tests were carried out to evaluate the proposed
activities. As a result, it was revealed that a change in
the diameter of the hole in the intermediate shaft front
intermediate bearing socket for supplying grease
increased the throughput of the lubricating fluid,
which in turn allowed keeping the temperature within
the normal range, and thereby increasing the
durability of the transfer gearbox by 4 times.
ACKNOWLEDGEMENTS
The reported study was funded by RFBR, project
number 19-29-06008\19.
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