Golden Dragon XML6125CLE Operating instructions

FOREWORD
This Repair Manual specifies the general repair methods for the chassis, electrical parts and body of
Golden Dragon XML6125CLE large buses, providing the data necessary for the repair of relevant
assemblies and standardizing and recommending relevant repair techniques and requirements.
All information contained in this catalogue are the latest products information while compiling. This
Catalogue is being compiled. The specifications or procedures in this catalogue may not be in accordance
with specific objects. Golden Dragon has the right to modify them without notification in advance. Any
detail should be subject to the modified parts should there be any modification.
Please contact with our After-sales Service Center if you need to know more details about our repair
data and other data or hope to further check the conditions on the repair site.
After-sales Service Center telephone: [phone]
This Manual is exclusively applicable for the Special Repair Stations of Xiamen
Golden Dragon Bus Co., Ltd.
Xiamen Golden Dragon Bus Co., Ltd.
June, 2019
1-1

Chapter Schedule of Service Manual
 The following table shows the numbers of all chapters contained in this Manual in
relation to the repair data of various relevant types of bus systems.
Chapter Model XML6125CLE
GI General Instructions GI- XML6125CLE -01
ED Electric drive system EN- XML6125CLE -01
PP Transmission shaft PP- XML6125CLE -01
FA Front axle FA- XML6125CLE -01
RA Rear axle RA- XML6125CLE -01
SU Air suspension system SU- XML6125CLE -01
SR Steering system SR- XML6125CLE -01
BR Brake system BR- XML6125CLE -01
WT Wheel and tyre WT- XML6125CLE -01
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General Instructions GI-1
Overview
 General precautions ꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏ GI-2
1. Key safety precautions
2. General repair rules
3. General cleaning rules
 How to use the Repair Manual ꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏ GI-5
1. Operating instructions
2. Definitions of directions
3. Bus identity information
 General technical specifications of repair ꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏ GI-8
1. Disassembly procedure requirements
2. Assembly procedure requirements
3. Pipeline connecting
4. Sealant application specifications
5. Thread sealant adhesive application specifications
6. Seal tape winding specifications
 Troubleshooting flow chart ꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏ GI-11
 Introduction of bus oils and fluids ꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏ GI-13
1. Bus lubricants
2. Automobile working fluids
 Table of standard bolt fastening torques ꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏ GI-22
 Bus model definitions ꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏꞏ GI-23
1-3

General Instructions GI-2
 General precautions
This Chapter contains the specifications and requirements to be followed during repair and
maintenance of the bus in order to avoid personal injuries and property losses arising from improper
operations or negligence and thus guarantee repair quality.
1. Key safety precautions
Improper or incorrect operations may cause troubles and accidents and thus personal injuries and (or)
property losses. Please consult your local distributor of Golden Dragon if you have any doubts on the
repair and maintenance of the bus.
Please strictly observe the operating requirements specified in column ‘Warnings’ to guarantee
operating safety as the No. 1 priority.
Warnings
Please observe the following requirements in addition to the precautions or warnings in each chapter
during operation of the bus so as to avoid any personal injury and (or) property loss.
 Wear a pair of protective goggles to protect your eyes.
 Remove all finger rings, watch, tie, loose jewelries and loose clothes before operation is started on
the bus.
 Tie your long hair reliable behind your head.
 Reliably pull up the parking brake, place the gearlever at ‘Neutral’ or ‘N’ position and block each
wheel with a wedge before operation is started on the bus.
 The engine shall be shut off normally and the starting switch shall be disconnected unless it needs
to run. It is recommended to remove the key from the switch.
 In order to avoid severe scalds, the operator shall avoid touching hot metal parts like engine,
exhaust manifold, radiator, muffler, exhaust pipe and tail pipe.
 Do not smoke while working on the bus because the engine’s fuel and the gases discharged from
the battery are both inflammables.
 Take special care while working on the battery because it contains corrosive sulfuric acids.
 Take care to avoid short circuits as there are high currents in the cables of battery and starter.
Otherwise, personal injuries and (or) property losses may be caused.
 Please carefully read and observe the Operating Instructions before using the jack.
 Use a safety bracket to support the bus if it is necessary to work underneath the chassis. It is
dangerous to work under the chassis if the bus is merely supported by one jack.
 If it is necessary to run the engine with the engine hood opened, please ensure that the parking
brake is reliably actuated, the wheels are properly wedged and the gearlever is placed at the
‘Neutral’ position before startup.
 In order to avoid inhalation of carbon monoxide, please run the engine only in a properly ventilated
place.
 The operator shall keep himself and his clothing and tools far away from various moving parts
when the engine is running, e.g. cooling fan and belt. Please take care not to step on or grip at
various types of pipes and hoses with efforts to avoid damages.
 Please take care not to leave any tool in the engine compartment. Otherwise, the tools may collide
with the moving parts to cause personal injury.
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General Instructions GI-3
2. General repair rules
 Fully and properly master the vehicle conditions, know about user requirements and keep a record of
relevant pre-operation and post-operation data.
 Observe the safety precautions mentioned in the Manual.
 Take necessary protective and preventive measures in order to avoid pollutions and damages to other
parts of the bus. Please clean the bus after operation.
 Provide a clean environment and observe the cleaning requirements mentioned in the Manual. Dirty
components may cause premature abrasions and unexpected troubles during repairs.
 Check and record necessary items and statuses according to the Manual.
 Replace all damaged or excessively worn-out components or assemblies.
 Always use original Golden Dragon components.
 Observe the assembly and disassembly regulations specified in the Manual to avoid damaging the
components.
Precautions for Towing
In case the bus is to be towed, please place the gearlever at the neutral position, fully release the parking
brake, eliminate any other potential risks to personal and bus safety, establish proper marks and strictly
observe relevant road safety laws and regulations.
 Ensure that the drive shaft of the vehicle under towing is disassembled. In case the differential or rear
axle shaft is in trouble, please remove both left and right rear axle shafts and seal the openings of the
wheel hubs to avoid losses of lubricating oils in the axles and ingress of dusts or foreign matters.
 Use heavy-duty cables to tow a vehicle. Fasten the cable securely to the hook of the frame.
 Connect the cable to the hook so that the angle between the towing direction and the traveling
direction of the vehicle under towing does not exceed 15 degrees both horizontally and vertically.
Avoid pulling the cable vehemently in case a hook is used to tow a vehicle. For instance, towing any
vehicle that sets in mire.
 Place the gearlever at the neutral position.
 Ensure that the starting switch is kept at the ‘ON’ position.
 Ensure that the engine of the vehicle under towing keeps running.
 If the engine is shut off, the brake system won't get any compressed air/vacuum. Such a situation is
very dangerous because the brake system can’t work if the engine is not running.
In addition, the power steering system won’t work either so that it would be hard to operate the
steering wheel, and
thus it is difficult to steer the vehicle.
It is noteworthy that the exhaust brake is disabled because the drive shaft has been removed.
 Start up slowly to minimize possible vibrations. The towing speed shall be less than 30km/h.
 If the engine of the vehicle under towing is in trouble, the towing work shall be carried out by a
special-purpose towing truck.
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General Instructions GI-4
3. General cleaning rules
 Choose a proper cleaning method according to relevant requirements so that the cleaning
requirements are satisfied and no component is damaged.
Cleaning methods include steam cleaning, pressure cleaning, light oil cleaning, acid or alkali
solution cleaning, neutral medium cleaning, trichloroethylene cleaning, Magnus solution cleaning, etc.
For instance, rubber parts shall not be cleaned with mineral oils. Use alcohols or dry fabrics to
remove sludge.
 Carry out cleaning work strictly according to the Instructions Manual of detergents or cleaning
equipment.。
 Take proper anticorrosive and antirust measures. Remove the used grease coating and apply new
coating on the component surface to protect it against rusts.
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General Instructions GI-5
 How to use the Repair Manual
The Repair Manual is compiled to guide the repair work of the bus. Some simple repair methods are not
included herein, e.g. the simple installation and removal of components. Only those important methods
that require guidance will be introduced herein. In some cases, some components as shown in the figures
may be slightly different from the ones on your bus. But these differences don’t matter much. The basic
principles and methods specified herein are still applicable.
1. Operation instructions
(1) There is a “table of content” on the first page of each chapter. It includes further data of the system.
(2) Firstly, check the structure and working principles of the system in the Manual for inspection of the
system.
(3) Each chapter includes a section of “troubleshooting”. Please refer to the “troubleshooting” section to
acquire necessary guidance on troubleshooting during operation.
(4) There is a ”dedicated tools” section in some chapters. Please use the dedicated tools for repair.
(5) Please confirm the numbers of the dedicated tools as specified in the applicable list of components
while placing an order for such dedicated tools.
2. Definitions of directions
(1) Definitions of left and right sides of the bus.
Left side and right side refer to the left side and
right side of the bus seen from the back of the bus
along its median line.
(2) Definitions of front and rear sides of the bus.
The front side refers to the forward traveling
direction and the rear side refers to the backward
traveling direction.
前Front
后Rear
左Left
右Right
3. Bus identity information
Carefully record the numbers and marks upon repair or inspection of the bus. Please provide relevant
numbers upon ordering spare parts or reporting technical problems so that we can provide timely and
accurate services for you.
（1） Bus name plate: the bus name plate is affixed to the inner side of the upper part of the front
embarking door as shown in the diagram.
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General Instructions GI-6126J12-01 GI-6
(2) Chassis name plate: the chassis name plate is affixed onto the girder of the right front wheel as
shown in the diagram.
品牌 Brand 金旅牌 GoldenDragon
产品名称 Product name
客车底盘 Bus chassis
型 号 Chassis model
最大总质量 Max total mass
发动机型号 Engine model:
整备质量 Curb weight
额定功率 Rated power
制造年月 Manufacture date
厦门金龙旅行车有限公司
Xiamen Golden Dragon Bus Co., Ltd.
(3) Chassis S/N: chassis S/N is engraved on the frame close to the right front wheel.
(4) Engine S/N: engine model and S/N are engraved on the engine set. Please refer to the corresponding
Engine Operation Manual. Please refer to the corresponding Engine Operation Manual for the specified
position.
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General Instructions GI-6126J12-01 GI-7
 General technical specifications of repair
1. Disassembly procedure requirements
 Before disassembly of any component, please take full considerations, park the bus on an even
and safe place, place the gearlever at the neutral position, flame out, disconnect the power supply
switch and wedge the front and rear wheels. It is very important to ensure the safety of repair
personnel and the bus.
 Thoroughly clean relevant parts before disassembly of any component;
 The disassembly of any assembly must be carried out at a clean place to avoid ingress of any
dust and foreign matter;
 Upon disassembly of any subassembly, please place all components on a clean worktable
according to the sequence of disassembly; It helps to avoid component loss and make it
convenient for assembly in this way.
 Use dedicated tools if possible to make it convenient for disassembly and avoid damages to the
components;
 Take care of the forces applied on the shaft or housing and avoid damaging the component while
disassembling any component with a tool. Disassembly of some components is forbidden; It is
forbidden to exert an external force on any driven part that is running;
2. Assembly procedure requirements
 Thoroughly clean all the components that need to be assembled. Do not allow ingress of any
dust and foreign matter into the transmission. Otherwise, unnecessary losses may be caused.
Take the following precautions during assembly;
 Fastening bolts: fasten the bolts with the required torque; apply lubricating oils and other
sealants if required;
 Reassemble in the correct sequence;
 Initial lubrication: consider lubricating greases for initial lubrication to avoid scratches and dry
frictions;
 Bearing installation: flanged bearing installer/remover is recommended for bearing installation.
Such type of installer/remover can exert forces on both the inner and outer rims of the bearing
simultaneously so that not only damages to the steel balls and inner/outer rims are avoided, but
also the concentricity of bearing, shaft and hole is guaranteed; Do not use installer/remover of a
pipe casing type because it exerts forces merely on one part of the inner and outer rims of the
bearing and thus may cause damages to the bearing;
 Installation of O-rings: apply silicon lubricants before assembly of O-rings;
 Installation of sealing gaskets: do not use removed sealing gaskets. Please use new gaskets
during reinstallation. Do not miss any sealing gasket. Otherwise, oil leakages or displacement
may be caused.
 Sealant application: the surface shall be clean and dry and the sealants shall be applied evenly
and continuously;
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General Instructions GI-6126J12-01 GI-8
3. Pipeline Connecting Methods
铰接头
Hinge joint
卡套式接头
Bite-type connector
垫圈
Washer
卡套
Clip
卡套螺母
Bite-type nut
接管
Take-over
扩口螺母
Flared nut
与管子的扩口构成密封面
Form a sealing face with flare of the
pipe
在螺纹处用填料密封
Seal the thread with stuffing
扩口式接头
Flared connector
锥管螺纹接头
Connector, taper pipe thread
 Hinge joint connecting
Connect pipeline with hollow stay bolt, and seal it by end face.
 Bite-type connecting
Bite-type joint installation requires vertical pipe tip cutting against the pipe center line; the tip shall
be round and
complete, and the cutting sleeve shall be properly fitted. Bushing is needed when installing nylon
pipe.
 Flared connecting
Seal by the sealing face formed by flare
 Pipe thread connector
Seal by thread
4. Sealant application specifications
 Sealant designation: Loctite 545 thread sealant;
 Evenly apply one 2 to 3mm-high coating of sealants along the first 3 to 5 threads at the end of the
pipe that would enter the casing;
 Check if the zone applied with sealants satisfies relevant requirements. Otherwise, apply
卡套
垫圈
卡套螺母 接管
扩口螺母 与管子的扩口构成密封面
在螺纹处用
填料密封
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General Instructions GI-6126J12-01 GI-9
additional sealants;
 Install pipe thread components after the requirements are satisfied.
5. Thread sealant adhesive application specifications
 Sealant adhesive designation: JB260 thread sealant adhesive.
 Evenly apply one 3 to 5mm-wide and 2 to 3mm-high coating in the axial direction along the full
length of the
thread of the bolt.
 Take another bolt of the same specification; place the two bolts in opposite directions; keep the
threads fully in contact and turn them together so that their threads are fully covered with the
sealant adhesives;
 Check the threads of the two bolts to see if there is any part that has no sealant adhesive thereon.
Apply
additional sealant adhesives if any.
 Install the bolts after the requirements are satisfied.
6. Seal tape winding specifications
 Seal tape specifications: tetrafluoroethylene seal tape 26mm×01mm×20m
 Remove the first 3 to 4 threads that enter the casing firstly of the pipe that need to be wound with
seal tapes and then wind the seal tapes evenly along the clockwise direction (seen in the axial
direction with the end that enters the casing pointing towards yourself) in 10 to 15 layers.
 The wound seal tapes shall be smooth without any torsion, twist or knot.
 Install pipe thread components after the requirements are satisfied.
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General Instructions GI-6126J12-01 GI-10
 Troubleshooting flow chart
Flow chart description
Confirm the troubles reported by the user: the first step is to know as more information as possible from
the user. Is the bus furnished with any accessory? When, where, how long, how often does this trouble
occur or repeat itself? It is necessary to familiarize with the proper operation of the system in order to
confirm the issues of concern to the user. Please read the User’s Manual or Repair Manual for any
necessary information.
1．Initial inspection: mainly visual inspection. Check the history record of repairs. Check if there is any
abnormal noise or smell. Collect relevant other information for the sake of effective repairs.
2．Routine system inspections: check the system in order to confirm if the system works properly. Then
carry out other diagnosis in orders.
3．Read and check relevant technical documents: fully utilize relevant technical documents and other
repair information and compare with the routine system inspection results.
5-1. The phenomena and causes of troubles can be identified in the User’s Manual or Repair Manual.
Please refer to the corresponding figures for proper treatment.
3．Routine s
y
stem ins
p
ection
2. Initial ins
p
ection
4．Read and check relevant technical
Identify the
trouble
6. Recheck the
p
roble
m
1. Confirm the troubles reported by the user
5.1 Check according to Troubleshooting
5.2 Check beyond the scope of the troubleshootin
g
5.3 Diagnosis of intermittent troubles
5.4 Solutions for buses in a proper running condition
7. Repair and check repair conditions
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General Instructions GI-6126J12-01 GI-11
5-2. It is necessary to carry out troubleshooting on site. Please refer to the Repair Manual, relevant
schematic diagrams, system descriptions and operation instructions and check if the system is
working in certain extreme environmental conditions (high temperature, humidity and pollution)
and special procedures. Please ask for technical support from relevant departments if necessary.
5-3. Intermittent troubles are troubles that do not occur continuously. They would occur only in some
conditions. Normally, intermittent troubles are caused by electrical, connector and wiring defects,
failing parts, additionally installed equipment or external interferences. In that case, it is necessary
to appraise the symptoms and conditions as described by the user and refer to existing repair
information for a diagnosis thereof.
5-4. User reported conditions may fit in with the bus design and therefore are part of the proper working
conditions of the bus. Or the conditions may be caused by user’s improper operations. In that case,
please explain the identified problems and system operations to the user or compare it to another
similar bus that is working properly in the same conditions.
6. Recheck the problem: if the problem can’t be successfully settled in the foregoing steps, please
appraise and check the problem again. It may be an intermittent trouble or proper working condition.
7. Repair and check repair conditions: after the cause of trouble is identified, repair it and check if the bus
works properly. Check if the trouble is eliminated. The bus may have to undergo a road test.
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General Instructions GI-6126J12-01 GI-12
 Introduction of bus oils and fluids
1. Bus lubricants
 Engine lubricating oil
1) Lubricating oils influence the main working properties of the engine.
a) Viscosity and viscosity-temperature characteristic: viscosity refers to the extent of
shearing force between layers of flowing lubricating oils; viscosity-temperature
characteristic refers to the changes of viscosity of lubricating oils with the changes of
temperature.
b) Foaming characteristic of lubricating oils: it refers to the generation of foams because of
the difficult separation of gases infiltrated into the oil due to the surface strains of
lubricating oils.
c) Stability of lubricating oils: it refers to the lubricating oil’s ability to keep its physical and
chemical properties stable for a long term, including resistance to vaporization, shearing
force, atmospheric oxidation and high-temperature oxidation.
d) Anticorrosion of lubricating oils: the lubricating oil’s ability to protect the targets from
corrosions.
e) Static dispersivity of lubricating oils: lubricating oils are highly capable of dispersing
gums, paint films and other solid substances so that they can be recycled together with the
lubricating oils and removed by the filter.
f) Resistance to abrasion: the lubricating oil’s ability to prevent the oil film from being
damaged.
2) Designation and variety of commonly used lubricating oils
Variety Viscosity and designation
SC 5W/20 10W/30 15W/40 30
40
SD, SD/CC 5W/30 10W/30 15W/40 30
40
SE, SE/CC 5W/30 10W/30 15W/40 20/20W
30 40
SF, SF/CD 5W/30 10W/30 15W/40 30
40
CC 5W/30 5W/40 10W/30 10W/40 15W/40 20W/40 30
40 50
CD 5W/30 5W/40 10W/30 10W/40 15W/40 20W/40 30
40
a) In the ‘variety’ column, the first letter ‘s’ indicates lubricating oils for gasoline engine and
‘C’ indicates lubricating oils for diesel engine; the second letter indicates the grade of the
oil in alphabetic order with C, D, E and F representing a rising grade.
b) In the ‘variety’ column, two letters indicate single-grade lubricating oils that are only
applicable to one type of engine; four or more letters that are separated by a ‘/’ (e.g.
SE/CD) indicate multi-grade general-purpose lubricating oils (applicable to both gasoline
engine and diesel engine).
c) In the ‘Viscosity and designation’ column, an Arabic number followed by a ‘W’ indicates
the viscosity level that enables engine startup at a certain low temperature in winter; an
Arabic number without a ‘W’ indicates lubricating oils not for winter use. The number
indicates the highest temperature for the lubricating oil;
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General Instructions GI-6126J12-01 GI-13
d) For instance: 10W/30 indicates that the engine oil can be used in a cold weather (engine
that can be normally started at -25℃) and also be used where there is a high thermal load.
3) Selection of lubricating oils
a) Lubricating oils that fit in with the engine’s working conditions and has a proper viscosity
shall be adopted. It is hard for the pump to feed oils with a high viscosity after the engine
is started and thus the engine abrasion may be increased; the oil film will be easily
damaged to dwarf the effects of lubrication if the viscosity is too low.
b) Lubricating oils with a higher grade can be a substitute of those with a lower grade and it
is not cost effective in this case merely. However, lubricating oils with a lower grade can’t
be a substitute of those with a higher grade. Otherwise, the engine parts may be damaged.
c) Cummins CNG engine oil recommendations and technical specification
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General Instructions GI-6126J12-01 GI-14
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General Instructions GI-6126J12-01 GI-15
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General Instructions GI-6126J12-01 GI-16
 Bus gear oil
The transmission gears of the manual transmission and the main reducer in the driving axle shall be
lubricated with gear oils.
1) Lubricating oils influence the main working properties of the engine.
a) Viscosity and temperature-viscosity characteristic: gear oils with a high viscosity are good
for lubrication, sealing, vibration reduction and noise reduction but will easily cause higher
internal friction forces and thus reduce transmission efficiency. It is also bad for lubrication
at a low temperature. Gear oils with a low viscosity help to reduce rotational resistances of
mechanical parts, increase transmission efficiency and achieve better cooling and cleaning
effects. However, the loading capacity will be reduced at a high temperature.
b) Low-temperature fluidity: it refers to the ability of gear oils to maintain sufficient fluidity at
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General Instructions GI-6126J12-01 GI-17
a low temperature. It reflects the minimum environmental temperature where gear oils are
used.
c) Resistance to wear: it is the ability of gear oils to keep oil films free of damage. Such ability
is particularly important to gear oils.
2) Brand and specification of gear oils
Standards comparable to API (American Petroleum Institute) standards are adopted in China,
i.e. gear oils are divided into general vehicle gear oils (SH0350-92), medium-duty vehicle gear oils
(GL-4) and heavy-duty vehicle gear oils (GL-5).
a) General vehicle gear oils (SH0350-92) have three viscosity designations, i.e. 80W/90,
85W/90 and 90.
b) Medium-duty vehicle gear oils (GL-4) normally include five viscosity designations, i.e. 75W,
80W/90, 90 and 85W/140.
c) Heavy-duty vehicle gear oils (GL-5) (GB13895—92) are applicable to gear transmissions
and hyperbolic gear transmissions in various rough working conditions like high-speed
impact loads and low-speed high torsion. They include the 75W, 80W/90, 85W/90, 85W/140,
90 and 140 viscosity designations.
3) Selection of vehicle gear oils
a) The varieties and grades of gear oils are selected according to the load of gear transmission.
 Heavy-duty vehicle gear oils must be adopted in case the surface contact pressure of
gears exceeds 3,000Mpa; sliding speed reaches 10m/s and working temperature of oils
reach 120 to 130℃. For instance, the lubricating oils of driving axles of hyperbolic
gears of imported cars and engineering trucks.
 Medium-duty vehicle gear oils may be adopted in case the surface contact pressure of
gears is below 3,000Mpa; sliding speed is below 10m/s and working conditions are not
severely rough. For instance, medium-duty vehicle gear oils may be adopted for the rear
driving axle of Dongfeng EQ1090 trucks even if it is driven by hyperbolic gears because
the load is not particularly heavy.
 General vehicle gear oils are normally adopted for general helical gears if the load is
light. For instance, general vehicle gear oils may be adopted for rear driving axle of
Jiefang CA1091.
b) Choose the designation of viscosity of gear oils according to the climatic conditions where
the vehicle is used.
 5W, 80W and 85W correspond to the minimum applicable temperatures of -40℃, -26℃
and -12℃ respectively. Choose them with reference to the minimum temperature where
the vehicle is used.
 90# gear oils can be adopted under normal circumstances. #140 gear oils may be
adopted in a highly hot region and for heavily loaded trucks.
 Hydraulic oils
1) Working conditions and main characteristics of hydraulic oils
A hydraulic system is installed for dump trucks, automobile cranes, loaders and various types of
engineering machineries and the working medium is hydraulic oil. The working conditions of
hydraulic oils require that the oils must have sound shearing stability, wear resistance, oxidation
stability and fluidity. Most importantly, their incompressibility must be guaranteed. The factor that
influences the incompressibility of hydraulic oils most is their solubility of air. If the air solubility is
too high at a certain temperature and pressure but would become lower in some other working
conditions, air bubbles may be created in the hydraulic oils. The compressibility of air bubbles will
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