GB/T 19120-2015 PDF English (GB/T 19120-2003: Older version)
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Tri-wheel Vehicles and Low-speed Goods Vehicles - Braking System - Structure, Performance and Test Methods
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GB/T 19120-2015: PDF in English (GBT 19120-2015) GB/T 19120-2015
GB
NATIONAL STANDARD OF THE
PEOPLE’S REPUBLIC OF CHINA
ICS 65.060
T 54
Replacing GB/T 19120-2003
Tri-wheel Vehicles and Low-speed Goods Vehicles -
Braking System - Structure, Performance and Test
Methods
ISSUED ON: MAY 15, 2015
IMPLEMENTED ON: OCTOBER 1, 2015
Issued by: General Administration of Quality Supervision, Inspection and
Quarantine;
Standardization Administration of the People’s Republic of
China.
Table of Contents
Foreword ... 3
1 Scope ... 5
2 Normative References ... 5
3 Terms and Definitions ... 5
4 Structural Requirements ... 7
5 Performance Requirements ... 12
6 Test Methods ... 18
Tri-wheel Vehicles and Low-speed Goods Vehicles -
Braking System - Structure, Performance and Test
Methods
1 Scope
This Standard specifies the structural requirements, performance requirements and
test methods of the braking system of tri-wheel vehicles and low-speed goods vehicles.
This Standard is applicable to the braking system of tri-wheel vehicles and low-speed
goods vehicles (collectively referred to as low-speed vehicles).
2 Normative References
The following documents are indispensable to the application of this document. In
terms of references with a specified date, only versions with a specified date are
applicable to this document. In terms of references without a specified date, the latest
version (including all the modifications) is applicable to this document.
GB/T 5345 Road Vehicles - Labelling of Containers for Petroleum-based or Non-
petroleum-based Brake Fluid
3 Terms and Definitions
The following terms and definitions are applicable to this document.
3.1 Braking Device
Braking device refers to a combination of parts and components that gradually
decelerate a moving low-speed vehicle, or, stop a moving low-speed vehicle, or,
maintain a stopped low-speed vehicle in a stationary state. Its functions are described
in 4.1.6. This device is constituted of control device, energy transmission device and
brake.
3.2 Control Device
Control device refers to a component directly driven by the driver to provide the energy
transmission device with the energy required to brake or control a low-speed vehicle.
This energy may be the energy of the driver’s muscle contraction or other energies
from the driver’s control, or, a combination of these energies.
3.12 Maximum Design Total Mass
Maximum design total mass refers to the maximum mass specified by the
manufacturer of tri-wheel vehicles or low-speed goods vehicles.
4 Structural Requirements
4.1 Basic Requirements
4.1.1 The design, manufacture and assembly of the braking device shall ensure that
low-speed vehicle can satisfy the requirements of this Standard under normal
conditions of use, no matter what vibration it is subjected to.
4.1.2 The design, manufacture and assembly of the braking device shall ensure that
the exposed part is resistant to corrosion and aging in the environment of normal use.
4.1.3 The brake linings shall not contain asbestos.
4.1.4 The various rod pieces of the braking system are not allowed to interfere or
friction with other parts in relative displacement, so as to prevent deformation and
damage of the rod pieces.
4.1.5 The braking line shall be a special-purpose corrosion-resistant high-pressure line.
The installation of braking lines shall ensure that they have good continuity, sufficient
length and flexibility to adapt to the normal movement required by the parts connected
to them without causing any damage. They shall have proper safety protection, so as
to avoid scratches, entanglement or other mechanical damages. Meanwhile, avoid
installation in places where they might come into contact with low-speed vehicle
exhaust pipes or any high-temperature sources. The flexible brake hoses are not
allowed to interfere with other parts, and shall not manifest any phenomena of aging,
cracking or flattened, etc. When other pneumatic devices fail, they are not allowed to
affect the normal operation of the braking system.
4.1.6 The braking device shall be equipped with the following functions:
a) Service braking: regardless of the speed, load, uphill and downhill, the service
braking system shall be able to control the low-speed vehicle to safely and
effectively decelerate and stop during the process of driving; service braking
shall be controllable; it shall ensure that the driver can brake with both hands
on his seat without leaving the steering wheel (handle).
b) Emergency braking (except for tri-wheel vehicles): emergency braking may
be a service braking system with emergency characteristics, or a system
separated from the service braking; the control device may be combined with
the control device of service braking, or, it may be combined with the control
device of parking braking. Emergency braking shall stop the low-speed
emergency braking system or the part of the service braking system not
affected by the failure shall be able to stop the low-speed vehicle in
accordance with the requirements of emergency braking.
f) When the service braking system and the emergency braking system share
the same control design and the same energy transmission device:
---If the service braking system is operated by the driver with his physical
strength, and is assisted by one or several energy storage devices, even
when the assist fails, it can still ensure the implementation of emergency
braking through the driver’s physical strength and the energy that is not
affected by the failure, and the force acting on the control device shall not
exceed the specified maximum value.
---If the braking force of the service braking system and energy transmission
are merely provided by the energy storage device controlled by the driver,
then, there shall be at least two completely independent energy storage
devices; each energy storage device shall have an independent energy
transmission device, which shall function on two or more wheel brakes.
The selection shall enable the low-speed vehicle to achieve the specified
emergency braking efficiency without affecting the stability of the low-
speed vehicle during the braking process. In addition, each energy storage
device shall be installed with the alarm device specified in 4.2.12.
g) For certain parts of the braking device, such as: the brake pedal and its
bracket, the master brake cylinder and its piston, the master brake valve, the
brake chamber, the wheel cylinder and its piston, and the connecting rod
pieces between them, as well as the brake lever of a tri-wheel vehicle and its
intermediate shaft shall be considered as parts that are not prone to failure.
These parts shall be large enough in size, easy to access for maintenance,
and at least have the same safety features as other important parts (for
example, steering rod system) of the low-speed vehicle. If the failure of these
parts and components would cause the low-speed vehicle to fail to meet the
specified performance of emergency braking, then, these parts and
components shall all be made of metal materials or materials with equivalent
performance as the metal materials. In addition, in the normal operation of the
braking device, no obvious deformation shall be generated.
4.2.3 When the control devices of the service braking system and the emergency
braking system are mutually independent, when the two sets of braking devices are
normally working, or one of them is not properly working, and the two sets of control
devices are simultaneously operated, the service braking and the emergency braking
shall not be disabled at the same time.
4.2.4 In the case of partial failure of the energy transmission device of the service
braking system, when operating the control device of the service braking system, a
4.2.8 Service braking shall act on all wheels of the low-speed vehicles, except for the
tri-wheel vehicles that satisfy the performance requirements in 5.2.
4.2.9 The braking force of the service braking shall be reasonably distributed between
axles (except for tri-wheel vehicles with only rear-wheel brakes).
4.2.10 The braking force of the service braking shall be symmetrically distributed
relative to the longitudinal center plane of the low-speed vehicle between the left and
right wheels on the same axle.
4.2.11 The service braking system and the parking braking system shall act on the
braking surface that is permanently connected to the wheels through components with
sufficient strength. Any braking surface shall not be disengaged from the wheels.
However, for the service braking system and the emergency braking system, the
braking surface is allowed to be briefly disengaged, for example, during gear-shifting;
after that, the service braking system and the emergency braking system shall continue
to achieve the stipulated efficiency. For the parking braking system, if it is merely
controlled by the driver on the seat by means of a device that does not function through
deflation, then, the braking surface is allowed to be disengaged.
4.2.12 After the brake is worn, the brake clearance shall be easily compensated by
manual or automatic adjustment devices. Its control and energy transmission device,
and the components of the brake shall have a certain reserve stroke. When necessary,
there shall be appropriate compensation devices. When the brake heats up, or, the
brake linings (blocks) reach a certain degree of wear, the braking efficiency can still be
guaranteed without immediate adjustment of the brake clearance.
a) Service brake may choose to install an automatic wear adjustment device.
After the brake is heated and cooled, the automatic wear adjustment device
can still ensure effective braking performance. In particular, after Type-I test
specified in 5.5, the low-speed vehicle can still normally run.
b) The wear of the service brake linings (blocks) shall make it convenient for
inspection from the external part or lower part of the low-speed vehicle. During
the inspection, only accompanying tools or equipment commonly used in low-
speed vehicles (for example, with appropriate inspection holes or some other
measures) shall be used. Or, an acoustic or optical alarm device may be
adopted. When the linings (blocks) need to be replaced, the alarm device may
alert the driver in the cab.
4.2.13 For the service braking system that uses energy storage to take actions, when
the specified emergency braking performance cannot be achieved without using the
stored energy of the energy storage device, in addition to the installation of a pressure
gauge, an alarm device shall also be installed. When the energy stored in any part of
the system drops to a certain value, the alarm device shall be able to send out a light
signal or an acoustic signal. Under this circumstance, regardless of the load of the low-
5.7.2.2 For the vacuum braking system, starting from the ambient air pressure, in
accordance with the conditions specified in 6.11.2, the energy supply device shall
enable the energy storage device to have the initial energy for the service braking
system to reach the performance specified in 5.2 within 3 min.
5.7.2.3 For the hydraulic braking system equipped with an energy storage device,
when braking is not actuated, the time required for the pressure in the energy storage
device to rise from the initial value (without replenishing energy to the energy storage
device, starting from the maximum factory-set working pressure, after 4 full-stroke
braking of the service braking, the pressure in the energy storage device) to the
maximum working pressure of the energy storage device shall not exceed 20 s.
6 Test Methods
6.1 Test Site
6.1.1 The test road surface shall be dry and smooth concrete, or, other road surfaces
with the same adhesion coefficient. No loose debris is allowed on the road surface.
6.1.2 The longitudinal gradient of the test road surface shall not exceed 2%. The
parking test gradient shall comply with the stipulations of relevant provisions.
6.1.3 The gradient of road camber shall be less than 2%.
6.2 Climatic Conditions
6.2.1 Wind speed: it shall be less than 5 m/s.
6.2.2 Temperature: it shall not exceed 35 °C.
6.3 Test Load
6.3.1 Fully loaded: the low-speed vehicle being tested is in the state of maximum
design total mass; its load shall be evenly distributed. When the low-speed vehicle is
fully loaded, the distribution of axle load mass shall comply with the manufacturer’s
stipulations. If there are several schemes for the distribution of the load mass among
the various axles (bridges), then, the distribution of the maximum total mass of the low-
speed vehicle among the various axles (bridges) shall ensure that the ratio of the load
mass of the various axles (bridges) to the maximum allowable load mass is the same.
6.3.2 Unloaded: fill the fuel tank to 90% of the factory-set volume; fill it up with coolant
and lubricant; bring along with the accompanying tools and spare tyres. In addition, it
also includes a mass of 200 kg (the mass of the driver, a tester and instruments).
6.4 Test Preparation
6.5.3 If the test fails, or, other types of brake components are to be appraised, when it
is necessary to re-test in whole or in part, it shall comply with the test sequence of this
Standard.
6.5.4 The pedal force shall act quickly and remain stable during the process of braking.
6.5.5 It is not allowed to use pedal drive.
6.5.6 During the test, the deviation and abnormal vibration of the low-speed vehicle
shall be observed and recorded.
6.6 Performance Test of Service Braking System
6.6.1 Test procedures
6.6.1.1 In accordance with the specified load and test speed, disengage the engine;
conduct the tests in sequence.
6.6.1.2 It is allowed to conduct 5 preliminary tests, so as to familiarize yourself with the
optimum braking performance when the wheels are not locked, and the low-speed
vehicle is not severely deviated.
6.6.1.3 Each test is conducted 4 times. The tests shall be carried out back and forth.
6.6.1.4 Before each braking, the brake is cold-state. In other words, the initial
temperature measured on the outer surface of the brake drum (disk) does not exceed
100 °C.
6.6.2 Test sequence
6.6.2.1 The unloaded braking test shall be carried out in accordance with the following
sequence:
a) The initial braking speed is the test speed specified in 5.2.1; the engine brake
is disengaged.
b) On the test road surface, draw the sideline of the test lane with a width
corresponding to the requirements for braking stability specified in Table 1.
Along the centerline of the test lane, drive to higher than the specified initial
speed. Place the transmission in neutral gear. When the vehicle taxies to the
specified initial speed, quickly step on the brake pedal to stop the low-speed
vehicle.
6.6.2.2 The fully loaded braking test shall be conducted in accordance with the
following sequence:
---The initial braking speed is the test vehicle speed specified in 5.2.1; the engine
brake is disengaged.
---The test method is the same as 6.6.2.1 b).
6.6.2.3 Test record
Record the actual initial braking speed, the braking distance and the actual control
force, etc.
6.6.3 Bench-test inspection
Drive the low-speed vehicle on a brake test bench roller with a dry surface, and no
loose substances or oil stains. Properly position it, then, actuate the roller; use the
brake. Measure the parameter values required by 5.2.2 and 5.6.4. In addition, record
whether the wheels are locked up.
When measuring braking, in order to obtain sufficient adhesion to avoid wheel locking,
it is allowed to add sufficient mass or drag an acting force equivalent to the additional
mass on the low-speed vehicle (the additional mass or acting force is not included in
the axle load). Or, measures may also be taken to prevent the low-speed vehicle from
moving (for example, by adding triangular pads or using tractions).
After the above-mentioned method is adopted, when the wheels are still locked up and
slippery on the roller, or, the complete-vehicle moves backward with the roller, and the
braking force still does not reach the requirements of qualification, then, the method of
road-test inspection shall be adopted for determination and judgment.
6.7 Emergency Braking Performance Test and Service Braking Partial
Failure Test
6.7.1 General rules of test
For low-speed goods vehicles with a combination of emergency braking system and
service braking system, partial failure test of the service braking system shall be carried
out. For low-speed goods vehicles with an independent emergency braking system, or
a combination of emergency braking system and parking braking system, emergency
braking test and residual braking performance test of partial failure of the service
braking shall be respectively conducted.
6.7.2 Test procedure
6.7.2.1 In accordance with the structure of the braking device, determine the test items
and the mode of failures.
6.7.2.2 In the simulation of brake failures, the method of disconnecting the pipeline
may be used. For the pneumatic braking system, the air pressure may be directly
discharged into the atmosphere. For the hydraulic braking system, the brake fluid may
be connected to another pipeline and returned to the reservoir.
maintain for 5 min. Then, the test is performed once in the opposite direction.
6.9.2.2 Traction test
The test vehicle is in stationary state (not braked); in accordance with the control force
specified in 5.6, carry out a parking braking. Then, use a traction device for the traction;
maintain the low-speed vehicle being tested stationary for 5 min.
When the traction increment is less than 20% of the total mass of the test vehicle, the
test vehicle shall remain stationary.
Then, the test is performed once in the opposite direction.
6.9.2.3 Bench test
In accordance with the stipulations of 5.6.4, conduct the test.
6.9.2.4 Test record and test result
Record the test gradient, the control force and its method, the total mass of the low-
speed vehicle, and the initial and final values of traction.
6.9.3 Dynamic test
6.9.3.1 The low-speed vehicle is fully loaded and accelerated to the initial speed
specified in 5.6.5. Then, disengage the engine; carry out a parking braking; the control
force shall not exceed the value specified in 5.6.2.
6.9.3.2 Record the braking control force, the mean fully developed deceleration and
the deceleration within 1 s before the low-speed vehicle stops.
6.10 Test of Energy Storage Device
6.10.1 Determination of capacity of energy storage device
6.10.1.1 Test requirements
6.10.1.1.1 The initial energy of the energy storage device is determined by the
manufacturer. The initial energy shall enable the service braking system to achieve the
specified braking performance, but it cannot exceed 90% of the energy provided by
the energy supply device.
6.10.1.1.2 During the test, the energy storage device shall not be replenished with
energy; the energy supply of the auxiliary device shall be disconnected; the engine
shall be stopped.
6.10.1.1.3 The load sensing device shall be in the “fully loaded” position (if installed).
......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.
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