GB/T 19120-2015Tri-wheel vehicles and low-speed goods vehicles—Braking system—Structure, performance and test methods (English PDF)

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.

3.3 Transmission Device

Transmission device refers to a combination of parts and components that act as a link between the control device and the brake. If the braking force is not generated by the driver but is generated or assisted by the energy controlled by the driver, then, the energy storage device is also a part of the energy transmission device.

3.4 Brake

Brake refers to the component in the braking device that generates the force that prevents the movement of a low-speed vehicle.

3.5 Part and Component of Braking Device

Part and component of braking device refers to one or multiple individual parts and components that are assembled to form a braking device.

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.

4.1.6 The braking device shall be equipped with the following functions.

4.2 Characteristic Requirements of Braking System

4.2.1 The braking system of low-speed vehicles shall satisfy the requirements specified for the service braking system, the emergency braking system and the parking braking system.

4.2.2 The components of the service braking system, the emergency braking system and the parking braking system of low-speed vehicles may be shared under the premise of satisfying the following requirements.

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 sufficient number of wheels shall still be braked. The selection of these wheels shall make the residual braking efficiency of service braking not lower than the requirements of 5.3.

4.2.6 When using other energy sources other than the driver's physical strength, there may be only one energy source (for example, hydraulic pump or air compressor), but the energy-driven device shall be safe and reliable.

4.2.7 In order to satisfy the requirements of 4.2.2, 4.2.4 and 4.2.6, an automatic device that can detect its failures under normal conditions shall be used.

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.

4.2.13 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.

5.1 Basic Requirements

5.1.1 The performance of the braking system specified in this Standard is determined by measuring the braking distance at a corresponding initial speed and / or the mean fully developed deceleration under the specified conditions. Braking distance refers to the distance travelled by the low-speed vehicle when the driver starts to actuate the braking control device to when the low-speed vehicle stops.

5.1.2 When testing low-speed vehicles, road tests shall be conducted under specified conditions to determine their braking performance.

5.1.3 The load state of the low-speed vehicles being tested shall all comply with the stipulations of various tests and stated in the test report.

5.2 Performance of Service Braking System

5.2.1 The braking distance and braking stability in the road-test inspection of tri-wheel vehicles or low-speed goods vehicles under the conditions specified in 6.6.2.1 and 6.6.2.2 shall comply with the stipulations of Table 1.

5.2.2 The requirements for braking force in the bench-test inspection of tri-wheel vehicles and low-speed goods vehicles under the conditions specified in 6.6.3 shall comply with the stipulations of Table 2.

5.6 Performance Requirements for Parking Braking System

5.6.1 Under the specified control force and unloaded state, during the road-test inspection, the parking braking device shall enable the low-speed vehicle to lock the working parts through a mechanical device even when there is no driver; ensure that the low-speed vehicle remains stationary on a slope with a gradient of 20%, and the adhesion coefficient between the tyre and the road surface is not less than 0.7, and for a duration of not less than 5 min.

5.7 Energy Storage Device and Energy Supply Device

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.

5.7.1 Capacity of energy storage device

5.7.1.1 It is required that low-speed vehicles whose braking device uses compressed air, vacuum and hydraulic energy storage shall install an energy storage device. The Initial Braking Speed

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.

6.2 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

6.4 Test Preparation

6.4.1 Measuring instruments

The measuring instruments shall be verified or calibrated, and within the validity period.

The installation of the instruments shall not affect the performance of the braking system. The measuring instruments and the accuracy are as follows. […]

6.4.2 Failure simulation preparation

In accordance with the stipulations of this Standard, and with the approval of relevant departments, additional devices and pipelines may be equipped to simulate failures of the braking system. The used devices shall not affect the normal braking performance of the test part.

6.5 Test Description

6.5.1 The test is divided into two parts. unloaded and fully loaded. The test shall be conducted in accordance with the sequence specified in this Standard. The sequence of items like parking braking and energy storage device may be chosen by the test department. Unloaded test items may be intensively tested, then, proceed to fully loaded test items. Changes to the test procedure shall be explained in the test report.

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

6.6.2 Test sequence

6.6.2.1 The unloaded braking test shall be carried out in accordance with the following sequence.

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.

6.7 Emergency Braking Performance Test and Service Braking Partial

Failure Test

6.11 Test of Energy Supply Device

6.11.1 Test procedures of pneumatic braking system

6.11.1.1, conduct the test. […]

6.11.2 Test procedures of vacuum braking system