Structure and principle
The longitudinal friction coefficient is a measuring device for measuring the friction coefficient of the longitudinal force on the road surface. It consists of a tractor, a trailer chassis, a trailer frame, a special water tank, a laptop computer operated by test software, a sprinkler and water volume control system, an electrical control system, and a friction sensor with a sensor. It consists of resistance test wheel system, 12-15% slip rate guarantee system, alarm and safety warning system.
The basic working principle is: it moves forward under the traction of the tractor, and there is a 0.5-1mm water film between the friction wheel and the ground. Due to the speed difference between the friction wheel and the running wheel, the test wheel produces a slip rate of 12-17%, which will generate a longitudinal force perpendicular to the driving direction. This longitudinal force serves as a characteristic value representing the friction coefficient of the road surface, and is determined by high-precision The force sensor measures and transmits it to the computer for processing; the road mileage is measured by a high-resolution encoder, and the microcomputer gives the corresponding table and curve of the road position and friction coefficient. After data processing by the software, the measurement results of the longitudinal force friction coefficient correspond to the road station number, and the longitudinal force coefficient for each section (5 meters, 10 meters, 20 meters, 100 meters, and 1 kilometers can be selected) is given. The vehicle speed is obtained from the encoder, and the sprinkler device automatically adjusts the water output according to the vehicle speed so that the thickness of the water film between the test wheel and the road surface is 0.5~1mm.
Parameter
|
Number
|
Projects and units
|
Unit
|
Demand
|
|
1
|
Volume (length, width, height)
|
mm
|
|
|
2
|
Operating temperature
|
℃
|
-35～+60
|
|
3
|
Maximum driving speed (full load)
|
km/h
|
130
|
|
4
|
Ground clearance
|
mm
|
100
|
|
5
|
Overall equipment quality
|
kg
|
500KG
|
|
6
|
Full load total mass
|
kg
|
560KG
|
|
7
|
Test relative error
|
%
|
≤2
|
|
8
|
Test repeatability error
|
|
≤±0.02
|
|
9
|
Microtexture test speed
|
km/h
|
96
|
|
10
|
Macro texture test speed
|
km/h
|
65
|
|
11
|
Minimum test speed
|
km/h
|
20
|
|
12
|
Load cell accuracy
|
%
|
≤0.02
|
|
13
|
Water tank and capacity
|
L
|
Comes with stainless steel water tank, capacity 600L
|
|
14
|
Continuous test distance
|
km
|
≧7
|
|
15
|
Test wheel lift pump set
|
Mpa
|
5
|
|
16
|
Test wheel air pressure
|
Mpa
|
0.207
|
|
17
|
Test slip rate
|
%
|
12~17
|
|
18
|
Test tires
|
|
4.00-8”
|
|
19
|
Insulated from ground
|
MΩ
|
≥1.5MΩ
|
|
20
|
Electronic calibration device
|
External electronic calibration device
|
|
21
|
Operating systems and software
|
English Windows operating system, software uses English drop-down style
|
|
22
|
safety braking system
|
The bottom bracket is equipped with an autonomous braking device to avoid insufficient braking or failure of the tractor caused by huge speed inertia during testing (relevant certification materials are required), and it is safe.
|
|
|
|
The bottom bracket should be equipped with a decoupling emergency braking device to avoid the huge risk of rollover and high-speed collision caused by accidental decoupling of the test equipment during testing.
|
FAQ（Frequently Asked Questions）
Qualification and Compliance Issues (Compliance&Standards)
Q1: Does the equipment comply with the technical standards of the Civil Aviation Administration of China (CAAC) and the International Civil Aviation Organization (ICAO)?
A: Yes, completely in line. Our friction coefficient testing equipment strictly follows ICAO Annex 14, FAA AC 150/5320-12C, and Civil Aviation Administration of China MH/T 5024 (Design Specification for Asphalt Concrete Pavement of Civil Airports) and relevant testing regulations. The flatness meter meets the standards of continuous flatness meters (such as the International Roughness Index IRI calculation specification). Third party authoritative measurement and testing reports can be provided upon equipment delivery.
Q2: Has the friction coefficient test vehicle passed the Civil Aviation Administration's notice (AC) or equipment certification?
A: Our equipment belongs to the catalog of runway friction coefficient testing models recognized by the Civil Aviation Administration of China (such as the continuous friction coefficient testing vehicle CFT that has been approved). When providing the bid, we will attach complete civil aviation equipment access qualifications, type inspection reports, and industry benchmark airport usage certificates.
Technical Performance and Accuracy Issues
Q3: What is the testing principle of the Longitudinal Force Friction Coefficient Test Vehicle (LFT)? What is the difference between lateral force testing (SFV) and lateral force testing?
A: Principle: LFT adopts the principle of fixed slip ratio (usually 13% -15%), and uses a dedicated test tire to roll on the track and apply a certain braking force. The sensor directly measures the longitudinal frictional resistance generated.
Difference: Longitudinal Force Test (LFT) provides a more realistic simulation of the tire stress state during takeoff and landing braking, and is a core method recommended by ICAO and FAA for evaluating runway macro/micro texture and anti-skid performance; And lateral force testing is mostly used for evaluating the stability of highway pavement.
Q4: How stable is the data of the device during high-speed (such as 65 km/h or 95 km/h) testing?
A: The device is equipped with a high-precision dynamic compensation system (including precision load sensors and speed encoders). Even under high flow rate testing at 95 km/h, the self-lubricating precision water spray system can ensure uniform water film thickness (standard 1mm), with a data sampling frequency of up to kHz, ensuring accurate and highly repetitive data even in high-speed fluctuations, with errors controlled within 0.03 pm.
Water System&Consumables
Q5: What is the capacity of the built-in water tank of the friction coefficient car? How much distance can be tested by filling it up once?
A: Friction coefficient vehicles do not come with water tanks and are usually used in conjunction with sprinkler trucks.
Usually 600-1000L, customized according to specific vehicle models. At a speed of 65 km/h and with a water film thickness of 1mm that meets ICAO standards, a single full water test can continuously test for approximately 5000-8000 meters, fully meeting the complete testing requirements of a single track and measurement line without the need for intermediate water replenishment.
Q6: What are the requirements for the standard tires used for testing? Is the procurement channel convenient?
A: The friction coefficient test uses smooth standard test tires that fully comply with ASTM E1551 (or relevant international standards). We randomly include X spare tires as a bonus. For subsequent consumption, buyers can directly order from us. We have sufficient original stock and can also provide third-party procurement channels that meet standard manufacturers.
Software, Data Export, and Airworthiness Management
Q7: Can the test data be viewed in real-time? How to generate reports required by the Civil Aviation Administration of China?
A: Can be viewed in real-time. The onboard control system is equipped with an industrial grade tablet/computer, and the software interface displays real-time friction coefficient curve, IRI flatness curve, testing speed, water film status, and GPS position. After the test is completed, the system can generate standard inspection reports in PDF, Excel, or Word format with just one click, and the report format fully complies with the review requirements of the civil aviation quality inspection department.
After sales&Maintenance
Q8: Does the equipment need regular calibration? How long is the calibration cycle? How can you assist?
A: To ensure the legal validity of the test data, it is recommended to calibrate the equipment once a year.
Daily self inspection: The device software has a built-in static calibration program, and operators can perform quick static self inspection at the airport through the standard calibration rack (weight).
Annual calibration: We provide on-site calibration services or assist in coordinating with national civil aviation metrology stations for authoritative calibration.
Q9: How is the response speed of after-sales service? How long is the spare parts cycle for core components?
A: Technical support: Provide 7 * 24-hour remote technical support and provide solutions within 2 hours.
On site response: If on-site handling is required, domestic airport (or designated area) after-sales engineers will arrive on site within 24-48 hours.
Spare parts guarantee: Core key components such as sensors and water spray pumps have long-term stock reserves in the headquarters warehouse, and can be shipped on the same day by SF/air freight.
