Road surface deflectometer

Technical Specifications:

1. Total length: 3600mm; 5400mm; 7200mm

2. Leverage ratio: 2:1

3. Length from pivot point to front measuring point: 2400mm

4. Stiffness: Using the center of the shaft hole as the fulcrum, load 200g at a distance of 1200mm from the fulcrum, and the deflection should not exceed 0.05mm

3、 Measurement method:

1. Connect the instrument lever back and forth as a whole, and check it according to the requirements.

2. One heavy-duty truck, the rear axle single axle needs to be calibrated according to regulations for road loading, and the tire pressure should also be adjusted according to regulations.

3. A thermal resistance meter with an accuracy of ℃ is used to measure the temperature of the road surface (as the deflection value varies with temperature).

4. Three red flags for directing traffic, three small iron bars with a diameter of 700-300mm and a diameter of 20

Road surface deflectometer

Preparation work:

1. Check and maintain the condition and braking performance of the standard vehicle used for testing, and ensure that the tire inner tube meets the specified inflation pressure.

2. Load (iron blocks or aggregates) into the car trough and measure the total weight of the rear axle using a ground balance to meet the required axle load regulations. During the driving and measurement process of the car, the axle load must not change.

3. Measure the tire contact area with new carbon paper.

4. Check the sensitivity of the deflection gauge dial gauge measurement.

Main structure:

It mainly consists of front lever, rear lever, base, dial gauge, bracket and other main parts. Connect the front and rear levers with four M12 bolts. When not in use, remove the bolts and separate the front and rear levers into the box. The rear lever is connected to the bracket seat, and the lever is connected to the base with a radial ball bearing, which overcomes the disadvantages of unstable and inflexible structure of using scattered ball bearings. It is also equipped with a dust cover to prevent dust and rainwater from entering, and sufficient lubricating grease is added. The base is equipped with leveling screws and a horizontal device for easy adjustment. There is a clamp on the dial gauge bracket that can be adjusted according to the height during measurement. Each instrument is equipped with a 0-10mm first level precision dial gauge.

Operating procedures:

1. Clean the instrument thoroughly.

2. After selecting the measurement, the distance between the center of the measured rear axle clearance of the car and the measuring point should not exceed 10 centimeters.

3. Install the dial gauge on the dial gauge holder, then move the deflection gauge to the road surface so that its measuring end is exactly at the center of the gap between the two tires (perpendicular to the center point of the axle), and adjust it horizontally. Use the leveling screw of the gauge clamp and dial gauge bracket to adjust the dial gauge reading to about 5 millimeters, so that the pointer points to zero, and the contact of the gauge touches the center of the measuring point screw, and record its reading B1

4. Drive the car forward so that its rear wheels are outside the influence radius, usually about 5 meters away from the measurement. At this time, move the dial gauge and wait for the reading to stabilize (becoming less than 0.01mm per minute). Record the reading C1.

5. Measure and record the temperature t of the road surface using a thermal thermometer.

6. Record the measurement results in the following equation.

7. Calculate the elastic deflection value of the road surface based on the recorded readings.