a. Point selection: On the test road section, along the left wheel track in the driving direction, select five representative measuring points, each measuring point is about 5-10 meters apart.

b. Instrument leveling:

(1) Put the instrument on the measuring point (see the appendix for the calibration method), and make the swinging direction of the pendulum consistent with the driving direction.

(2) Move the pendulum to the right and press the release switch. Make the snap ring enter the slot of the release switch, put it in the horizontal release position, and then release the release switch, at this time the pointer should be pulled to be close to the needle puller.

(3) Press the release switch to move to the left, and the pointer should point to zero. If it does not point to zero, it is necessary to adjust the adjustment screw that drives the pointer. Readjust the drive pointer screw until the pointer points to zero.

c. Calibration slide length:

(1) Use a brush to remove loose particles and debris from the measuring range.

(2) Let the pendulum hang freely, set the standard ruler (126mm) in the direction of the parallel swing of the external force of the rubber sheet, loosen the firm handle, and turn the lifting handle. Slowly lower the pendulum. When the rubber sheet on the sliding block just touches the road, lift the lifting handle to raise the sliding block, move the pendulum to the right, and move the lifting handle to lower the pendulum for a certain distance, then lower the lifting handle to make the pendulum Slowly move to the left until the edge of the rubber sheet just touches the road, aligning with the end of the 126mm ruler. Lift the lifting handle by hand again to lift the sliding block upwards, and make the pendulum continue to move to the left, put down the lifting handle, and then slowly move the pendulum to the right to make the edge rubber of the rubber sheet contact the road surface again. After the distance between the two contact points of the rubber sheet and the road surface should be 126 mm, tighten the fastening handle and calibrate it again. If the sliding length does not meet the standard, raise or lower the instrument Use the leveling screw on the front of the base to adjust, but the vial must be leveled. Make the sliding length meet the requirements. Afterwards, place the pendulum in the horizontal release position.

d Measurement: Sprinkle the road surface with water, and scrape it with a rubber brush to wash away the slurry, then sprinkle water, and press the release switch to slide the pendulum on the road surface, and the pointer can indicate the friction coefficient value of the road surface (paragraph 1) One time may not be recorded). When the pendulum swings back, catch the pendulum rod with your left hand, lift the lift lever with your right hand to raise the sliding block, and move the pendulum to the right to press the switch to make the pendulum snap ring enter the release switch, and move the pendulum pin to close Set the needle piece, repeat this, measure five times (sprinkle water each time), record the value of each time. The difference between the five values is not more than three units (one and a half divisions of the dial). If the difference is more than three units, the cause should be investigated, and the above operations should be repeated until the specified requirements are met.

Measuring results:

(1) For each measuring point, the average value of five measurement counts is used to represent the friction coefficient value of the measuring point, and the average value of the friction coefficient of five measuring points is used. Represents the friction coefficient value of the measured road section.

(2) Measure the reading, the reading of the pointer on the dial (referred to as “pendulum value”), divided by 100, is the friction coefficient of the road surface. For example: if the pendulum value is 33, the coefficient of friction is 0.33.