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how does a speedometer work on a motorcycle
The speedometer shows the speed of the car through the swing of the pointer. To put it simply, there is a system in the speedometer (turntable with pointer shaft, shaft with permanent magnet, bearing, hairspring and other parts) to control the swing of the pointer. The swing range of the pointer is ultimately determined by the speed output by the transmission (that is, the rotating shaft of the speedometer is driven by a flexible shaft, and the flexible shaft is output from the automobile transmission or transfer case. The worm gear on the shaft is connected to the worm gear in the worm drive pair ). Due to the manufacturing process and assembly errors of these parts, as well as natural wear and tear during use, and magnetic changes of magnetic components, the indication error of the speedometer will be caused.
Another important reason for the error is related to the car tires, because the displayed number of the speedometer is only related to the rotational speed output by the transmission, but the actual vehicle speed is not only related to the rotational speed, but also related to the rolling radius of the tire. Car tires gradually wear out with the increase of mileage during use, and their rolling radius gradually decreases, and the level of tire pressure also affects the size of the rolling radius. Therefore, there will be an error between the indicated value of the speedometer and the actual vehicle speed. According to regulations, the allowable error range of the speedometer is +20%~-5%. That is, when the actual vehicle speed is 40km/h, the indicated value of the speedometer should be between 38~48km/h, or when the indicated value of the speedometer is 40km/h, the actual speed should be between 33.3~42.1km/h.
At present, there are mainly two methods of checking and checking the speedometer: road test method and indoor bench test method. The road test method is that the car passes through a test road of a predetermined length at the same speed according to the different speeds on the speedometer, measures the time for passing the road section, and then calculates the actual speed, and then compares it with the speedometer to obtain the speed at different speeds. Table indication error. The indoor bench test method is mainly carried out through the test bench of the drum type speedometer.
Motorcycle odometer structure diagram:
Use a Phillips screwdriver to unscrew a Phillips screw on the side of the front kill drum, then take out the mileage line, let the front wheel hang in the air and turn the front wheel to see if the mileage tooth rotates with the front wheel. Then tighten the screws. Screw the end with the nut onto the odometer screw.
Diagram of working principle of motorcycle mileage meter:
The rightmost one represents the decimals of kilometers and generally uses black characters on a white background (that is, hundreds of meters). There are mileage errors in the production of motorcycle odometers, and the allowable error range is ±15%, and the errors produced by different odometer manufacturers are also different, so accurate values cannot be obtained through calculation.
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