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electronic speedometer for motorcycle
Motorcycle speedometer Generally, the speedometer of JH125 is a mechanical one. It uses the rotation of the front wheel to drive the speed gear in the front wheel drum, and then the speed gear drives the mileage line. The mileage line drives the speedometer. Therefore, when your car runs very fast, the speed of the front wheel is relatively high, which means that the speed of the speedometer is high. When you are stationary, the front wheel does not rotate, which means that there is no power to drive the speedometer. You can try not to touch the front wheel to the ground and turn the front wheel quickly by hand. Its tachometer will also respond.
Another important reason for the error is related to the car tires, because the displayed number of the speedometer is only related to the speed output by the transmission, but the actual speed is not only related to the speed, but also related to the rolling radius of the tires. The automobile tires wear gradually with the increase of driving mileage in the course of use, and their rolling radius decreases gradually. The 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 speed. According to the regulations, the allowable error range of the speedometer is+20% ～ - 5%. That is, when the actual speed is 40 km/h, the indicated value of the speedometer should be between 38 and 48 km/h, or when the indicated value of the speedometer is 40 km/h, the actual speed should be between 33.3 and 42.1 km/h.
At present, there are two main calibration methods of speedometer: road test method and indoor bench test method. The road test method is to measure the time when a car passes a predetermined length of test road at a constant speed according to different speeds on the speedometer, then calculate the actual speed, and then compare it with the speedometer to calculate the indication error of the speedometer at different speeds. The indoor bench test method is mainly tested by the roller type speedometer test bench.
In order to prevent the error between the actual speed and the value displayed by the speedometer from being too large, which will affect the driving safety, the vehicle owner is required to periodically identify the speedometer in the corresponding safety regulations.
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