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how to fix speedometer needle
The driving shaft of the speedometer is driven by the transmission or transfer gear through the flexible shaft. The speedometer is composed of a permanent magnet fastened with the driving shaft, an aluminum bowl with shaft and pointer, a cover, a dial fastened on the watch case, etc. When not working, the aluminum bowl makes the pointer at the zero position of the scale under the action of the disc spring (hairspring).
When the car is driving, the driving shaft rotates with the permanent magnet, and the magnetic force line of the permanent magnet generates eddy current on the aluminum bowl. The interaction between the eddy current and the magnetic field of the permanent magnet generates torque to overcome the elastic force of the disc spring and deflect the aluminum bowl towards the rotation direction of the permanent magnet, so the aluminum bowl rotates an angle with the pointer. Since the strength of the eddy current is directly proportional to the vehicle speed, the rotation angle of the pointer is directly proportional to the vehicle speed, and the pointer indicates the corresponding vehicle speed on the dial.
How：
When performing the speedometer calibration test, first let the meter rotate freely, then place it on the test bench and run it at different speeds, and compare the speedometer with the standard pointer readings on the test bench. Make the speedometer run on the test bench and pay attention to the noise situation. The noise should be lower than the required standard.
The time for the test should be a number that allows the speedometer to run to record several miles. Except for a few number wheels that are rotating, all the number wheels should be arranged symmetrically. A simpler method is to stop when the pointer is above zero to see if it is aligned. If there is too much grease on the meter head, wipe it off. Wipe clean the flexible shaft and outer cover. Some speedometers have lubricating felt or linoleum thread on the shaft. Modern speedometers generally do not need lubrication.
The adjustment method of speedometer varies according to different models. It is recommended to go to the 4S store for professionals to operate. The speedometer is used to check the driving speed of the vehicle. It supports two units: mile per hour or kilometer per hour. The speed measurement is realized through the speed sensor. The driving speed of the vehicle is closely related to the radius of the wheel and the rotating shaft structure.
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