how to calibrate tachometer

• 2022-04-11

During the calibration test of speedometer, first let the instrument rotate freely, then put it on the test bench, run at different speeds, and compare the readings of standard pointer on the speedometer and the test bench. Operate the speedometer on the test bench and pay attention to the noise. The noise shall be lower than the required standard.

The time of the test should be to run the speedometer to record the number of miles. All the digital wheels except a few rotating ones shall be arranged in a symmetrical manner. A relatively simple 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, wipe it clean. The flexible shaft and cover should also be cleaned. Some speedometers have lubricating felt or felt line on the axle. Modern speedometers generally do not need lubrication.

When lubricating the flexible shaft of the speedometer, just add a little special lubricating oil. Too much oil will flow from the flexible shaft to the head of the speedometer. The accuracy of speedometer the accuracy of speedometer and odometer is related to tire size, rear axle pinion ratio and the gear driving the speedometer. Changing the size of tires and adopting different rear axle speed ratios will change the accuracy of speedometer and odometer. In order to ensure high accuracy, automobile manufacturers have equipped the speedometer with drive gears of different specifications.

Since the pinion can be replaced, it can ensure that the correct speed and mileage readings are provided under the given tire size and rear axle speed ratio. On dodge and other Chrysler cars, the error of speedometer decreases from 0-5% to 0-3%. The method is to increase the number of teeth of the worm gear of the output shaft of the transmission and the driving pinion of the speedometer. This allows many different transmission ratios to match more different tire sizes and rear axle speed ratios.

A gear adapter is now produced abroad. With the gear adapter, all speedometer gears can be interchanged. The shaft hole in the adapter is eccentric. Any of the three sets of drive gears can be installed to ensure the required transmission ratio. The calibration of the speedometer is carried out by mechanical method, that is, the hairspring is used to balance the torque of the magnet, so as to calibrate at least three points of the dial. The test bench of the speedometer is required to rotate the speedometer at the specified speed. This shall be carried out according to the operating procedures provided by the speedometer manufacturer.