JJG 779-2004Verification regulation of speed and milege meter for standard equipment (English PDF)

3.1 Speedometer (1)

3.2 Odometer constant k (1)

3.3 Vehicle coefficient w (1)

3.4 Speedometer constants (1)

3.5 Speed stability (1)

5.1 Standard device signal source frequency accuracy and 4h frequency stability (2)

5.2 Speed range (2)

5.3 Speed uncertainty (2)

5.4 0.5h speed stability (2)

5.5 Speed resolution (2)

5.6 Counting tolerance (2)

6.1 Appearance requirements (2)

6.2 Output Interface Requirements (2)

6.3 Working noise requirements (2)

6.4 Accessories and manual requirements (2)

7.1 Verification conditions (3)

7.2 Verification items and verification methods (3)

7.3 Processing of verification results (5)

7.4 Verification cycle (6)

Appendix A Speedometer Standard Equipment Verification Record (7)

Appendix B Verification certificate back format (8)

Speedometer standard device verification procedure

1 Scope

This procedure is applicable to the first verification, subsequent verification and inspection in use of standard equipment for various speedometers.

2 Citations

OIML International recommends No. 55-1981 speedometers for motor vehicles, mechanical odometers and instantaneous recorders.

Care should be taken to use the currently valid version of the cited literature.

3 terms and units of measure

3.1 Speedometer

A meter used by a motor vehicle to indicate the instantaneous speed of a vehicle is called a speedometer and is used to indicate that the wheel is in motion during travel.

The meter that converts the mileage corresponding to the total number of revolutions is called the odometer. The two instruments that are installed in the same chassis are called the speed.

Schedule.

3.2 Odometer constant k Depending on the type of signal (number of revolutions or pulses of the drive shaft), and the odometer or instantaneous recorder indication and/or Record the characteristic quantity of the number of signals that must be accepted for each additional 1km mileage. The constant k should be in the revolution/km or pulse/km table.

Show.

3.3 Vehicle coefficient w According to the type of signal (number of revolutions or number of pulses of the drive shaft) and the vehicle's device is emitted and transmitted every kilometer of travel the characteristic quantity of the number of signals to the odometer or transient recorder.

The coefficient w must be expressed in the same unit as the constant k.

The coefficient w varies with the load, size, tire pressure and wear level of the vehicle. It must be tested in the standard.

Determined under the test conditions.

3.4 Speedometer constant Signal frequency at 60km/h speed according to signal type (drive shaft revolution or number of pulses) and speedometer Feature amount.

The speedometer constant can be expressed as the number of revolutions per minute, that is, the revolution/km, which can also be expressed as the number of pulses per minute.

Ie pulse/km. When both the odometer and the speedometer use the same drive system, the speedometer and the odometer are used.

An odometer constant k.

3.5 Speed stability

The ratio of the maximum, minimum difference and average value measured every 3 minutes during the 0.5 h period.

4 Overview

The speedometer standard device (hereinafter referred to as the standard device) is used to determine the speedometer and odometer for motor vehicles.

And the speedometer can also be used to verify the corresponding accuracy of the tachometer.