QC/T 556-1999: Automobile Brake Temperature Measurement and Thermocouple Mounting

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Scope

1.1 Thermocouple. thermocouple materials shall be selected reasonably; the
standardized thermocouple wires are preferred (see Appendix A for the recommended
thermocouple materials). Its diameter is 0.3~0.5mm, which shall meet the technical
requirements for product exit-factory.
Two types of thermocouple construction are recommended.
1.1 Plug thermocouple (see Figure 1).
Figure 1
1.1.2 Armored thermocouple. the thermocouple made of thermocouple wires,
insulating materials and metal sleeves through processing, welding and assembling; it
can be ordered from the manufacturer as needed.
1.2 Display and recording device. reasonably select the secondary instrument for
displaying and recording the dynamic temperature of the brake.
Electronic potentiometer, DC digital voltmeter, digital thermometer, tape drive, light
oscilloscope, etc. Their indicator errors shall be less than 5% of their measured value;
while dynamic response time of the instrument shall be no greater than 0.2s.
Steel tube Φ3 Thermocouple wire winding and silver welding
Silver shall fill the inner hole
3.1.1 Separately mount the thermocouple as required in 2.1, 2.2, 2.3.
3.1.2 Install the temperature measuring instrument; use appropriate lead wire to
connect with the thermocouple; place the free end of the thermocouple in the freezing
device, thermostat or relatively stable room temperature as required. When it is
necessary to use the compensation wire, pay attention to the matching between the
compensation wire and the thermocouple materials.
3.1.3 When recording by a light oscilloscope or tape drive, the calibration device must
be used to calibrate the used thermocouple together with recorder.
3.1.4 Adjust the measuring instrument, so that it can work normally.
3.1.5 Record the ambient temperature
3.2 Measure and record the brake temperature during the brake test.
3.2.1 Measurement of the brake lining (block) temperature. start the recorder; record
the temperature change during the braking process; record the temperature change
within 15s after the brake drum (disc) stops rotating (brake action is not released), if
necessary.
3.2.2 Measurement of brake drum (disc) temperature. start the recorder; record the
temperature change during the braking process.
3.2.3 Measurement of brake fluid temperature. start the recorder; record the
temperature change of the brake fluid during the test; record the temperature once
every 1min after the completion of the test (brake action is released) till the temperature
begins to decline significantly.
3.3 Temperature compensation when the free end of the thermocouple is not 0°C.
3.3.1 Correction factor method.
Where.
t - measured temperature;
ti – indication temperature of the instrument;
t0 – temperature on the free end;
K – correction factor, different thermocouple has different K value. See Appendix B.
3.3.2 Adjust the starting point of the instrument. disconnect the measuring line; adjust
the pointer of the instrument to t0; close the measuring line during the measuring

Basic Data

Standard ID	QC/T 556-1999 (QC/T556-1999)
Description (Translated English)	Automobile Brake Temperature Measurement and Thermocouple Mounting
Sector / Industry	Automobile and Vehicle Industry Standard (Recommended)
Classification of Chinese Standard	T24
Word Count Estimation	10,178
Date of Issue	6/21/1905
Date of Implementation	1999-03-15
Older Standard (superseded by this standard)	JB 3936-1985
Regulation (derived from)	State-Reform-Development-Office-Industry (2005) No. 743
Summary	This standard applies to the temperature measurement of car brake performance tests.