7 trimming paired sections, 8 calibration with test weights – Rice Lake Truck Scales User Manual
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Survivor
®
SR Siderail Truck Scale Assembly Instrucitons
8.7
Trimming Paired Sections
Now that you’ve trimmed all individual load cells for equal output, pairs of load cells on opposite sides of the scale
must be trimmed for equal sectional output. This process is called section signal trimming.
1. Park the loaded weight cart in the middle of the scale and directly over an imaginary line connecting an
end pair of cells (1 and 8 in the example at right). Record the indicator reading.
Figure 8-9. Trimming Paired Section 1:8.
2. Move the weight cart directly over the next paired cell section (2, 7 in Figure ) and record the indicator
reading.
Figure 8-10. Trimming Paired Sections 2:7, 3:6, and 4:5.
Do the same for the last two paired sections (cells 3, 6 and 4, 5)
.
3. Choose the lowest reading of the four as your reference section, which will not be adjusted. Using the
section potentiometers, reload the other three sections in turn and trim the sections to match the
reading of the reference section. Recheck section readings a second time as the adjustment made may be
somewhat interactive.
4. As a final verification of the load cell trimming, do a final corner check. Place a 1000 lb. weight on one
corner of the platform and record the raw-count reading on the indicator. Move the weight to all the other
corners in turn and record those readings. The readings should be within 1% of each other.
8.8
Calibration with Test Weights
The calibration procedure can only be done after all trimming as described above has been completed. A qualified
scale technician with a test weight truck and the expertise to access the scale indicator’s Setup or Calibration mode
must perform the calibration procedure.
Figure 8-11. Calibration with Test Weights
.
Equipment Required
Truck scales are routinely calibrated using 25% of the capacity weight of the scale. Certified Class F test weights
equaling at least 12.5% of the scale’s capacity will be required for calibrating a commercial legal-for-trade truck
scale. In addition, some type of weight for a substitution test of an additional 12.5% of the capacity will be
required. This can be the test-weight truck, bags of sand, or any convenient items easy to load onto the scale. This
total calibration weight of 25% of scale capacity (12.5% test weights, 12.5% substitution weight) is required by
weights and measures officials for commercial truck scales in most states. Check with your local weights and
measures officials for the requirements in your jurisdiction.
Industrial scales not used for legal-for-trade transactions do not require certified test weights. Weight equal to 25%
of scale capacity is recommended for calibrating such scales.
See Handbook 44 for detailed calibration requirements and procedures.
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