CWT Troubleshooting & Maintenance Flashcards
6 cards from real CWT practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 CWT Troubleshooting & Maintenance flashcards as text
A floor scale in a warehouse reads zero correctly when empty but consistently reads 5 lb light on all test weights. What type of error is this?
Answer: Span error (sensitivity error)
When a scale reads zero correctly but its error is proportional across the range (consistently off by the same percentage or fixed amount at all loads), it has a span or sensitivity error that requires span recalibration.
What is 'hysteresis' in the context of load cell performance?
Answer: The difference in output readings for the same load applied during increasing versus decreasing loading sequences
Hysteresis is the difference between a load cell's output when a given load is approached from below (increasing) versus from above (decreasing), reflecting mechanical memory in the sensing element.
A CWT performs a maintenance inspection and finds that the scale's check rods are bent. What is the likely effect on scale performance?
Answer: The check rods may be supporting part of the load, causing the scale to read light
Bent check rods can contact the scale structure and mechanically transfer part of the load away from the load cells, causing the scale to consistently underweigh loads.
Which preventive maintenance activity is most important for ensuring the long-term accuracy of a vehicle scale installed in an outdoor pit?
Answer: Regular cleaning of the scale pit and inspection of load cells for moisture and corrosion
Outdoor vehicle scale pits are prone to water accumulation, debris, and corrosion that degrade load cells over time, so pit cleaning and cell inspection are the most critical preventive maintenance tasks.
A technician observes that a scale's digital indicator shows random single-digit jumps in the last digit even with a stable load. What is the most likely cause?
Answer: Electrical noise or radio frequency interference (RFI) affecting the analog signal path
Random last-digit instability on a digital scale is typically caused by electrical noise or RFI coupling into the analog signal from the load cell before it is digitized by the A/D converter.
After completing maintenance and recalibration of a commercial scale, what is the final step a CWT must take before returning the scale to service?
Answer: Document all work performed and ensure any required regulatory seals or security provisions are in place
Complete documentation of maintenance activities and restoration of any legally required seals or security features are mandatory final steps before a commercial scale is returned to service.