CST Vehicle Scale Systems & Applications 1 — Questions and Answers
Question 1: What is the federal maximum gross vehicle weight (GVW) limit for vehicles operating on U.S. interstate highways?
- 60,000 lbs
- 70,000 lbs
- 80,000 lbs (Correct answer)
- 90,000 lbs
Correct answer: 80,000 lbs
Federal law limits gross vehicle weight to 80,000 lbs on interstate highways under the Federal Bridge Formula.
Question 2: What type of foundation is most commonly required for a properly installed pit-mounted truck scale?
- Wooden frame with concrete anchors
- Reinforced concrete with drainage provisions (Correct answer)
- Asphalt pad with steel supports
- Gravel base with moisture barrier
Correct answer: Reinforced concrete with drainage provisions
Pit-mounted truck scales require reinforced concrete foundations with drainage to prevent water accumulation that can damage load cells and electronics.
Question 3: What is the primary purpose of a summing board (junction box) in a multi-load-cell vehicle scale?
- To amplify the output signal from each load cell
- To combine and balance individual load cell signals into one output (Correct answer)
- To provide power distribution to all load cells
- To convert analog signals to digital format
Correct answer: To combine and balance individual load cell signals into one output
A summing board combines signals from multiple load cells and allows trim resistors to balance the outputs, providing a single accurate signal to the weight indicator.
Question 4: What is the minimum deck length typically required for a single-draft weighing of a standard 18-wheel tractor-trailer?
- 40 feet
- 50 feet
- 60 feet
- 70 feet (Correct answer)
Correct answer: 70 feet
A standard tractor-trailer combination is approximately 70 feet long, requiring a 70-foot deck to ensure the entire vehicle is on the scale during a single-draft weighing.
Question 5: What is the primary purpose of approach ramps on a truck scale installation?
- To provide visual alignment guidance for drivers
- To ensure vehicles travel in a controlled, level manner onto the deck preventing shock loading (Correct answer)
- To provide additional weighing capacity beyond the main deck
- To protect the scale pit from rainwater runoff
Correct answer: To ensure vehicles travel in a controlled, level manner onto the deck preventing shock loading
Approach ramps ensure vehicles transition smoothly and levelly onto the scale deck, preventing shock loading and dynamic errors that would compromise accuracy.
Question 6: Which type of load cell configuration is most commonly used in modern truck scales?
- Single-ended shear beam
- S-type tension/compression load cell
- Double-ended shear beam (Correct answer)
- Ring torsion load cell
Correct answer: Double-ended shear beam
Double-ended shear beam load cells are preferred in truck scales because their symmetric design resists the high lateral and horizontal forces experienced during vehicle weighing.
Question 7: What does NTEP stand for, and what is its significance for vehicle scales used in commercial trade?
- National Technical Equipment Program; a voluntary accuracy standard
- National Type Evaluation Program; certifies that a scale design meets NIST Handbook 44 requirements for legal-for-trade use (Correct answer)
- National Testing and Equipment Protocol; federal safety compliance program
- National Trade Equipment Program; standardizes scale pricing structures
Correct answer: National Type Evaluation Program; certifies that a scale design meets NIST Handbook 44 requirements for legal-for-trade use
NTEP (National Type Evaluation Program) evaluates and certifies that scale designs comply with NIST Handbook 44, making them legal for trade transactions in the United States.
CST Vehicle Scale Systems & Applications 1
What is the federal maximum gross vehicle weight (GVW) limit for vehicles operating on U.S. interstate highways?