AIT Technical Skills & Application 2 — Questions and Answers
Question 1: When using a micrometer to measure shaft diameter, which technique ensures the most accurate reading?
- Apply maximum torque to the thimble until it stops
- Use the ratchet stop to apply consistent measuring pressure (Correct answer)
- Tighten the lock nut before taking the reading
- Hold the part vertically and read from below
Correct answer: Use the ratchet stop to apply consistent measuring pressure
The ratchet stop limits measuring force to a consistent level, preventing over-tightening that would compress the part and give a falsely small reading.
Question 2: A journeyman electrician must calculate the ampacity of a conductor. The formula is based on which primary factors?
- Wire color coding and insulation thickness only
- Conductor material, cross-sectional area, and ambient temperature rating (Correct answer)
- The breaker size and length of the run only
- Voltage class and manufacturer brand
Correct answer: Conductor material, cross-sectional area, and ambient temperature rating
Ampacity depends on conductor material (copper vs aluminum), cross-sectional area (AWG/kcmil), and the temperature rating of the insulation in the installation environment.
Question 3: In welding, what is the purpose of a preheat treatment applied to base metal before welding?
- To increase the carbon content of the weld pool
- To reduce the hardening and cracking risk by slowing post-weld cooling (Correct answer)
- To eliminate the need for post-weld heat treatment
- To make the base metal softer so the electrode melts more easily
Correct answer: To reduce the hardening and cracking risk by slowing post-weld cooling
Preheating slows the cooling rate after welding, reducing thermal gradients that cause hydrogen-induced cracking and martensitic hardening in high-carbon or alloy steels.
Question 4: An apprentice plumber is installing a drain line and needs to maintain a proper slope for gravity drainage. What is the standard minimum slope per foot for a 3-inch drain line?
- 1/16 inch per foot
- 1/8 inch per foot
- 1/4 inch per foot (Correct answer)
- 1/2 inch per foot
Correct answer: 1/4 inch per foot
The International Plumbing Code requires a minimum slope of 1/4 inch per foot for drain lines 3 inches and smaller to ensure self-scouring velocity.
Question 5: Which type of bearing is best suited for absorbing both radial and axial (thrust) loads simultaneously in a gearbox application?
- Deep-groove ball bearing
- Cylindrical roller bearing
- Angular contact ball bearing (Correct answer)
- Needle roller bearing
Correct answer: Angular contact ball bearing
Angular contact ball bearings are designed with an offset contact angle that allows them to support combined radial and axial loads, making them standard for gearbox output shafts.
Question 6: When reading a hydraulic circuit diagram, a symbol showing a rectangle with a single arrow pointing in one direction represents which component?
- A double-acting hydraulic cylinder
- A fixed-displacement hydraulic motor
- A fixed-displacement hydraulic pump (Correct answer)
- A flow control valve
Correct answer: A fixed-displacement hydraulic pump
In ISO hydraulic symbols, a rectangle (or circle) with one arrow pointing inward represents a fixed-displacement pump; one arrow pointing outward represents a fixed-displacement motor.
Question 7: An HVAC technician measures superheat in a refrigeration system. Superheat is defined as the temperature difference between which two values?
- Condensing temperature and ambient temperature
- Suction line temperature and the saturation temperature at suction pressure (Correct answer)
- Liquid line temperature and subcooling temperature
- Discharge temperature and condensing temperature
Correct answer: Suction line temperature and the saturation temperature at suction pressure
Superheat is measured at the suction line: actual suction line temperature minus the saturation (boiling) temperature corresponding to suction pressure — confirming full vaporization before the compressor.
AIT Technical Skills & Application 2
When using a micrometer to measure shaft diameter, which technique ensures the most accurate reading?