ITMC Mechanical Systems & Equipment Maintenance 4 — Questions and Answers
Question 1: During a routine inspection, a technician finds a roller chain with 3% elongation. The correct action is to:
- Lubricate the chain and continue service
- Replace the chain immediately (Correct answer)
- Adjust sprocket alignment
- Increase chain tension
Correct answer: Replace the chain immediately
A chain elongation of 2-3% or more causes pitch mismatch with sprocket teeth, leading to rapid wear and should be replaced.
Question 2: Which lubrication method delivers a metered, continuous supply of oil directly to rolling element bearings in high-speed applications?
- Grease packing
- Oil mist lubrication (Correct answer)
- Splash lubrication
- Wick lubrication
Correct answer: Oil mist lubrication
Oil mist systems atomize oil and deliver it via air pressure to bearings, minimizing churning losses at high speeds.
Question 3: A centrifugal pump installed below the fluid reservoir operating with a positive suction head is called a:
- Booster pump configuration
- Flooded suction installation (Correct answer)
- Priming lift installation
- Negative head arrangement
Correct answer: Flooded suction installation
A flooded suction installation has the pump inlet below the fluid level, so gravity feeds the fluid to the pump without priming.
Question 4: When diagnosing a pneumatic cylinder that extends but will not retract, the technician should first check the:
- Compressor output pressure
- Directional control valve for proper shifting (Correct answer)
- Cylinder bore for scoring
- Air line filter for restriction
Correct answer: Directional control valve for proper shifting
A 4-way directional control valve that fails to shift will prevent the cylinder from reversing direction.
Question 5: What does the term 'interference fit' mean in the context of shaft and bearing assembly?
- The shaft is smaller than the bearing bore, requiring a spacer
- The shaft is slightly larger than the bore so assembly requires force or heat (Correct answer)
- The shaft and bore are the same size for a slip fit
- The bearing is press-fit only at operating temperature
Correct answer: The shaft is slightly larger than the bore so assembly requires force or heat
An interference fit means the shaft OD is slightly larger than the bore ID, requiring force or thermal expansion to assemble.
Question 6: Which of the following is a primary indicator of imbalance in a rotating machine as seen on a vibration spectrum?
- High vibration at 2× running speed (2X)
- High vibration at 1× running speed (1X) (Correct answer)
- Sub-synchronous vibration below 1X
- High-frequency vibration above 10X
Correct answer: High vibration at 1× running speed (1X)
Mass unbalance generates a strong vibration component at exactly 1× running speed (1X) in the radial direction.
Question 7: A hydraulic pump that makes a high-pitched whining or screaming noise is most likely experiencing:
- Aeration (air ingestion)
- Cavitation (Correct answer)
- High system pressure
- Worn drive coupling
Correct answer: Cavitation
Cavitation causes high-pitched noise as vapor bubbles collapse violently inside the pump, and can rapidly erode pump components.
ITMC Mechanical Systems & Equipment Maintenance 4
During a routine inspection, a technician finds a roller chain with 3% elongation.
The correct action is to: