ITMC Mechanical Systems & Equipment Maintenance 3 — Questions and Answers
Question 1: A hydraulic system pressure gauge reads normal but the actuator moves slowly. The most likely cause is:
- High system pressure
- Internal leakage past a worn control valve spool (Correct answer)
- Excessive fluid viscosity at low temperature
- Clogged pressure relief valve
Correct answer: Internal leakage past a worn control valve spool
Internal valve spool leakage allows flow to bypass the actuator, reducing speed while maintaining gauge pressure.
Question 2: When replacing a timing chain or belt, technicians must ensure the:
- Tension is set as tight as possible
- Timing marks on the crankshaft and camshaft are aligned (Correct answer)
- Old sprockets are also replaced with new ones
- Chain is lubricated with grease
Correct answer: Timing marks on the crankshaft and camshaft are aligned
Proper alignment of timing marks ensures correct valve timing relative to piston position.
Question 3: A shaft keyway coupling transmits torque primarily through:
- Friction between the hub and shaft
- A key seated in mating keyways on the shaft and hub (Correct answer)
- Set screws threaded into the hub
- Interference fit alone
Correct answer: A key seated in mating keyways on the shaft and hub
The key transfers torque by bearing against the sides of the keyways cut into both the shaft and the hub.
Question 4: Which maintenance strategy uses real-time equipment condition data to schedule repairs only when needed?
- Corrective maintenance
- Preventive maintenance
- Predictive maintenance (Correct answer)
- Run-to-failure maintenance
Correct answer: Predictive maintenance
Predictive maintenance monitors equipment condition parameters to forecast failure and schedule intervention before breakdown.
Question 5: When tightening a bolted flange joint in a pressurized piping system, the correct procedure is to:
- Tighten one bolt fully before moving to the next
- Tighten all bolts to 25% torque in a star (cross) pattern, then increase in stages (Correct answer)
- Hand-tighten only to avoid gasket damage
- Tighten the top bolts first, then bottom bolts
Correct answer: Tighten all bolts to 25% torque in a star (cross) pattern, then increase in stages
A cross-pattern, multi-pass torquing procedure ensures even gasket compression and prevents leaks.
Question 6: What type of coupling is used to connect two shafts when slight angular misalignment cannot be avoided?
- Rigid sleeve coupling
- Jaw (spider) flexible coupling (Correct answer)
- Oldham coupling
- Flanged rigid coupling
Correct answer: Jaw (spider) flexible coupling
Jaw flexible couplings tolerate minor angular, parallel, and axial misalignment through the elastomeric spider insert.
Question 7: The function of a pressure relief valve in a hydraulic circuit is to:
- Maintain constant flow to actuators
- Limit maximum system pressure to prevent component damage (Correct answer)
- Filter contaminants from the fluid
- Control actuator direction
Correct answer: Limit maximum system pressure to prevent component damage
A pressure relief valve opens when system pressure exceeds its set point, diverting flow back to tank to protect components.
ITMC Mechanical Systems & Equipment Maintenance 3
A hydraulic system pressure gauge reads normal but the actuator moves slowly.
The most likely cause is: