ITMC Preventive Maintenance & Troubleshooting 4 — Questions and Answers
Question 1: A pneumatic cylinder is slow to extend but retracts at normal speed. The MOST likely cause is:
- A failed return spring
- A restriction in the extend-side flow path or a leaking piston seal (Correct answer)
- Low compressor output pressure
- A faulty solenoid coil
Correct answer: A restriction in the extend-side flow path or a leaking piston seal
Slow extension with normal retraction points to a restriction or internal piston seal leak on the extend side, reducing effective force and speed in one direction.
Question 2: When using a dial indicator to check shaft runout on a lathe, the total indicator reading (TIR) represents:
- The average deviation from true center
- The total range from minimum to maximum reading over one full rotation (Correct answer)
- The distance the shaft has moved axially
- Half the actual eccentricity value
Correct answer: The total range from minimum to maximum reading over one full rotation
TIR (Total Indicator Reading) is the full range between the highest and lowest dial indicator values recorded during one complete shaft rotation.
Question 3: A conveyor belt is tracking to one side consistently. What is the MOST common PM adjustment to correct this?
- Increase belt tension uniformly
- Adjust the tail pulley to steer the belt back to center (Correct answer)
- Replace the belt with a wider one
- Add side guides to the conveyor frame
Correct answer: Adjust the tail pulley to steer the belt back to center
Adjusting the tail (or training) pulley tilts it slightly, which steers the belt back toward the center of the conveyor.
Question 4: What is the significance of the P-F curve in predictive maintenance?
- It shows the relationship between pressure and flow in hydraulic systems
- It represents the time between a detectable potential failure and functional failure (Correct answer)
- It graphs the probability of failure over equipment lifespan
- It defines the performance curve of a centrifugal pump
Correct answer: It represents the time between a detectable potential failure and functional failure
The P-F curve shows the interval between when a potential failure can first be detected (point P) and when functional failure occurs (point F), defining the window for predictive intervention.
Question 5: A technician is torquing bolts on a critical flange connection. The CORRECT procedure is to:
- Tighten all bolts fully in a clockwise sequence
- Tighten bolts in a star (cross) pattern in multiple passes to the final torque (Correct answer)
- Apply thread lubricant and tighten to hand-tight only
- Tighten the most accessible bolts first to specification
Correct answer: Tighten bolts in a star (cross) pattern in multiple passes to the final torque
A cross (star) pattern in multiple incremental passes ensures even load distribution across the flange and prevents warping or uneven gasket compression.
Question 6: Which electrical test is used to detect insulation breakdown between motor windings and the motor frame (ground)?
- Continuity test
- Megohmmeter (megger) test (Correct answer)
- Hi-pot test
- Clamp-on ammeter test
Correct answer: Megohmmeter (megger) test
A megohmmeter applies high DC voltage to measure insulation resistance between windings and ground, identifying insulation degradation or breakdown.
Question 7: During troubleshooting, a technician uses the 'half-split' method. This technique means:
- Replacing half the suspected components and retesting
- Dividing the system in half to isolate the fault location, then repeating (Correct answer)
- Testing the first and last components in a circuit only
- Splitting maintenance tasks between two technicians for speed
Correct answer: Dividing the system in half to isolate the fault location, then repeating
The half-split (binary search) method divides the system at its midpoint to determine which half contains the fault, then repeats until the fault is isolated.
ITMC Preventive Maintenance & Troubleshooting 4
A pneumatic cylinder is slow to extend but retracts at normal speed.
The MOST likely cause is: