Technical Skills & Application Flashcards
7 cards from real CEM practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Technical Skills & Application flashcards as text
A CEM reviewing oil analysis data notices a sharp increase in silicon content across multiple machines sharing the same job site. The MOST likely root cause is:
Answer: Dirt ingestion through compromised air filtration systems
Silicon is the primary elemental marker for dust and dirt ingestion, and a fleet-wide spike on one site strongly indicates a common air filtration failure or improper filter servicing.
Which specification MOST directly limits the allowable worn clearance in a diesel engine main bearing?
Answer: OEM maximum wear clearance published in the engine service manual
OEM service manuals specify maximum allowable main bearing clearance; exceeding this value causes oil pressure drop and accelerated crankshaft wear.
When pressure-testing a hydraulic accumulator for pre-charge nitrogen pressure, the technician should:
Answer: Use a dedicated nitrogen charging kit and check gas pressure only with the hydraulic side depressurized
Accumulators must be hydraulically depressurized before checking nitrogen pre-charge to prevent dangerous measurement error and injury; only nitrogen (inert gas) is used.
A scraper elevator chain stretches beyond tolerance after only half the expected service life. Which maintenance factor is MOST likely responsible?
Answer: Under-lubrication of the chain pins and bushings
Inadequate lubrication of chain pins and bushings accelerates wear and elongation, dramatically shortening chain service life.
On a wheel excavator, the stabilizer cylinders lock up and become inoperative after the machine sits overnight. No hydraulic fluid loss is observed. The MOST probable cause is:
Answer: Internal rust or corrosion causing piston seizure due to moisture intrusion
Stabilizer cylinders exposed to temperature cycling can allow condensation, and if protective coatings are worn, moisture causes corrosion and seizing of the piston-to-barrel interface overnight.
What is the function of a torque converter lock-up clutch in heavy equipment power trains?
Answer: It mechanically couples the engine to the transmission input at higher speeds to eliminate slippage and improve efficiency
The lock-up clutch bypasses the fluid coupling in the torque converter at cruise speeds, creating a direct mechanical drive that eliminates torque converter heat and improves fuel efficiency.
A pneumatic tire on a rigid-frame haul truck shows accelerated wear on the outer shoulder only. Which operational condition BEST explains this wear pattern?
Answer: Excessive cornering speed on haulage curves causing lateral scrub
Outer shoulder wear on haul truck tires is the classic signature of excessive lateral forces during cornering, which scrubs material from the outer edge.