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Preventive Maintenance and Lubrication Flashcards

7 cards from real CPM practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 Preventive Maintenance and Lubrication flashcards as text

  1. Which NLGI grease consistency grade is most commonly used for general-purpose rolling element bearings?

    Answer: NLGI 2

    NLGI 2 has a peanut-butter consistency that suits most plain and rolling element bearings.

  2. A lubricating oil's viscosity index (VI) describes what property?

    Answer: How much its viscosity changes with temperature

    A higher VI means the oil's viscosity changes less as temperature rises or falls.

  3. An oil labeled ISO VG 68 has a nominal kinematic viscosity of 68 cSt at what temperature?

    Answer: 40°C

    ISO viscosity grades are defined by kinematic viscosity at 40°C.

  4. What is the most likely result of over-greasing a sealed-housing ball bearing?

    Answer: Higher operating temperature from grease churning

    Excess grease is churned by the rolling elements, generating friction heat and possibly blowing out seals.

  5. What can happen when two greases with incompatible thickeners are mixed in a bearing?

    Answer: The mixture can soften, bleed oil, and lose its ability to stay in place

    Incompatible thickeners can break down the grease structure, causing softening and leakage.

  6. The dropping point of a grease is best defined as:

    Answer: The temperature at which grease becomes fluid enough to drip

    Dropping point is the temperature at which grease passes from semi-solid to liquid under test conditions.

  7. Which oil additive is used mainly to reduce foaming in gearboxes and hydraulic reservoirs?

    Answer: Silicone-based antifoam agent

    Small amounts of silicone antifoam help air bubbles break at the oil surface.