Lubrication Systems & Maintenance Flashcards

What type of lubrication system is most appropriate for high-speed spindle bearings in machine tools requiring minimal lubricant quantity?

Answer: Oil mist or air-oil (minimum quantity) lubrication

High-speed spindle bearings benefit from oil mist or air-oil systems that deliver very precise, minimal lubricant quantities to prevent churning and heat buildup at high RPMs.

In a splash lubrication system for a gearbox, what determines how much oil is picked up and distributed?

Answer: The depth of oil immersion of the rotating gear teeth

In splash lubrication, rotating gear teeth dip into the oil sump and fling oil to other components; the depth of immersion and gear speed determine the quantity of oil distributed.

Which condition monitoring technique is MOST effective for detecting early-stage bearing defects in lubricated machinery?

Answer: Vibration analysis using high-frequency envelope detection

High-frequency envelope (demodulation) vibration analysis detects the characteristic impact frequencies of bearing defects long before they become audible or visible.

What does 'relubrication interval' mean in the context of grease-lubricated bearings?

Answer: The scheduled time or operating hours between grease additions

The relubrication interval is the recommended time or operating hours between adding fresh grease to a bearing to maintain an adequate protective film.

When calculating the relubrication interval for a grease-lubricated rolling element bearing, which factor MOST significantly reduces the interval?

Answer: Operating speed increasing (higher DN value)

Higher operating speeds (elevated DN value) increase heat and mechanical working of the grease, shortening the relubrication interval significantly.

In oil analysis, what does a high particle count from a laser particle counter PRIMARILY indicate?

Answer: Elevated contamination level, potentially from wear or ingression

A high particle count indicates elevated contamination levels — from internal wear debris, ingressed dirt, or degradation products — requiring investigation of the contamination source.

What is the purpose of a kidney-loop (off-line) filtration system connected to a lubricated machine?

Answer: To continuously filter oil independently of the main system flow to improve cleanliness

A kidney-loop system continuously circulates and filters a portion of the oil reservoir independently, progressively improving oil cleanliness without affecting main system flow.