Hydraulic Systems & Fluid Management Flashcards
7 cards from real MEOC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Hydraulic Systems & Fluid Management flashcards as text
What is the primary function of the hydraulic system in a mini excavator?
Answer: To convert engine power into pressurized fluid force for operating attachments and travel
The hydraulic system converts engine power into pressurized fluid that actuates the boom, arm, bucket, and travel motors.
Which hydraulic fluid specification is most commonly required for mini excavators operating under standard US conditions?
Answer: ISO VG 46 or ISO VG 68 hydraulic oil
ISO VG 46 or VG 68 hydraulic oils provide the correct viscosity range for typical mini excavator operating temperatures and manufacturer specifications.
What is 'cavitation' in a mini excavator hydraulic system?
Answer: Formation of vapor bubbles in fluid due to localized low pressure, causing component damage
Cavitation occurs when vapor bubbles form in low-pressure zones and violently collapse, eroding pump and valve surfaces.
What is the purpose of the hydraulic return filter on a mini excavator?
Answer: To remove contaminants from fluid returning to the reservoir
The return filter captures particles and debris in fluid flowing back to the reservoir, preventing re-circulation of contaminants through precision components.
When should the hydraulic filter on a mini excavator be replaced?
Answer: At manufacturer-specified service intervals or when the restriction indicator signals restricted flow
Manufacturers specify replacement intervals based on operating hours, and bypass indicators alert operators when a filter is restricting flow before the interval is reached.
What is the function of the hydraulic relief valve in a mini excavator?
Answer: To limit maximum system pressure by diverting fluid to the reservoir when pressure exceeds a preset value
The relief valve opens at a preset pressure limit, diverting fluid back to tank and protecting pumps, hoses, and cylinders from over-pressure damage.
Which symptom most strongly indicates air contamination in a mini excavator hydraulic system?
Answer: Spongy, jerky, or inconsistent movement of boom, arm, or bucket functions
Air is compressible, so entrained air causes erratic, spongy cylinder response instead of the smooth, positive movement provided by incompressible fluid.