ITMC Hydraulic Systems 4

Question 1

What ISO cleanliness code reading of 18/16/13 means in a hydraulic system?

Accepted Answer

Particle count levels per milliliter at 4, 6, and 14 micron size ranges

Answer

Each ISO 4406 number represents a range of particle counts per milliliter at 4µm, 6µm, and 14µm respectively.

Question 2

A hydraulic motor stalls under load even though system pressure is adequate. What is the most likely cause?

Accepted Answer

Excessive internal leakage within the motor

Answer

Worn motor components allow internal bypass of fluid, reducing torque output even when supply pressure is sufficient.

Question 3

Which hydraulic fitting connection type is least prone to leakage under high-pressure pulsating conditions?

Accepted Answer

O-ring face seal (ORFS)

Answer

ORFS fittings use an elastomeric O-ring on a flat face, providing a positive seal unaffected by pressure pulses.

Question 4

What does the term 'pump volumetric efficiency' measure?

Accepted Answer

Actual flow output compared to theoretical flow based on displacement and speed

Answer

Volumetric efficiency accounts for internal pump leakage; a new pump may be 95%+ efficient while a worn pump drops significantly.

Question 5

When troubleshooting a hydraulic system with no actuator movement, which component should typically be checked first?

Accepted Answer

Fluid level and pump output

Answer

Confirm the pump is producing flow and pressure before suspecting downstream components in a no-movement diagnosis.

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