ASME ASME Mechanical Power Transmission 2

Question 1

In ASME/AGMA gear design, 'pitting resistance' (contact fatigue) life is primarily dependent on which stress?

Accepted Answer

Hertz contact stress at the pitch point

Answer

Pitting resistance life depends on Hertzian contact stress at the tooth surface, which causes surface fatigue (pitting) if excessive.

Question 2

What is the advantage of helical gears over spur gears for high-speed power transmission?

Accepted Answer

Helical gears have higher contact ratio, providing smoother and quieter operation

Answer

Helical gears have a higher contact ratio because multiple teeth are in contact simultaneously, resulting in smoother, quieter operation at high speeds.

Question 3

In V-belt drive design per ASME/RMA standards, what does 'effective tension' represent?

Accepted Answer

The difference between tight-side and slack-side tension, equal to the transmitted force

Answer

Effective tension is the net force transmitting power, equal to the difference between the tight-side tension and the slack-side tension.

Question 4

What is the primary advantage of a chain drive over a V-belt drive for power transmission?

Accepted Answer

Chain drives have no slip, providing a positive, constant velocity ratio

Answer

Chain drives provide a positive, non-slip drive with a constant velocity ratio, unlike belt drives which can slip under overload.

Question 5

Under ASME power transmission standards, what is the purpose of a 'service factor' for chain drives?

Accepted Answer

To modify the rated chain load capacity for the type of driven load and power source

Answer

The service factor for chain drives modifies the chain's rated load capacity to account for the type of load (smooth, moderate shock, or heavy shock) and the type of prime mover.

ASME - American Society of Mechanical Engineers Practice Test

ASME - American Society of Mechanical Engineers Practice Test

ASME ASME Mechanical Power Transmission 2