433A Hydraulic Systems 2

Question 1

What is cavitation in a hydraulic pump?

Accepted Answer

Formation and collapse of vapor bubbles in the fluid due to low inlet pressure

Answer

Excess pressure in the pump

Answer

Overheating of the pump housing

Answer

Wear of the pump gears

Question 2

What is the difference between a fixed displacement pump and a variable displacement pump?

Accepted Answer

A fixed pump delivers the same volume per revolution regardless of pressure, while a variable pump can adjust its output volume

Answer

Fixed pumps are larger than variable pumps

Answer

Fixed pumps operate at higher pressure

Answer

Variable pumps do not need a relief valve

Question 3

Why is the viscosity of hydraulic fluid critical to system performance?

Accepted Answer

If too thin, internal leakage increases and lubrication is poor; if too thick, flow resistance and cavitation risk increase

Answer

It determines the fluid color

Answer

It only affects the reservoir level

Answer

Viscosity does not change with temperature

Question 4

What type of hydraulic valve uses a spool to direct fluid flow?

Accepted Answer

Spool-type directional control valve

Answer

Check valve

Answer

Relief valve

Answer

Needle valve

Question 5

What is the purpose of a counterbalance valve in a hydraulic circuit?

Accepted Answer

To prevent uncontrolled movement of a load that could overrun the pump flow, such as lowering a heavy load

Answer

To balance the pressure between two pumps

Answer

To equalize flow to two cylinders

Answer

To measure the weight of the load

Question 6

How is flow rate in a hydraulic system typically measured?

Accepted Answer

With a flow meter installed in the line

Answer

With a pressure gauge

Answer

With a thermometer

Answer

By measuring the reservoir level change