FREE Millwright Hydraulic Systems and Schematics Questions and Answers

Question 1

In a hydraulic schematic, what is the function of a symbol showing a rectangle with a spring line and an arrow drawn diagonally through it?

Accepted Answer

A variable pressure relief valve

Answer

This symbol represents a variable pressure relief valve. The rectangle is the valve body, the arrow indicates it's adjustable (variable), and the spring shows it is spring-loaded to open at a set pressure, protecting the system from over-pressurization.

Question 2

What is the primary function of an accumulator in a hydraulic system?

Accepted Answer

To store hydraulic energy and absorb shocks

Answer

An accumulator stores hydraulic fluid under pressure, typically using a compressed gas bladder. This stored energy can be used to absorb shocks, supplement pump flow for short periods, or maintain system pressure if the pump is shut down.

Question 3

A loud whining or screeching noise from a hydraulic pump is often a symptom of what condition?

Accepted Answer

Pump cavitation

Answer

Cavitation is the formation and collapse of vapor bubbles in the fluid, typically caused by a starved inlet (clogged suction strainer, low fluid level). This condition is very destructive to the pump and produces a characteristic high-pitched whining sound.

Question 4

According to Pascal's Law, if a 100 lb force is applied to a 1-square-inch piston, what is the maximum weight that can be lifted by a 10-square-inch piston in the same system?

Accepted Answer

1,000 lbs

Answer

Pascal's Law states that pressure is transmitted equally throughout a confined fluid (P = F/A). The pressure is 100 lbs / 1 sq. in = 100 PSI. This pressure acts on the larger piston, so the lifting force is 100 PSI * 10 sq. in = 1000 lbs.

Question 5

What does the designation '4/3' for a directional control valve indicate?

Accepted Answer

4 ports and 3 positions

Answer

The first number in a directional control valve designation indicates the number of ports (ways) for fluid to flow. The second number indicates the number of distinct positions the valve spool can be in to direct that flow.

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FREE Millwright Hydraulic Systems and Schematics Questions and Answers