OECP Hydraulic Systems & Pneumatics

Question 1

What does Pascal's Law state as it applies to hydraulic systems?

Accepted Answer

Pressure applied to a confined fluid is transmitted equally in all directions

Answer

Fluid flows from high pressure to low pressure only

Answer

Hydraulic pressure decreases as fluid temperature increases

Answer

Force equals mass times acceleration in hydraulic circuits

Question 2

What is the primary function of a hydraulic pump in a construction equipment system?

Accepted Answer

To convert mechanical energy into hydraulic flow

Answer

To increase fluid pressure by compressing the hydraulic fluid

Answer

To store hydraulic fluid under pressure for emergency use

Answer

To filter contaminants from circulating hydraulic fluid

Question 3

Which type of hydraulic pump is most commonly used in heavy construction equipment due to its ability to handle high pressures and provide variable displacement?

Accepted Answer

Piston pump

Answer

Gear pump

Answer

Vane pump

Answer

Centrifugal pump

Question 4

What does hydraulic fluid viscosity refer to in the context of system performance?

Accepted Answer

The fluid's resistance to flow, commonly described as its thickness

Answer

The fluid's resistance to oxidation and thermal breakdown

Answer

The fluid's boiling point when subjected to system pressure

Answer

The fluid's ability to compress under heavy actuator loads

Question 5

What is the purpose of a hydraulic relief valve in a construction equipment circuit?

Accepted Answer

To limit maximum system pressure and protect components from damage

Answer

To increase system pressure when actuators are under heavy load

Answer

To filter foreign particles from circulating hydraulic fluid

Answer

To direct fluid flow to specific actuators based on operator input

Question 6

In a hydraulic system, what is the primary function of a directional control valve?

Accepted Answer

To control the direction of fluid flow to actuators

Answer

To regulate the speed of hydraulic actuators by restricting flow

Answer

To maintain constant system pressure regardless of load

Answer

To cool hydraulic fluid returning from actuators

Question 7

What is cavitation in a hydraulic system and why is it harmful?

Accepted Answer

Vapor bubbles form in low-pressure zones and collapse violently in high-pressure areas, causing component damage

Answer

Excessive heat generation in hydraulic fluid causes the fluid to vaporize inside the pump

Answer

Contamination of fluid with metal particles causes abrasive wear on pump components

Answer

Pressure loss due to worn pump seals allows air to enter the suction side