Question 1

Which of the following will have most influence over the rpm of a hydraulic pump?

Accepted Answer

The rpm (revolutions per minute) of a hydraulic pump is most directly influenced by the input flow of oil. The input flow determines how quickly the pump can operate, as it needs a certain amount of fluid to turn.

Question 2

Technician A says that spool valves may be controlled hydraulically or electrically.Technician B says that spool valves can be controlled manually or pneumatically.Who is correct?

Accepted Answer

Spool valves can indeed be controlled by various methods including hydraulically, electrically, manually, and pneumatically, making both Technician A and Technician B correct.

Question 3

What is the usual cause of a hydraulic oil that has a milky appearance?

Accepted Answer

The milky appearance of hydraulic oil is typically caused by contamination with water. When water mixes with hydraulic oil, it becomes emulsified, leading to a cloudy or milky appearance. This can significantly affect the performance and lifespan of the hydraulic system.

Question 4

Technician A says that a single acting cylinder can have a wet side and a dry side.Technician B says that an example of a double-acting cylinder would be the ram used to raise a dump truck box.Who is correct?

Accepted Answer

The answer of Technician A says that a single acting...

Question 5

What type of valve is used as the primary directional control valve in most hydraulic circuits?

Accepted Answer

Spool valves are commonly used as the primary directional control valves in hydraulic circuits due to their ability to control the direction of fluid flow efficiently.

Question 6

What does a hydraulic analyzer test?

Accepted Answer

A hydraulic analyzer is designed to test various parameters of a hydraulic system, including circuit flow, peak pressure, and circuit leakage, among others.

Question 7

Technician A says that pump flow at maximum pressure should be at least 75% of the flow measured at 0 pressure in simple hydraulic cylinder circuit.Technician B says that one way of checking internal leakage in a simple hydraulic cylinder circuit is to disconnect the return hose when the cylinder is actuated,and watch for leakage.Who is correct?

Accepted Answer

Both A and B are correct. Technician A is correct because the pump flow at maximum pressure should be at least 75% of the flow measured at 0 pressure in a simple hydraulic cylinder circuit. This is because the pump must be able to overcome the pressure in the circuit in order to move the cylinder. Technician B is correct because one way of checking internal leakage in a simple hydraulic cylinder circuit is to disconnect the return hose when the cylinder is actuated and watch for leakage. If there is leakage, it indicates that there is a problem with the cylinder seals or other components.

Question 8

What is the nominal diameter of hydraulic hose rated at #6 dash?

Accepted Answer

The nominal diameter of a hydraulic hose rated at #6 dash is 3/8 inch. The dash number in hydraulic hose sizing corresponds to the diameter of the hose in sixteenths of an inch. Therefore, a #6 dash size means 6/16 or 3/8 inch.

Question 9

Technician A says that when coupling hydraulic fittings,pipe seal compound should usually be applied to female ends only.Technician A says that when final torquing hydraulic fittings,two wrenches should always be used.Who is correct?

Accepted Answer

Technician B is correct because when final torquing hydraulic fittings, two wrenches should be used to prevent twisting or damaging the fittings. Technician A is incorrect because pipe seal compound is typically applied to male threads, not female ends.

Question 10

Which of the following terms would properly define a hydraulic cylinder?

Accepted Answer

A hydraulic cylinder is a type of linear actuator that creates motion in a straight line using hydraulic fluid.

Question 11

Which of the following types of hydraulic hose should be used to sustain the highest pressures and surge spikes?

Accepted Answer

Spiral wire braid hoses are designed to handle the highest pressure levels and are specifically engineered to resist pressure spikes and flexing, making them suitable for high-pressure applications.

Question 12

Technician A says that ISO 32 is the most commonly used viscosity grade for hydraulic fluids.Technician B says that ISO 32 is equivalent to SAE 20 grade.Who is correct?

Accepted Answer

The answer of Technician A says that ISO 32 is...

Quiz 13: Hydraulics