Hydraulic Principles

Question 1

List 4 advantages of hydraulic control of heavy equipment machinery functions.

Answer 1

1. Hydraulic components are relatively compact. They are powerful yet are light in weight and generally occupy a small space.
2. Cooling and lubrication of system components is easy to accommodate
3. The operator can easily control several functions at one time which increases productivity.
4. Hydraulic systems are easily protected from overload conditions without component breakdown or engine stall.

Question 2

Work is defined as a:
A. Push or pull.
B. Force acting through a distance.
C. Force applied to a resistance.
D. Potential energy.

Answer 2

force acting through a distance.

Question 3

Energy is defined as:

Answer 3

The ability to do work.

Question 4

The law of conservation of energy states that:

Answer 4

energy cannot be created of destroyed.

Question 5

A hydraulic actuator converts:
A. Mechanical energy into heat energy.
B. Heat energy into mechanical energy.
C. Mechanical energy into hydraulic energy.
D. Hydraulic energy into mechanical energy.

Answer 5

Hydraulic energy into mechanical energy.

Question 6

Potential energy in a hydraulic system is responsible for creating:
A. Force
B. Motion
C. Actuator speed.
D. Mechanical energy.

Answer 6

Force

Question 7

Laminar flow refers to:

Answer 7

flow that moves in a straight parallel flow path.

Question 8

Excessively turbulent flow in a hydraulic system will result in excessive:
A. Flow losses.
B. Internal leakage.
C. Pressure losses.
D. Lack of actuator speed.

Answer 8

Pressure losses.

Question 9

Actuators connected in a series provide:
A. High torque but limited speed.
B. High torque and high speed.
C. Limited torque but high speed.
D. Low power losses.

Answer 9

Limited torque but high speed.

Question 10

Hydraulic fluids that have a low VI number.
A. Have wide viscosity changes with temperature.
B. Do not have wide viscosity changes with temperature.
C. Have a low viscosity.
D. Have good oxidation resistance.

Answer 10

A. Have wide viscosity changes with temperature.

Question 11

Two conditions that indicate that an oil is excessively oxidized are:

Answer 11

1. Smells burnt.

2. Has a watery feel.

Question 12

State the two conditions that a hydraulic fluid must meet in order to be classified as biodegradable.

Answer 12

1. 70-80% of the fluid must be able to be broken down by micro organisms.
2. Fluid must not harm living organisms.

Question 13

List four entry points of ingressed contamination.

Answer 13

1. Reservoir air breathers.
2. Pump inlet leakage.
3. Cylinder seals.
4. Unclean maintenance procedures.

Question 14

Degradation failures are caused by:

Answer 14

gradual surface wear.

Question 15

List four disadvantages of hydraulic control of heavy equipment machinery functions.

Answer 15

1. Fluids under pressure can result in personal injury or death if not handled safely.
2. Oil leakage is a source of contamination and fire.
3. Temperature variations effect component reliability and machine performance.
4. Air trapped in the flow of oil can produce erratic and spongy machine operation and result in component damage.

Question 16

Force is the push or pull that is capable of producing or changing the motion of a body.
A. True
B. False

Answer 16

True

Question 17

List four common forms of energy

Answer 17

1. Mechanical energy.
2. Heat energy.
3. Electrical energy.
4. Chemical energy.

Question 18

In an engine, chemical energy in the fuel is converted to mechanical energy in the engine combustion chamber.

1. True
2. False

Answer 18

False

Question 19

Kinetic energy in a hydraulic system is created by:

Answer 19

the flow of oil through the system.

Question 20

List three conditions that could result in turbulent flow.

Answer 20

1. Installing conductors that are too small.
2. Abrupt changes in conductor cross section.
3. Abrupt changes in flow direction.

Question 21

Hydraulic actuators that are connected in series will have the same pressure applied to each actuator.
A. True
B. False

Answer 21

False

Question 22

Describe the pressure and flow characteristics of a hydraulic circuit that has multiple actuators connected in parallel.
A. Pressure characteristics are ___________
B. Flow characteristics are _____________

Answer 22

A. Pressure characteristics are the same pressure is applied to each actuator.
B. Flow characteristics are the flow is split amongst the actuators.

Question 23

The oil characteristic that has the most significant effect on the oil's lubricating ability is:
A. Oxidation resistance.
B. Demulsification.
C. Viscosity.
D. Corrosion resistance.

Answer 23

C. Viscosity

Question 24

Which of the following hydraulic fluids is not a fire resistant fluid?
A. Water oil emulsion.
B. Invert emulsion.
C. Water glycol fluid.
D. Petroleum based fluid.

Answer 24

D. Petroleum based fluid.

Question 25

Why is it a common service procedure to replace the hydraulic filter on a new piece of machinery after about 100 hours of operation?

Answer 25

To remove built in contamination from the system.

Question 26

A rapid total disabling of a system or component is known as an:
A. Intermittent failure.
B. Catastrophic failure.
C. Degradation failure.
D. Structural failure.

Answer 26

B. Catastrophic failure.