Hydraulics Review

Question 1

All fluids readily transmit?

Answer 1

Pressure

Question 2

What is the advantage of hydraulics

Answer 2

It’s Lightweight, minimal maintenance requirements, simple to inspect, very efficient (98%)

Question 3

Name a simple hydraulic system

Answer 3

1. Pump
2. Pipes or hoses
3. Valve
4. Actuating cylinder
5. Reservoir

Example: Hydraulic Brake System

Question 4

Which hydraulic system has all components located in one unit?

Answer 4

Power pack

Question 5

What is viscosity?

Answer 5

Internal resistance to flow

Question 6

Type of hydraulic fluid that is flammable

Answer 6

Mineral Base MIL-H-5606 (flammable)

Question 7

Describe MINERAL-BASE MIL-H-5606

Answer 7

• PETROLEUM BASE
• COLORED RED
• IT WILL BURN
• SYNTHETIC RUBBER SEALS made of neoprene or Buna-N

Question 8

If a system using MIL-H-5606 is
contaminated

Answer 8

flush the system with
system fluid

Question 9

Describe PHOSPHATE ESTER-BASE Mil-H-8446

Answer 9

made of phosphate ester
• colored light purple
• fire resistant but not fire proof
• clean with stoddard solvent
-Seals are made from butyl rubber or ethylene-propylene elastomers
-Skydrol
-Moisture can contaminate
-High flash point

Question 10

In PHOSPHATE ESTER-BASE, ________ can contaminate it, and it is known as Skydrol ________

Answer 10

Moisture

Skydrol 500b

Question 11

If a hydraulic system requires mineral
based fluid, but skydrol is used, the system
is _______. Fluids will _________,
and _________

Answer 11

Contaminated, not blend, and seals will fail.

Question 12

Repeated or prolonged exposure may
cause drying of the skin, which if
unattended, could result in complications,
such as _________ or even ________________

Answer 12

Dermatitis, secondary infection from bacteria

Question 13

A Hydraulic line that is too short for the flare to
reach its seat before tightening, when pulling it
into place by tightening may cause_____ ____ _______

Answer 13

A Distort in the flare

Question 14

Baffles and/or fins to keep
fluid from swirling which can
cause______ and lead to pump
_______

Answer 14

Foam, Cavitation

Question 15

What is a stand pipe used for?

Answer 15

It is used for normal
operation to assure fluid is
available for the emergency pump

Question 16

What is chattering?

Answer 16

its an indication that air is
entering the pump

Question 17

What is the main purpose of pressurized reservoir in
a hydraulic system

Answer 17

It prevents
hydraulic pump cavitation

Question 18

What must you do before removing pressurized hydraulic reservoir filler cap?

Answer 18

Relieve system pressure

Question 19

Filter elements are

Answer 19

Pleated cellulose micron type

Question 20

Hydraulic fluid filtering elements
constructed of porous paper are normally?

Answer 20

discarded at regular intervals and replaced
with new filtering elements

Question 21

What is Constant displacement?

Answer 21

it delivers a
uniform rate of fluid flow

Question 22

What is Constant-delivery?

Answer 22

Delivers a fixed
quantity of fluid through the outlet port
during each revolution regardless of
pressure demands

Question 23

POWER-DRIVEN PUMPS are changed by a pump __________within the _______

Answer 23

Compensator, pump

Question 24

What is the Pressure Regulator used for?

Answer 24

It is Used to manage pump output and
maintain system pressure within a
predetermined range

Question 25

What does the Accumulator do

Answer 25

It Dampens pressure surges caused by actuating a unit in the system

Question 26

Describe the Bladder type accumulator

Answer 26

It is a One-piece- metal sphere with a large opening at the bottom for inserting a bladder and sealed with a large screw type plug. • Similar to diaphragm type • Has a bladder that separates the air charge from the fluid

Question 27

When servicing accumulators

Answer 27

Hydraulic system cycles on and off with great frequency, the accumulator air charge may be low

Question 28

What is the most common selector valve type

Answer 28

Four way closed center selector valve (four port)

Question 29

What does the restrictor valve do?

Answer 29

Limits the rate of flow of the fluid • Slows the actuator operation

Question 30

What does the Hydraulic fuse do?

Answer 30

Blocks fluid flow if a large leak should occur • Shuts off fluid flow if a sufficient pressure drop occurs across the fuse • A hydraulic fuse serves the same function as a fuse or circuit breaker in electrical

Question 31

What does the shuttle valve do?

Answer 31

It’s an Automatic selector valve that will direct either normal system hydraulic pressure or emergency fluid pressure into an actuator cylinder

Question 32

What is a sequence valve?

Answer 32

Causes one hydraulic operation to follow another and is mechanically operated

Question 33

What does Quick-Disconnect couplings do?

Answer 33

in hyd systems, they provide a means of quickly connecting and disconnecting hydraulic lines without loss of fluid or entrance of air into the system

Question 34

HYDRAULIC MOTORS • Operate in the _______ of a hydraulic pump It _______ fluid into the piston chambers and it will turn the shaft

Answer 34

Reverse, Forces

Question 35

What are Hydraulic seals used internally on a sliding or moving assembly are normally called?

Answer 35

Packings

Question 36

ORings prevents both _______ and _______ leakage

Answer 36

Internal, External

Question 37

What do backup rings do?

Answer 37

They prevent high pressure from extruding the seal between the moving and stationary part

Question 38

How is BUNA-N identified?

Answer 38

Identified with a blue stripe or dot

Question 39

In a Open System you open the open ______ selector valves

Answer 39

Center

Question 40

Lack of pressure may be due to?

Answer 40

Sheared pump shaft - Defective relief valve - Pressure regulator - Lack of fluid - Check valve backward

Question 41

Engine Driven Compressors requires a

Answer 41

Moisture Separator

Question 42

The Pressure Control Valve acts as a_____ ______

Answer 42

Relief valve

Question 43

When installing seals over______ or _____objects protect the seal by placing a plastic or metal sleeve over the ______

Answer 43

Threads, Sharp, Threads

Question 44

Hydraulic motor converts

Answer 44

Rotary motion from fluid

Question 45

Good hydraulic fluids have 4 things

Answer 45

1)Flashpoint 2) High Resistance 3) Chemical Stabilty 4) Low Viscosity