2 Flashcards
1
Q
The main advantage of a ball and roller bearing is:
A
They have low starting friction
2
Q
Deep groove ball bearings are designed for:
A
Radial loads and moderate thrust loads
3
Q
Angular contact ball bearings are designed for:
A
Moderate combined thrust and radial loads
4
Q
Tor F
Deep groove ball bearings can carry heavier radial loads than radial bearings with filling slots because the deep groove bearings have more balls.
A
False
5
Q
T or F
The only difference between a heavy duty bearing and a light duty bearing is the size of the balls.
A
False
6
Q
When handling bearings which of the following should not be done?
A
Wash out completely, all grease in which a bearing comes packed
7
Q
T or F
Pressure should always be applied to the outer race when removing a ball bearing from a shaft.
A
False
8
Q
What would happen if you attempted to pull a bearing on the shallow shoulder of an angular contact bearing?
A
It would disassemble the bearing
9
Q
When a bearing must be pulled by the outer race because of a gear or shaft shoulder, what is the most important thing to remember?
A
Maintain a constant steady pull
10
Q
Why shouldn’t galvanized pipe be used as a drift to remove bearings
A
Because the zinc can chip off into the bearing
11
Q
T or F
Sometimes the inner bearing cap can be used to pull a bearing
A
True
12
Q
A three way puller is particularly useful in pulling:
A
Gears through the spokes
13
Q
T or F
It is a good idea to smooth off a shaft with emery cloth before mounting a ball bearing
A
False
14
Q
A shaft shoulder for a bearing should be about ? the height of the inner race
A
1/2
15
Q
What should be the maximum temp used to treat a bearing on a shaft?
A
225 deg F
16
Q
What will happen if a ball bearing is fit loosely on a shaft?
A
Inner ring will slip and rotate on shaft
17
Q
T or F
A ball or roller bearing should be fit onto the shaft as tightly as possible to prevent rotation of the inner race.
A
False
18
Q
T or F
Face to face mounting of duplex bearings allows a moderate amount of alignment
A
True
19
Q
T or F
Tandem mounting of duplex bearings is used for heavy radial loads
A
False
20
Q
T or F
If one bearing in a duplex set is bad it is permissible to replace the bad bearing as long as it is replaced by one made by the same manufacturer
A
False
21
Q
T or F
The wiping lip of a seal should usually be turned toward the inside of the housing
A
True
22
Q
Oil lubrications will permit about ? the bearing speed of grease lubrication
A
Twice
23
Q
T or F
The main advantage of oil lubrication over grease lubrication is it’s ability to circulate and cool the bearing
A
True
24
Q
About how full should a bearing housing be filled with grease
A
1/3
25
What is the main detrimental affect of over lubrication in a grease lubricated bearing?
Heat
26
What is the best method of removing grease from an over lubricated bearing while it is in service?
Remove the drain plug and leave out for 15-20 min.
27
Ball or roller bearings which have failed because they have been pinched in the housing can be recognized by:
A definitely defined load track on opposite sides of the outer race diagonally across
28
T or F
| A cracked inner race may mean that the shaft is oversized
True
29
Which one of the following should not be done in working with anti friction bearings
Use cotton waste to wipe bearings
30
The oil reservoir of an anti friction bearing is usually filled?
To cover the bottom half of the bottom ball
31
The libricating oil film in a sleeve bearing is about ? thick.
.001” to .003”
32
T or F
If you are looking at the end of a shaft turning counterclockwise the shaft will tends to assume a position to the left of the centerline in a journal bearing when the oil film is fully established
False
33
In 1839 Mr.babbit devises a material for sleeve bearing which consisted of
Tin, copper, and antimony
34
The two types of thrust bearings in general use on large hydroelectric units are:
The spring type and tilting shoe type
35
T or F
| The GE type generator thrust bearing obtains its equalizing action from springs under the stationary segments.
True
36
T or F
| The protective material on the bearing surfaces of the GE type generator thrust bearing should not be removed
False
37
T or F
The basic elements of a Kingsbury thrust bearing are rotating thrust collar, stationary tilting shoes, base ring, housings, lubricating system, cooling system and equalizing springs.
False
38
T or F
| A Kingsbury thrust bearing is said to be “equalizing” if the load on the shoes is adjusted automatically
True
39
T or F
The principle behind the load carrying capacity of the Kingsbury type bearing is the formation of a wedge shaped oil film
True
40
T or F
| The main advantage of calcium base grease is its water resistance
True
41
T or F
| A trimetql bearing consists of a thin overlay of Babbitt in a leased bronze lining on a steal back
True
42
T or F
| Turbine oil stability is its ability to resist foaming
False
43
T or F
| Viscosity index is a measure of an oils rate of change of viscosity with temperature
True
44
The purpose of an oil lubricated oil bearing is to
Carry oil to the bearing from the reservoir
45
A machine is a device used for converting force to useful work. It can be used to:
All three (change size of force, direction of force, and speed or rate a force is acting)
46
Of the below statements concerning machine efficiency, which one is not a true statement?
Transformers are less efficient than reciprocating pumps
47
A shaft or journal re loving in an oil lubricated bearing is usually identified with?
Fluid friction
48
A bearing that supports or restricts the longitudinal motion of a rotating shaft is called a:
Thrust bearing
49
All of the below factors have an effect on the formation of the desired oil wedge. Which one must operators give the most careful attention to prevent bearing damage?
Shaft or journal speed
50
Lubricating oil is normally fed into a horizontal journal bearing from the?
Top
51
Journal and thrust bearings are more susceptible to damage during?
Both start up and shut down operations
52
While bearing clearances will vary because of different design and loading characteristics, it is generally est. that for each in. Of shaft diameter the clearance should be about?
.001”
53
T or F
| The GE type generator thrust bearing obtains its equlalizing action from springs under the stationary segments.
True
54
Tor F
| the protective material on the bearing surfaces of a GE type generator thrust bearing should not be removed.
False
55
Tor F
the basic elements of a Kinsbury thrust bearing are a rotating thrust collar, stationary tilting shoes, base ring, housings, lubricating system, cooling system and equalizing springs.
False
56
T or F
| A Kingsbury thrust bearing is said to be "equalizing" if the load on the shoes is adjusted automatically
True
57
T or F
The principle behind the load carrying capacity of the Kingsbury type bearing is the formation of the wedge shaped oil film
True
58
T or F
| The main advantage to calcium base grease is its water resistance
True
59
T or F
| A trimetal bearing consists of a thin overlay of Babbitt on a leaded bronze lining on a steal back
True
60
T or F
| Turbine oil stability is its ability to resist foaming
False
61
T or F
| Viscosity index is a measure of an oils rate of change of viscosity with temperature.
True
62
The purpose of an oil ring in an oil lubricated oil bearing is to:
Carry oil to the bearing from the reservoir
63
A machine is a device used for converting force to useful work. It can be used to:
All three
| change size of force, and speed or rate a force is acting
64
of the below statements concerning machine efficiency, which one is not a true statement?
Transformers are less efficient than reciprocating pumps.
65
A shaft or journal revolving in an oil lubricated bearing is usually identified with:
FLuid friction
66
a bearing that supports or restricts the longitudinal motion of a rotating shaft is called a:
Thrust bearing
67
all of the below factors have an effect on the formation of the desired oil wedge. Which one must the operators give the most careful attention to prevent bearing damage?
Shaft or journal speed
68
Lubricting oil is normally fed into a horizontal journal bearing from the:
top
69
journal and thrust bearings are more susceptible to damage during:
Both start up and shut down operations
70
while bearing clearances will vary somewhat because of different design and loading characteristics, it is generally est that for each inch of shaft diameter the clearance should be about:
.001"
71
all of the below statements relating to bearing load are true except:
Heavily loaded bearings generally require an oil low in viscosity.
72
all of the below statements concerning oil grooves in bearings are true except:
The oil bgroove is generally located in the high pressure area of the bearing.
73
An increase in bearing temp may indicate:
A combination of all three
| change in surrounding air temp, insufficient oil, dirty oil
74
anti friction or roller bearings are made to carry:
any or all of the above
| radial, thrust, or angular
75
ball bearing life may be shortened by:
all of the above
76
if the oil reservoir in a ring oiled bearing is carried too high the ring:
turns more slowly due to the increased friction in turning through the oil
77
the desired oil wedge is formed in a Kingsbury thrust bearing by:
tilting pivoted shoe
78
the below statements concerning a Kingsbury spherical thrust bearing are all true except:
The Kingsbury spherical thrust bearing combines the functions of a lower generator guide bearing and a thrust bearing.
79
Which of the following statements concerning vertical turbine guide bearings is true?
The lignum-vitae strips are inserted in the bearing shell.
80
Which of the below features is not normally found on a horizontal turbine thrust bearing installation?
Provisions for pressurized lubrication.
81
High pressure oil is injected into the bottom of a horizontal shaft turbine journal bearing help:
all of the above
lifting the weight of the rotating element off of the bearing Babbitt, during periods of starting and stopping, provides oil film between the surfaces at extremely low speeds.
82
Which of the following features is not normally found on a Gibbs horizontal turbine shaft thrust and journal bearing?
pivoted blocks and shoes
83
The revolving runner of a hydraulic turbine is said to have
rotating plane motion
84
the balls of the flyball governor, when the speed of rotation is increasing or decreasing, is said to have:
spherical motion
85
critical speed is defined as:
a speed that creates a centrifugal force greater than the elastic resolving force of the shaft.
86
all of the below statements concerning critical speed are true except:
each shaft will have only one critical speed
87
A mechanism that produces the snapping action when circuit breakers are opened or closed uses the principle of the:
toggle
88
which one of the below statements concerning belts and pulleys are not true?
the idler is to reverse direction of rotation of a belt drive
89
select one of the below statements concerning gears that is false.
Herringbone gears cause end thrust on the shafts.
90
most flexible couplings:
require some form of lubrication to reduce friction
91
hydraulic couplings are generally used with:
variable speed units
92
magnetic drives can be used as a:
all three:
| clutch, slip coupling, reversible drive
93
the property which causes fluid lubricants to stick to solid bearings, or he force that attracts fluids to solids is:
adhesion
94
a rapid rise in total bearing friction is caused by:
All of the above
| loss of fluid film, reduction in cohesion and an increase in adhesion qualities of the lubricant, excessive heat.
95
the ideal lubricant is one that will:
All of the above:
carry bearing load at max operating temp, maintain max adhesion at normal operating speeds, maintain proper degree of fluid friction.
96
which one of the below statements concerning the effect of lubrication on antifriction is not true?
the friction is generally lower when lubricated than when dry.
97
bearing lubricants:
all three:
| reduce friction, carry away bearing heat, reduce wear and erosion of bearing surfaces.
98
the viscosity of an oil is generally measured by a:
viscosometer
99
which one of the below engine oils would have highest viscosity rating?
SAE 50
100
the rate of change in the viscosity of an oil for a given temp change refers to its:
viscosity index
101
a grease with a consistency number of 6 is:
harder than a number 2
102
the type of flood oil system used when the lubricated surfaces are to be always submerged in oil is:
bath
103
which of the below items that affect the ability of an oil to perform properly cannot be removed by a centrifuging process:
acid
104
grease is used in preference to oil to lubricate certain types of plain bearings because:
all three:
| minimizes leakage, reduces throw, provides an effective seal.
105
the ideal quantity of grease for an antifriction bearing on a shaft 2 1/2 in in diameter would be:
1/3 to 1/2 full
106
centralized lubrication most nearly means:
the positive delivery of a predetermined amount of lubricant from one central point to a scattered # of lubrication points.
107
The pump that has 3 moving parts, a power rotor and two idler rotors is:
screw pump
108
in gear pumps the liquid is carried:
between the teeth and pump casing
109
the pump with no moving parts is the :
jet pump
110
the energy which a body or system of bodies has by virtue stresses, or the energy of position is:
potential energy
111
the cross section of the passage into which the water is discharged by the impeller of a volute pump gradually___ in area as the discharge opening of the pump Is approached.
increases
112
multistage centrifugal pumps are used where the discharge head is:
high
113
an impeller that has a side wall or shroud on each side of the vanes is classified as:
closed
114
the clearance between the rotating and stationary rings of a centrifugal pump is normally____ of an inch.
.012+.020
115
all centrifugal pumps are equipped with stuffing boxes or mechanical seals to prevent leakage through the clearance between the:
pump shaft and casing.
116
in stuffing boxes where the packing is placed on both sides of the lantern ring, the water is called:
seal water
117
one of the most common causes of centrifugal pump trouble is:
leaking stuffing boxes
118
the static force exerted by a column of water one foot high on an area of one square inch is:
.434 psi
119
the relation between capacity, rotative speed and head developed by an impeller is called:
specific speed
120
the ____ indicates the ratio, expressed in %, of useful output to the input, at different capacities and heads
efficiency curve
121
the frictional heat released in pumps is normally carried away by:
the liquid leaving the pump discharge
122
T or F
| The term "specific speed" relates more to casing design and less to impeller design.
false
123
a 90 degree pipe bend has as much friction as ___feet of straight pipe
16ft
124
reciprocating pumps are:
positive displacement
125
the addition of energy to a liquid to move it from one point to another is called:
pumping
126
the faces of mechanical seals are held together by:
springs
127
which of the following would not be used with a pelton wheel?
wicket gates
128
pelton wheels:
may use two or more jets per wheel to obtain increased power
129
power available at the nozzle varies:
directly with the head and quantity of water.
130
water hammer:
can damage a penstock if not kept within reasonable limits
131
the purpose of an auxillary needle is to:
provide a means for reducing flow to an impulse wheel rapidly while reducing the flow more slowly through the penstock.
132
to deliver the same amount of power, a smaller diameter runner is required for a reaction turbine than for an impulse wheel because:
the entire circumference of the runner of the reaction turbine is being acted on by the water stream.
133
which of the following would not be found on a reaction turbine?
stripper
134
for most reaction turbines, greatest efficiency is obtained when the wicket gates are:
80-90% open
135
a draft tube:
increases the effective head of the turbine.
136
readings from a pressure gauge on the crown plate of a reaction turbine give a good indication of the :
seal ring effectiveness
137
a Kaplan turbine:
propeller blades adjust automatically to maintain best efficiency for gate position and variations in head.
138
Net head most nearly means:
gross or static head less the frictional losses in ft
139
which of the below factors would not generally contribute to cavitation damage?
little or no variation in effective head
140
how much head would not be required to develop 10,000hp from a turbine operating at 80% efficiency from a stream with a flow of 100cu/ft/sec
1100ft
141
what is the best speed of rotation in rpm for a pelton wheel 54in in diameter, on which the net head is 625ft?
360
142
commutator segments are insulated from each other by:
sheet mica
143
most DC generator brushes that carry the current from the commutator to the external circuit are made of:
carbon and graphite
144
the degree that the neutral plane of a DC generator will shift under load is:
proportional to the load
145
DC generators are generally classified according to the manner in which:
the field windings are connected to the armature circuit
146
the effects of armature reaction in a DC generator are reduced by the use of:
commutating or interpoles
147
a shunt wound DC generator will build up to full terminal voltage with no external load connected to it due to:
self excitation
148
the part of a DC generator into which the working voltage is induced is the:
armature
149
the field coil windings of a self excited DC generator are:
any of the above:
| series, shunt,compound
150
the rated voltage value of a DC generator will be reached faster if the generator is:
self excited
151
A shunt most nearly means a:
parallel circuit
152
which of the following is true regarding the speed regulation of a shunt motor?
it has a constant speed characteristic under carrying loads
153
a DC series motor is more adaptable where a:
wide variation of torque is req'd and wide variation in speed are allowable
154
when the load is applied to a DC shunt motor, hich one of the following will happen?
speed decreases- counter EMF goes down
155
the counter EMF of a DC motor is zero when the:
armature is not turning
156
the horsepower developed by a motor depends mainly upon which of the following 2 factors?
speed and torque
157
a motor which has an output of 820 watts and an input of 960 watts has an efficiency of approx.:
85%
158
if the no load speed of a shunt motor is 1800 rpm and the full load speed is 1475rpm, the speed regulation is:
22%
159
the generated voltage (counter emf) if a motor:
opposes the impressed voltage
160
too much resistance inserted in the field circuit of a shunt or compound motor will:
allow the motor to overspeed and destroy itself
161
the main purpose of the commutator on a DC motor is to:
automatically reverse the armature polarity each time the brushes move from one segment to another.
162
the variable resistance placed in the rotor circuit of the wound rotor AC motor is for the purpose of:
starting torque control
163
the more common method of starting a synchronous motor is:
with a squirrel cage type of winding on the outer edge of the field poles.
164
the synchronous speed of an induction motor is the:
speed of the revolving field
165
what factor determines the rotor speed of an induction motor?
any or all of the above
| frequency, slip, # of poles
166
A synchronous motor differs from an induction motor in that it:
all of the above
| not self starting, requires an AC and DC power supply, may be used for power factor correction.
167
the direction of rotation of an induction is:
same as direction of revolving field
168
the principle parts of an induction motor are the:
stator and rotor
169
the type of connection used with a 3 phase squirrel cage motor where 58% of the line voltage is impressed on the field coils for starting, and 100% full load operation is called.
wye-delta
170
when large induction motors are started across-the-line under loaded conditions:
all of the above statements are true
171
under what conditions can a 3 phase synchronous motor be used to correct a lagging power factor?
when the counter EMF is caused to become greater than the terminal voltage
172
the speed of a synchronous motor is governed by the:
line frequency and number of poles in the motor.
173
the difference between the speed of the revolving field of the stator and the actual speed of the rotor of an induction motor is called the:
slip
174
why does the capacitor motor have a higher starting torque than the inductively displaced split-phase motor?
greater displacement between its start and main winding currents.
175
in a split-phase starting arrangement to allow a single-phase AC induction motor to start automatically, the starting winding may be placed in series with a capacitor. the effect of this capacitor is to:
produce a revolving field by shifting the phase relationship between the starting winding and running winding.
176
a motor is rated at 10hp. it is drawing 10,000 watts from the line. its efficiency is therefore:
75%
177
an armature is always the:
conductors into which voltage is induced
178
the AC field is always the:
conductors through which DC exciter current flows
179
the output of a revolving field type AC generator Is taken from:
fixed terminals
180
the revolving field type AC generator is most widely used because:
All of the above
181
the armature windings of a 3 phase AC generator are physically placed so that the induced voltages are out of phase by:
120 degrees
182
the output frequency of an AC generator is dependent upon the:
number of poles and rotor speed
183
the field pole windings on AC generators are connected in:
series
184
the load rating of an AC generator is determined by the:
internal heat it can withstand
185
the voltage output of an AC generator is controlled by:
varying the DC exciter voltage
186
All of the below statements apply to a wye-connected AC generator except
the phase winding voltage is equal to the phase-to-phase voltage
187
Armature reaction is most nearly associated with the effects of:
armature flux
188
the terminal voltage of an AC generator is affected by:
All 3 of the above factors
189
the terminal voltage of an AC generator will change with a change in load characteristics. the below statements apply to this principle and are all true except for:
the terminal voltage will tend to drop with a leading power factor
190
before connecting two or more 3 phase AC generators in parallel it is necessary that:
All 3 of the above
191
the voltage of an AC generator rises from the 4600 volts at full load to 5350 volts at no load. The % regulation is approximately:
16
192
which one of the following items would not cause a low lagging power factor?
transmission lines
193
in order to maintain losses as low as possible, what would be the best location for sources of VARs?
Adjacent to the customers equipment
194
which of the following changes in system operating conditions would tend to change a lagging power factor from .85 to .90?
an increase in the field excitation of a synchronous condenser
195
a synchronous condenser which is in operation at the time of a system disturbance:
will have a stabilizing effect on the system
196
during off peak periods on power system it may sometimes be necessary to operate the synchronous condenser under excited:
because long transmission lines cause static capacitive effect which may over balance the inductive effect of the load during that time.
197
when a synchronous condenser is producing VARs:
an increase in DC field current will cause an increase in reactive power
198
which one of the following statements concerning capacitors is not correct?
capacitors increase the amount of current being carried in a circuit.
199
in a system using capacitors for power factor correction:
all three
installed in parallel, installed is sufficient # to supply desired amount of reactive power, not economically practical to correct power factor unity.
200
capacitors are:
sometimes installed in series with the distribution circuit
201
From the power triangle diagram below, what would be the power factor of the circuit if a 40kva capacitor were installed?
97%
202
the voltage output of an AC generator is controlled by:
varying the DC exciter voltage
203
the major difference between various voltage regulator systems is merely the method by which:
field circuit resistance and current are controlled
204
the voltage held by the vibrating type voltage regulator can be adjusted by:
varying the weight (W) and adjusting the tension of DC solenoid spring
205
all of the following statements concerning the rheostat type voltage regulator are true except for:
the primary purpose of the exciter field rheostat is to adjust the generator output voltage.
206
wide range excitation control is sometimes provided for in voltage regulator arrangments for large generators using separately excited main exciters by using a:
wheatstone bridge rheostat
207
when the regulator control switch for the amplidyne voltage regulator is in the ON the position the effect is to:
all 3 above
reduce exciter field current, lower exciter voltage, and decrease the field current and terminal voltage of the AC generator.
208
in order to provide for proper division of reactive current between AC generators operating in parallel, their voltage regulators incorporate a scheme called:
cross current compensation
209
of the following statements concerning synchronous condensers, which one is not true?
the excitation range is maintained less than that for AC generators to prevent loss of synchronism
210
in the rheostat type voltage regulator, when the terminal voltage of the AC generator starts to fall the action of the torque motor:
short-circuits more of the high resistance plates
211
system stability can be maintained and a faster time response to load changed obtained by using voltage regulators equipped with:
both a feedback control system and an electronically controlled separate motor
212
voltage drop in a distribution system may be overcome by:
all three
changing from an overhead to an underground system, using load tap changing transformers, using feeder voltage regulators
213
which of the following statements concerning regulated feeder voltage is not true?
the degree of illumination provided by incandescent lamps will not be affected by variations of voltage in the order of 1%
214
the principle of operation of a feeder voltage regulator is very similar to that of a:
transformer
215
in an induction type voltage regulator
only the primary winding rotates
216
the purpose of the short-circuited winding in an induction type voltage regulator is to:
control voltage drop
217
which one of the following statements most nearly describes the operating principle of a step type voltage regulator?
auto transfer with taps and a reversing switch.
218
the total # of 5/8% voltage steps provided in most type voltage regulator is?
32
219
the kind on insulating coolant preferred for use in the step type voltage regulator is:
transformer oil
220
a grounded feeder system using step type voltage regulators will require:
three regulators wye-connected with a common neutral.
221
two fully loaded 10% regulators are supplying a balanced three phase load of 600 amps at 240 volts. what is the rating of each regulator?
144,000va
222
a program designed to improve vlv care and operating and maintenance procedures will promote:
all three
| plant reliability, plant safety, and plant efficiency
223
the metal offering the greatest resistance to cavitation is:
stainless steel
224
chromium and nickel are both added to steel to improve its ability to:
resist acid corrosion and cavitation
225
resistance to flow through a vlv can be caused by:
All three
| metal roughness, proturberance inside the vlv, change in the direction of flow
226
which of the following fittings would not normally be used with a gate vlv?
outside lever and weight
227
a quick opening vlv should be closed slowly to:
prevent hydraulic shock caused by water hammer
228
all of the below vlvs may be float operated except?
blowoff vlvs
229
which of the below vlvs would normally be used to regulate fluid volume in a hydroelectric plant?
needle vlvs
230
what type of gate vlv would most likely be used to reduce as much as possible the erosive action of water flowing at high velocity through high pressure gates?
paradox
231
all of the following vlvs are normally used for crest control except:
paradox gate
232
vlvs are rated by the ___ and temp they are designed to handle.
pressure
233
the highest working pressure rating used for vlvs is:
steam
234
pressure drop can be defined as a ___ in energy or a ___ in pressure, in a pipeline, due to the resistance in it.
loss:reduction
235
what type of connections would you use on a large vlv?
flanged
236
a ___ vlv has a "s" shaped path and is used for ___ flow.
globe:throttling
237
stem packing is used to prevent fluid from leaking between the vlv___ and the vlv body.
stem
238
which vlv does not require packing?
diaphragm vlv
239
air vents include:
ball float vlvs, vacuum breakers, coffin vlv, safety and relief vlvs
240
piston operated vlvs require ___ pressure to operate.
hydraulic
241
needle vlvs are used for?
all of the above
| regulating flow, a shutoff vlv, impulse wheels
242
if all other factors are held constant, the volume of a dry gas decreases:
in direct proportion to an increase in its pressure.
243
absolute pessure is equal to:
gauge pressure plus 14.7psi
244
if 500 cubic inches of gas under a pressure of 15 psia is compressed to 20 cubic inchies, what will the new pressure be?
375psia
245
the quantity and pressure of air discharged from a centrifugal fan depends on the:
all three
| size of fan rotor, speed of fan rotor, and density of air
246
increasing the speed of an unbalanced shaft will:
move the center of gravity further from the axis of rotation thereby increasing the unbalance
247
which of the following conditions would not normally contribute to a reciprocating air compressor explosion?
excessive compressed air demands
248
large reciprocating air compressors are generally unloaded while starting and stopping to:
reduce the starting torque and permit more gradual stopping
249
the temp at which molecules of water vapor begin to condense upon the surface of objects as air is cooled is called the:
dew point
250
high outlet compressed air temps could be caused by all of the following except?
low oil level
251
air receivers are installed on all reciprocating air compressors to:
all of the above
| dampen pressure waves, reduce pressure drops and remove moisture or sludge.
252
the five essential parts basic to every compression refrigeration system are:
evaporator, compressor, condenser, receiver, and expansion vlv.
253
when a receiver safety vlv blows prematurely ___ could be the problem.
safety vlv set below cut-out pressure.
254
one lb per square inch of air pressure is equivalent to ___ inches of mercury.
2.036
255
T or F
| centrifugal compressors are positive are positive-displacement devices.
false
256
For every ___ lower intake air temjp, the gain in efficiency of an air compressor is approx. 1%.
5 degrees
257
T or F
| air compressors are used for the operation of both oil and air blast circuit breakers.
true
258
T or F
| the most common type of modern air compressor is the rotary vane type
false
259
T or F
| keeping the reservoir oil at the prescribed level will help maintain the proper oil temp.
true
260
T or F
| kerosene is the recommended agent for cleaning air filters in an air compressor.
False
261
T or F
| eliminating dust- laden intake air can minimize the possibility of explosions in air compressors.
true
262
what is the area in square inches of a piston 6 in in diameter?
28.3
263
the pressure at the bottom of a column of oil 20ft high is __ psi.
8
264
the result of pressure acting on an area is called ___.
force
265
the pressure required to push oil through three 100psi check vlvs in series is ___psi.
300
266
factors affecting the speed of an actuator are the flow rate of oil and the piston ___.
area
267
the volume of oil a cylinder will hold can be determined by multiplying the piston are by the ___.
Stroke length
268
resistance to flow creates ___.
pressure
269
the pressure available to force liquid into a pump is usually ___.
atmospheric
270
the rate at which work is performed is determined by the __ and ___ size (hydraulic components)
actuator:pump
271
if a force of 950lbs is applied over a 30sq in area, the pressure developed would be ___psi.
31.6
272
the function of a directional vlv to control the fluid___.
direction
273
the quantity of force exerted over a distance with no time element considered is called___.
work
274
horsepower can be calculated by multiplying the GPM by the pressure and the constant___.
.000583
275
when fluid flow is turbulent, friction varies as the square of the ___.
velocity
276
the design of a hydraulic circuit begins with the ___.
actuator
277
a relief vlv limits the maximum pressure at the ___ port to the directional vlv.
inlet
278
force per unit area is called ___.
pressure
279
the input hydraulic component in a hydraulic system is called the __.
pump
280
what is considered the source of power in a hydraulic circuit
prime mover
281
inlet pressure of a pump is usually measured in __.
inches H.G.
282
a hydraulic device which uses the impact or kinetic energy in the liquid to transmit power is called a ___ device.
hydrodynamic
283
when a device is operated by pressure on a confined fluid, it is called a ___ device, pressure being the force per unit area (lbs/ sq. in. or psi)
hydrostatic
284
the tendency to cause flow (or the push) may be supplied by a mechanical pump or maybe caused simply by the ___ of fluid.
weight
285
pressure per sq in which is created by the height of the fluid is called ___. this varies with the type of fluid being considered depending upon its weight per cubic foot (density).
pressure head
286
atmospheric pressure= ___ pounds per sq in absolute
14.7
287
the pressure at the top of the barometer tube is ___.
0psi
288
30 psig= ___psia
44.7
289
the flow of a fluid can be measured by either velocity (e.g. ft per second, or ft per min) or by ___.
flow rate
290
5GPM= ___ cubic in per min.
1155
291
a difference in pressure at 2 different points in a horizontal hydraulic line indicates that there is ___.
flow
292
working pressure at the pump outlet is the sum of the ___ created by fluid friction within the piping and system components and the pressure needed to perform the work req'd.
pressure
293
when the particles of the fluid move parallel to each other and to the walls of the pipe, flow is said to be ___.
laminar
294
abrupt changes in flow direction or too high a velocity of the fluid may cause ___ flow.
turbulent
295
two forms of energy within the hydraulic fluid are ___ and potential.
kinetic
296
if flow ___ at various points in a hydraulic system remains constant, the same of the pressure energy and kinetic energy are also constant (ignoring frictional loss).
rate
297
working lines carry main system flow from the pump inlet through the system and also return flow to reservoir. ___ lines carry fluid for control and operation of other vlvs or components. drain lines return leakage oil to reservoir.
pilot
298
a circle with an energy triangle at the circumference pointing outward for a pump or ___ in the case of a motor is called a graphical symbol.
inward
299
how many envelopes are in the symbol for relief vlv?
one
300
connecting lines drawn to the bottom of the reservoir symbol represent lines that terminate ___ fluid lvl.
below
301
how many positions does the directional vlv in fig 2-18 have.
three
302
the hydraulic fluid is the medium for power transmission, and it also serves as a sealer, coolant, and ___.
lubricant
303
the hydraulic fluid should be compatible with materials used for ___.
sealing
304
viscosity is the measure of a fluids resistance to ___.
flow
305
kinematic viscosity is the most common way of measuring ___.
viscosity
306
if viscosity is too high, pressures req'd for operation will increase due to increased fluid ___.
friction
307
the measure of a fluids rate of change in viscosity with change in temp is called viscosity____.
index
308
heat, pressure, water, contaminants, metal surfaces are ___.
catalysis
309
the property of an oil which allows water to separate from its, is called oxidation ___.
demulsibility
310
a good grade of premium quality hydraulic oil contains various:
additives
311
fire resistant fluids may be of the water-in-oil emulsion type, water glycol, oil-in-water, and___.
synthetics
312
the four primary purposes of hydraulic fluids are ___.
All of the above
313
high specific gravity fluids may be more critical in causing pump ___.
cavitation
314
the close mechanical fit and the ___ of the oil, determine leakage rate.
viscosity
315
pour point is the lowest temperature at which a fluid will ___.
flow
316
synthetic fluids are usually more suitable for operation at higher ___ than water based fluids,
temperatures
317
resistance encountered when moving one layer of liquid over another is ___ ___.
absolute viscosity
318
a chemical reaction between a metal and a chemical is called ___.
corrosion
319
which one of the following is not a catalyst to oxidation?
Acid
320
invert emulsions depend on ___ content for their fire-resistant properties.
water
321
phosphate esters attack elastomers, and are not compatable with some ___ and ___.
paints: plastics
322
pipe sizes are specified by ___ size and wall thickness.
nominal
323
the schedule # for standard pipe is ___.
40
324
one advantage of tubing over pipe is the ease of ___ to shape.
bending
325
the specified sizes for tubing refer to the ___>
O.D.
326
sealing between sections of tubing is obtained by the use of various types of ___.
fittings
327
the four primary purposes of hydraulic fluid are ___.
all of the above
328
lip type seals are used principally on ___ shafts.
rotating
329
an elastic or rubber-like material that contains no natural rubber is called an ___.
elastometer
330
nitrile (Buna-N) has a reasonably wide temp. range, which is ___ degrees Fahrenheit.
250 degrees F
331
one of the several ways to reduce leakage is with the use of ___ mounted vlvs.
back
332
back mounting refers to panel type installations where pipe or tubing is ___ connected to subplates.
permanently
333
what type of seal is installed in an annular groove?
O-ring
334
after installation a seal began to wear quickly and leak, which meant it was probably not ___ before installation
lubricated
335
at too high a temp a seal may harden, swell or ___.
soften
336
what type of inexpensive sealing material is widely used in modern hydraulic systems?
nitrile
337
to prevent a return line in a reservoir from bottoming, it is often cut off at an angle of ___ degrees.
45
338
an adequate reservoir size for a 10GPM pump would be ___ gallons
30
339
the plate that prevents the return fluid from recirculating directly back to the inlet is called the ___.
baffle
340
the returning fluid to the reservoir is usually ___ then the supply fluid.
warmer
341
the filler hole in a reservoir is provided with a ___screen.
removable
342
reservoirs are made with connections on top that are set on ___ to keep out.
risers
343
what is NOT one of the 3 most common standard reservoir designs?
wedge shaped
344
fluids with a ___ viscosity index must be kept warm by heaters.
low
345
reservoir temp is controlled by ___.
all of the above
346
for reservoir capacity of at least ____ should be provided.
20%
347
a strainer is called a ___ filter.
coarse
348
a particle one micron in size equals ___ inch.
.000039
349
a filter designed to signal the operator when the element needs cleaning is called a ___ filter.
indicating
350
three general areas for locating a filter are inlet, pressure and ___ lines.
return
351
what type of filter element provides precise control of pore size?
surface
352
filtering materials are classified as absorbent or ___.
adsorbent
353
what type of filter passes the entire flow entering its inlet through the element.
full flow
354
the smallest particle an eye can see is approximately ___ microns.
40
355
hydraulic circuit components fail as a result of contamination and ___.
design
356
if the fluid within the hydraulic pump clearances become heavily contaminated, ____ will probably occur,
seizure
357
which of the following is not a mechanism of wear?
filtration
358
contamination blockage which prevents and then allows a solenoid spool to shift is called a ___ failure.
transient
359
an increase in the pressure differential across a filter will cause an ___ in power consumption.
increase
360
when specifying the correct filter for a given application , which of the following would not be considered?
flow sampling method
361
which is not a source of contamination in a hydraulic system?
entrained
362
the preferred location for dynamic sampling is directly ___ of the return line filter.
upstream
363
after hydraulic system assembly, tubing must not be soldered, welded or ___.
brazed
364
when transferring clean oil, the transfer pump should be equipped with a ___ filter.
5 micron
365
filters that can trap much smaller particles than inlet line strainers are ___ ___ filters.
pressure line
366
the higher the sieve or mesh # the ___ the screen.
finer
367
to test for filter material compatibility, the filter element is immersed for ___ hrs is system fluid.
72
368
in cylindrical shaped filter elements, ___ tubes are used to support the media against pressure differential.
perforated
369
hydraulic fiberglass filter elements tend to have a ___ filtering structure.
pleated
370
to eliminate the possibility of filter elements collapse, a ___ vlv is used.
bypass
371
to monitor initial and subsequent lvls of contamination ____ points must be provided.
sampling
372
ram type cylinders are usually returned by ___.
gravity
373
double acting cylinders are returned by ___.
hydraulics
374
with a delivery of 3GPM to the cap end of a two inch diameter cylinder, the speed is ___ in.min
220.6
375
the force exerted by a 3 in diameter ram at 2000 psi is ___ pounds.
14,137
376
what pressure is developed when exerting a 14000 lb force over a piston area of seven sq in? ___psi
2,000
377
the displacement of a hydraulic motor is the amount of fluid in cubic in to make one ____.
revolution
378
torque ratings of hydraulic motors are usually given in pound- in. or pound-ft. per ____PSI.
100
379
a winch req's 50lb/ ft maximum torque to operate. what size hydraulic motor is needed if max pressure is limited to 1,500 PSI? ___ lb- inches per 100 psi
40
380
a 20 pound- inch motor operates with a torque load of 500 pound- inches. what is the operating pressure? ___psi
2,500
381
which of the following is not a class of hydraulic motors?
LMPG
382
in "balanced" design motors the vanes are held out against the cam ring surface by the use of system ___.
pressure
383
in high performance vane motors, coil springs hold the vanes against the ring. the vanes are essentially in hydraulic ___.
balance
384
torque is developed in the in-line piston motor through the angular relationship of the pistons to the ___.
swash plate
385
when the displacement of a variable motor is increased, the torque availability is ___.
increased
386
the most efficient hydraulic motor is the ___ type.
piston
387
motor displacement is varied in response to workload changes by the ___ control.
compensator
388
devices which usually cannot rotate continuously in one direction are ____.
Both A & C
| variable generators and torque generators
389
internal gear motors fall into two categories; direct drive and ___.
orbiting
390
a hydraulic motor which will not permit continuous rotation in either direction is a ___ motor.
limited rotation
391
directional vlvs control the ___ of fluid flow.
direction
392
directional vlvs that shift to definite positions are sometimes referred to as ___ positioning vlvs.
finite
393
a simple ___ vlv permits fluid flow in one direction and blocks flow in the reverse direction
check
394
check vlvs containing heavier springs than a nominal 5 psi are often used as a simple ___ vlvs
relief
395
directional vlvs are used to reverse a cylinder or motor are usually ___ ___ vlvs.
four way
396
directional control vlvs may be shifted ____.
all of the above
| mechanically, electrically, hydraulically
397
a solenoid operated spring offset vlv has ___ finite positions
two
398
an integral part of a prefill vlv that prevents hydraulic shock is a ___ ___.
decompression vlv
399
pilot pressure for a solenoid controlled pilot operated directional vlv may be supplied ___.
both A & B
| internally and externally
400
the device that can be added to a solenoid controlled pilot operated vlv to control the rate of main spool shift is called an ___.
pilot choke
401
when large vlv spools are shifted hydraulically, pilot pistons are sometimes used to obtain ____ shift times.
faster.
402
the adjustable- orifice deceleration vlv provides an external adjustment to utilize full spool travel regardless of ___ ___ through the vlv.
flow rate
403
a simple kind of flow control that restricts the distance a spool can shift is:
stroke limiter
404
Line mounted directional spool vlvs are more frequently found in ___ applications.
mobile
405
T or F
| is the graphic symbol a 2 position 4 way control vlv?
False
406
at which flow rate does a tapered plunger design vlv lose control?
low
407
the type of vlv that allows load creep is a ___ ___ vlv.
window orifice
408
a vlv that slows a drill head from fast advance to feed speed is a ___ vlv.
deceleration
409
vlvs that use atmospheric pressure to push large volumes of fluid through them are ___ vlvs
prefill
410
which of the following is not an actuator category?
directional
411
the work of pumping consists of discharging a quantity of liquid or gas against a/an:
resistance
412
the motion exerted by pumps on the fluids pumped may be due to:
all of the above
| reciprocating action, centrifugal action, jet action
413
fluid density, height fluid must be raised, pipe friction, and static pressure all relate to:
total pump head
414
check vlvs are sometimes installed in the suction line of pumps to:
prevent suction loss or shutdown
415
what type of pump can be operated with the discharge vlv closed
centrifugal
416
what type of pump operates on the velocity, restriction principle?
ejector
417
what type of pump is best suited for the handling of dirty water
non positive displacement
418
the purpose of the volute type of casing or diffusion vanes of centrifugal pumps is to:
reduce the velocity and increase the pressure of the discharging fluid
419
the laws governing the temperature-pressure relations of the liquids explain why a force must be used to cause a liquid flow into a pump and relate most nearly to :
net positive suction head
420
inter stage leakage in multistage centrifugal pumps is most usually controlled by the use of:
wearing rings
421
the purpose of wearing rings or labrynth rings in centrifugal pumps is to:
all three of the above
| control inter stage losses, reduce recirculation losses, and reduce maintenance costs,
422
the finction of the lantern ring in the stuffing box of a centrifugal pump is to:
distribute sealing or lubricating water around the pump shaft
423
in what part of a centrifugal pump is the kinetic energy in the fluid converted to potential or pressure energy??
the casing
