Name: ________________________ Class: ___________________ Date: __________ ID: A
1
MECH 1300 Final Review
True/FalseIndicate whether the statement is true or false.
____ 1. A larger Cv represents a smaller pressure drop at a given flow rate.
____ 2. Controlling the flow rate coming out of the rod end of a cylinder is called meter-in.
____ 3. Flow control valves control the flow rate of fluid in a circuit.
____ 4. Flow control valves are the only way to control the flow rate in a hydraulic circuit.
____ 5. A disadvantage of a flow control valve is that they cause increased inefficiency.
____ 6. Nonpositive displacement pumps typically operate by spinning the fluid with an impeller.
____ 7. Positive displacement pumps operate by opening up a cavity very quickly to create a vacuum.
____ 8. The three main types of construction for a positive displacement pumps are gear, vane, and piston.
Multiple ChoiceIdentify the choice that best completes the statement or answers the question.
____ 9. A system in which the motion is the mode of transmittal is know as a a. Hydrostatic System c. Thermodynamic Systemb. Hydrodynamic System d. Principle System
____ 10. A cylinder with a diameter of 300mm is loaded with a force of 50kN. What is the pressure (in kPa) inside the cylinder?a. 707 Pa c. 707 kPab. 176 kPa d. .70735 kPa
____ 11. Hydraulic fluid is flowing at a constant rate of 10 gpm through a conduit that has a 1.5in ID. What is the flow velocity in ft/s?a. 1.767 ft/s c. 1307 ft/sb. 2.634 ft/s d. 1.815 ft/s
Name: ________________________ ID: A
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CompletionComplete each statement.
12. Complete this circuit for a cylinder with meter-out control on the retract stroke. This circuit also rerquires a hydraulic motor and a pressure relief valve to be complete.
Short Answer
13. What are two of the most important advantages of fluid power transmission?
Name: ________________________ ID: A
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14. What are the two areas that fluid power is divided into?
15. Fluid power applications fall into what three industrial segments?
16. What are the five basic components of a hydraulic system?
17. A cylinder with a diameter of 2.5 in is loaded with a force of 15,000 lb. What is the pressure inside the cylinder?
18. A cylinder with a diameter of 100mm is loaded with a force of 35kN. What is the pressure (in kPa) inside the cylinder?
19. An object weighs 2000 lbs. What is its mass?
20. Oil flows at a velocity of 10 ft/s through a conduit with an ID of 0.5 in. Determine the flow rate.
21. A cylinder with a bore diameter of 4 inches and a rod diameter of 2.25 in is to be used in a system with a maximum pressure of 3500 psi. What are the maximum extension and retraction forces?
22. A cylinder with a bore diameter of 200mm and a rod diameter of 60mm is to be used in a system with a maximum pressure of 20,000kPa. What are the maximum extension and retraction forces?
23. A cylinder is required to extend against a load of 25,000 lb with a maximum pressure of 2500psi. What is the minimum cylinder diameter required?
24. A cyinder with a bore diameter of 1.5 in and a rod diamter of 0.625 in is to be used in a system with a 8gpm pump. What are the extension and retraction speeds?
25. A cylinder with a bore diameter of 3.5 in is required to extend at a velocity of 2ft/s. What flow rate (in gpm) is required to achieve this speed?
26. A cylinder with a bore diameter of 63 mm is required to extend at a velocity of 0.5 m/s. What flow rate (in lpm) is required to achieve this speed?
27. Assuming a constant flow rate, will a double-acting, single rod cylinder travel faster on the extend stroke or on the retract stroke?
28. A cylinder with a bore diamter of 4 in and a rod diamter of 1.75 in is required to extend against a loacd of 20,000lb and to retract against a load of 1000lb. What pressure is required for each stroke?
29. What type of cylinder has a rod that extends from both ends, so that work and can be done on both ends?
30. What are the three types of control valves used in hydraulic systems?
31. What is the purpose of a check valve?
Name: ________________________ ID: A
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32. Describe the difference between inline and subplate mounting of hydralic valves.
33. A cylinder with a bore diameter of 2 in and a rod diameter of 1 in is to be used in a system with a 10 gpm pump. What are the extension speeds when regenerating and when not regenerating?
34. A cylinder with a bore diameter of 2 in and a rod diameter of 1 in is to be used in a system with a 10 gpm pump. The system has a maximum pressure of 2500 psi. What are the maximum extension forces when regenerating and when not regenerating?
35. Know your Schematic Symbols:
36. What is the purpose of a pressure relief valve?
37. Describe the difference in operation between a direct-acting pressure relief valve and a pilot-operated pressure relief valve.
38. Define the terms cracking pressure, full-flow pressure, and pressure override with repect to pressure relief valves.
39. How is an unloading valve different from a pressure relief valve?
40. What is the purpose of a pressure reducing valve?
41. What is the purpose of a sequence valve?
Name: ________________________ ID: A
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42. What is the purpose of a counterbalance valve?
43. What is the purpose of a break valve?
44. Use the graph below to determine the cracking pressure of the relief valve if the full-flow pressure is set to 2000 psi.
Name: ________________________ ID: A
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45. Identify each pressure control valve symbol shown:
46. What is shifting shock?
47. Describe the operation of a solenoid.
48. What is the purpose of a proportional valve? How are they different from solenoid valves?
49. A cylinder is initially filled with 4ft3of air at a pressure of 20 psig. The air is compressed to a volume of
1ft3. What is the pressure in psig after compression.
50. A cylinder is initially filled with 5ft3of air at a pressure of 30 psig. The air is compressed to a volume of
2ft3. What is the pressure in psig after compression.
51. A cylinder is initially filled with 3m3of air at a pressure of 150 kPa gauge. The air is expanded to a volume
of 5m3. What is the pressure in kPa gauge after expansion?
52. Convert 68ºF to ºR
53. Convert 28ºC to K
Name: ________________________ ID: A
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54. Air in a fixed volume container is initially at atmospheric pressure (0 psig) and 75ºF. Its temperature is then raised to 160ºF. What is the gauge pressure at the final temperature?
55. Air in a fixed volume container is initially at atmospheric pressure (0 kPa gauge) and 25ºC. Its temperature is then raised to 85ºC. What is the gauge pressure at the final temperature?
56. Air initially at 60ºF and 100 psig occupies a volume of 6ft3. If the air is heated to 310ºF while its volume is
reduced to 3ft3, what is the resulting final pressure?
57. Air initially at 15ºC and 800 kPa occupies a volume of 3m3. If the air is heated to 160ºC while its volume is
reduced to 0.3m3, what is the resulting final pressure?
58. Air initially at 68ºF and atmospheric pressure is compressed from 70ft3to12ft3. Assuming the process is adiabatic, what is the final pressue (in psig) of the gas?
59. A suction cup with an inside diameter of 1 in is used in a vacuum system that pulls 19 in Hg. What is the maximum lifting force?
Problem
60. For the following system:Input diameter = 1 in, output diameter = 2.5 in, input force = 250 lb. Calculate the output force and calculate how far we need to move the input cylinder to move the output cylinder 1 in.
61. A 15ft diameter cylindrical tank is filled with oil (γ = 0.0324lb / in 3) to a height of 30 ft. What is the pressure at the bottom of the tank?
62. A hydraulic system operates at 15 gpm and 3000 psi. How much hydraulic horsepower is being generated?
Name: ________________________ ID: A
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63. What is the purpose of a pump?
64. What are the three main types of construction for positive displacement pumps?
65. Describe how nonpositive displacement pumps work.
66. Describe how positive displacement pumps work.
67. A pump has a displacement of 30cm3
rev and is driven at 1200 rpm. What is its theoretical flow rate?
68. A flow rate of 40 lpm is required for a system. If a 1200 rpm electric motor is use to drive the pump, what should the displacement be to achieve this rate?
69. A hydraulic pump with a displacement of 2 in 3
rev is selected for a system that will operate at a maximum
pressure of 2000 psi. What is the required torque?
70. An electric motor drives a pump at 1200 rpm with a torque of 400 in· lbs. What is the power input to this pump?
71. An electric motor drives a pump at 1600 rpm with a torque of 25N. What is the power input to this pump?
72. What kind of pump is this?
73. What kind of pump is this?
Name: ________________________ ID: A
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74. What type of pump is this?
75. Define:AcuatorLinear ActuatorRotary ActuatorDouble Acting Cylinders
76. Name the types of single acting cylinders.
77. Define and know what they are used for:Tandem CylinderTelescopic CylinderHydraulic Ram PressDouble Rod Cylinder
78. Know these:
Name: ________________________ ID: A
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79. Identify the number of ways, number of positions and the actuation method for each of the directional control valves shown:
Name: ________________________ ID: A
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80. Match the neutral type to its description for each symbol:
81. know/define:Pilot to openPilot to closeBall ValveDetentShuttle valveDiverterTandem centerPressure relief valve
82. A valve with a CV of 2 gpm
psi has a pressure drop of 25 psi. What must the flow rate be throught the
valve? The system uses standard hydraulic oil. (S g = 0.9).
83. A valve with a CV of 2.3 lpm
kPa has a pressure drop of 150kPa. What must the flow rate be throught the
valve? The system uses standard hydraulic oil. (S g = 0.9).
Name: ________________________ ID: A
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84. A valve with a CV of 1.5 gpm
psi has a pressure drop of 20 psi. What must the flow rate be throught the
valve? The system uses standard hydraulic oil. (S g = 0.9).
85. A valve with a CV of 2 gpm
psi is being considered for use in a system that has a flow rate of 20gpm.
What will the pressure drop be across the valve? The system uses standard hydraulic oil. (S g = 0.9).
86. A valve with a CV of 2.5 lpm
kPa is being considered for use in a system that has a flow rate of 50lpm.
What will the pressure drop be across the valve? The system uses standard hydraulic oil. (S g = 0.9).
87. A valve with a CV of 1.5 gpm
psi is being considered for use in a system that has a flow rate of 30gpm.
What will the pressure drop be across the valve? The system uses standard hydraulic oil. (S g = 0.9).
88. Know/Define:Design SpeedFree SpeedSlideRunning TorqueStarting TorqueStall TorqueGrippersEscapements
89. Know these:
Name: ________________________ ID: A
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90. Know These:
91. Know these DCV’s
92. An air-powered machine consumes 35 scfm at 90 psig. If the directional control valve that will control this machine can have a pressure drop of no more than 8 psi, what is the minimum CV ? Assume the temperature
of the air is 68ºF.
Name: ________________________ ID: A
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93. Know/Define:Closed Loop SystemOpen Loop SystemSolenoid ValveProportional ValveElectroHydraulic Pump Control
94. Define:Boyles LawGay-Lussac’s LawCharles’s LawGeneral Gas LawVacuumIsothermal SystemAdiabatic System
Essay
95. Chapter 2 Review knowledge:
Define:Pascal’s LawBernoulli’s EquationFlow VelocityFlow RateBulk ModulusViscosityStatic Head PressureLaminar FlowTurbulent FlowLinear ActuatorRotary Actuator
ID: A
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MECH 1300 Final ReviewAnswer Section
TRUE/FALSE
1. ANS: T PTS: 1 2. ANS: F PTS: 1 3. ANS: T PTS: 1 4. ANS: F
variable displacement can be used
PTS: 1 5. ANS: T PTS: 1 6. ANS: T PTS: 1 7. ANS: T PTS: 1 8. ANS: T PTS: 1
MULTIPLE CHOICE
9. ANS: B PTS: 1 10. ANS: C PTS: 1 11. ANS: D PTS: 1
COMPLETION
12. ANS:
PTS: 1
ID: A
2
SHORT ANSWER
13. ANS: Multiply force and change direction quickly without damage to the system.
PTS: 1 14. ANS:
Hydraulics and Pneumatics
PTS: 1 15. ANS:
mobile hydraulic, industrial hydraulic and industrial pneumatic
PTS: 1 16. ANS:
Power Input Device, Control Devices, Power Output Device, Conductors, Liquid
PTS: 1 17. ANS:
3056 psi
PTS: 1 18. ANS:
4456 kPa
PTS: 1 19. ANS:
2000/32.2 = 62.11
PTS: 1 20. ANS:
6.11 gpm
Q = v * A
A = .1963
v = 10ft/s * 12in/1ft *60s/min =7200 in/min
Q = 7200 * .1963 = 1413.36
to gpm 1413.36 * 1/231 = 6.11 gpm
PTS: 1 21. ANS:
FE = 43980lb,FR = 30060lb
PTS: 1
ID: A
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22. ANS: FE = 628kN,FR = 571kN
PTS: 1 23. ANS:
3.57 in
PTS: 1 24. ANS:
1046 in/min (1.45 ft/s), 1265 in/min (1.76 ft/s)
PTS: 1 25. ANS:
60.0 gpm
PTS: 1 26. ANS:
93.5 lpm
PTS: 1 27. ANS:
The retract stroke
PTS: 1 28. ANS:
1592 psi, 98 psi
PTS: 1 29. ANS:
Double Rod Cylinder
PTS: 1 30. ANS:
Directional control valves. pressure control valves and flow control valves.
PTS: 1 31. ANS:
To allow flow in one direction and to block flow in the other direction.
PTS: 1 32. ANS:
Inline mounted have ports threaded directly into the valve, while subplate mounted valves have unthreaded connections on the bottom of the valve. The valve is then attached to a sub-plate that has matching connections. The sub-plate has the threaded connections to which the fittings are attached.
PTS: 1
ID: A
4
33. ANS: 2941 in/min
PTS: 1 34. ANS:
1964 lb, 7855 lb
PTS: 1 35. ANS:
see text/notes
PTS: 1 36. ANS:
A pressure relief valve limits the maximum pressure in a hydraulic circuit.
PTS: 1 37. ANS:
A direct-acting pressure relief valve has a single stage in which a poppet or ball is subjected to pressure on one side and pressure on the other. A pilot operated pressure relief valve has a two-stage arrangement in which a pilot poppet opens,which causes a pressure drop across a main piston, causing it to open and allow full flow back to the tank.
PTS: 1 38. ANS:
Cracking pressure - the pressure at which the pressure relief valve just begins to open. Full-flow pressure - the pressure at which the pressure relief valve is fully open and sending all the pump flow back to the tank. Pressure override - the difference between the full flow and cracking pressures.
PTS: 1 39. ANS:
An unloading valve reads the pressure in an external line, while a pressure relief valve reads the pressure in its own line.
PTS: 1 40. ANS:
To maintain a reduced pressure in a branch circuit.
PTS: 1 41. ANS:
To force to actuators to actuate in sequence.
PTS: 1 42. ANS:
To counterbalance a weight being held by a hydraulic cylinder
PTS: 1
ID: A
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43. ANS: To prevent an overrruning load from driving the hydraulic motor.
PTS: 1 44. ANS:
Approximately 1650 psi
PTS: 1 45. ANS:
1) Pressure relief valve2) Pressure unloading valve3) Pressure reducing valve
PTS: 1 46. ANS:
Occurs when directional control valves are shifted into the closed position. Shifting the valve closed can cause a pressure spike on the outlet line.
PTS: 1 47. ANS:
A solenoid operates on the principle that when a current is applied to a coil of wires a magnetic field is generated within the coil. The magnetic field is used to move a plunger, which can be used to shift a valve spool.
PTS: 1 48. ANS:
Proportional valves allow the valve spool to be precisely positioned between the open and closed positions, which allows the valve to control flow rate and pressure in additioin to direction. Solenoid valves only control direction because they only have two states: open or closed.
PTS: 1 49. ANS:
124.1psig
p1 = 20psig + 14.7psia = 34.7psia
p2 =p 1V1
V2
= 34.7 * 41
= 138.8psia
p2 = 138.8psia − 14.7psia = 124.1psig
PTS: 1
ID: A
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50. ANS: 97.05 psig
p1 = 30psig + 14.7psia = 44.7psia
p2 =p 1V1
V2
= 44.7 * 52
= 111.75psia
p2 = 111.75psia − 14.7psia = 97.05psig
PTS: 1 51. ANS:
49.6kPa gauge
p1 = 150kPagauge + 101kPa abs= 251kPa abs
p2 =p1V1
V2
= 251 * 35
= 150.6kPa abs
p2 = 150.6kPa abs− 101kpa abs= 49.6kPagauge
PTS: 1 52. ANS:
528
68+460=528
PTS: 1 53. ANS:
301K
28+273 = 301
PTS: 1 54. ANS:
2.3psig
T1 = 75+ 460= 535
T2 = 160+ 460= 620
p1 = 0psig + 14.7psia = 14.7psia
p2 = 14.7 *620535
= 17.03psia
17.03− 14.7= 2.3psig
PTS: 1
ID: A
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55. ANS: 20.33 kPa gauge
T1 = 25+ 273= 298K
T2 = 85+ 273= 358K
p1 = 0kPagauge + 101kPa abs= 101kPa abs
p2 = 101 *358298
= 121.33kPa abs
121.33− 101= 20.33kPagauge
PTS: 1 56. ANS:
324.98 psigGeneral gas lawT1 = 520
T2 = 770
pabs = 100+ 14.7= 114.7psia
p2 = 770 * 114.7 * 6520 * 3
= 339.68psia
p2 = 339.68− 14.7= 324.98psig
PTS: 1 57. ANS:
13445 kPa gaugeGeneral gas lawT1 = 288
T2 = 433
pabs = 800+ 101= 901kPa abs
p2 = 433 * 901 * 3288 * 0.3
= 13546kPa abs
p2 = 13546kPa abs− 101= 13445kPagauge
PTS: 1 58. ANS:
158.92 psig
PTS: 1
ID: A
8
59. ANS: 7.32 lbs
Convert to psig
19inHg *−0.491psig
1inHG= −9.32psig
A = 3.142 * 12
4= 0.785
F = p * A = −9.32 * 0.785= −7.32
Negative signifies that the object is being drawn toward the suction cup
PTS: 1
PROBLEM
60. ANS: 1563 lbs, 6.25 in
PTS: 1 61. ANS:
11.7 psi
Static Head PressurepH = γ ⋅ h
h = 30 * 12 = 360 in
=0.0324 * 360 = 11.7 psi
PTS: 1 62. ANS:
26.3 hp
(3000 * 15) / 1714 = 26.3
PTS: 1 63. ANS:
To create flow
PTS: 1 64. ANS:
gear, vane and piston
PTS: 1
ID: A
9
65. ANS: Nonpositive displacement pumps typically operate by spinning the fluid with an impeller.
PTS: 1 66. ANS:
Positive displacement pumps operate by opening up a cavity very quickly to create a vacuum.
PTS: 1 67. ANS:
36 l/min
PTS: 1 68. ANS:
33.3 in3
rev
PTS: 1 69. ANS:
637 in lbs
PTS: 1 70. ANS:
8 hp
PTS: 1 71. ANS:
4.18kW
PTS: 1 72. ANS:
Gear pump
PTS: 1 73. ANS:
Vane pump
PTS: 1 74. ANS:
Piston pump
PTS: 1 75. ANS:
see notes/text
PTS: 1
ID: A
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76. ANS: Push, pull, single return
PTS: 1 77. ANS:
see notes/text
PTS: 1 78. ANS:
See notes/text
PTS: 1 79. ANS:
Four-way, three position, solenoid actuatedtwo-way, two-position, manual lever actuatedthree-way, two position, pilot actuated
PTS: 1 80. ANS:
B, D, A, C
PTS: 1 81. ANS:
see notes/text
PTS: 1 82. ANS:
Q = CV *P
S g
=10.54gpm
PTS: 1 83. ANS:
Q = CV *P
S g
=29.69lpm
PTS: 1 84. ANS:
Q = CV *P
S g
=7.07gpm
PTS: 1
ID: A
11
85. ANS:
p =Q2
CVÊËÁÁ ˆ
¯˜̃
2 * S g = 90psi
PTS: 1 86. ANS:
p =Q2
CVÊËÁÁ ˆ
¯˜̃
2 * S g = 360kPa
PTS: 1 87. ANS:
p =Q2
CVÊËÁÁ ˆ
¯˜̃
2 * S g = 360psi
PTS: 1 88. ANS:
see text chapter 12 and notes
PTS: 1 89. ANS:
See Chapter 12 and notes
PTS: 1
ID: A
12
90. ANS:
PTS: 1 91. ANS:
See page 439 in text
PTS: 1 92. ANS:
1.236AbsolutesPOUT = 90+ 14.7= 104.7psia
T = 68+ 460= 528oR
CV =Q
22.48T
∆p * p OUT
= 3522.48
5288 * 104.7
=1.236
PTS: 1
ID: A
13
93. ANS: See Chapter 13 in text/notes
PTS: 1 94. ANS:
See Text
PTS: 1
ESSAY
95. ANS: Read Chapter 2
PTS: 1