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Final f08


									IT 221 Final Exam NAME _________________________

You may use whatever reference material you like to answer these questions, but please DO YOUR OWN WORK. Do not collaborate with other class mates
Answer the following and submit under my door, or in the box on my round table, or to Bonnie in the IT office by 5PM Wednesday November 19, 2008. Circle the correct answer 1. The square jaw clutch permits engagement when a large differential is speed exists between the driving and the driven shaft. a) True b) False 2. Which of the following is not an overrunning clutch. a) sprag b) centrifugal c) friction d) roller e) all are overrunning clutches 3. Plain bearings rely upon a film of oil to minimize friction between the rotating shaft and stationary frame. a) True b) False 4. A Kingsbury bearing is a rolling element bearing. a) True b) False 5. When mounted on a rotating shaft, which of the following bearings is/are capable of only radial load. a) spherical b) rollerc) ball d) tapered roller e) all can carry both radial and thrust load 6. A clutch is a mechanism that engages and disengages power transfer between a prime mover and a load. a) True b) False 7. The most commonly used type of cam follower in industry is the a) flat face b) knife edge c) roller d) none of the above 8. Compound levers provide a compact method of achieving high mechanical advantage. a) True b) False 9. A crankpin mechanism might be used to drive a reciprocating table. a) True b) False 10. Toggle mechanisms trade distance advantage for force advantage. a) True b) False

11. The primary benefit of the quick return mechanism is a) to assure parallel motion of the coupler link b) to convert rotational motion to translational motion c) to provide alternately, slow feed and rapid return movement d) to assure timed rotary operation 12. Which of the following devices includes a cam trapped inside the follower. a) Geneva lock b) Scotch yoke c) eccentric d) ratchet 13. The result of using mutilated gears could be periodic motion. a) True b) False 14. Pressure is force on a surface divided by the area normal to the direction of the applied force. a) True b) False 15. Which of the following pumps is positive displacement? a) gear b) vane c) crescent d) piston e) all of the above 16. Directional control valves often use spool mechanisms. a) True b) False 17. Pistons with rods typically have a preferential direction for piston force. a) True b) False 18. Piston size (diameter) is selected based on a) safety considerations b) force requirements c) cost tradeoffs d) available pressure e) both b and d 19. Rotary actuators have limited angular displacement a) True b) False 20. Which conductor should be used if the system will never require disassembly and minimum cost is important? a) hose b) wire reinforced elastomer c) tubing d) pipe 21. A double acting cylinder must have both a supply and return line. a) True b) False 22. Pneumatic piston compressors use inlet and outlet check valves. a) True b) False

23. Pneumatic flow capacity is often quoted in a) gal/min b) scfm c) pounds/hour d) liters 24. Pneumatic systems require lubrication to operate properly. a) True b) False 25. Pneumatic prime movers are called a) pumps b) motors c) regulators

d) compressors

26. Pneumatic systems vent the used air to the atmosphere. a) True b) False

27. The FLR unit provides filtering, regulation, and lubrication. a) True b) False 28. Based on OHM's law, for a given resistance, higher voltage produces _____ current. a) less b) more c) same d) voltage is not related to current 29. Electrical power is a) current squared times resistance b) voltage squared divided by resistance c) current times voltage d) all of the above

30. Plant and house wiring circuits are a) both series and parallel b) series c) parallel d) three phase 31. AC electricity involves rapid alternation of electron direction about a given point. a) True b) False

32. Three phase electricity contains _____ times as much power as single phase. a) one b) three c) nine d) depends on the voltage level e) none of the above 33. Electric current creates a magnetic field. a) True b) False

34. Electromagnetic relays a) contain coils b) involve moving contacts c) may have numerous contacts d) may latch when activated e) all of the above 35. Brushes a) are made of carbon b) conduct electricity from the rotor c) are spring loaded d) rub against the commutator e) all of the above

36. The rotor of a DC motor contains loops of wires. a) True b) False 37. The commutator is a switch that a) activates based on a signal from a solenoid b) assures that like poles are always alligned c) limits current flow to the field poles d) includes temperature protection 38. The torque magnitude of a DC motor is related to the strength of only the field magnet. a) True b) False 39. Speed of a DC motor can be controlled using a rheostat. a) True b) False 40. The DC motor will not operate on AC current. a) True b) False 41. The speed of the AC motor is a function of a) field magnet strength b) material the rotor is made from c) supplied current magnitude d) frequency of the AC 42. A squirrel cage motor is a ______ motor. a) DC b) AC c) Universal

d) all of the above

43. With three phase power supply, the motor must have separate windings for each phase. a) True b) False 44. Temperature is a central concept in the understanding of thermodynamics. a) True b) False

45. Two bodies in contact will seek an equilibrium temperature. a) Law of Conservation of Energy b) Zeroth Law of Thermo c) First Law of Thermo 46. Work can be removed from a process where heat is flowing. a) joule's constant b) First Law of Thermo c) Law of Conservation of Energy 47. Thermodynamic efficiency and device efficiency are the same thing. a) True b) False 48. Thermodynamic efficiency for refrigeration is called a) Thermodynamic efficiency b) Coefficient of Performance c) Efficiency d) Coolant Capacity e) Compressor Charge Pressure d) Second Law of Thermo e) both c and d d) Second Law of Thermo e) Third Law of Thermo

49. The linear motion produced by external combustion engines is converted to rotary motion using a double rocker mechanism. a) True b) False

50. Watt's improvement to the Newcomen engine made it double acting. a) True b) False

51. Cogeneration is a technique of de-mineralizing and purifying water. a) True b) False

52. Combustion in internal combustion engines produces a) high temperature gas b) high pressure gas c) carbon dioxide d) water vapor e) all of the above

53. Typical hardware found in a four stroke engine include all but which of the following. a) wrist pin b) crank shaft c) compressor d) piston e) oil rings

54. The proper order of the four strokes of the four stroke engine are

a) power, exhaust, compression, intake b) intake, power, exhaust, compression c) exhaust, intake, compression, power d) power, intake, compression, exhaust e) none of the above

55. The four stroke engine relies upon vacuum to ingest fuel and air. a) True b) False

56. The compression stroke is required because a) high pressure is needed for combustion b) high air density is needed for combustion c) high oxygen density is needed for combustion d) explosion efficiency improves with confined volume e) none of the above

57. Overhead cam engines require fuel injection. a) True 58. Two stroke engines a) do not have moving valves b) require mixing oil in the fuel c) have a narrower high efficiency speed range than four stroke engines d) have fewer moving parts than four stroke engines e) all of the above b) False

59. A 2 inch diameter pneumatic piston has a stroke of six inches when pressurized with 100 psi air pressure. How much work does the piston accomplish?

60. A four start worm is used with a 24 tooth worm gear in a gear reducer. What is the gear ratio?

If a motor attached to the worm turns at 2000 rpm, at what speed does the output shaft turn at?

If the input torque is 20 foot-pounds, what is the output torque?

61. What is the displacement of a four cylinder engine having a bore of 3.25 inches and a stroke of 3.5 inches?(Show your work)

If the head volume is 3.75 cubic inches, what is the compression ratio? (Show your work)

62. Explain the operation of the four stroke engine (one paragraph)

63. Compare the four stroke engine to a) the two stroke engine (one paragraph)

b) the diesel engine (one paragraph)

64. Relate the four stroke engine to each of the following and give examples of each found in the engine: a) mechanical system (one paragraph)

b) pneumatic system (one paragraph)

65. Explain the operation of a steam generating plant (one paragraph)

Please sign your name if you did not collaborate with others in providing the answers for this exam.______________

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