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Millwright – Hydraulics – Study Guide & Practice Questions
a. None - correct answer ✔✔1. How much volume is delivered if the swash plate in an axial piston pump is positioned at 90°? a. None b. Full capacity of the pump rating c. Approximately half of the pump capacity d. Depends on the fluid viscosity c. The load requirements - correct answer ✔✔2. What is the first consideration when designing a fluid power system? a. Ease of maintenance b. Compatibility with existing parts c. The load requirements d. Location of equipment b. 3 to 5 psi - correct answer ✔✔3. What is the cracking pressure of a check valve? a. 10 psi b. 3 to 5 psi c. 1 psi d. Above 10 psi b. 74° - correct answer ✔✔4. What is the standard included angle of a JIC fitting?
a. 37° b. 74° c. 25 1⁄2° d. 37 1⁄2° c. Adjusting the cushion - correct answer ✔✔5. What is the function of the screw located in the end of a cylinder block? a. Draining the cylinder for maintenance b. Tightening the rod in place to ensure it doesn't move during service or installation c. Adjusting the cushion d. Inspection port for examining the condition of the piston seals b. Joint Industrial Council - correct answer ✔✔6. What does JIC stand for? a. Joint Incident Committee b. Joint Industrial Council c. Joint Incident Council d. Joint Industrial Committee c. The incomplete filling of the pumping chamber - correct answer ✔✔7. What is cavitation? a. When a pump is installed in a flooded application b. When a pump can't handle the load c. The incomplete filling of the pumping chamber
a. Cylinder moving b. Accumulator closing c. Broken line d. Wrong fluid d. Pressure drop - correct answer ✔✔12. What happens in a system when an accumulator closes suddenly? a. Increase in pressure b. MPRV opens c. Pump over amps d. Pressure drop a. Close to the pump - correct answer ✔✔13. Where is a Maximum Pressure relief valve located? a. Close to the pump b. Anywhere on the return line c. Mounted on the tank d. Doesn't matter, as long as it is in the system a. Radial piston pump - correct answer ✔✔14. What type of pump is required to handle high viscosity fluid? a. Radial piston pump b. Any positive displacement pump c. Lobe pump
d. Georotor d. Prevents the return oil from directly re-entering the pump inlet - correct answer ✔✔15. What is the function of a baffle plate in a hydraulic tank? a. Prevents cavitation b. Keeps dirty oil on one side of the reservoir c. Prevents aeration d. Prevents the return oil from directly re-entering the pump inlet a. Internal gear has 1 less tooth than external female gear - correct answer ✔✔16. How is a gerotor pump recognized? a. Internal gear has 1 less tooth than external female gear b. Internal gear teeth are jagged c. External gear is non lubricated d. Internal gear has 1 more tooth than the external female gear. c. Returns fluid back to tank after system pressure is reached - correct answer ✔✔17. What does an unloading valve do? a. Allows one operation to occur before another b. Maintains system pressure c. Returns fluid back to tank after system pressure is reached d. Replaces the MPRV when it is taken out for servicing d. Regulator - correct answer ✔✔18. In a fluid system, what is used to maintain a constant pressure?
d. Tandem center DCV b. Microns - correct answer ✔✔22. How are filters sized? a. Mesh b. Microns c. Viscosity d. Parts per million a. Pressure reducing valve - correct answer ✔✔23. What is a type of hydraulic valve that is normally open? a. Pressure reducing valve b. Unloading valve c. Sequencing valve d. All of them are normally open d. To create a partial vacuum on the inlet - correct answer ✔✔24. What is the principal function of a positive displacement pump? a. To handle high viscosity fluid b. To create positive pressure in a cylinder c. To create enough pressure to bypass a cylinder cushion d. To create a partial vacuum on the inlet c. Flow control valve - correct answer ✔✔25. What type of valve controls a system GPM?
a. Directional control valve b. Regulator c. Flow control valve d. Sequencing valve a. Motion - correct answer ✔✔26. Fluid power actuators convert fluid into which of the following? a. Motion b. Pressure c. Work speed d. Extreme pressure a. 5" F = P A F = 7.5 Tons x 2200 = 16500lbs 16500x1.1 = 18150lbs P = 950psi A = 18150lbs/950 psi A = 19.105 inches squared A = d(squared) x 0. 19.105/0.7854 = d (squared) 24.3255 = d (squared) d = 4.93" round up
c. 1592 psi d. 796 psi b. Flow - correct answer ✔✔30. Solid filled equilateral triangles on a schematic indicate what? a. Pressure b. Flow c. Direction of air d. Line restrictions a. Figure 8 shape - correct answer ✔✔31. An external gear pump resembles what shape? a. Figure 8 shape b. "O" shape c. Depends on the manufacturer d. Triangle d. The potential contact point of the two gears - correct answer ✔✔32. The internal seal of an internal gear pump is: a. A slinger b. A partial vacuum c. Cork d. The potential contact point of the two gears
c. Driven using timing gears - correct answer ✔✔33. Lobe pump rotors must be: a. Pre-lubed b. Made of Stainless steel c. Driven using timing gears d. Sanded at the teeth to ensure laminar flow is delivered a. Odd number of forms between both elements - correct answer ✔✔34. Pumping chambers in a gerotor pump are created by: a. Odd number of forms between both elements b. Rubbing on the side walls c. No volute d. Flooded application b. Increase oiling system for better efficiency - correct answer ✔✔35. Some pistons have grooves cut in the diameter with no lead. The function of these grooves are what? a. Decrease efficiency b. Increase oiling system for better efficiency c. To allow for wear d. To create a partial vacuum b. Fixed displacement - correct answer ✔✔36. If a swash plate in an axial piston pump is not adjustable, the pump is:
b. It allows one operation to occur before another - correct answer ✔✔40. What is the function of a sequencing valve? a. It controls the speed of a cylinder b. It allows one operation to occur before another c. It regulates air assistance to the pistons d. It dumps excessive pressure from a system a. Debris in oil - correct answer ✔✔41. If a pump has worn impellor tips, what is the cause? a. Debris in oil b. High viscosity c. Tips are made to improve laminar flow d. Oil is air entrained a. Completely plugged vent - correct answer ✔✔42. A closed hydraulic tank starts to cave in. What would cause this condition? a. Completely plugged vent b. Too high of a volume pump c. More than one actuator activated at the same time d. Viscosity of the fluid is too high b. Cavitation - correct answer ✔✔43. What causes vibration to occur on the inlet line of a pump? a. Plugged vent on an open style tank b. Cavitation
c. The style of pump is a non positive displacement pump d. Oil has oxidized d. 231 - correct answer ✔✔44. How many cubic inches are in 1 gallon of oil? a. 213 b. 321 c. 312 d. 231 b. Material, OD, wall thickness - correct answer ✔✔45. How do you choose hydraulic tubing? a. Surface finish, OD, material b. Material, OD, wall thickness c. ID, Wall thickness, flexibility d. OD, ID, Wall thickness b. Sequence valve - correct answer ✔✔46. What type of valve allows one operation to occur before another? a. Unloading valve b. Sequence valve c. Directional control valve d. Relief valve a. To create a partial vacuum on the inlet - correct answer ✔✔47. What is the principal function of a positive displacement pump?
d. Always be kept clean - correct answer ✔✔51. For fluid to properly function over long periods of time, it must be: a. Kept at low temperatures b. Have the strainers changed weekly c. Have the filters changed weekly d. Always be kept clean b. Prevent the returning fluid from directly entering the pump inlet - correct answer ✔✔52. The function of a baffle plate in a hydraulic tank is what? a. Strengthen the tank b. Prevent the returning fluid from directly entering the pump inlet c. Allow for systems with two or more pumps d. Prevent contaminants from entering the inlet line a. Motion - correct answer ✔✔53. Fluid power actuators convert fluid force into: a. Motion b. Pressure c. Flow d. Horse power c. 841 in/min Speed = Flow rate / Area
Speed = 15 gpm x 231 / (2.5 sq x 0.7854)-(1 sq x 0.7854) Speed = (3465in/min)/4.12 in sq Speed = 841 in/min - correct answer ✔✔54. Calculate the retract speed of a cylinder with a 2.5" bore, and a rod diameter of 1", with a supply of 15gpm. a. 75 in/min b. 706 in/min c. 841 in/min d. 500 in/min a. Equally in all directions, at right angles to the containing surface - correct answer ✔✔55. PASCAL's law states that when pressure is applied to a fluid at rest in a confined space, force is transmitted: a. Equally in all directions, at right angles to the containing surface b. In the direction of fluid flow c. Randomly, in all directions, based on the fluid viscosity d. Randomly, in all directions, at obtuse angles to the containing surface b. Envelopes - correct answer ✔✔56. In a fluid power directional control valve symbol, the squares are called what? a. Boxes b. Envelopes c. Valve position d. Valve casing
c. The style of housing d. The size of the pumping chamber c. Fluid pressure - correct answer ✔✔61. The most efficient way to maintain contact of vanes to the cam ring surface is by: a. Fluid viscosity b. Centrifugal force c. Fluid pressure d. Pre-loaded spring tension b. An odd number of forms between elements - correct answer ✔✔62. Pumping chambers in a gerotor pump are created by? a. Tolerance between elements b. An odd number of forms between elements c. Speed of the elements d. Always installing them in a flooded application b. 14.7 psia - correct answer ✔✔63. The pressure available to create a volume of delivery from a positive displacement pump is: a. 14.7 psi b. 14.7 psia c. 14.7 inches of vacuum d. Minimum 100 psi
a. Safe guard for the pump - will not allow pressure to exceed the setting - correct answer ✔✔64. What function does an MPRV serve? a. Safe guard for the pump - will not allow pressure to exceed the setting b. Allows higher pressures to be reached c. Used in "Meter - in" situations d. Allows two pumps of different GPM ratings to be interchanged a. Micron rating - correct answer ✔✔65. Hydraulic filters are sized with what? a. Micron rating b. Mesh rating c. Strainer # d. ISO #'s b. Nut ID - correct answer ✔✔66. What determines the length of flare on a hydraulic fitting? a. Nut OD b. Nut ID c. Amount protruding from the block d. Horse power of the crimper d. Discharge valve - correct answer ✔✔67. What is the last valve to open when starting a pump? a. Suction valve b. Relief valve c. Regulator
