In hydrodynamic lubrication, film thickness remains unaffected by change in speeds.

a) True

b) Increase with increase in speed

c) Decrease with increase in speed

d) Disappear as the speed tends to infinty

1 Answer

Answer :

b) Increase with increase in speed

Related questions

Description : A journal bearing with hydrodynamic lubrication is running steadily with a certain amount of minimum film thickness. When the load and speed are doubled, how does the minimum film thickness vary? [IES-2008 ... Gets reduced to one-fourth of original value (d) Gets reduced to half of original value

Last Answer : (a) Remains unchanged

Description : Assertion (A): Hydrostatic lubrication is more advantageous when compared to hydrodynamic lubrication during starting and stopping the journal in its bearing. Reason (R): In hydrodynamic lubrication, the fluid film pressure is ... (c) A is true but R is false (d) A is false but R is true

Last Answer : (b) Both A and R are individually true but R is not the correct explanation of A

Description : Assertion (A): Oil as a cutting fluid result in a lower coefficient of friction. Reason (R): Oil forms a thin liquid film between the tool face and chip, and it provides 'hydrodynamic lubrication'. [IES- 2000] (a ... explanation of A (c) A is true but R is false (d) A is false but R is true

Last Answer : (c) A is true but R is false

Description : Assertion (A): In steady rotating condition the journal inside a hydrodynamic journal bearing remains floating on the oil film. [IES-2008] Reason (R): The hydrodynamic pressure developed in steady rotating conditions in journal ... A (c) A is true but R is false (d) A is false but R is true

Last Answer : (a) Both A and R are true and R is the correct explanation of A

Description : Hydrostatic and hydrodynamic lubrication are the same thing. a) True b) False

Last Answer : b) False

Description : Which one of the following pair is correctly matched? [IES-2000] (a) Beauchamp tower ........................First experiments on journal bearings (b) Osborne Reynolds ........................ ... .Pivot and Collar bearings (d) Ball bearings...............................Hydrodynamic lubrication

Last Answer : (a) Beauchamp tower ........................First experiments on journal bearings

Description : For elasto-hydrodynamic lubrication (A) There should be relative motion between the surfaces of the journal and the bearing and wedge shaped clearance space (B) There should be external source like ... be elastic deformation of the parts in contact (D) There should be metal to metal contact

Last Answer : (C) There should be elastic deformation of the parts in contact

Description : For hydrodynamic lubrication (A) There should be relative motion between the surfaces of the journal and the bearing and wedge shaped clearance space (B) There should be external source like pump to ... be elastic deformation of the parts in contact (D) There should be metal to metal contact

Last Answer : (A) There should be relative motion between the surfaces of the journal and the bearing and wedge shaped clearance space

Description : A journal bearing is a ______ contact bearing working on the hydrodynamic lubrication and which supports load in____ direction. a) Sliding, Axial b) Rolling, Radial c) Sliding, Radial d) Rolling, Axial

Last Answer : c) Sliding, Radial

Description : In an oil-lubricated journal bearing, coefficient of friction between the journal and the bearing. [IES-1995] (a) Remains constant at all speeds. (b) is minimum at zero speed and increases ... speed. (d) becomes minimum at an optimum speed and then increases with further increase in speed.

Last Answer : (d) becomes minimum at an optimum speed and then increases with further increase in speed.

Description : What is the main advantage of hydrodynamic bearing over roller bearing? (a) Easy to assemble [IES-2005] (b) Relatively low price (c) Superior load carrying capacity at higher speeds (d) Less frictional resistance

Last Answer : (c) Superior load carrying capacity at higher speeds

Description : Consider the following statements: [IES 2007] For a journal rotating in a bearing under film lubrication conditions, the frictional resistance is- 1. Proportional to the area of contact 2. Proportional to the viscosity of lubricant 3. ... 4 (b) 1 and 4 only (c) 2, 3 and 4 only (d) 2 and 3 only

Last Answer : (a) 1, 2, 3 and 4

Description : Satisfactory hydrodynamic film in a journal bearing is formed when (a) Journal speed is low; unit pressure on the bearing is high and viscosity of lubricant used is low [IES-2006] ... journal speed, unit pressure on bearing and lubricant viscosity exists resulting in low coefficient of friction

Last Answer : (c) Journal speed is high; unit pressure on the bearing is high and viscosity of lubricant used is high

Description : If fluid film pressure is high and surface rigidity is low than mode of lubrication is called as elastohydrodynamic lubrication. a) True b) False

Last Answer : a) True

Description : What is meant by hydrodynamic film lubrication?

Last Answer : In high-speed turbines the lubricating oil will be at the sides and there is metal to metal contact when turbine at rest. When the turbine speeds up there is pressure pushing the oil through the ... the oil film breaks the barrier and it takes the load on itself. This is hydrodynamic lubrication. 

Description : Increase in values of which of the following results in an increase of the coefficient of friction in a hydrodynamic bearing? [IES 2007] 1. Viscosity of the oil. 2. Clearance between shaft and bearing. 3. Shaft speed. Select the ... 1 and 2 only (b) 1 and 3 only (c) 2 and 3 only (d) 1, 2 and 3

Last Answer : (b) 1 and 3 only

Description : In hydrostatic bearings (A) The Oil film pressure is generated only by the rotation of the journal (B) The oil film is maintained by supplying oil under pressure (C) Do not require external supply of lubricant (D) Grease is used for lubrication

Last Answer : (B) The oil film is maintained by supplying oil under pressure

Description : Thick film lubrication describes a phenomenon where two surfaces are _______ separated. a) Completely b) Partially c) Not d) None of the mentioned

Last Answer : a) Completely

Description : With the increase in speed of the vehicle, the back pressure will a. decrease b. increase c. remains unaffected d. depends on other factors

Last Answer : ANSWER b. increase

Description : Which one of the following is correct? [IES-2008] A hydrodynamic slider bearing develops load bearing capacity mainly because of- (a) Slider velocity (b) wedge shaped oil film (c) Oil compressibility (d) oil viscosity

Last Answer : (b) wedge shaped oil film

Description : Boundary lubricated bearing is (A) Thick film bearing (B) Thin film bearing (C) Hydrodynamic bearing (D) Hydrostatic bearing

Last Answer : (B) Thin film bearing

Description : A steam carrying pipeline is insulated with two layers of insulating materials with the inferior insulation material forming the inner part. If the two insulating layers are interchanged, the heat conducted ... ) Remain unaffected (D) May increase or decrease; depends on the thickness of each layer

Last Answer : Option C

Description : The most suitable bearing for carrying very heavy loads with slow speed is (a) Hydrodynamic bearing (b) ball bearing [IAS 1994] (c) Roller bearing (d) hydrostatic bearing

Last Answer : (d) hydrostatic bearing

Description : The bearing characteristic number in a hydrodynamic bearing depends on- (a) Length, width and load (b) length, width and speed. [IES-1996] (c) Viscosity, speed and load (d) viscosity, speed and bearing pressure.

Last Answer : (d) viscosity, speed and bearing pressure.

Description : In hydrodynamic bearing, (A) The axis of journal is eccentric with respect to axis of bearing (B) The axis of journal is concentric with respect to axis of bearing (C) The axis can be either eccentric or concentric depending upon speed (D) None of the above

Last Answer : (A) The axis of journal is eccentric with respect to axis of bearing

Description : For an elliptical hole on a flat plate, if width of the hole in direction of the load decrease, Stress Concentration Factor will______ a) Increase b) Decrease c) Remains constant d) Can’t be determined. Varies from material to material

Last Answer : a) Increase

Description : How the interest-level of a country is affected by FDI? (1) increases (2) decreases (3) remains unaffected (4) there is increase or decrease

Last Answer : (2) decreases Explanation: A higher international interest rate will decrease FDI since it means a higher cost of fund in international market, and vice versa. Interest rate is a measure of the cost of capital ... to a decrease in FDI. Interest rate and FDI can both be the cause and effect of other.

Description : How the interest-level of a country is affected by FDI ? (1) increases (2) decreases (3) remains unaffected (4) there is increase or decrease

Last Answer : decreases

Description : Assertion (A): In equilibrium position, the journal inside a journal bearing remains floating on the oil film. [IES-1995] Reason (R): In a journal bearing, the load on the bearing is perpendicular to the axis of the ... explanation of A (c) A is true but R is false (d) A is false but R is true

Last Answer : (b) Both A and R are individually true but R is not the correct explanation of A

Description : Assertion (A): In hydrodynamic journal bearings, the rotating journal is held in floating condition by the hydrodynamic pressure developed in the lubricant. Reason (R): Lubricant flows in a converging-diverging channel. [IES-1994] ... A (c) A is true but R is false (d) A is false but R is true

Last Answer : (a) Both A and R are individually true and R is the correct explanation of A

Description : Hydrodynamic bearing is a self-acting bearing. a) True b) False

Last Answer : a) True

Description : How does the hydrostatic lubrication differ from hydrodynamic type?

Last Answer : In hydrostatic lubrication which is used in slow speed turbines the lubricating oil is pressurised externally where as in hydrodynamic system it forms oil film by its speed which pushes the lubrication oil to form film.

Description : Starting friction is low in case of the __________ lubrication. (A) Boundary (B) Hydrodynamic (C) Hydrostatic (D) Mixed/semi-fluid

Last Answer : (C) Hydrostatic

Description : The coefficient of fluctuation of speed of flywheel is 1. ratio of maximum and minimum speeds during the cycle 2. ratio of maximum fluctuation of speed to the mean speed 3. ratio of mean ... maximum fluctuation of speed during the cycle 4. sum of maximum fluctuation of speed and the mean speed

Last Answer : 2. ratio of maximum fluctuation of speed to the mean speed

Description : The coefficient of fluctuation of speed, when the maximum and minimum speeds are 300rpm and 290 rpm (A) 0.034 (B) 0.017 (C) 0.008 (D) 0/004

Last Answer : (A) 0.034

Description : The difference the maximum and minimum speeds during a cycle is called (A) Fluctuation of speed (B) Maximum fluctuation of speed (C) Coefficient of fluctuation of speed (D) None of the above

Last Answer : (B) Maximum fluctuation of speed

Description : The coefficient of fluctuation of speed of flywheel is, (A) Ratio of maximum and minimum speeds during the cycle (B) Ratio of maximum fluctuation of speed to the mean speed (C) Ratio of ... maximum fluctuation of speed during the cycle (D) Sum of maximum fluctuation of speed and the mean speed

Last Answer : (B) Ratio of maximum fluctuation of speed to the mean speed

Description : The maximum fluctuation of speed of flywheel is, (A) Difference between maximum and minimum speeds during the cycle (B) Difference between maximum and mean speeds during the cycle (C) Difference ... and minimum speeds during the cycle (D) Mean of maximum and minimum speeds during the cycle

Last Answer : (A) Difference between maximum and minimum speeds during the cycle

Description : Different types of bearings are designed to operate at different operating speeds. Speed is specified as the maximum (a) rpm (b) metres/second (c) metres/minute (d) metres/hour

Last Answer : (b) metres/second

Description : The purpose of lubrication in an antifriction bearing is (a) to reduce the friction between balls and races (b) dissipation of frictional heat prevention of corrosion (c) protection of the bearing from dirt and other foreign particles (d) all of the mentioned

Last Answer : (d) all of the mentioned

Description : Which bearing is Antifriction bearing A. Thick lubrication bearing B. Thin lubrication bearing C. Rolling or ball bearing D. None

Last Answer : C. Rolling or ball bearing

Description : Rolling contact bearing is also called as A. Plastic bearing B. Thin lubrication bearing C. Thick lubrication bearing D. Antifriction bearing.

Last Answer : D. Antifriction bearing.

Description : For hydrostatic lubrication (A) There should be relative motion between the surfaces of the journal and the bearing and wedge shaped clearance space (B) There should be external source like pump to ... be elastic deformation of the parts in contact (D) There should be metal to metal contact

Last Answer : (B) There should be external source like pump to supply lubricant under pressure

Description : Antifriction bearings are (a) sleeve bearings (b) hydrodynamic bearings (c) thin lubricated bearings (d) none of the mentioned

Last Answer : (d) none of the mentioned

Description : Antifriction bearings are A. Sleeve bearings B. Hydrodynamic bearings C. Thin lubricated bearings D. None of the above

Last Answer : D. None of the above

Description : Which one of the following types of bearings is employed in shafts of gearboxes of automobiles? [IES-1999] (a) Hydrodynamic journal bearings (b) Multi-lobed journal bearings (c) Antifriction bearings (d) Hybrid journal bearings

Last Answer : (c) Antifriction bearings

Description : Match List I with List II and select the : [IES-2002] List I (Bearings) List II (Load type) A. Hydrodynamic Journal bearing 1. High radial and thrust load combined B. Rectangular Hydrostatic bearing 2. Radial load only C. Taper Roller ... (a) 2 3 1 4 (b) 4 1 3 2 (c) 2 1 3 4 (d) 4 3 1 2

Last Answer : (a) 2 3 1 4

Description : In hydrodynamic bearing, when the shaft begins to rotate in clockwise direction, (A) The journal climbs to the right side of the bearing without metal to metal contact (B) The journal climbs to the left ... sinks down to the bottom of the bearing (D) The journal is at the center of the bearing

Last Answer : (A) The journal climbs to the right side of the bearing without metal to metal contact

Description : Sommerfeld number is (A) Similar to bearing characteristic number (B) Similar to Reynold’s number (C) Dimensionless parameter that contains all the design parameters (D) Used to find out dynamic load carrying capacity of the hydrodynamic bearing

Last Answer : (C) Dimensionless parameter that contains all the design parameters