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

If fluid film pressure is high and surface rigidity is low than mode of lubrication is called as

elastohydrodynamic lubrication.

a) True

b) False
by

1 Answer

Answer :

a) True
by

Related questions

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 generated by the rotation of the journal. [IES-1998] (a) Both A and R are individually true and R is the correct explanation of A (b) Both A and R are individually true but R is not the correct explanation of A (c) A is true but R is false (d) A is false but R is true

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

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) Both A and R are individually true and R is the correct explanation of A (b) Both A and R are individually true but R is not the correct explanation of A (c) A is true but R is false (d) A is false but R is true

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

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. Proportional to the speed of rotation 4. Independent of the pressure Which of the statements given above are correct? (a) 1, 2, 3 and 4 (b) 1 and 4 only (c) 2, 3 and 4 only (d) 2 and 3 only

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

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

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

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

Description : 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

Last Answer : b) Increase with increase in speed

The deep groove ball bearing has immense rigidity. (a) True (b) No, it has point contact and hence low rigidity (c) It has surface contact (d) It has line contact

Description : The deep groove ball bearing has immense rigidity. (a) True (b) No, it has point contact and hence low rigidity (c) It has surface contact (d) It has line contact

Last Answer : (b) No, it has point contact and hence low rigidity

Deep groove ball bearing has immense rigidity. a) True b) No it has point contact and hence low rigidity c) It has surface contact d) It has line contact

Description : Deep groove ball bearing has immense rigidity. a) True b) No it has point contact and hence low rigidity c) It has surface contact d) It has line contact

Last Answer : b) No it has point contact and hence low rigidity

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

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

Last Answer : b) False

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] (a) Remains unchanged (b) Gets doubled (c) Gets reduced to one-fourth of original value (d) Gets reduced to half of original value

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

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

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

Which of the following isn’t the property of a taper roller bearing? (a) High rigidity (b) Easy dismantling (c) Take low radial and heavy loads (d) It is unsuitable for high speed applications

Description : Which of the following isn’t the property of a taper roller bearing? (a) High rigidity (b) Easy dismantling (c) Take low radial and heavy loads (d) It is unsuitable for high speed applications

Last Answer : (c) Take low radial and heavy loads

Which of the following isn’t the property of taper roller? a) High rigidity b) Easy dismantling c) Take low radial and heavy loads d) All are the properties of tapper roller

Description : Which of the following isn’t the property of taper roller? a) High rigidity b) Easy dismantling c) Take low radial and heavy loads d) All are the properties of tapper roller

Last Answer : c) Take low radial and heavy loads

Flexible shafts have ______ rigidity in bending moment. a) High b) Low c) Very high d) Extremely low

Description : Flexible shafts have ______ rigidity in bending moment. a) High b) Low c) Very high d) Extremely low

Last Answer : b) Low

Flexible shafts have _______ rigidity in torsion making them flexible. a) Low b) High c) Very high d) Infinitely small

Description : Flexible shafts have _______ rigidity in torsion making them flexible. a) Low b) High c) Very high d) Infinitely small

Last Answer : b) High

Flexible shafts have ______ rigidity in bending moment. a) High b) Low c) Very high d) Extremely low

Description : Flexible shafts have ______ rigidity in bending moment. a) High b) Low c) Very high d) Extremely low

Last Answer : b) Low

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 pump to supply lubricant under pressure (C) There should be elastic deformation of the parts in contact (D) There should be metal to metal contact

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

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 supply lubricant under pressure (C) There should be elastic deformation of the parts in contact (D) There should be metal to metal contact

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

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 supply lubricant under pressure (C) There should be elastic deformation of the parts in contact (D) There should be metal to metal 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

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 bearings balances the load on the journal. (a) Both A and R are true and R is the correct explanation of A (b) Both A and R are true but R is NOT the correct explanation of A (c) A is true but R is false (d) A is false but R is true

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

In sliding contact bearings, a positive pressure can be built up and a load supported by a fluid only by the use of a: [IES-2005] (a) Diverging film (b) Converging-diverging film (c) Converging film (d) Flat film

Description : In sliding contact bearings, a positive pressure can be built up and a load supported by a fluid only by the use of a: [IES-2005] (a) Diverging film (b) Converging-diverging film (c) Converging film (d) Flat film

Last Answer : (c) Converging film

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] (b) Journal speed is low; unit pressure on the bearing is low and viscosity of lubricant used is low (c) Journal speed is high; unit pressure on the bearing is high and viscosity of lubricant used is high (d) Appropriate combination of journal speed, unit pressure on bearing and lubricant viscosity exists resulting in low coefficient of friction

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

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

Explain fluid - film lubrication with diagram.

Description : Explain fluid - film lubrication with diagram.

Last Answer : Fluid film lubrication:  i) It is carried out by introducing the liquid lubricants in between the moving or sliding surface. The lubricant film covers the irregularities of the sliding or moving surface ... like watches, clocks, guns, sewing machines, scientific instrument etc.  Diagram

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

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

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

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

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

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

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

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

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 journal. (a) Both A and R are individually true and R is the correct explanation of A (b) Both A and R are individually true but R is not the correct explanation of A (c) A is true but R is false (d) A is false but R is true

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

Crests and roots of the threads may lead to leakage in fluid tight threads if flattened or rounded to a circular arc. a) True b) False

Description : Crests and roots of the threads may lead to leakage in fluid tight threads if flattened or rounded to a circular arc. a) True b) False

Last Answer : b) False

Is it logical to use fluid analogy to understand the phenomenon of stress concentration? a) True b) False

Description : Is it logical to use fluid analogy to understand the phenomenon of stress concentration? a) True b) False

Last Answer : a) True

Spiral spring is quite rigid. a) Yes b) No it is flexible c) It is of moderate rigidity d) Rigidity can’t be determined

Description : Spiral spring is quite rigid. a) Yes b) No it is flexible c) It is of moderate rigidity d) Rigidity can’t be determined

Last Answer : b) No it is flexible

One which is applicable to a welded joint (i)Less rigidity (ii) Heavy (iii) Difficult process (iv) None

Description : One which is applicable to a welded joint (i)Less rigidity (ii) Heavy (iii) Difficult process (iv) None

Last Answer : (iv) None

Calculate the shaft diameter on rigidity basis if torsional moment is 196000N-mm, length of shaft is 1000mm. Permissible angle of twist per meter is 0.5’ and take G=79300N/mm2. a) None of the listed b) 41.2mm c) 35.8mm d) 38.8mm

Description : Calculate the shaft diameter on rigidity basis if torsional moment is 196000N-mm, length of shaft is 1000mm. Permissible angle of twist per meter is 0.5’ and take G=79300N/mm2. a) None of the listed b) 41.2mm c) 35.8mm d) 38.8mm

Last Answer : b) 41.2mm

While designing shaft on the basis of torsional rigidity, angle of twist is given by? a) Ml/Gd4 b) 584Ml/Gd4 c) 292 Ml/Gd4 d) None of the mentioned

Description : While designing shaft on the basis of torsional rigidity, angle of twist is given by? a) Ml/Gd4 b) 584Ml/Gd4 c) 292 Ml/Gd4 d) None of the mentioned

Last Answer : b) 584Ml/Gd4

While designing shaft on the basis of torsional rigidity, angle of twist is given by? a) Ml/Gd4 b) 584Ml/Gd4 c) 292 Ml/Gd4 d) None of the mentioned

Description : While designing shaft on the basis of torsional rigidity, angle of twist is given by? a) Ml/Gd4 b) 584Ml/Gd4 c) 292 Ml/Gd4 d) None of the mentioned

Last Answer : b) 584Ml/Gd4

The keyway, (A) Reduces strength of shaft (B) Reduces rigidity of shaft (C) Increases stress concentration (D) All of above

Description : The keyway, (A) Reduces strength of shaft (B) Reduces rigidity of shaft (C) Increases stress concentration (D) All of above

Last Answer : (D) All of above

The shafts will have same strength on the basis of torsional rigidity, if (A) Diameter and length of both shafts is same (B) Material of both shafts is same (C) Angle of twist for both shafts is same (D) All of above conditions are satisfied

Description : The shafts will have same strength on the basis of torsional rigidity, if (A) Diameter and length of both shafts is same (B) Material of both shafts is same (C) Angle of twist for both shafts is same (D) All of above conditions are satisfied

Last Answer : (D) All of above conditions are satisfied

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

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

Last Answer : (C) Hydrostatic

Pick out the wrong statement. (A) Superheated steam is preferably not used for process heating because of its low heat transfer film co-efficient (B) In a shell and tube heat exchanger, the shell pressure drop is maximum for orifice baffles (C) S.I. unit of fouling factor is Watt/m2 .°K (D) Longitudinal fins are used in extended surface heat exchangers, when the direction of fluid flow is parallel to the axis of the tube

Description : Pick out the wrong statement. (A) Superheated steam is preferably not used for process heating because of its low heat transfer film co-efficient (B) In a shell and tube heat exchanger ... surface heat exchangers, when the direction of fluid flow is parallel to the axis of the tube

Last Answer : (C) S.I. unit of fouling factor is Watt/m2 .°K

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) Both A and R are individually true and R is the correct explanation of A (b) Both A and R are individually true but R is not the correct explanation of A (c) A is true but R is false (d) A is false but R is true

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

Stress concentration is defined as the localization of high stresses due to irregularities present in the component and no changes of the cross section. a) True b) False

Description : Stress concentration is defined as the localization of high stresses due to irregularities present in the component and no changes of the cross section. a) True b) False

Last Answer : b) False

What is meant by hydrodynamic film lubrication?

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. 

For the majority of bearings, actual life is considerably greater than rated life. (a) True (b) False

Description : For the majority of bearings, actual life is considerably greater than rated life. (a) True (b) False

Last Answer : (a) True

A cylinder roller creates lesser noise than a deep groove ball bearing. (a) True (b) False

Description : A cylinder roller creates lesser noise than a deep groove ball bearing. (a) True (b) False

Last Answer : (b) False

For majority of bearings, actual life is considerably greater than rated life. a) True b) False

Description : For majority of bearings, actual life is considerably greater than rated life. a) True b) False

Last Answer : a) True

Cylinder roller creates lesser noise than deep groove ball bearing. a) True b) False

Description : Cylinder roller creates lesser noise than deep groove ball bearing. a) True b) False

Last Answer : b) False

Compressed length is smaller than the solid length. a) True b) False

Description : Compressed length is smaller than the solid length. a) True b) False

Last Answer : b) False

Strength of parallel fillet weld is greater than strength of transverse fillet weld. a) True b) False

Description : Strength of parallel fillet weld is greater than strength of transverse fillet weld. a) True b) False

Last Answer : b) False