Explain boundary lubrication with diagram.

Explain boundary lubrication with diagram.
by

1 Answer

Answer :

Boundary lubrication: This type of lubrication is done when a continuous fluid film of lubricant cannot persist & direct metal to metal contact is possible due to certain reasons. This happens when i) a shaft starts moving from rest or ii) the speed is very low or iii) the load is very high or iv) The viscosity of oil is too low. ii) Under such conditions, the space between the moving parts is lubricated with a thin layer of oil lubricant. The oil is adsorbed by physical or chemical forces or both on the metallic surfaces. iii) The adsorbed layers cannot get removed easily & thus avoids direct metal to metal contact. The load is carried by the layers of the adsorbed lubricant on the metallic surfaces. iv) The property which is responsible for this kind of adsorption is “Oiliness.” 


Diagram 

image

by

Related questions

Describe sacrificial anodic protection with neat diagram.

Description : Describe sacrificial anodic protection with neat diagram.

Last Answer : Method: The metallic structure to be protected from corrosion is connected to anodic metal (upper placed in galvanic series) by an insulated wire. Thus externally added metal like Zn, Al, Mg, etc ... hot water tanks to prevent corrosion. The protection of underground pipelines is shown in Fig.

Explain the mechanism of oxidation corrosion

Description : Explain the mechanism of oxidation corrosion

Last Answer : The electrons are transferred from metal atom to oxygen. Metal loses electron while oxygen accepts electron forms their respective ions these two types of ion combine together to from metal oxide. 

Explain the significance of proximate analysis.

Description : Explain the significance of proximate analysis. 

Last Answer : Significance: Proximate analysis provides following valuable information in assessing the quality of fuel i) Moisture: - Lesser the moisture better is the quality of coal. ii) Volatile Matter: - Lower / ... iv) Fixed Carbon: - Higher the percentage of fixed carbon, greater is the calorific value.

What is used as a photocatalyst? a) Titanium dioxide b) Lead chromate c) Cobalt pigments d) Iron oxide

Description : What is used as a photocatalyst? a) Titanium dioxide b) Lead chromate c) Cobalt pigments d) Iron oxide

Last Answer : a) Titanium dioxide

Which raw material is used to impart colour to the glass? a) Al2O3 b) CoO c) CaO d) MgO

Description : Which raw material is used to impart colour to the glass? a) Al2O3 b) CoO c) CaO d) MgO

Last Answer : b) CoO

Suggest the type of lubricant used for the following jobs: i) Clock ii) I.C. Engines iii) Gears iv) Sewing machine

Description : Suggest the type of lubricant used for the following jobs: i) Clock ii) I.C. Engines iii) Gears iv) Sewing machine

Last Answer : i) Clock : Vegetable and animal oils like palm oil, hazel nut oil, neat foot oil, etc ii) I.C. Engines: Mineral oils containing additives are used. iii) Gears: Thick mineral oils containing ... Mineral oil, silicones, thin vegetable and animal oils like palm oil, hazel nut oil, neat foot oil.

Define lubricant. Give the classification of lubricants with at least one example of each type.

Description : Define lubricant. Give the classification of lubricants with at least one example of each type.

Last Answer : Lubricant: Any substance introduced between two moving or sliding surface to reduce the frictional resistance between them is known as lubricant. Classification: i) Solid lubricants: Examples: graphite, ... acids like oleic acid, Stearic acid etc., silicones, blended oils, and mineral oils.

Name and describe the method used for coating large and irregularly shaped articles for prevention of corrosion.

Description : Name and describe the method used for coating large and irregularly shaped articles for prevention of corrosion.

Last Answer : Metal spraying is the method used for coating large and irregularly shaped articles for prevention of corrosion. Diagram: Process:- In this method ,coating metal sprayed on the surface of ... . The molten metal then sprayed on the surface of base metal with the help of compressed air.

Write composition, 2 properties and two uses of CNG.

Description : Write composition, 2 properties and two uses of CNG.

Last Answer : Properties: - 1) It is cheaper than petrol or diesel. 2) Its ignition temp is high (5400C). 3) It is odorless & non corrosive. 4) It is light weight gas. 5) ... petrol / CNG) 2) It is also used in locomotive generators to generate electricity that drives the motors of the train.

Define fuel. Give the classification of fuel based on their occurrence with two examples of each type.

Description : Define fuel. Give the classification of fuel based on their occurrence with two examples of each type.

Last Answer : Fuel: A fuel can be defined as any combustible substance which during combustion gives large amount of heat energy.  Classification of Fuel : I) Primary or Natural Physical State i) Solid - e.g wood ... diesel oil, lubricating oil iii)Gaseous- e.g LPG, water gas ,producer gas ,coal gas, biogas

Distinguish between hardening and normalising.

Description : Distinguish between hardening and normalising.

Last Answer : Hardening Normalizing 1. It is the process of heating steel at high temperature (800-9000C) and then suddenly cooled by dipping or quenching in some suitable medium. 1. It is the ... hardening. 6. It creates stresses in structure 6. It removes coarser grained structure.

Give the classification of plain carbon steel. Write composition, one property and one use of different plain carbon steel.

Description : Give the classification of plain carbon steel. Write composition, one property and one use of different plain carbon steel.

Last Answer : Classification: a) Mild or low carbon steel - 0.05 to 0.3% carbon b) Medium carbon steel - 0.3 to 0.6% carbon c) High carbon steel - 0.6 to 1.5% carbon ... Wooden working tools, chisels, saws, drills, metal cutting tools for lathes, cutters, knives, blades, razors etc.

Write chemical reactions taking place in zone of reduction of blast furnace.

Description : Write chemical reactions taking place in zone of reduction of blast furnace.

Last Answer : Write chemical reactions taking place in zone of reduction of blast furnace.

Define cloud point and viscosity index of a lubricant

Description : Define cloud point and viscosity index of a lubricant

Last Answer : Cloud point: Cloud point indicates the temperature at which the oil becomes cloudy in appearance, due to separation of wax. Viscosity Index: The rate of change of viscosity of a liquid (Oil) with the change of temperature is known as viscosity index.

Distinguish between solid fuel and liquid fuel.

Description : Distinguish between solid fuel and liquid fuel.

Last Answer : Property Solid Liquid 1.Calorific Value Low Higher 2.Ignition Temperature  Very high Moderate 3.Cost  Cheap Costly 4.Ash content High Negligible 5.Velocity of combustion Non controllable Easily Controllable

Give two applications of biodiesel.

Description : Give two applications of biodiesel.

Last Answer : 1) It is an alternative fuel formulated exclusively for diesel engines with little or no modification in engines. 2) It is also used as a heating fuel in domestic & commercial boilers. 3) It is used in rockets.

Define calorific value & ignition temperature

Description : Define calorific value & ignition temperature 

Last Answer : Calorific value: - It is defined as “the total amount of heat produced by the complete combustion of unit mass or unit volume of the fuel.” Ignition temperature:-It is the minimum temperature at which combustion of a fuel takes place when the firing is once started.

List any four constituents of paint.

Description : List any four constituents of paint. 

Last Answer : 1) Pigments 2) Drying Oil / Medium 3) Thinners 4) Driers5) Extenders 6) Plasticizers

Define Cementation. Name its types.

Description : Define Cementation. Name its types.

Last Answer : Cementation: It is the process of heating the base metal in a revolving drum containing a powder of coating metal. Types: i) Sherardizing ii) Chromizing iii) Colorizing

Name any four factors affecting electrochemical corrosion.

Description : Name any four factors affecting electrochemical corrosion.

Last Answer : A) Nature of metal:  1) Position of metal in a galvanic series: A metal having higher position in a galvanic series has more chemical reactivity and therefore, it gets attacked by gaseous and ... as a conducting medium and promotes corrosion. e.g:- Rusting of Fe is promoted in humid atmosphere.

What is the effect of alloying element Cr & V on the properties of steel?

Description : What is the effect of alloying element Cr & V on the properties of steel?

Last Answer : Effect of alloying element Cr:- i) It increases hardness, toughness and tensile strength. ii) It increases wear resistance and resistance to corrosion. Effect of alloying element V:  ... tensile strength, ductility and shock resistance. ii) It increases air hardening and cutting quality.

Define heat treatment. Give any two purposes of heat treatment.

Description : Define heat treatment. Give any two purposes of heat treatment.

Last Answer : Heat treatment:- The process of heating steel to a certain high temperature and then cooling it at a controlled rate in order to develop certain physical properties without changing its chemical composition ... 7) To remove trapped gases. 8) To improve machinability and mechanical properties.

State any two functions of Blast furnace.

Description : State any two functions of Blast furnace.

Last Answer : 1. To reduce the ore to metallic. 2. To remove the impurities in the form of slag.

Name two important ores of iron? Mention its formula.

Description : Name two important ores of iron? Mention its formula.

Last Answer : Name two important ores of iron? Mention its formula.

For given applied voltage, with the increase in frequency of the applied voltage?

Description : For given applied voltage, with the increase in frequency of the applied voltage?

Last Answer : For given applied voltage, with the increase in frequency of the applied voltage eddy current loss will remain unchanged.

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

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

Pick out the wrong statement. (A) In the McCabe-Thiele diagram for binary distillation, vertical feed line represents saturated liquid feed and horizontal feed line represents saturated vapour feed (B) In small columns, local efficiency is larger than Murphree efficiency; in large columns local efficiency is smaller than Murphree efficiency (C) For Laminar flow over a plate of length L, the local mass transfer co￾efficient at a distance L from the leading edge is 1.5 × 10 -2m/s. Then the average mass transfer co-efficient for the plate is 2 × 10 -2m/s (D) The concentration and hydrodynamic boundary layers over a flat plate are of equal thickness, if Schmidt number is equal to unity

Description : Pick out the wrong statement. (A) In the McCabe-Thiele diagram for binary distillation, vertical feed line represents saturated liquid feed and horizontal feed line represents saturated vapour feed (B) In ... layers over a flat plate are of equal thickness, if Schmidt number is equal to unity

Last Answer : (C) For Laminar flow over a plate of length L, the local mass transfer co￾efficient at a distance L from the leading edge is 1.5 × 10 -2m/s. Then the average mass transfer co-efficient for the plate is 2 × 10 -2m/s

How promising is the "air lubrication" idea to increase the speed of ships and reduce the consumption of fuel?

Description : How promising is the "air lubrication" idea to increase the speed of ships and reduce the consumption of fuel?

Last Answer : I think passive systems, like shark skin like surfaces, will be more promising than active systems, as those also consume energy. I am also not sure how the bubbles would affect the vessels buoyancy.

What category are ventilation irrigation fertilization and lubrication are called?

Description : What category are ventilation irrigation fertilization and lubrication are called?

Last Answer : Soil

What category are ventilation irrigation fertilization and lubrication?

Description : What category are ventilation irrigation fertilization and lubrication?

Last Answer : Feel Free to Answer

What category are ventilation irrigation fertilization and lubrication are called?

Description : What category are ventilation irrigation fertilization and lubrication are called?

Last Answer : Soil

What product do you use for roller bearing lubrication?

Description : What product do you use for roller bearing lubrication?

Last Answer : Lubrimagic Green is a great product to use for bearing lubrication. You can visit their website at www.synchrony.com/Magnetic_Bearings.

The failure of ball bearings used in electric motors can result from _____________. A. failure to clean the bearing before repacking B. failure to maintain proper alignment C. excess lubrication forcing the bearing full of grease and eliminating all areas of expansion D. all of the above

Description : The failure of ball bearings used in electric motors can result from _____________. A. failure to clean the bearing before repacking B. failure to maintain proper alignment C. excess lubrication forcing the bearing full of grease and eliminating all areas of expansion D. all of the above

Last Answer : Answer: D

If deck machinery is expected to be idle for an extended period of time you should____________. A. have electrical safety gloves available in case of electrical shock before running B. perform a 'high pot' test to determine the condition of the insulation C. water wash the motor and controller to remove any salt that may interfere with smooth operation D. check run at regular intervals to inusre correct operation and to renew the internal coating of lubrication

Description : If deck machinery is expected to be idle for an extended period of time you should____________. A. have electrical safety gloves available in case of electrical shock before running B. perform ... run at regular intervals to inusre correct operation and to renew the internal coating of lubrication

Last Answer : Answer: D

The only point in the steering stand shown in the illustration which needs periodic lubrication is the ______________. EL-0098 A. repeater assembly ball bearings B. steering wheel bearing C. operation selector switch D. course selector pointer

Description : The only point in the steering stand shown in the illustration which needs periodic lubrication is the ______________. EL-0098 A. repeater assembly ball bearings B. steering wheel bearing C. operation selector switch D. course selector pointer

Last Answer : Answer: B

During its operation, loud buzzing and resultant welding of contacts of a magnetic relay may be caused by __________. A. overheating of the contactor coil B. low voltage on the operating coil C. low insulation resistance to ground D. lubrication of the contact bearing points

Description : During its operation, loud buzzing and resultant welding of contacts of a magnetic relay may be caused by __________. A. overheating of the contactor coil B. low voltage on the operating coil C. low insulation resistance to ground D. lubrication of the contact bearing points

Last Answer : Answer: B

Turbine-Generator Lubrication Oil System Function

Description : Turbine-Generator Lubrication Oil System Function

Last Answer : Turbine-Generator Lubrication Oil System Function For large turbine-generators forced lubrication system and water cooling system should be continuously required during the operation of the turbine-generator and ... when the oil pressure is low. A second backup dc pumps are sometimes provided.

What do you understand by timed cylinder lubrication ?

Description : What do you understand by timed cylinder lubrication ?

Last Answer : For effective lubrication, lub oil needs to be injected between two piston rings when piston is at bottom of stroke so that piston rides in oi during upward movement. This way lot of lub oil can be saved and used properly.

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

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.

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

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

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

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

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