Where oil lubrication is preferred over grease lubrication?

Where oil lubrication is preferred over grease lubrication?
by

1 Answer

Answer :

a) Determined by speed and operating temperature.

b) Oil lubrication recommended.

c) When speed and temperature is high.

d) When heat to be conducted away from bearing.

e) When adjacent machine components are oil lubricated.

f) High viscous oil for low speed machine, low viscous oil for high speed machine.

g) At temp<125 ºC, synthetic oils recommended. 
by

Related questions

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

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

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 is the logic in lubrication oil pump system?

Description : What is the logic in lubrication oil pump system?

Last Answer : Normally main oil pump (MOP) will feed the required lub oil to turbine governor and lubrication. If the pressure drops to 5.3 kg/cm2 6.6 kV 373 kW Aux. Oil Pump will start. If further pressure falls to

What is the purpose of lubrication oil?

Description : What is the purpose of lubrication oil?  

Last Answer : Keep oil film in bearings, avoid metal to metal contact between bottom of journal and bearings avoid damage to bearings by lubricating the bearings. This also removes heat from that part. 

Before reassembling any machinery, you should _____________. A. replace all bearings regardless of length of service B. apply a heavy coat of oil to all mating surfaces C. clean any corroded surfaces and file all burrs smooth D. coat all parts with alemite grease

Description : Before reassembling any machinery, you should _____________. A. replace all bearings regardless of length of service B. apply a heavy coat of oil to all mating surfaces C. clean any corroded surfaces and file all burrs smooth D. coat all parts with alemite grease

Last Answer : Answer: C

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

How does the hydrostatic lubrication differ from hydrodynamic type?

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.

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. 

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

Which of the listed conditions will occur if dirt and grease are allowed to accumulate between the commutator segments of a motor? A. A partial short circuit. B. A dead short circuit. C. Misalignment of the motor shaft. D. Overspeeding of the motor.

Description : Which of the listed conditions will occur if dirt and grease are allowed to accumulate between the commutator segments of a motor? A. A partial short circuit. B. A dead short circuit. C. Misalignment of the motor shaft. D. Overspeeding of the motor.

Last Answer : Answer: A

Magnet chatter or 'pumping' occurring in a magnetic contactor can be caused by ______________. A. dirt or grease on pole faces B. mechanical interference in the contacts C. chattering contacts on the control relay D. magnetic lock out of the contacts

Description : Magnet chatter or 'pumping' occurring in a magnetic contactor can be caused by ______________. A. dirt or grease on pole faces B. mechanical interference in the contacts C. chattering contacts on the control relay D. magnetic lock out of the contacts

Last Answer : Answer: C

Grease coatings on electrical contact surfaces increase contact resistance and should be removed with a/an _______________. A. small wire brush B. compressed air jet C. clean dry cloth D. 10% solution carbon solvent and water

Description : Grease coatings on electrical contact surfaces increase contact resistance and should be removed with a/an _______________. A. small wire brush B. compressed air jet C. clean dry cloth D. 10% solution carbon solvent and water

Last Answer : Answer: C

When replacing a power transistor fitted with a heat sink in a circuit, a coating of silicone grease is applied between the transistor case and the heat sink. This is done to ____________. A. lubricate the transistor B. lubricate the heat sink C. aid in the removal of the heat sink D. provide maximum heat transfer

Description : When replacing a power transistor fitted with a heat sink in a circuit, a coating of silicone grease is applied between the transistor case and the heat sink. This is done to ____________. A. lubricate ... the heat sink C. aid in the removal of the heat sink D. provide maximum heat transfer

Last Answer : Answer: D

Why do we grease the bearings?

Description : Why do we grease the bearings?

Last Answer : a) Grease lubricant gives good protection against ingress of moisture and dirt into motor. b) Easy to seal against leakage of grease into motor compared to oil. c) Low friction torque at starting. 

What is the best to remove an engine grease/oil stain from the painted part of a vehicle?

Description : What is the best to remove an engine grease/oil stain from the painted part of a vehicle?

Last Answer : Start with some Automotive Wax and Grease Remover. Available at Automotive Paint Stores.

What is the substance such as oil or grease that is used to reduce friction.?

Description : What is the substance such as oil or grease that is used to reduce friction.?

Last Answer : What is the answer ?

Removal of oil and grease from sewage, is known A. Screening B. Skimming C. Filtration D. None of these

Description : Removal of oil and grease from sewage, is known A. Screening B. Skimming C. Filtration D. None of these

Last Answer : ANS: B

Primary treatment of sewage consists of removal of A. Large suspended organic solids B. Oil and grease C. Sand and girt D. Floating materials

Description : Primary treatment of sewage consists of removal of A. Large suspended organic solids B. Oil and grease C. Sand and girt D. Floating materials

Last Answer : ANS: A

Skimming tanks are A. Used to remove the grease and oil B. Those from which sludge is skimmed out C. Tanks provided with self- cleansing screens D. Improved version of grit chambers

Description : Skimming tanks are A. Used to remove the grease and oil B. Those from which sludge is skimmed out C. Tanks provided with self- cleansing screens D. Improved version of grit chambers

Last Answer : ANS: A

During preliminary treatment of a sewage A. Oil and grease are removed from skimming tanks B. Floating materials are removed by screening C. Girt and sand are removed by girt chambers D. All the above

Description : During preliminary treatment of a sewage A. Oil and grease are removed from skimming tanks B. Floating materials are removed by screening C. Girt and sand are removed by girt chambers D. All the above

Last Answer : ANS: D

_______is suitable as a lubricant for heavy-duty applications of rolling contact bearing. (a) Grease (b) Lubricating oil (c) Graphite (d) Air

Description : _______is suitable as a lubricant for heavy-duty applications of rolling contact bearing. (a) Grease (b) Lubricating oil (c) Graphite (d) Air

Last Answer : (b) Lubricating oil

________is suitable as a lubricant for low and moderate loads applications of rolling contact bearing. (a) Grease (b) Lubricating oil (c) Graphite (d) Air

Description : ________is suitable as a lubricant for low and moderate loads applications of rolling contact bearing. (a) Grease (b) Lubricating oil (c) Graphite (d) Air

Last Answer : (a) Grease

Preheating before welding is done to (A) Make the plate softer (B) Burn oil & grease sticking to plate surfaces (C) Avoid plate distortion (D) Prevent cold cracks

Description : Preheating before welding is done to (A) Make the plate softer (B) Burn oil & grease sticking to plate surfaces (C) Avoid plate distortion (D) Prevent cold cracks

Last Answer : (D) Prevent cold cracks

Tractor engine oil should be changed and all grease points should be lubricated after every working hrs 1. 15 2. 30 3. 60 4. 120

Description : Tractor engine oil should be changed and all grease points should be lubricated after every working hrs 1. 15 2. 30 3. 60 4. 120

Last Answer : ans 4

The most likely cause of brake fade is: a. Oil or grease on the brake drums b. Worn stators c. The pilot reducing the brake pressure d. The brake pads overheating

Description : The most likely cause of brake fade is: a. Oil or grease on the brake drums b. Worn stators c. The pilot reducing the brake pressure d. The brake pads overheating

Last Answer : d. The brake pads overheating

Why it is sometimes necessary to preheat the base material before welding? a) To remove oil and grease b) To remove moisture from inside the material c) To prevent the possible risk of cracking d) Not required if using cellulosic electrodes as these will provide enough heat

Description : Why it is sometimes necessary to preheat the base material before welding? a) To remove oil and grease b) To remove moisture from inside the material c) To prevent the possible risk of cracking d) Not required if using cellulosic electrodes as these will provide enough heat

Last Answer : c) To prevent the possible risk of cracking

The most likely cause of brake fade is: a. Oil or grease on the brake drums b. Worn stators c. The pilot reducing the brake pressure d. The brake pads overheating

Description : The most likely cause of brake fade is: a. Oil or grease on the brake drums b. Worn stators c. The pilot reducing the brake pressure d. The brake pads overheating

Last Answer : d. The brake pads overheating

An auto transformer is preferred over an ordinary two winding transformer due to: a) Safety of operation b) Availability of taps on secondary c) Copper savings d) All the above

Description : An auto transformer is preferred over an ordinary two winding transformer due to: a) Safety of operation b) Availability of taps on secondary c) Copper savings d) All the above

Last Answer : Ans: C

Why is short pitch winding preferred over full-pitch winding ?

Description : Why is short pitch winding preferred over full-pitch winding ?

Last Answer : Advantages · Sinusoidal waveform: Waveform of the emf can be approximately made to a sine wave and distorting harmonics can be reduced or totally eliminated. · Economical :Conductor ... harmonics are eliminated, the eddy current and hysteresis losses are reduced which increases overall efficiency

Why core balance CT is preferred over residual connected CT’s to sense earth fault in 6.6 kV feeders?

Description : Why core balance CT is preferred over residual connected CT’s to sense earth fault in 6.6 kV feeders?

Last Answer : a) To avoid relay mal-operation due to CT saturation b) Better sensitivity is got. c) High pickup and TMS avoided in IDMT earth fault relay. 

Why AC systems are preferred over DC systems?

Description : Why AC systems are preferred over DC systems?

Last Answer : Due to following reasons, AC systems are preferred over DC systems: a. It is easy to maintain and change the voltage of AC electricity for transmission and distribution. b. Plant cost for AC ... the sine wave current will naturally tend to zero at some point making the current easier to interrupt.

Mineral oils (e.g. petroleum oils) are preferred over fatty oils (e.g. mustard oil, ghee, tallow, palm oil, olive oil etc.) as a lubricant due to its (A) Poor oxidation stability and high gum forming tendency (B) Greater tendency of decomposition at elevated temperature (C) Hydrolysis tendency in presence of water (D) All (A), (B) and (C)

Description : Mineral oils (e.g. petroleum oils) are preferred over fatty oils (e.g. mustard oil, ghee, tallow, palm oil, olive oil etc.) as a lubricant due to its (A) Poor oxidation stability and high gum forming ... at elevated temperature (C) Hydrolysis tendency in presence of water (D) All (A), (B) and (C)

Last Answer : (D) All (A), (B) and (C)

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.

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

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