Important Answers: Design of Bearings Miscellaneous Elements

1.   Classify the bearings.

Based on nature of contact between bearing surfaces.

Sliding contact bearing.

Rolling contact (or) Antifriction bearing.

Based on load applied

Radial bearing (Circumferentially loaded)

Thrust bearing (Axially loaded)

2.What is the advantage of Teflon which is used for bearing?

It has lower co efficient of friction

It can be used at high temperature

It is practically chemically inert

It is dimensionally stable

3.What are the stresses induced in flywheel arms?

Tensile stress due to centrifugal force.

Bending stress due to Torque.

Stress due to belt tension.

Specify the types of flywheel.

Solid piece flywheel.

a. Web type              b. Rim and hub type.

Split wheel

a. Rim and hub type only

4.Name the type of lubricant used in journal bearing?

Graphite

Grease

Mineral oil and synthetic oil

5.What is the function of a flywheel?

A flywheel is a machine member serves a reservoir which stores energy during the period when the supply of energy is more than the requirement and releases it during the period when the requirement of energy is more than the supply.

6. Specify the types of lubricant with example.

       Liquid lubricants  - Mineral and synthetic oils.

       Semisolid lubricants      - Grease ,

       Solid lubricants    - Graphite

7. State the merits of hydrostatic bearing.

The hydrostatic bearing steady loads without any relative motion between the journal and the Bearing.

8. Define co-efficient of fluctuation of energy in a flywheel.

It is the ratio of fluctuation of energy to the work done per cycle.

9.   What are the bearing materials?

Aluminium Alloy, Copper alloy, Babbit, Cast iron steel, Silver etc.

 10.State the different failure theories and the type of materials for which these are applicable?

Maximum principal theory –brittle material.

Shear Stress Theory –Ductile Material.

11.What is known as self – acting bearing?

The pressure is created within the system due to rotation of the shaft, this type of bearing is known as self – acting bearing.

12. What is flywheel?

Flywheel is a machine elements used to minimize the fluctuation of speed in an engine.

13. What is the function of flywheel?

A flywheel used in machine serves as a reservoir which stores energy during the period when the supply of energy is more than the requirement and releases it dulling the period when the requirement of energy is more than the supply.

14. Define the term ‘fluctuation of speed’ and ‘fluctuation of energy’.

The ratio of maximum fluctuation of speed to the mean speed is called co efficient of fluctuation of speed. The ratio of fluctuation of energy to the mean energy is called coefficient of fluctuation of energy.

15.State the type of stresses induced in a rim flywheel?

Tensile stress due to centrifugal force

Tensile bending stress caused by the restraint of the arms and

The shrinkage stresses due to unequal rate of cooling of casting.