Rolling Contact Bearing MCQ Quiz in मराठी - Objective Question with Answer for Rolling Contact Bearing - मोफत PDF डाउनलोड करा
Last updated on Mar 13, 2025
Latest Rolling Contact Bearing MCQ Objective Questions
Top Rolling Contact Bearing MCQ Objective Questions
Rolling Contact Bearing Question 1:
Fixed plate bearings are suitable for the span up to ________.
Answer (Detailed Solution Below)
Rolling Contact Bearing Question 1 Detailed Solution
Bearings: These are the devices used in long-span bridges to avoid the development of high stresses in the main girders due to temperature changes or deflections.
They are classified as:
a) Shallow or fixed plate bearings – suitable for spans up to 12 m.
b) Deep cast base bearings – suitable for spans 12 m to 20 m.
c) Rocker bearings – suitable for spans more than 20 m.
d) Sliding plate bearings – suitable for girders of span 12 to 20 m.Rolling Contact Bearing Question 2:
Which bearing offers lowest friction
Answer (Detailed Solution Below)
Rolling Contact Bearing Question 2 Detailed Solution
Concept:
A bearing is a machine component that supports another machine element. It permits relative motion between the contacting surfaces while carrying the load.
Classification of Bearings:
- Based on the direction of the load
- Radial bearing
- Thrust bearing
- Based on the nature of the contact
- Sliding contact bearing
- Rolling contact bearing
The rolling contact bearing can be further classified into:
- Ball bearings
- Roller bearings
Types of journal bearing are:
a) Aero-static bearing: In this bearing, pressurized gas (generally air) acts as the lubricant in the system which separates the two surfaces in relative motion. The two surfaces do not touch, thus no problem of friction, wear, etc. A diagram of the air bearing is shown below:
b) Hydrodynamic bearing: In this, the shaft and the journal are in contact at stationary conditions. As the shaft rotates, it pressurizes the fluid and due to wedging action, a gap is created between the two surfaces.
c) Hydrostatic bearing: In these bearings, fluid is supplied using an external device (pump). The fluid is usually oil, water, etc. They provide lubrication even at stationary conditions.
Rolling Contact Bearing Question 3:
The life of a ball bearing at a load of 10 kN is 8000 hours. If the load is increased to 20 kN, keeping all other conditions the same, then its life in hours is
Answer (Detailed Solution Below)
Rolling Contact Bearing Question 3 Detailed Solution
Concept:
The approximate rating of the service life of a ball or roller bearing is based on the given fundamental equation.
\({\rm{L}} = {\left( {\frac{{\rm{C}}}{{\rm{P}}}} \right)^{\rm{k}}} \times {10^6}{\rm{revolution}}\)
where L is rating life, C is a basic dynamic load, P is an equivalent dynamic load
k = 3 for ball bearing
k = 10/3 for roller bearing
Calculation:
Given:
L1 = 8000 hr, P1 = 10 kN, P2 = 20 kN
\(L = {\left( {\frac{C}{P}} \right)^3}\Rightarrow L\ \ \ \alpha \ \ { {\frac{1}{P^3}} }\\ \Rightarrow \frac{{{L_1}}}{{{L_2}}} ={\left( {\frac{P_2}{P_1}} \right)^3}= {2^3}\\ \Rightarrow {L_2} = \frac{{{L_1}}}{{8}}=\frac{{{8000}}}{{8}}=1000\ hours\)
Rolling Contact Bearing Question 4:
If the load on a ball bearing is halved, its life
Answer (Detailed Solution Below)
Rolling Contact Bearing Question 4 Detailed Solution
Concept:
\({{\bf{L}}_{90}} = {\left( {\frac{{\bf{C}}}{{{{\bf{P}}_{\bf{e}}}}}} \right)^n}\)
where,
C = Dynamic Capacity, Pe = Equivalent bearing load,
n = Exponent of life equation.n = 3.0 for ball bearings, 10/3 for roller bearings
[Note: Dynamic load capacity remains constant for a given bearing.]
Calculation:
Given:
\({{\rm{P}}_{{\rm{e}}2}} = \left( {\frac{{{{\rm{P}}_{{\rm{e}}1}}}}{2}} \right) \ldots \ldots \ldots \left( {\rm{i}} \right)\)
Pe1, Pe2 = Initial and final equivalent load
\({{\rm{L}}_{{{90}_1}}} = \left( {\frac{{\rm{C}}}{{{{\rm{P}}_{{\rm{e}}1}}}}} \right){\rm{\;Initial\;bearing\;life}}\)
\({{\rm{L}}_{{{90}_2}}} = \left( {\frac{{\rm{C}}}{{{{\rm{P}}_{{\rm{e}}2}}}}} \right){\rm{\;Final\;bearing\;life}}\)
From eq. (i) we have,
\({{\rm{L}}_{{{90}_2}}} = {\left( {\frac{{2{\rm{C}}}}{{{{\rm{P}}_{{\rm{e}}1}}}}} \right)^3}\)
\({{\rm{L}}_{{{90}_2}}} = 8{\rm{\;}} \times {{\rm{L}}_{{{90}_1}}}\)
Therefore, its life will increase 8 times.
Rolling Contact Bearing Question 5:
Match List-I with List-II and select the correct answer using the codes given below the lists :
|
List - I |
List – II |
|
A. Ball Bearing |
1. Carrying both radial and thrust loads |
|
B. Tapered Roller Bearing |
2. Self-aligning property |
|
C. Spherical Roller Bearing |
3. Light Loads |
|
D. Needle Roller bearing |
4. Heavy loads with oscillatory motion |
Answer (Detailed Solution Below)
Rolling Contact Bearing Question 5 Detailed Solution
Explanation:
Ball-bearing:
- It is a type of rolling-element bearing that uses balls to maintain the separation between the bearing races.
- Ball bearings are used for light loads.
Tapered Roller Bearing:
- Tapered roller bearings are capable of carrying both radial and axial loads.
- They are often used in pairs to take the thrust load in both directions.
- The taper roller bearing consists of rolling elements in the form of a frustum of a cone. They are arranged in such a way that the axes of individual rolling elements intersect in a common apex point on the axis of the bearing.
- The taper roller bearing consists of rolling parts and inner and outer raceways in the form of conical surfaces. The outer raceway or outer ring is called ‘cup’ and inner raceway is called ‘cone’.
Needle roller bearing
- These bearings are relatively slender and completely fill the space so that neither a cage nor a retainer is needed.
- These bearings are used when heavy loads are to be carried with an oscillatory motion.
- For example, piston pin bearing in heavy-duty diesel engines where the reversal of motions tends to keep the roller in correct alignment.
Spherical Roller Bearing:
- A Spherical plain bearing is a bearing that permits angular rotation about a central point in two orthogonal directions.
- The outer surface of the inner ring and the inner surface of the outer ring are spherical and are collectively considered the raceway and they slide against each other.
- The centre point of the sphere in the outer ring raceway is at the bearing axis. Therefore, the bearings are self-aligning and insensitive to misalignment of the shaft relative to the housing, which can be caused, for example, by shaft deflection.
- Spherical roller bearings are designed to accommodate heavy radial loads, as well as heavy axial loads in both directions.
Rolling Contact Bearing Question 6:
Which of the following is antifriction bearing?
Answer (Detailed Solution Below)
Rolling Contact Bearing Question 6 Detailed Solution
Concept:
- The antifriction bearing consists of rolling elements, races, and cage.
- Rolling elements are available in different shapes such as balls, parallel rollers, taper rollers, barrels, and needles.
- They are made of chromium or chrome-nickel steel with ground or polished surface.
- The load of the rotating member is carried by the rolling elements.
- Example: Ball bearing, Roller bearings, Needle bearing
Rolling Contact Bearing Question 7:
Two identical ball bearings have ratio of their rated life 27: 8. The ratio of their operating loads is
Answer (Detailed Solution Below)
Rolling Contact Bearing Question 7 Detailed Solution
Concept:
The approximate rating of the service life of a ball or roller bearing is based on the given fundamental equation.
\({\rm{L}} = {\left( {\frac{{\rm{C}}}{{\rm{W}}}} \right)^{\rm{k}}} \times {10^6}{\rm{revolution}}\)
where L is rating life, C is a basic dynamic load, W is an equivalent dynamic load/operating load.
k = 3 for ball bearing
k = 10/3 for roller bearing
Calculation:
Given: L1 : L2 = 27: 8
\(\frac{{27}}{8} = \frac{{{{\left( {\frac{C}{{{P_1}}}} \right)}^3}}}{{{{\left( {\frac{C}{{{P_2}}}} \right)}^3}}} = {{{{\left( {\frac{P_2}{{{P_1}}}} \right)}^3}}} \Rightarrow \frac{{{P_2}}}{{{P_1}}} = \frac{3}{2} \Rightarrow \frac{{{P_1}}}{{{P_2}}} = \frac{2}{3}\)
Rolling Contact Bearing Question 8:
The frictional torque, transmitted in the case of flat pivot bearing for uniform pressure is equal to
Where, W → total axial load carrled by pivot
μ → coefficient of friction
R → radius of bearing surface
Answer (Detailed Solution Below)
Rolling Contact Bearing Question 8 Detailed Solution
Explanation:
Flat pivot bearing:
- Frictional torque transmitted (Uniform Pressure Theory), \(T =\frac{2}{3}\mu WR\)
- Frictional torque transmitted (Uniform Wear Theory), \(T =\frac{1}{2}\mu WR\)
Conical pivot bearing:
- Frictional torque transmitted (Uniform Pressure Theory), \(T=\frac{2}{3}\mu WR.\csc α \)
- Frictional torque transmitted (Uniform Wear Theory), \(T=\frac{1}{2}\mu WR.\csc α \)
where, W = Axial load, R = Bearing radius, α = Semi angle of cone
From the above expressions, We can conclude that the frictional torque transmitted in a conical or flat pivot bearing assuming uniform pressure in comparison to the assumption of uniform wear is more.
Additional Information
|
Sr. No. |
Particular |
Frictional torque |
|
|
Uniform Pressure |
Uniform Wear |
||
|
1 |
Flat Pivot Bearing |
\(\frac{2}{3}\mu WR\) |
\(\frac{1}{2}\mu WR\) |
|
2 |
Conical Pivot Bearing |
\(\frac{2}{3}\mu WR.\csc \alpha \) |
\(\frac{1}{2}\mu WR.\csc \alpha \) |
|
3 |
Trapezoidal or Truncated Conical Pivot Bearing |
\(\frac{2}{3}\mu W.\csc \alpha \left[ {\frac{{r_1^3 - r_2^3}}{{r_1^2 - r_2^2}}} \right]\) |
\(\frac{1}{2}\mu W.\csc \alpha \left( {{r_1} + {r_2}} \right)\) |
|
4 |
Flat Collar Bearing |
\(\frac{2}{3}\mu W\left[ {\frac{{r_1^3 - r_2^3}}{{r_1^2 - r_2^2}}} \right]\) |
\(\frac{1}{2}\mu W\left( {{r_1} + {r_2}} \right)\) |
|
5 |
Single Disc or Plate Clutch |
\(\frac{2}{3}\mu W\left[ {\frac{{r_1^3 - r_2^3}}{{r_1^2 - r_2^2}}} \right]\) |
\(\frac{1}{2}\mu W\left( {{r_1} + {r_2}} \right)\) |
| 6 | Cone Clutch | \(\frac{2}{3}\mu W.\csc \alpha \left[ {\frac{{r_1^3 - r_2^3}}{{r_1^2 - r_2^2}}} \right]\) | \(\frac{1}{2}\mu W.\csc \alpha \left( {{r_1} + {r_2}} \right)\) |
Rolling Contact Bearing Question 9:
A ball bearing has a specific dynamic radial capacity of 40 kN. What equivalent radial load P can the bearing carry at 400 rpm, if the desired life H is 5000 hours for 90% of the bearings?
Answer (Detailed Solution Below)
Rolling Contact Bearing Question 9 Detailed Solution
Concept:
The approximate rating of service life of a ball or roller bearing is based on the fundamental equation.
\({\rm{L}} = {\left( {\frac{{\rm{C}}}{{\rm{W}}}} \right)^{\rm{k}}} \times {10^6}{\rm{revolution}}\)
where L is rating life, C is basic dynamic load, W is equivalent dynamic load
k = 3 for ball bearing
k = 10/3 for roller bearing
The relationship between life in revolutions (L) and life in working hours (LH) is given by:
L = 60 N.LH revolutions
where N is the speed in rpm
Calculation:
Life in revolutions = 60 N.LH = 60 × 400 × 5000 = 120 × 106 rev
Life in millions of revolutions \(L= {\left( {\frac{C}{W}} \right)^3}\)
\(W = \frac{{40}}{{{{\left( {120} \right)}^{\frac{1}{3}}}}}kN = 8.1\;kN\)
Rolling Contact Bearing Question 10:
Identify the type of bearing given in the figure.
Answer (Detailed Solution Below)
Rolling Contact Bearing Question 10 Detailed Solution
Explanation:
Bearing
- A bearing is the machine element, which supports another moving machine element known as a journal.
- It permits relative motion between the contact surfaces of the members while carrying the load.
Classification of bearings:
Depending upon the direction of the load to be supported
- Radial bearing – The load acts perpendicular to the direction of motion of the moving the element.
- Thrust bearing – The load acts along the axis of rotation. The bearing may move in either direction.
Thrust bearing
- A thrust bearing is used to guide or support the shaft which is subjected to a load along the axis of the shaft. Such types of bearings are mainly used in turbines and propeller shafts
There are two types of thrust bearings
- Foot step or Flat pivot bearing – The loading shaft is vertical and the end of the shaft rests within the bearing.
- Collar bearing – The shaft continues through the bearing. The shaft may be vertical or horizontal with a single collar or many collars.
Flat collar bearings
- The shaft may be vertical or horizontal with single or multiple collars.
- In designing collar bearings, it is assumed that the pressure is uniformly distributed over the bearing surface.
- The bearing pressure for a single collar and water-cooled multi-collared bearings may be taken the same as foot step bearings.
- Collar bearings are thrust bearing having a suitably formed face or faces that resist the axial pressure or decreases the intensity of pressure of one or more collars on a rotating shaft.