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Design of Roller Contact Bearing

Here are the key steps to solve this problem: 1. Calculate the load rating (C) required for each phase using the radial and axial load values. 2. Calculate the life (Lh) for each phase using the load rating, speed and duration. 3. Calculate the equivalent life (Le) considering the percentage duration of each phase. 4. Select a standard bearing with a dynamic load rating greater than the required load rating (C). 5. Check if the bearing life (Lh) calculated using the standard bearing meets the required life of 10000 hours at 93% probability of survival. Selecting a suitable bearing based on load capacity and life calculations considering the repeated cyclic nature of the loads is important

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Jatin Chaudhari
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719 views60 pages

Design of Roller Contact Bearing

Here are the key steps to solve this problem: 1. Calculate the load rating (C) required for each phase using the radial and axial load values. 2. Calculate the life (Lh) for each phase using the load rating, speed and duration. 3. Calculate the equivalent life (Le) considering the percentage duration of each phase. 4. Select a standard bearing with a dynamic load rating greater than the required load rating (C). 5. Check if the bearing life (Lh) calculated using the standard bearing meets the required life of 10000 hours at 93% probability of survival. Selecting a suitable bearing based on load capacity and life calculations considering the repeated cyclic nature of the loads is important

Uploaded by

Jatin Chaudhari
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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ROLLING CONTACT BEARINGS

▪ Rolling contact bearings are also called anti-friction bearing due to its low friction characteristics.
These bearings are used for radial load, thrust load and combination of thrust and radial load.
These bearings are extensively used due to its relatively lower price, being almost maintenance
free and for its operational ease. However, friction increases at high speeds for rolling contact
bearings and it may be noisy while running.
▪ These bearings are of two types-
1. Ball Bearings
2. Roller Bearings
▪ Ball Bearings= Ball Bearings are a type of rolling-element bearing that uses balls to maintain
the separation between the moving parts of the bearing. The purpose of a ball bearing is to
reduce rotational friction and support radial and axial loads. Radial Ball bearings can support
moderate radial loads and moderate axial loads (parallel to the shaft). They can operate at
high speeds (400,000 RPMs and higher)

▪ Roller Bearings= Roller Bearings are a type of rolling-element bearing that uses cylinders
(rollers) to maintain the separation between the moving parts of the bearing. The purpose of
a roller bearing is to reduce rotational friction and support radial and axial loads. Compared
to ball bearings, roller bearings can support heavy radial loads and limited axial loads (parallel
to the shaft). They can operate at moderate to high speeds
Main components of Roller Contact Bearing
▪Determine expected life in hours of SKF bearing
no. 22216 if it is subjected to an axial load of
20KN and radial load of 80KN. Outer race
rotates at 65rpm. The operating temperature is
140oc and probability of survival is 92%. Take
service factor as 20%.
Step no 5: Calculation of life in hours for survival probability of 92%(Lh)
▪The bearing of a shaft of a machine is
subjected to an axial load of 5 KN and radial
load of 12KN when operating at 1000 Rpm.
Select suitable type and size of the bearing.
If it is required to have a life of at least
10000hours with a probability of survival of
92%.
Step no 3: Calculation for required dynamic Capacity for bearing (C):
▪A deep groove ball bearing is subjected
to a radial load of 8 KN and axial load of
4.5 KN. The bearing rotates at 500
Rpm. The expected life is 20000 hours
with survival probability of 92%. The
operating temperature is 135oc. Select
suitable standard bearing.
▪A deep groove ball bearing having SKF number 6312
is subjected to load cycles as below which is repeated.
Phase Radial load Axial load N(Rpm) %
(KN) (KN)
I 3 1.5 300 20%
II 5 2 280 35%
III 8 3 250 45%

Under each phase the loads average with high shock.


Outer race under rotation operating temperature
140oc. Determine expected life of bearing in hours
with probability of survival 92%.
▪ One of the gearbox shafts is supported by rolling contact
bearing at its ends. One of its bearing is subjected to the
following repeated load cycle.
Phase Radial load Axial load N(Rpm) Duration
(KN) (KN) (Sec)
I 4 2 300 2
II 3 1 400 3
III 2.5 1 340 1

Select suitable type and size of the bearing based on economical


criteria. The expected life is 10000 hours, having probability of
survival of 93%. The bearing operating temperature is 140oc.
The shaft is subjected to minor shocks.

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