Brochure

Mtd. Ball
Bearings
G-222
®
Mounted Ball Bearing Engineering Section
Combined Load - Ball Bearings
For applications where a combination of both radial
and thrust loads are applied to the bearing the equiva-
lent radial load must be calculated and applied to the
L10 life formula.
1. Use Table 3 (below) and Table 4 (page G-228) to
identify the relative axial load factor (ND2).
2. Determine the relative axial load (RAL):
3. Match the nearest relative axial load value in Table
3 to the corresponding “e” value. For precise calcula-
tion, linearly interpolate the values for “e” for your
exact relative axial load value.
4. Calculate Fa/Fr and compare value to the “e” value
found in step #3 above.
5. Choose values for “X” and “Y” based on step #3 & 4
and from Table 3. Linear interpolation is recommend-
ed for exact calculations.
6. Calculate equivalent radial load using the following
equation:
P = XFr + YFa
7. Calculate the adjusted life (Lna) using the life calcu-
lation formula above.
Variable Load Formula
Root mean load (RML) is to be used when a number of
varying loads are applied to a bearing for varying time
limits. Maximum loading still must be considered for
bearing size selection.
RML* =
Where:
RML = Root Mean Load (lbs.)
L
1
, L
2
, etc. = Load in pounds
N
1
, N
2
, etc. = Percent of total time operated at
loads L
1
, L
2
, etc.
*Apply RML to rating at mean speed to determine
resultant life.
Mean Speed Formula
The following formula is to be used when operating
speed varies over time.
High Load Applications
Applications where the loading approaches the load
listed in the rating tables on pages G-230 to G-233 at
5000 hours life and 150/250 RPM, should be reviewed
and given special consideration.
Modications to consider Include:
• Shafting size should be closely controlled for a
line to line to a light press t.
• Skwezloc
®
Locking Collar or double lock is the
preferred lock.
• Lubricants with “EP” extreme pressure additives
may be required.
• Care in housing selection, load direction, and
mounting techniques should be exercise
RAL =
- applied thrust load
- relative axial load factor
F
a
ND
2
Table 3 Equivalent Load Calculation Data - Ball Bearings
Relative
Axial Load
e
Fa / Fr ≤ e Fa / Fr > e
x y x y
24.92 0.19
1 0 0.56
2.30
50.03 0.22 1.99
99.91 0.26 1.71
149.35 0.28 1.55
200.10 0.30 1.45
300.15 0.34 1.31
500.25 0.38 1.15
749.65 0.42 1.04
999.05 0.44 1.00
S
1
N
1
+ S
2
N
2
+ S
3
N
3
100
Mean Speed =
S
1
S
2
, etc = Speeds in RPM
N
1
N
2
, etc = Percentage of total time operated
at speeds S
1
S
2
, etc
Load Ratings and Life Continued
(L
1
3
N
1
)
+ (L
2
3
N
2
)
+ (L
3
3
N
3
)
100
3