2-3 Verifying and examining load weights
Selection guidelines
2-4
1
2
3
4
5
6
7
8
9
10
11
Apx
Sel
ect
ion gui
del
ines
Calculating average loads (average radial and axial loads, average output
rotational speed)
When the radial and/or axial loads vary during motion, calculate and verify the life of the cross roller
bearing converting the loads to their average values.
Radial load coefficient and axial load coefficient
Table 2: Radial load coefficient (X), axial load coefficient (Y)
Formula (5)
X
Y
.5
1
≤
La)/dp
·
Fa
R)
(Lr
2(Fr
Fr
Fa
av
av
av
av
+
+
+
1
0.45
1.5
La)/dp
·
Fa
R)
(Lr
2(Fr
Fr
Fa
>
+
+
+
av
av
av
av
0.67
0.67
Formula (2): Average radial load (Frav)
n
n
10/3
n
n
n
10/3
10/3
10/3
t
n
···
t
n
t
n
Fr
t
n
···
Fr
t
n
Fr
t
n
Fr
2
2
1
1
2
2
2
1
1
1
+
+
+
+
=
av
The maximum radial load in section t
1
is given by Fr
1
,
while the maximum radial load in section t
3
is given by
Fr
3
.
Formula (3): Average axial load (Faav)
n
n
10/3
n
n
n
10/3
10/3
10/3
t
n
···
t
n
t
n
Fa
t
n
···
Fa
t
n
Fa
t
n
Fa
2
2
1
1
2
2
2
1
1
1
+
+
+
+
=
av
The maximum axial load in section t
1
is given by Fa
1
,
while the maximum axial load in section t
3
is given by
Fa
3
.
Formula (4): Average output rotational speed
(Nav)
n
n
n
t
···
t
t
t
n
···
t
n
t
n
N
2
1
2
2
1
1
+
+
+
+
+
+
=
av
Symbols used in the formulas
Fr
av
Average radial load
N(kgf)
Refer to the
average load.
Fa
av
Average axial load
N(kgf)
Refer to the
average load.
Lr ,La
————
m
See Fig.1.
R
Offset amount
mm
See Fig.1 and
Table 1.
dp
Pitch circle diameter
of a roller
mm
See Fig.1 and
Table 1.
Time
+
Fr
1
Fr
2
Fr
3
Radi
al
load
–
Time
O
ut
put
rot
at
io
na
l
sp
ee
d
n
1
n
2
n
3
t
1
t
2
t
3
Fig. 2: Illustration of load
i ti
+
–
Time
A
xi
al
load
Fa
1
Fa
2
Fa
3
+
–
