Gamet BearingsExclusive North American distributor for Gamet Bearing.

Koyo Technical Information

a. Purpose and method of preload

1) Purposes of preloading

  • To improve bearing positioning accuracy in both the radial and axial directions and rotation accuracy by suppressing shaft deflection (vibration).
  • To improve gear engagement accuracy by increasing bearing rigidity.
  • To reduce the possibility of failure, such as smearing, by suppressing the sliding of rolling elements.
  • To prevent noise that may be caused by vibration and resonance.
  • Keep rolling elements in place with respect to the bearing rings.

2) Preloading methods

Bearings can be preloaded by the locating method or by the spring method. Typical preloading methods are given in the table.

  • When the size of the preload is the same, the locating method produces a smaller deflection in bearings than the spring method if the bearing is exposed to an axial load. This results in a high rigidity.
  • When the spring method is used, the spring absorbs load variation or shaft elongation and contraction, making it possible to apply the preload stably with minimum variation.
  • A greater preload is achievable when the locating method is used.

3)Typical preloading methods

Position preloadingConstant pressure preloading

Method using matched pair bearing with standout adjusted for preloading (see below).

Method using spacer with dimensions adjusted for preloading.

Method using nut or bolt capable of adjusting preload in axial direction.
(In this case, starting friction moment during adjustment should be measured so that proper preload will be applied.)

Method using coil spring or diaphragm spring.
b. Amount of preload — Matched pair angular contact ball bearings
b.1. S: slight preload

Unit: N

Bore diameter No.7900C7000C7200C
00
01
02
5
7
8
6
6
10
10
15
15
03
04
05
8
15
15
15
15
20
25
25
35
06
07
08
15
25
25
25
35
35
35
50
65
09
10
11
35
35
40
50
50
65
85
85
100
12
13
14
40
50
65
65
85
85
115
130
160
15
16
17
65
65
85
100
100
130
195
225
260
18
19
20
100
100
100
145
160
175
260
290
325
21
22
24
100
145
145
195
210
225
360
385
420
26
28
30
195
195
245
245
260
275
485
520
585
32
34
245
345
290
325
645
645
b.2. L: light preload

Unit : N

Bore diameter No.7900C70007000C72007200CACT000ACT000B
00
01
02
15
20
25
30
30
50
20
20
30
50
60
80
30
40
50




03
04
05
25
40
50
60
60
100
40
40
60
100
145
145
70
80
100




06
07
08
50
70
80
145
145
145
80
100
100
145
245
390
100
145
195
195
195
245
295
390
440
09
10
11
100
100
120
245
245
295
145
145
195
490
540
635
245
245
295
245
295
390
490
540
685
12
13
14
120
145
195
390
440
490
195
245
245
785
835
930
345
390
490
390
440
590
785
785
1030
15
16
17
195
195
245
590
635
735
295
295
390
980
1080
1270
590
685
785
590
685
735
1080
1270
1320
18
19
20
295
295
345
785
880
880
440
490
540
1470
1670
1860
785
880
980
980
980
1030
1770
1860
1910
21
22
24
345
390
490
980
1080
1180
590
635
685
2060
2250
2450
1080
1180
1270
1180
1320
1420
2150
2450
2550
26
28
30
590
635
735
1370
1470
1770
735
785
835
2750
2940
3330
1470
1570
1770
1770
2010
2400
3230
3720
4410
32
34
785
880
2150
2450
880
980
3630
3920
1960
2150
2500
3090
4660
5730
e. M: medium preload

Unit : N

Bore diameter No.7900C70007000C72007200CACT000ACT000B
00
01
02
30
40
50
80
80
145
50
50
80
145
145
245
80
100
145




03
04
05
50
80
100
145
145
245
100
100
145
245
295
390
145
195
245




06
07
08
100
140
155
295
390
390
195
245
295
590
785
880
295
390
440
345
390
440
685
735
835
09
10
11
195
195
235
540
635
785
345
390
440
1080
1180
1370
540
590
735
490
540
685
930
1030
1270
12
13
14
235
295
390
880
980
1080
490
540
635
1470
1670
1860
785
930
980
735
835
1130
1420
1520
2010
15
16
17
390
390
490
1180
1370
1570
685
735
880
2150
2450
2940
1180
1370
1570
1130
1370
1420
2110
2500
2600
18
19
20
590
590
685
1670
1770
1960
980
1080
1180
3230
3430
3920
1770
1960
2150
1860
1960
2010
3380
3530
3680
21
22
24
685
785
980
2150
2350
2650
1270
1470
1670
4310
4900
5390
2350
2450
2840
2250
2600
2800
3770
4760
5100
26
28
30
1180
1270
1470
3140
3430
3920
1770
1960
2150
5880
6370
6860
3140
3430
3720
3380
3920
4610
6230
7210
8480
32
34
1570
1810
4410
4900
2350
2450
7350
7840
4120
4410
4850
6030
8920
11100
f. H: heavy preload

Unit : N

Bore diameter No.70007000C72007200C
00
01
02
145
145
245
100
100
145
245
295
390
145
195
245
03
04
05
295
295
490
195
245
295
540
635
785
345
390
490
06
07
08
635
785
785
390
490
590
930
1270
1570
590
785
880
09
10
11
980
1180
1370
635
735
880
1770
2060
2450
1080
1180
1470
12
13
14
1570
1770
2060
980
1090
1270
2940
3330
3720
1670
1860
2060
15
16
17
2150
2350
2550
1370
1470
1770
3920
4310
4900
2350
2750
2940
18
19
20
2840
3140
3530
1960
2060
2150
5390
5880
6370
3430
3920
4410
21
22
24
3920
4410
4900
2350
2550
2840
7060
7840
8820
4900
5290
5490
26
28
30
5390
5880
6860
3140
3920
4410
9310
9800
10300
5880
6370
6860
32
34
7840
8820
4900
5390
10800
11800
7840
8330