Basic size of mm

d	8
D	28
B	9

The basic rated load is kN

trends C	4.62
static state Co	1.96

Fatigue load limit Pu	0.083

Rated rotation speed is r/min

Refer to the speed	60000
Limit speed 1)	30000

Mass kg	0.03

model

Both sides are sealed	638-2RZ
One side is sealed	638-RZ

Dimensions are mm

d	8
d1 ～	14.8
d2 ～	-
D2 ～	22.6
r1,2 min	0.3

Shoulder gear and chamfer size mm

da min	10.4
Da max	-
Da max	25.6
ra max	0.3

Calculation coefficient

kr	0.025
fo	12