KG
Drawing of 638 ZZ: ⌀8 × ⌀28 × 9 mm638 ZZZZ
Fig. 1: 638 ZZ, end view and section; internal parts simplified per ISO 8826-1. Dimensions in mm

There is no photo of this product: the drawing shows the dimensions of 638 ZZ

Load: radial medium; axial low, on both sidesDeep groove ball

Bearing KG 638 ZZ

Price on request
Available to order

Specifications

Manufacturer number
ISO designation
d
8 mm
Bore diameter dBearing bore = shaft diameter. Source: supplier data
D
28 mm
Outside diameter DOutside diameter = housing bore. Source: supplier data
B
9 mm
Width BRing width. Source: supplier data
Seal
ZZshields, both sides
Clearance
normal clearance
C
4.095 kN
Basic dynamic load rating CLoad for one million revolutions at 90 % reliability; the L10 life is calculated from it as (C/P)^p. ISO method, manufacturer’s figure: do not carry it over to another brand. Source: supplier data
C0
1.773 kN
Basic static load rating C0Permissible load without rotation and under shock; ISO 76 method, manufacturer’s figure. Source: supplier data
Limiting speed
25,200 rpm
Limiting speedMechanical limit; depends on the seal (SKF 6200: 36,000 open, 17,000 with 2RSH). Source: supplier data
m
0.027 kg
MassWeight of the product. Source: supplier data
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Equivalents

the same size 8 × 28 × 9 from other brands

2 products
Series illustration (not a photo of this item): 638 ZZ
You are viewingKG 638 ZZ

Not enough data for a firm conclusion: what is missing is written in the row.

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Details

what this bearing is, questions

About the bearing

D 28d 8B 9
d×D×Bsize 8 × 28 × 9mm
Cdynamic 4.095kN
C0static 1.773kN
mweight 0.027kg

Deep groove ball bearing 638-ZZ, design ZZ: metal shields on both sides.

C, C₀, m and limiting speed 25,200 rpm: KG data. Another brand publishes its own figures, so compare them against that brand’s catalogue.

Frequently asked questions

How does 2RS differ from ZZ?

2RS has rubber seals that touch the inner ring and keep out dust and water better, which is the usual choice for field machinery. ZZ has metal shields that do not touch, allow higher speeds, and protect against dirt less well.

Can I fit another brand instead of this bearing?

Without checking, only an exact equivalent: the size, seal, clearance and design match according to the brand’s catalogue. Positions with the same geometry differ in seal, clearance or design, and each one says so in the equivalents block. Load ratings differ between manufacturers, so for a heavily loaded unit compare C.

How do I get a price and a lead time?

Press “Request a quote” and send the part number and quantity. We reply with the price, availability and delivery terms for your country.

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