Page 314 - needle bearings

Linear roller bearings
NTN

Linear Roller Bearings

This roller bearing with cylindrical rollers having the
function capable of circulating within the raceway block Requirements and tolerances for raceway
ensures smooth infinite linear motion on a flat surface. surface and mounting surface
The cylindrical rollers are retained and guided by the Table 2 shows the requirements and tolerances for the
cage and the ribs of the raceway block. raceway surface, on which linear roller bearing rolls, and
The cage is of such a construction as not allow the bearing mounting surface. Where adhesion of a hard
adjacent rollers to contact with one another. Hence, the foreign matter to the raceway surface is forecast, the
friction coefficient is low. raceway surface must be protected with a proper
protective cover.
The reference surface for mounting is the back face
and opposite face to NTN mark.

Table 2 Requirements for raceway surface and mounting surface
Characteristics Allowable value or tolerance range
Raceway surface roughness (max) 0.2a
Raceway surface hardness HRC58ʙ64

Effective hardened layer depth of as described in applicable
raceway surface (min) Dimensions Table
Parallelism of mounting surface
ɹɹɹɹɹ∆ x ʢSee Fig. 2ʣ 0.05 mm per 100 mm
Fig. 1 ɹɹɹɹɹ∆ yʢSee Fig. 3ʣ 0.01 mm per 100 mm

Bearing accuracy
All the linear roller bearings are manufactured within NTN mark here
the dimensional tolerance range of 0 to -2.5Жm for
bearing height (H). And these bearings are delivered
classified into 5-stepped tolerance classes. (See Table 1)

Table 1 Classification of bearing height H by accuracy class Fig. 2
Unit : Жm
Class code Tolerance for height (H)
1H 0ʙʵ 5
2H ʵ 5ʙʵ10
3H ʵ10ʙʵ15
4H ʵ15ʙʵ20
5H ʵ20ʙʵ25
Fig. 3

How to mount
Fix linear roller bearing using the tapped holes which
are provided on the mounting reference surface. (See
Fig. 4)

Fig. 4

B-252