Page 319 - needle bearings

One-way clutches
NTN

Shaft and housing requirements
Table 3 shows the shaft and housing requirements. A

Table 3 Shaft and housing requirements (recommended)
˚
Shaft Housing
Characteristics
Type HF Type HFL Type HF Type HFL B
Roundness (max) IT3 (IT4) IT4 (IT5) AʹDʵʢ0.2ʙ0.3ʣmm
BʹFwʵʢ0ʙ0.025ʣmm
Cylindricality (max) IT3 (IT4) IT4 (IT5)
DʹOuter diameter of one-way clutch mm
Surface roughness 0.2a 1.6a FwʹRoller inscribed circle diameter mm
Surface hardness HRC58ʙ64 ʵ (Refer to applicable Dimensions Table.)
Effective hardened 0.4mm ʵ
layer depth (min) Fig. 3

Lubrication Precautions in selecting
Oil lubrication is optimum for these one-way clutches, NTN makes it a rule to conduct functional verification
but generally grease lubrication is mostly applied to this tests on its manufactured one-way clutches under various
type of one-way clutch. NTN one-way clutches are filled test conditions. However, be noted that the clutch lifetime
up with a suitable grease. These clutches need no further could reduce depending on the following factors;
grease replenishment, but subject to general applications. application to high load torque, high oscillation cycle and
In replenishing, good care must be exercised of too fine oscillation, etc., large radial load acting on one-way
much grease filling. Too much filling could cause clutch unit, and use of a shaft with lower hardness.
interference with smooth clutching. Furthermore, lock failure could occur in the cases of
fast idling speed, frequent use in idling, and application
incurring vibration.
Allowable operating temperature When using these one-way clutches under the special
For Type HF and HFLʜOil lubrication : -10 to 120˚C conditions stated above, feel free to contact NTN for
Grease lubrication : -10 to 70˚C further instructions.
However, consult with NTN for application under
temperature exceeding the said temperature range.
When it is forecast that clutching function
How to mount failure of one-way clutch(ex. clutch slip in
engaging) could result in serious damage to
It is convenient to use a press-fitting mandrel as
illustrated in Fig. 3 for assembling and mounting these person or equipment, appropriate safety devices
one-way clutches. In that case, press-fit the outer ring, must be provided separately.
with its stamped mark side kept in contact with the
mandrel shoulder.
In assembling, be careful to prevent the outer ring
from twisting. Avoid to hammer directly the outer ring
and, in press-fitting, bring a proper jig in contact with
the outer ring side face without fail. Furthermore,
when press-fitting in an housing with shoulder, good
care must be exercised to prevent the bearing side
face from coming into contact with the housing
shoulder and to thereby avoid deformation of the
bearing.
Also, shaft can be easily assembled by turning it in
clutch idling direction. Where impossible to do so, provide
the shaft end with a tapered (chamfered) guide to
facilitate assembling-in.

B-257