Page 86 - needle bearings

Needle roller and cage assemblies for connecting rod bearings
NTN

The respective profile accuracy of connecting rod hole,
Radial clearance crank and piston pin outer surfaces shall be as specified
Table 1 shows the recommended clearance values in Table 3.
though the radial clearance differs depending on bearing Furthermore, the parallelism of crank pin and piston pin
clearance, load, revolutions and ambient temperature. shall be 0.02mm or less against 100mm. (Fig. 1)
The proper radial clearance can be got by proper The surface roughness shall be 0.2a for connecting rod
selection and combination of roller diameter, connecting and 0.1a for pin outer surface as a guideline.
rod hole diameter and pin diameter. Table 2 shows the
examples of selection and combination of those.
Table 3 Recommended accuracy of connecting rod and pin
Unit : Жm
Pin diameter classification mm
Table 1 Recommended clearance values
Unit : Жm Parts Characteristics
ʙ14 14ʙ18 18ʙ25 25ʙ30 30ʙ40
Pin diameter
mm Large end side Small end side Connecting Roundness (max) 3 4 4 5 5
Over incl. rod
Cylindricality (max) 2 3 3 4 4
6 10 9ʙ23 5ʙ17 Roundness (max) 2 2 3 3 4
Pin
10 18 10ʙ24 5ʙ17
Cylindricality (max) 1 1 2 2 3
18 30 10ʙ24 5ʙ17
30 40 18ʙ33 ʵʵ

Table 2 Radial clearance values obtainable by selection and
combination
П0.02
Case of needle roller and cage assembly Type PK for crank pin
Crank pin hole diameter 22mm H6 (0 to +13Жm)
Crank pin diameter 14mm h5 (0 to -8Жm)
Unit : Жm
Hole diameter
sorting class 0ʙʴ4 ʴ4ʙʴ8 ʴ8ʙʴ13
Sorting class of
Pin diameter needle roller used ʵ4ʙʵ6 ʵ2ʙʵ4 0ʙʵ2
sorting class
0ʙʵ3 10ʙ17 10ʙ17 10ʙ18
ʵ3ʙʵ6 13ʙ20 13ʙ20 13ʙ21
ʵ6ʙʵ8 16ʙ22 16ʙ22 16ʙ23 100

Fig. 1
Connecting rod and pin specifications
Connecting rod (bore surface), crank pin and piston pin
(outer surface) can be used as direct raceway surface.
However, these surfaces must be resistible to great load
while maintaining high accuracy. For that, connecting
rods and pins acting as the direct raceway surface must
comply with the specifications specified hereunder.
Any connecting rods shall be made of cement steel,
e.g. chrome molybdenum steel (SCM415, etc.), nickel
chrome molybdenum steel (SNCM420, etc.) and any
crank pins and piston pins shall also be made of cement
steel, e.g. chrome steel (SCr420, etc.), all of which shall
be surface-hardened by carburizing.
The surface hardness of each shall range from HRC58
to 64 and adequate depth of effective carburizing-
hardened layer shall be secured up to Hv550. The depth
of effective carburizing-hardened layer differs depending
on actual load and pin diameter.
Feel free to contact NTN for the more detailed
information.

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