Page 25 - needle bearings

Calculation of Bearing Loads
NTN

(2) Loads acting on cross shaft gears The separating force (Ks) acting direction and axial load
Figs. 3.4 and 3.5 illustrate the loads acting on straight- (Ka) acting direction illustrated in Fig.3.5 are the positive
too bevel gears and spiral bevel gears which are used direction respectively. On the other hand, the rotational
with cross shafts. direction and helix angle direction are to be defined
Table 3.2 shows how to calculate these loads. viewing from the large end side of the gear. Hence, for
The load acting on straight-tooth bevel gear can be the gear illustrated in Fig. 3.5 these directions are
determined from Table 3.2, assuming the helix angle as clockwise and to right.
Ќ =0.
The symbols and units used in this table are as follows.

Kt ɿTangential load acting on gear K tp
(Tangential force) N (kgf)
Ks ɿRadial load acting on gear
K ap
(separating force) N (kgf)
K sp
Ka ɿParallel load acting on gear shaft K ag
(axial load) N (kgf) K sg
HP ɿTransmission power kw
n ɿRotational speed r/min
Dpm ɿMean pitch circle diameter mm Ktg
Ћ ɿGear pressure angle
Ќ ɿGear helix angle
Ў ɿPitch cone angle of gear Fig. 3.4 Load acting on bevel gears

In general, the relationship between the loads acting on
pinion and pinion gear can be expressed as follows, due K t
to the perpendicular intersection of two shafts.

KspʹKag ʜʜʜʜʜʜʜʜʜʜʜʜʜʜʜ(3.5)
KapʹKsg ʜʜʜʜʜʜʜʜʜʜʜʜʜʜʜ(3.6) K a
D pm
where, K s 2
KspɼKsg ɿPinion and pinion gear separating force N (kgf) Ў Ќ
KapɼKagɿAxial load acting on pinion and pinion gear N (kgf)

For spiral bevel gears, the loading direction differs
depending on the direction of helix angle, rotational
direction and whether the spiral bevel gear is located at
the drive side or the driven side. Fig.3.5 Bevel gear diagram

Table 3.2 Loads acting on bevel gears Unit N
Rotational
direction Clockwise Counter clockwise Clockwise Counter clockwise
Driving gears
Helix angle To right To left To left To right
6 6
19.1ʷ10 ɾH 1.95ʷ10 ɾH
Tangential load Kt Kt
Dpmɾn Dpmɾn
cosЎ cosЎ
Drive side Ks Kt tanЋ tanЌsinЎ Ks Kt tanЋ tanЌsinЎ
cosЌ cosЌ
Separating force Ks
cosЎ cosЎ
Driven side Ks Kt tanЋ tanЌsinЎ Ks Kt tanЋ tanЌsinЎ
cosЌ cosЌ
sinЎ sinЎ
Drive side Ka Kt tanЋ tanЌcosЎ Ka Kt tanЋ tanЌcosЎ
cosЌ cosЌ
Axial load Ka
sinЎ sinЎ
Driven side Ka Kt tanЋ tanЌDPTЎ Ka Kt tanЋ tanЌcosЎ
cosЌ cosЌ

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