Needle Roller Bearings - Ntn-snr.com

Calculation of Bearing Loads
NTN
(2) Loads acting on cross shaft gears
Figs. 3.4 and 3.5 illustrate the loads acting on straighttoo
bevel gears and spiral bevel gears which are used
with cross shafts.
Table 3.2 shows how to calculate these loads.
The load acting on straight-tooth bevel gear can be
determined from Table 3.2, assuming the helix angle as
=0.
The symbols and units used in this table are as follows.
Kt Tangential load acting on gear
(Tangential force) N (kgf)
Ks Radial load acting on gear
(separating force) N (kgf)
Ka Parallel load acting on gear shaft
(axial load) N (kgf)
HP Transmission power kw
n Rotational speed r/min
Dpm Mean pitch circle diameter mm
Gear pressure angle
Gear helix angle
Pitch cone angle of gear
In general, the relationship between the loads acting on
pinion and pinion gear can be expressed as follows, due
to the perpendicular intersection of two shafts.
The separating force (Ks) acting direction and axial load
(Ka) acting direction illustrated in Fig.3.5 are the positive
direction respectively. On the other hand, the rotational
direction and helix angle direction are to be defined
viewing from the large end side of the gear. Hence, for
the gear illustrated in Fig. 3.5 these directions are
clockwise and to right.
K ag
K sg
K tg
K tp
K ap
K sp
Fig. 3.4 Load acting on bevel gears
K t
KspKag (3.5)
KapKsg (3.6)
where,
KspKsg Pinion and pinion gear separating force N (kgf)
KapKagAxial load acting on pinion and pinion gear N (kgf)
K s
K a
D pm
2
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
Driving gears
Rotational
direction
Helix angle
Clockwise Counter clockwise Clockwise Counter clockwise
To right To left To left To right
Unit N
Tangential loadKt
Kt 19.1106 H
Dpmn
1.9510 6 H
Dpmn
Drive side
KsKt
tan cos tansin
cos
KsKt
tan cos tansin
cos
Separating forceKs
Driven side
KsKt
tan cos tansin KsKt tan cos tansin
cos
cos
Axial load Ka
Drive side
KaKt
tan sin tancos KaKt tan sin tancos
cos
cos
Driven side
KaKt
tan sin tan
KaKt tan sin tancos
cos
cos
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