Timken Super Precision Bearings for Machine Tool Applications

ENGINEERING
A
Straight Bevel Gear
Tangential force
F tG =
(1.91 x 10 7 ) H (newtons)
D mG n G
F aG
F sG
F tG
F tP
F aP
F sP
=
Thrust force
(1.26 x 10 5 ) H (pounds-force)
D mG n G
Fig. 37. Straight bevel gearing.
F aG = F tG tan G sin G
Separating force
F sG = F tG tan G cos G
Spiral Bevel and Hypoid Gearing
In spiral bevel and hypoid gearing, the direction of the thrust
and separating forces depends upon spiral angle, hand of spiral,
direction of rotation, and whether the gear is driving or driven (see
4). The hand of the spiral is determined by noting whether the tooth
curvature on the near face of the gear (Figure 38) inclines to the
left or right from the shaft axis. Direction of rotation is determined
by viewing toward the gear or pinion apex.
In spiral bevel gearing:
Clockwise
C o u nterclockwise
–
Positive
thrust away from
+
pinion apex
Negative
thrust toward
pinion apex
F tP = F tG
In hypoid gearing:
F tP =
F tG cos P
cos G
Hypoid pinion effective working diameter:
N p cos G
D mP = D mG
( N G )( cos P )
Tangential force
F tG =
(1.91 x 10 7 ) H (newtons)
D mG n G
F aG
F sG
F tG
F tP
F aP
F sP
Fig. 38. Spiral bevel and hypoid gears –
the direction of thrust and separating
forces depends upon spiral angle, hand
of spiral, direction of rotation, and
whether the gear is driving or driven.
Fig. 39. Spiral bevel
and hypoid gearing.
=
(1.26 x 10 5 ) H (pounds-force)
D mG n G
Hypoid gear effective working diameter:
D mG = D pG - b sin G
38 TIMKEN MACHINE TOOL CATALOG