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Bevel - 1

Bevel gears are used for power transmission between intersecting shafts, with types including mitre gears, angular bevel gears, and crown gears. They have applications in various machinery such as automobiles and drilling machines. Important terminologies include pitch cone, cone distance, and force analysis related to the gear's operation.

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19 views22 pages

Bevel - 1

Bevel gears are used for power transmission between intersecting shafts, with types including mitre gears, angular bevel gears, and crown gears. They have applications in various machinery such as automobiles and drilling machines. Important terminologies include pitch cone, cone distance, and force analysis related to the gear's operation.

Uploaded by

nithyashreegr.221mn038
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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BEVEL GEARS

BEVEL GEARS
- Power transmission between intersecting
shafts
- Straight teeth gears generate noise at high
speeds due to sudden nature of contact.
- In spiral bevel gears engagement is smooth
TYPES OF BEVEL GEARS
Mitre Gears: When bevel gears of the same
size are used on intersecting shafts at right
angles, they are called as mitre gears.
Angular bevel gears: Bevel gears mounted on
intersecting shafts, making other than 90° , they
are called as angular bevel gears.
Crown gears: When the pitch angle of a bevel
gear is 90°, it is called crown gear.
Applications
• Rear axle drives of automobiles
• Spindle drive of drilling machines
• Elevating drive of cross-rail of a planar.
Important terminologies
Pitch Cone: It is a cone which rolls without
slipping, when in peripheral contact.
Pitch Cone angle: Angle subtended at the apex,
by the gear axis and a pitch cone generator ( δp-
pitch cone angle for pinion, δp- pitch cone angle
for the gear )
Cone distance: Length of the pitch line, from the
apex to the base. It is also called as cone radius
Back cone: An imaginary cone, perpendicular to
the pitch cone, at the end of the tooth.

Back cone radius, Rb: It is the length of the back


cone.
δ = Shaft angle
δp = pitch cone angle of pinion
δg = pitch cone angle of gear
Dp= PCD of pinion
Dg = PCD of gear
From the geometry of the figure,
tan δp = Rp/ Rg
= 1 / VR
= 1/i
tan δg = Rg / Rp
= VR
=i
Equation 12.72 a,b – Old DDHB
Equation 12.32 a,b – New DDHB
Cone distance L = (Rp2+ Rp2)
Virtual number of teeth
It is the number of teeth which a spur gear
would have, the radius of which is equal to the
back cone distance Rb, and with the pitch of the
bevel gear.

Z’ = Z/ cos δ
Z1’= Z1/ cos δp
Z2’= Z2/ cos δg
Force Analysis
Force Analysis
Ft = T / (D/2)
Fs = Ft tan α, where α is pressure angle
Axial component
Fs
Radial component
Axial component Fa1 = Fs sin δ1
Radial component Fr1 = Fs cos δ1
i.e, Fa1 = Fs sin δ1 = Ft tan α sin δ1
Fr1 = Ft tan α cos δ1

Similarly,
Fa2 = Ft tan α cos δ1
Fr2 = Ft tan α sin δ1

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