presentation08 gears.ppt [modalità...

HELICAL GEARS

GeometryKK N

K M K N

K M

Spur gearsSpur gears

Helical gears

HELICAL GEARS

Geometry and manufacturing

Primitive helix

Base helix

Base helix

Spur gear generation Helical gear generation

HELICAL GEARS

Geometry

costan

tantan bb

R

cos

HELICAL GEARS

Contact and force transmission

cos bN S

sin tanb bT NS

b

RNM

tantan LLs b

RNM cos

tan tanbM MT

tan

cosLs

cosT

R R

HELICAL GEARS

Definitions and properties

mRp 2

(Tangential) Pitch

cosppn

mZ

p ( g )

Normal (= orthogonal) Pitch

nn mp

n

cosmmn Normal module

costantan n Normal pressure angle

INCIDENT AXES TRANSMISSION

Spherical motion

Gear 2

Gear 1Gear 1

Bevel gearings

2

1

1

2

sinsin

BEVEL GEARS

Bevel gears

sσ1

μ

C

s2

s1

σ

ε

σ2

PrimitiveBase cone

Primitive cone

BEVEL GEARS

Bevel gears

PrimitiveBase cone

Primitive cone

SKEW AXES TRANSMISSION

Worm-gearsGear axisGear axis

Worm axis

SKEW AXES TRANSMISSION

Worm-gears

Gear axis2

G W

W

pR

G i

Z Wp p i

2 W R

W Z2

Rp

ZZ

pW= worm pitchp = gear pitchp = gear pitchi = worm threadsR = gear pitch radiusg pZ = gear teeth

SKEW AXES TRANSMISSION

Other solutions

Cylindrical gears with helical teethHypoidal gearing

(bevel gears with curve-shaped teeth)y g (bevel gears with curve shaped teeth)