Introduction
Primitive Gears
Parallel
gearing
Right-angle gearing
Leonardo
da Vinci’s
Endless
Screw
Antique
Calculator
Why Do We Use Gears?
Gears are some off tthe mostt iimporttantt
ellementts used iin machiinery..
There are ffew mechaniicall deviices tthatt do
nott have tthe need tto ttransmiitt power and
mottiion bettween rottattiing shafftts..
Gears nott onlly do tthiis mostt sattiisffacttoriilly,, butt
can do so wiitth uniifform mottiion and relliiabiilliitty..
IIn addiittiion,, tthey span tthe enttiire range off
applliicattiions ffrom llarge tto smallll..
Advanttages::
• Gears offffer posiittiive ttransmiissiion off power..
• Gears range iin siize ffrom smallll miiniiatture iinsttrumentt
iinsttallllattiions,, tthatt measure iin onlly severall miilllliimetters iin
diiametter,, tto huge powerffull gears iin tturbiine driives tthatt
are severall metters iin diiametter..
• Gears can proviide posiittiion ttransmiissiion wiitth very hiigh
angullar or lliinear accuracy,, such as used iin
servomechaniisms and miilliittary equiipmentt..
• Gears can couplle power and mottiion bettween shafftts
whose axes are parallllell,, iinttersecttiing or skew..
• Gear desiigns are sttandardiized iin accordance wiitth siize
and shape whiich proviides ffor wiidespread
iintterchangeabiilliitty..
Kneader
Typical
commercial
gearbox
IItt iis usualllly more
attttracttiive economiicalllly tto
splliitt a llarger speed rattiio
iintto a number off sttages
(paiirs off gears) ratther
tthan tto effffectt iitt wiitth a
siinglle paiir..
There are tthree sttages
here:: tthe ffiirstt spiirall bevell
pair is followed by two
helliicall paiirs..
Hobbing a Single Helical Gear
(Nortthern Tooll Gear)
The hob is situated above
the operator's left thumb
Hob
Hob (Cutter) for
Generating Gear Teeth
Hobbing a
Double
Helical Gear
(Gear Works)
Doublle
Helliicall
Hiigh
Speed
Gear on a
5..5 m
Hobbiing
Machiine
(John Brown,, Cllydebank)
Industrial Gearbox
(Daviid Brown)
The oiill spray
head iis
llocatted jjustt
tto riightt off
nearestt
piiniion
Gearbox for Coal Pulveriser
(Gear Works)
Selection of Small Gears
(Kao Fu Gears)
Gear for Cement Industry
(Machiineffabriiek P van derWagen & Zn)
Speed Reducer
(NORD Gears)
Scania Gearbox
Why Speed Reducers?
Speed reducers are much more common
tthan speed-up driives nott so much because
tthey reduce speed,, butt ratther because
tthey amplliiffy ttorque..
Thus gears are used tto accelleratte a car
ffrom restt,, nott tto proviide tthe iiniittiiall llow
speeds (whiich coulld be accomplliished by
easiing up on tthe accellerattor pedall) butt tto
iincrease tthe ttorque att tthe wheells whiich iis
necessary tto accelleratte tthe vehiiclle.
curs in engleza organe de masini II
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