worm_gear.ppt

worm gear design procedure

1. WORM GEAR

2. Introduction
Thewormgearsareusedtotransmitpower
betweenNon-intersecting,Non-parallel
shafts.
TheNon-intersectingnotnecessarytoplaced
atrightangles.
Thecrossed-helicalandhypoidgearsarealso
usedtoconnectNon-intersectingandNon-
parallelshafts.Butitissuitableforlowspeed
ratios(upto8)andlowpowerratings.

3. Continue…
Wormgearscanbeusedforhighspeedratios
(300:1)
Thewormgeardriveconsistsofawormanda
wormwheel.
Ifatoothofahelicalgearmakescomplete
revolutionsonthepitchcylinder,theresulting
gearisknownasaworm.Thematinggearis
calledwormgearorwormwheel.
Theworminwormandwormgeardriveis
sameasscrewinscrewandnutpair.

4. Application, Merits and Demerits
Itisusedasainmaterialshandlingequipment,
machinetoolsandautomobiles.
Advantage:
Theoperationissmoothandsilent.
Itisusedforspeedratiosashighas300:1
Itiscompactaswellasspur&helicalgear
Thewormgeardrivesareirreversible.Itmeans
thatthemotioncannotbetransmittedfromworm
wheeltotheworm.Thispropertyofirreversible
isadvantageousinloadhoistingapplicationlike
cranesandlifts.

5. Continue…
Disadvantage:
Theefficiencyislowcomparedwithother
typesofgeardrives.
Theyarecostly.
Sinceslidingoccurs,theamountofheat
generationisquitehigh.
Thepowertransmittingcapacityofwormgear
driveislow(100kW).

6. Types
1.Single-envelopingwormdrive:
Ifthewormaddendumformsacylindrical
surface,andiftheworm-gearteetharecurved,
thenthedriveiscalledsingle-enveloping.
2.Double-envelopingwormdrive:
Ifthewormaddendumhasanhourglassform,and
iftheworm-gearteetharealsocurved,thenthe
driveiscalleddouble-enveloping.

8. THANK YOU