Post on 15-Aug-2015
M.Arslan SohailTS1(A)
GEARS
What is
GEAR ?“A DEVICE OR A MECHANISM
THAT TRANSMIT FORCE OR POWER.”
“CHANGE THE DIRECTION OF FORCE”
OR
TEETH
EXAMPLE
FORCE
TYPES OF GEARS
Spur gears or straight-cut gears are the simplest type of gear. These gears can be
meshed together correctly only if they are fitted to parallel shafts.
SPUR GEAR
Helical gears offer a refinement over spur gears. The leading edges of the teeth are not parallel to the axis of rotation, but are set at
an angle.
HELICAL GEAR
DOUBLE HELICAL GEARDouble helical gears, or herringbone gears,
overcome the problem of axial thrust.
BEVEL GEARA bevel gear is shaped like a right
circular cone with most of its tip cut off. It changes the vertical motion to
horizontal motion.
GEAR WHEEL/WORM WHEEL
Worm gears resemble screws. A worm gear is usually meshed with a spur gear or a helical gear, which is called the gear, wheel, or worm wheel.
Rack and pinion.A rack is a toothed bar or rod that can be thought of as a sector gear with an infinitely large radius. Torque can be converted to linear force by meshing a rack with a pinion: the pinion turns; the rack moves in a straight line.
TERMINOLOGIESDRIVER:
A gear that is directly connected to a motor.DRIVEN:
A gear that is not directly connected to a motor.
CARRIER:A gear that is used to rotate two gears in same direction.
> ><
> ><
IDLERA gear that is used to rotate two gears in same direction. But it is not connected to any shaft.
GEAR TRAIN:
BACKLASH
The distance between teeth of embedded gears.
GEAR CALCULATIONS
DIATEETH
SPEEDR.P.M
R.P.M 1/DIAMETER ∝DIAMETER TEETHS ∝R.P.M 1/TEETH ∝
SPEED × TEETH = SPEED × TEETH
GEAR CALCULATIONS
DIATEETH
SPEEDR.P.M
SPEED × TEETH = CONSTANT SPEED × TEETH = CONSTANT
Driver
Driven
DrivenDriver
APPLICATIONS IN TEXTILE
Used in parts of looms.Worm gears use in drive to cams.Spiral bevel gears find application in sewing machines.bobbins and spindles on roving machines.Parallel helical gears are invariably used in drawing machines.Conveyer belts for laps in blow room.