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PRESENTED BY: SUBMITTED TO
TAUHA NADEEM, SIR MAZAR JAMEEL
SUMBUL TUFAIL,
ALI AITBAR KADRI,
SAKINA ZAHID.
GEAR
It is a mechanism to transmit or to
change the direction of motion/force.
What is a gear?
This shows how motion is transferred from the pedal to the
tyre.
Example #1:
This shows how one gear connected to the motor, can cause the other gear to move in the opposite direction which changes the direction of the motion.
Example #2:
Another simplistic example:
This shows how the size and number of teeth affects the
speed of the gear.
The relationship between the teeth and speed of a gear:
This shows how increase in one variable causes a decrease in
the other and vice versa.
Hyperbola showing the relationship of speed and teeth:
•Gear train: when 2 or more gears are joined together for a particular purpose.•Driver gear: a gear which is connected to the motor.•Driven gear: a gear which is connected to the driver gear.
The actual formula:
Velocity of driven= Velocity of driver * (# of teeth in driver gear/ # of teeth driven)
•Manipulation of the formula:
Velocity of driven/ Velocity of driver= # of teeth in driver gear/ # of teeth driven
Number of teeth in driven gear
15 20 25 30 35
Velocity of driven gear 667
500
400
334
286
Velocity of driven= Velocity of driver * (# of teeth in driver gear/ # of teeth driven) = (200*50/15) = 667
15 20 25 30 350
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Number of teeth in driven gear
Velo
city
of
dri
ven
gear
Twist factor:It measures how much turns a yarn
has and can be calculated by counting the number of twists in an inch of yarn.
Twist is inserted into the fine strand of fibres to hold the fibres together. Without twist, the fine strand of fibres would be
very weak and of little practical. Formula:
Twist factor= (turns per centimetre) √linear density
Twist factor 30 35 35
Turns per centimetre 6 7 8
Twist factor= (turns per centimetre) √linear density 30 = (x) √25 30/5 = x 6 = x
30 35 400
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Twist factor
Tu
rns
per
cen
tim
etr
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