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Power Motion Products
Bearings:
- A bearing is a mechanical device that supports the many parts
of a machine.
- Its primary purpose is to reduce friction.
- Bearing are made to support radials loads.
o Radial load
o Thrust load
o Combines radial & thrust load
Types:
Plain Bearing
o Cylindricalo thrust
Anti-Friction Bearing
o Ball Bearing
o Roller Bearing
Couplings:
- Used to connect two pieces of shafting.
Types:
Sleeve coupling (straight through)
Multi jaw coupling (used for light duty)
Three Jaw Insert Type
Fig: Radial BearingFig: Thrust Bearing
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Gears:
Spur Gears:
- cylindrical in shape with teeth on the outer circumstances
that are straight and
parallel to the axis (hole).
- No axial thrust due to thrust load.
Bevel Gears:
- A Bevel Gears is shaped like a section of a cone usually
operate on a shaft at 90
degree.
Variation:
Pinion wire
Stem pinion
Rack
Internal gears
Helical Gears:
- Similar to spur gears except that the teeth of a helical
gears are cut at an angle (helix angle) to the axis
(hole).
Right Hand Configuration
Left Hand Configuration- Opposite hand helical gears runs on
parallel shafts.
- Gears of the same hand operate with shaft at 90
degree.
Low impact stresses
Reduced noise
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- The teeth may be straight or spiral
Miter Gears:
- Miter Gears are identical to bevel gears except that in a
miter gear set,both gears
always have the same no. of teeth.
- The ratio is always 1 to 1
- Miter gears are not used when an application called for a
change of speed.
Gear Trains:
Types:
Simple gear trains
Compound gear trains
Reverted gear trains
Epicyclic gear trains
Differentials:
- Transmit motion from engine shaft to rear drive wheels
- Rotate wheels at different speed while taking turn.
- Uses helical gears.
Terminologies:
Pitch Circle:
The imaginary circle that comes in contact with imaginary circle
of another gear when
the two are in mesh.
Addendum:The distance from the top of a tooth to the pitch
circle.
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Dedendum:The distance from the pitch circle to the root circle.
It equals the addendum + theworking clearance.
Whole Depth:The distance from the top to the bottom of the gear
tooth.
Working Depth:The total depth of a tooth space. It is equal to
the addendum + the dedendum (or theworking depth + the
variance).
Working Clearance:The distance from the working depth to the
root circle.
Pressure Angle:- also referred as tooth shape.- Angle at which
the pressure from the tooth of one gear is passed on to the
tooth
of another gear.- Spur gear has two pressure angle; 141/2 and 20
degree.- 141/2 pressure angle is the original standard tooth shape
and is still widely used
today.- 20 degree , new & improved shape is a stronger and
better tooth because of
wider base; specially on pinion gear with small no. of
teeth.
Notes & Formulaes:The mating worm & worm gears must have
the same
Pitch
No. of threads
Tooth dimensions
Pressure anglesLead angle
Module m = D/T = 1/diametric pitch
Gear Ratio = T1/T2
Circular Pitch = 22/7*D/T
N1/N2 = D2/D1 = T2/T1
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