02. basic mechanical.pptx

7/29/2019 02. Basic Mechanical.pptx

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Production of Power (Motion)

Transmission of Power (Motion)

Joining two or more parts


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Welding

Riveting Using Adhesives

Others

Permanent

Nut Bolt

Screw

Others

Temporary
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Gear Drive

Belt pulley drive

Chain sprocket drive

Cam Drive

Shaft

Springs

Free Wheels


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A gear is a rotating machine part havingcut teeth, or cogs, which mesh withanother toothed part in order to transmittorque.

Two or more gears working in tandem are

called a transmission and can produce amechanical advantage through a gear ratioand thus may be considered a simplemachine.


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Spur

Helical

Bevel

Rack

Worm


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These gears can be meshed together correctlyonly if they are fitted to parallel axles.

This type of gear is easiest to manufacture.

Used when the shafts are parallel, andgear ratios required are not very large.Applications:


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Spur Gear

Parallel Axis


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Bigger is Gear

Smaller is Pinion


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Helical gears offer a refinement over spurgears. The leading edges of the teeth arenot parallel to the axis of rotation, but areset at an angle.

The angled teeth engage more gradually

than do spur gear teeth causing them torun more smoothly and quietly. Thus theyare quieter in application as compared tospur gears.


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Used in the gearbox of a

modern automobile.

One use of this to avoidaxial movement duringmotion


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Bevel gears are gears where the axes of the twoshafts intersect and the tooth-bearing faces of thegears themselves are conically shaped.

Bevel gears are most often mounted on shafts thatare 90 degrees apart. So it can be used to changethe direction of power transmission by 90 degrees.

The teeth may be straight cut as in spur gears orcan be spirally cut as in helical gears. The figureabove shows a spiral bevel gear.


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In differential drives and hand drills

among many other applications.

Applications


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Torque can be converted to linear force bymeshing a rack with a pinion: the pinionturns; the rack moves in a straight line.

Used in automobiles toconvert the rotation of

the steering wheel intothe left-to-right motionof the tie rod(s).

Applications


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Worm gears resemble a screw. A wormgear is usually meshed with an ordinary

looking, disk-shaped gear, which iscalled the gear, wheel, or worm wheel.

In a worm-and-gear set, the worm can

always drive the gear, but gear cannotdrive the worm. This is a self-lockingproperty of a worm gear.


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One way motiontransfer

Locking


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A very high gearratio can be obtainedusing a wormgear. This is a simpleand compact way toachieve a high torque,low speed gear ratio.

to open lock gates

Applications


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Used to generate a particular motion of follower

Like y=Sin(x)


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Helical or coiled

Spiral

Leaf Spring


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Ball bearings

Roller Bearings

Magnetic Bearings


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Ball bearings

Roller Bearings

Magnetic Bearings

02. basic mechanical.pptx

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