SIMPLE MACHINES, SIMPLE MACHINES, MECHANISMS AND MECHANISMS AND TECHNIQUESTECHNIQUES

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Relating to the programForces and movements Simple machinesSome notions about drawingTechniques and capsulesThe mechanism of motionThe systems in projects

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The program…The program…In the material world, on page 174 of the QEP, you will find…

Learning progressionLearning progressionOn page 6 of the learning progression in science and technology in primary school, you will find:

Still on page 6 in the learning progression for science and technology, you will also find:

ForcesForcesThere are several types of forces. Today we will look at two, compression and tension.

Generally, forces act on bodies one of two ways:

1. By pushing: This is what is called compression;

2. By pulling: This is what is called tension.

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CompressionCompressionCompression is a force that

exerts a push on a body. When this force is applied, it

causes or modifies the motion of the body.

It may also distort it. F

F

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TensionTensionTension is the force that pulls a

body. When this force is applied, it may

cause or modify the motion of the body.

Finally, it may also cause distortion.

F F

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MovementsMovements The mobile parts of a technical

object may move according to three types of movement.

1. Rotation

1. Translation

1. Helical movement

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Types of movementTypes of movement

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Simple machinesSimple machines

Simple machines are machines used to reduce the force necessary for the accomplishment of a task.

Humans have learned to use simple machines to help in their everyday tasks.

With an arrangement of simple machines, we obtain complex machines.

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Simple machines Simple machines (continued)(continued)

Simple machines serve three main functions:

1.They transmit forces;2.They change the direction of a

force;3.They modify the intensity of the

force.

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Simple machines Simple machines (continued(continued))

Here are five simple machines:

1.The lever2.The inclined plane and the

wedge3.The screw4.The pulley5.The wheel, the winch and gears

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The leverThe lever

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The inclined plane or the The inclined plane or the wedgewedge

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The screwThe screw

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The pulleyThe pulley

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The wheel and gearsThe wheel and gears

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Some notions about drawing …Some notions about drawing …

For technical drawing, there are international conventions such as:◦ Type of line

Thick Medium Fine

◦Basic lines Visible contour line (thick, continuous line) Hidden contour line (medium dashed line) Axis line (fine line with stroke at the center) Dimension line (fine, continuous line with arrows) Extension line (fine, continuous line) Leader line (fine line with one arrow)

◦Views◦Dimensions (in mm)

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Basic linesBasic lines

Ø 8 FACING Ø14 X 3 DEEP

80

50

45

40°

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20

2040

Extension line

Visible contour line

Hidden contour line

Axis line

Dimension line

Leader line

Basic lines Basic lines (continued)(continued)

Multiple viewsMultiple views

Among the six possible views, we choose to show those that are necessary to describe the shape of the object.

FACE VIEW RIGHT VIEW

TOP VIEW

LEFT VIEWBACK VIEW

BOTTOM VIEW

Three views are usually sufficient to describe an object. Many simple objects only require one or two views.

Making a complex machineMaking a complex machine

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Cartridge

A glance at the materialsA glance at the materials

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THE LEVER

TEETER-TOTTER

WHEELBARROW

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WEDGE AND INCLINED PLANE

NAIL CLIPPER

Techniques and capsulesTechniques and capsules

• Work techniques

• Safety capsules

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Construction of a complex Construction of a complex machine machine

Your turn to play…..

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Movement mechanismsMovement mechanismsThere are many mechanisms,

classified into two categories:

1.The transmission of motion;2.The transformation of motion.

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Movement mechanismsMovement mechanisms1. Transmission of motion

A transmission of motion mechanism is a mechanism that transmits the same movement from one part of an object to another.

Here are three of the most common mechanisms:

Gears;Friction wheels;Pulleys and belts.

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GearsGears

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Friction wheelsFriction wheels

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Pulleys and beltsPulleys and belts

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Movement mechanisms Movement mechanisms ((continuedcontinued))

Your turn to play…..

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Movement mechanisms Movement mechanisms ((continuedcontinued))

2. Transformation of motion

A transformation of motion mechanism is a mechanism that changes the nature of the movement, that is from a translation to a rotation or vice versa..

Here are the transformation mechanisms:

Rod and crank; Cam and rod; Rack and pinion; Nut and bolt; Crankshaft.

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Rod and crankRod and crank

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Crank: Mechanical part by which a force can transmit a rotary movement around an axis.

Rod: Rigid rod that is used to produce a movement.

Axis

Cam and rodCam and rod

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Rod or roller: Rigid rod leaned on the cam.

Cam: Mechanical part whose function is to push an element to move it.

Rack and pinionRack and pinion

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Rack: Straight geared rod.

Pinion: Gear

Nut and boltNut and bolt

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Bolt: Threaded cylindrical rod.

Nut: Female part of bolt

CrankshaftCrankshaft

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Crankshaft: « U » shaped axle with at least one rod that transforms a rectilinear movement into a rotary movement.

Movement mechanisms Movement mechanisms ((continuedcontinued))

Your turn to play…..

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The systems in projectsThe systems in projects

Rod and crank: periscopeRod and cam: mouse/crocRack and pinion: periscopeRod and crankshaft: Mechanical

bugsWheels: odometer Others…

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Thank you!Thank you!

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