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What is a Mechanism Description

Example of a Mechanism Description

An outline for writing a Description

Putting it all together

Ref: Finkelstein Ch4

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Technology involves physical devices calledmechanisms.

Writing mechanism descriptions is a criticalability of an engineer.

The engineer creates a mechanismdescription to document and specify thedevice so the customer can decide if it fulfillstheir needs.

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Mechanism descriptionsare preciseportrayals of material devices with two ormore parts that function together to dosomething.

Range in Complexity A pair of pliers

A bicycle

An automobile

A jet plane like the Boeing 787

The space shuttle

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A mechanism descriptions primary focus ison the physical characteristics or attributes ofthe device and its parts.

Thus they tell the size, shape, color, finish,fit, etc. for the complete mechanism and itsfor each of its parts.

Descriptions typically include figures,

diagrams, or photographs.

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Internal Combustion Engine Mechanism Description the complete engine, the

cylinder head, the block, the valves, the pistons, thecrankshaft,

Describe the complete engine Describe the cylinder head

Describe the block

Describe the piston which also has piston rings,connecting rod, piston rod, and crankshaft bearings.

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Introduction Define the mechanism with a technical definition

and add extensions necessary for the reader tounderstand the discussion.

Describe the mechanisms overall function orpurpose.

Describe the mechanisms overall appearance

List the mechanisms parts in the order in which

they will be described.

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Discussion Step 1

Define first part with a technical definition.

Describe the parts overall function or purpose.

Describe the parts shape, material, etc. Transition to the next part.

Steps 2 to n

Repeat as for step 1 for the remainder of the parts.

Conclusion Summarize and provide closure.

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The Mechanism a 33-kilohm resistor The 33-kilohm, 1-watt carbon resistor is a circuit

component that impedes the flow of electriccurrent.

The resistor impedes the movement of electrons,thereby generating a thermal response dependingon temperature, cross section, and length of theresistive element. The resulting resistance

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The resistor consists of the following parts:the carbon element, the wire leads, thecasing, and the color bands.

The Part Description The carbon element is the capsule of resistive

material that coverts electrical energy into heat.The carbon element serves as the primary active

The carbon element is cylindrically shaped and is2.4 cm long with a diameter of .32 cm. It is

composed of finely ground carbon particles mixedwith a ceramic binding compound. The element isgray with

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The 33-kilohm 1-watt carbon resistor is acircuit component that impedes the flow ofelectric current through the use of a carbonelement. The resistor is made up of four

parts: the carbon element,

Together, these parts form one of the most

commonly used circuit components inelectronic systems today.

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Mechanism description almost require visualaids.

BUT only include visual aids that add to thedescription You are writing the description of a basic car

Your figure if a basic Ford sedan or a Ferrari.

The visuals specifically relate to the textdiscussion and numbered in sequence asreferenced.

USE APPROPRIATE VISUAL AIDS!!!

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Review the 33-Kilohm 1-watt carbon resistordescription.

End of chapter also has the description of acommon wire nail.

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Instructions inform the reader by explaininghow to perform a procedure

Examples : product manuals, assemblyinstructions, how to instructions.

Instructions also persuade readers. How?

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General Instructions- instructions thatexplain how to perform a generic procedure

Specific Instructions instructions thatexplain how to perform under conditionsinvolving particular equipments,surroundings or other variables

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Brief introduction explaining the purpose andimportance of the procedure.

List of materials, equipment, tools and skillsrequired.

Actual instructions: numbered, step-by-step,detailed explanation of how to perform theprocedure.

Typically one or more visuals for clarification

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Use short and simple commands that startwith a verb.

Avoid recipe shorthand that omits smallwords such as a, anand the.

Separate steps unless closely related orsimultaneous.

Use subdivisions for complicated or long

steps.

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Remember : Note, Caution, Warning andDangerNote alerts to information that will make theprocedure easier or more efficient.

Caution alerts to risk of equipment failure ordamage.Warning alerts to possible equipmentdamage, serious injury or death.

Danger alerts to probable serious injury ordeath.

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