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When we move from doing conventional writing to using the Information Mapping method, some old habits die hard. One is the tendency to cram a lot of information into paragraphs. We’ll look at improving an excerpt from a document submitted to us by a relatively inexperienced Mapper.
The
“Before”
The writer prepared the following Block of information about automotive turbochargers based on content he got from the Web site howstuffworks.com.
| Basic function of the turbocharger |
The turbocharger is bolted to the exhaust manifold of the engine. The exhaust from the cylinders spins the turbine, which works like a gas turbine engine. The turbine is connected by a shaft to the compressor, which is located between the air filter and the intake manifold. The compressor pressurizes the air going into the pistons. The exhaust from the cylinders passes through the turbine blades, causing the turbine to spin. The more exhaust that goes through the blades, the faster they spin.
On the other end of the shaft that the turbine is attached to, the compressor pumps air into the cylinders. The compressor is a type of centrifugal pump—it draws air in at the center of its blades and flings it outward as it spins.
In order to handle speeds of up to 150,000 rpm, the turbine shaft has to be supported very carefully. Most bearings would explode at speeds like this, so most turbochargers use a fluid bearing. This type of bearing supports the shaft on a thin layer of oil that is constantly pumped around the shaft. This serves two purposes: It cools the shaft and some of the other turbocharger parts, and it allows the shaft to spin without much friction.
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Analysis and
Recommendations
This example shows some of the hazards of incorporating content wholesale from somewhere else, even from as good a site as www.howstuffworks.com. Here you have, in the same Block, four different information types:
- Process (how the turbocharger works)
- Fact (where the turbocharger is bolted)
- Concept (the definitions of the compressor and the fluid bearing), and
- Structure (the description of the parts of the turbocharger and how they fit together).
Mixing so many information types in one Block not only makes the Block quite long and bulky, but it also forces readers to change what they are thinking about almost every sentence. That is one of the reasons we strongly recommend including only one information type per Block wherever possible—it makes Blocks shorter and easier to understand. To further aid understanding, a graphic rather than just a text description would make the equipment much easier for the reader to visualize.
For clarity, the writer needs to break the information into at least three Blocks.
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The
“After”
One approach to re-structuring the information could look like this:
| Turbocharger terms |
To understand what a turbocharger does, you will need to be familiar with the following terms.
Turbine: a type of machine in which the kinetic energy of a moving fluid, such as water, steam, or gas, is converted to rotary motion.
Compressor: a kind of turbine; a centrifugal pump that reduces volume and increases pressure of gases in order to condense them. It draws air in at the center of its blades and flings it outward as it spins, to pressurize air going to the cylinders.
Fluid bearing: a bearing that supports its load on a thin layer of liquid or gas. It allows a shaft to spin with much less friction and vibration than an ordinary ball bearing. |
| Parts of a turbocharger |
This diagram shows the main parts of a basic turbocharger.
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| How it works |
The idea behind all turbochargers is forcing more air into your engine’s cylinders than in a normal engine. More air combined with more fuel per combustion event results in a larger explosion in each cylinder and more power.
This table explains how a turbocharger increases engine power.
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Stage |
Description |
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1 |
Hot exhaust gases from the engine spin the turbine at high RPMs and are then expelled through the outlet. |
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2 |
The turbine transfers rotational power to a shaft.
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3 |
The fluid bearings allow the shaft to rotate at high speed with very little friction or wear.
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4 |
The spinning compressor blades at the other end of the shaft
- pull fresh air in through the air inlet
- compress it, and
- send it at high pressure through the air outlet to the cylinder.
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5 |
Compressed air and fuel are ignited in the cylinder, transmitting power through the piston to the drive shaft. | |
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Conclusion
By applying some of the principles and techniques of Information Mapping, this revised version provides the reader with less information to process at once, and only one type of information in each Block.
Content brought in from another source—either a legacy document or outside material as the writer used here—usually requires some re-thinking and re-working to make it effective for your audience.
In the next Doc Advisor we’ll look at an opposite kind of problem: too little information.
| In Information Mapping’s flagship
workshop, Developing
Usable Content and Documentation, learn
how to make your documentation easy to understand and use,
whether your end users are your customers or employees. Or, contact
us to find out how our professional services team can help
create or update your procedures and processes for an improved
bottom line. Use the Information
Mapping method to change the
way you write and work! |
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Copyright, Trademark, and Other Information
Published by
Information Mapping Canada
357 Jane Street | Toronto, ON
M6S 3Z3 Canada
Information Mapping® and Formatting Solutions® are
registered trademarks, and the Method™ is a trademark, of
Information Mapping, Inc.
© Copyright March 2009. All rights
reserved.
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