ITS 311: IT Communications

Chapter 8: Describing Mechanisms


This chapter discusses technical documentation of devices and other mechanisms. Objectives important to this chapter:

  1. Definition of mechanism
  2. General and specific descriptions
  3. Material found in a mechanism description
  4. Spatial, functional, and chronological order
Definition of mechanism

In technical writing, a mechanism can be a physical device, any object used in a procedure, or a procedure itself. Descriptions of mechanisms may be found in user and maintenance manuals, in sales and reference material, and in technical journals. As is common to the chapters in this text, the author cautions the technical writer to determine the technical knowledge of the audience before deciding on the level of detail required for a description.

General and specific descriptions

A general description is defined on page 259 as an overview of the device. It includes a physical description of the device, a list of its parts, the purpose and users of the device, and its general use. A specific description of a mechanism adds more detail about each part, including how the parts fit together.

The author offers a model outline for writing a mechanism description. She uses the term functional description to mean the description of the parts, physical characteristics, and appearance of the mechanism. Her outline has three main parts:

  • Introduction, intended audience, general description, and theory of purpose and use of the mechanism
  • Functional description
  • Concluding material, possible references to other related mechanisms, and conclusions about the mechanism

This outline may be adapted to include more or less detail as required the needs of the audience of the document.

Spatial, functional, and chronological order

The description of the parts of a device may follow any of several orders. The writer has several options, and should choose an option that is most useful to the intended audience. Three methods are described in detail:

  • spatial order - the order in which the parts would be seen if considered from top to bottom, bottom to top, outside to inside, or other arrangement logical to the device
  • functional order - the order in which the parts would be used or encountered by an operator
  • chronological order - the order in which the parts would be assembled or disassembled, often accompanied by an exploded diagram of the parts