Engineering Drawings for Spur and Helical Gears

The THORS Engineering Drawings for Spur and Helical Gears course introduces the learner to the most common elements of spur and helical gear engineering prints including the gear data block and typical drawing notes and their specification. Users will be able to relate each element of a spur or helical gear drawing to the equipment and capability required to produce that part.

Learning Objectives

  • Understand all the aspects unique to spur and helical gear drawings.
  • Identify the focal points for a spur gear and helical gear drawing.
  • Explain the need for the gear data block and the different elements contained within it.
  • Describe the importance and properties of the notes section of gear drawings.
  • Summarize why spur and helical gear drawings require specific dimensions and list them.
  • Apply learned skills to additional spur and helical gear drawing examples.
  • Recall why size is a focal point on gear drawings and how it applies to OEMs.
  • State why tooth size designation is a focal point on spur and helical gear drawings.
  • Discuss why quality is a focal point on spur and helical gear drawings.
  • Recite why material and heat treatment is a focal point on spur and helical gear drawings.
Course Length: 3 HRS

Table of Contents


  • Common Features

Dimensions for Spur and Helical Gears

  • Outside Diameter Dimension
  • Pitch Diameter or Pitch Circle Diameter Dimension

Distinct Characteristics

  • Information in the Title Block
    • Material Information
    • Size and Weight Information
    • Tolerance
  • Surface Finish
    • Surface Finish Parameters
    • Surface Finish Symbols
    • Surface Finish Representation

Spur and Helical Gears Drawing Examples

  • Spur Example 1
  • Spur Example 2
  • Helical Example 1

Template: Gear Data Block

  • Accuracy Data
  • Addendum
  • Backlash for Set
  • Center Distance
  • Chordal Tooth Thickness
  • Circular Pitch
  • Circular Tooth Thickness, Normal
  • Contact Diameter
  • Cumulative Pitch Deviation, Total
  • Diametral Pitch
  • Fillet Radius
  • Form Diameter
  • Gear Type
  • Heat Treatment
  • Helix Deviation, Total
  • Helix Form Deviation
  • Helix Slope Deviation
  • Mating Part Number
  • Module
  • Number of Teeth
  • Number of Teeth in Mate
  • Outside Diameter
  • Pitch Circle Diameter
  • Pitch Line Velocity
  • Pressure Angle
  • Profile Deviation, Total
  • Profile Form Deviation
  • Profile Slope Deviation
  • Revolutions Per Minute
  • Root Diameter
  • Single Pitch Deviation
  • Span Measure
  • Tolerances
  • Tool Number
  • Tool Tip Radius
  • Tooth Form
  • Whole Depth
  • Hand
  • Helix Angle

Notes Specific to Spur and Helical Gear Drawings

  • Finish All Over (FAO)
  • Informational Notes
  • International Tooth Standards
  • Gear Finishing
  • Hardness Scale
  • Relationship between Pitch Circle Diameter (PCD), Diametral Pitch (DP), and Number of Teeth
  • Standards Conformity

Focal Points

  • Size
    • Outside Diameter and Overall Length
    • Face Width
    • Internal Diameter
    • Weight and Material Handling
  • Tooth Size Designation
    • Diameter Pitch (Module)
    • Pressure Angle
  • Quality
    • Blank Quality
    • Gear Quality
    • Machined Feature Quality
  • Material and Heat Treatment
    • Material
    • The Relationship between Material and Heat Treatment
    • Heat Treatment

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