Parkinson Gear Tester: Construction and Working

Introduction

• Purpose: Used for gear inspection in gear metrology.
• Also Known As: Gear rolling tester.
• Inspection Method: Composite method for inspecting variation in center distance, runout, and profile variation of gears.

Construction

• Base: Foundation on which the setup is placed.
• Table: Instrument setup is placed on the table, which in turn is on the base.
• Carriages:
  • Fixed Carriage: Holds the master gear.
  • Movable Carriage: Moves horizontally with rollers and is spring-loaded towards the fixed carriage. Holds the gear to be tested.
• Spindles:
  • Each carriage carries a rotating spindle perpendicular to it.
• Coil Spring: Positioned between the two carriages to maintain tension.
• Dial Indicator: Attached horizontally to the base to monitor the movable carriage's position.

Working Principle

• Gear Meshing: The master gear and the test gear are kept in tight mesh by spring force, allowing free rotation.
• Movement Detection:
  • Imperfections in the test gear cause the sliding carriage to move horizontally.
  • Horizontal displacement is sensed by the dial indicator.
  • The tire gauge indicator's plunger, in contact with the carriage, gets pressed, indicating deflection.

Inspection Output

• Dial Indicator Measurement: Indicates if a gear should be accepted based on deflection.
• Electronic Sensors: Modern setups use electronic sensors instead of the dial indicator.
  • Graphical Output:
    • Circular graph: Indicates satisfactory gears.
    • Irregular graph: Indicates gear errors.
  • Circle Types:
    • Unsatisfactory Circle: Indicates a faulty gear.
    • Moderate Circle: Indicates a moderate gear.
    • Fully Satisfactory Circle: Indicates a perfect gear.

Conclusion

• Advancements: Transition from dial indicators to electronic sensors for more accurate detection and recording of gear motion and output.
• Significance: Helps in determining the quality and usability of gears in manufacturing and maintenance.