• Girth Gear

Eddy Current used for gear inspections use a pencil probe or single coil probe and should not be confused with the technology used in ASTM E2905.

Single coil Eddy Current probe relies on the operator traversing the probe back and forth on the tooth flank (Fig. 1); the probe must intersect a fault to get a signal (Fig. 2), so there is a high probability of missing some parts of the gear flank. The signal from the single coil probe is a voltage signal that must be interpreted and the results manually recorded. This judgement call relies soley on the inspector.

Eddy Current Single Coil Path

ASTM E2905 Gear Scan Method

Scanning a gear flank is done in seconds. The data is captured and displayed as in a colour format that provides on-site analysis of flaws and indications for immediate results.

ASTM E2905 Gear Scan Method

  • Using E2905, discontinuities cannot be missed.
  • The gear flank and root are scanned in one pass.
  • Electronic reports that can be archived for future reference.
  • Recognized in AGMA as an accepted method for gear inspections.


AstmE2905 Figure3Figure 4: E2905 illustrating a Pit on a gear flank

  •       With 2 and 3D Dimensional Isometric Displays, we can see the defects as it is in the material.
  • Knowledge of the defect type helps in determining the root causes and eliminates the potential for errors.
  • E2905 will display the actual characteristics of the defects, (see Figure 4); this is a Pit.
  • Figure 4: E2905 illustrating a crack on a gear flankFigure 5: E2905 illustrating a crack on a Gear FlankUsing E2905, it is very easy to see a crack or a pit on a gear tooth compared to interpreting the Eddy Current signal in Figure 5.
  • E2905 is used in this configuration and has consistently shown the ability to discriminate between dents, pits and cracks.
  • In other words, a pit looks like a pit (see Figure 4) and a crack looks like a crack (see Figure 5).




  • Excellent for Bull Gear Inspections
  • Excellent for Kiln Gear Inspections
  • Excellent for Roasters, Dryers and Sugar Mill Girth Gear Inspections
  • Excellent for SAG and Ball Mill Girth Gear Inspections