Parkinson gear tester

 Parkinson gear tester

Composite Inspection

The composite test of a gear is a method of inspection in which the work gear is rolled in tight double flank contact with a master gear. AGMA defines this type of inspection as “radial composite deviation.” No backlash is provided, as the work gear is spring-loaded against the reference gear on the inspection machine. The composite action test is made on an inspection instrument that will allow variation in the center distance during rolling. This variation in center distance will yield a “tooth-to-tooth” and a “total composite” indication that can be read on a simple dial indicator or recorded graphically.

Composite inspection is a useful shop-friendly tool to determine the general quality of a gear including size, runout, tooth-to-tooth rolling action, and to detect nicks. It is not an appropriate method to determine individual tooth flank errors.

Schematic concept of gear rolling device (Figure 4).

Figure 4: Schematic concept of gear rolling device.

Graphical record from composite inspection (Figure 5).

Figure 5: Graphical record from composite inspection.

Features 1. Involutes profile accuracy testing. 2. Lead checking for helical gears. 3. Gear run out checking. 4. Backlash of theoretical center distance. 5. Actual center distance. 6. Over all run out. 7. Involutes teeth projector. 

Limitations of Parkinson gear tester: 1.Accuracy ±0.001mm 2.Maximum gear diameter is 300mm 3. Errors are not clearly identified. 4.Measurement dependent upon the master gear. 5. Low friction in the movement of the floating carriage.