Grinding the Zenith Axis Racks

Grinding the Zenith Axis Racks
of the CSIRO's Parkes Telescope

Click on images to see the full-size versions

Initial Grinding of the Racks to Remove Burs

An experienced team of gear specialists from Hofmann Engineering in Western Australia were contracted to do the grinding. Before the grinding of the rack teeth proper could commence, the burs were rough-ground off the teeth.

The Grinding of the Rack Teeth

A blue dye was painted onto the zenith drive pinions. As the dish was slowly lowered, the unevenly high areas of contact on the rack teeth were highlighted.

Once the raised areas were highlighted, they were ground down so that there would be an even pressure exerted on the full length of the teeth by the zenith drive pinions. First the top part of the racks were ground.

Then the middle part was ground. This meant getting into some very awkward positions.

Finally, the men from Hofmann's got into the very confined area of the well of the counterweight, in order to grind the last part of the racks. It was a tough job! Daniel Jukic worked in the right-hand side well.

Clive Murphy supervised the grinding and co-ordinated the tipping of the dish, while Chris Titterton worked in the left-hand side well.

The tough men of Hofmann's and Narrabri. L-R: Chris Titterton, Daniel Jukic and Clive Murphy.

A Job Completed

The completed racks. The blue dye was applied again, to show how the drive pinions evenly contacted with the rack teeth (compare these with the images above). A job well done.

Jon Crocker, Ken Reeves and Tom Lees cleaned away the shards and grime left over from the grinding of the teeth. Jon Crocker and Clive Murphy then applied a special lubricant grease to give a final polish to the rack teeth and to improve long term wear characteristics.

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