Lufkin Gearbox Repair
The client had a plastic extruder with a severe humming and vibration in the gearbox which was worsening. The problem was found to be a damaged and worn shaft, which had caused damage to some gears. The shaft was repaired, and damaged gears replaced with only two days of down time.
On initial inspection of the gearbox, I found extensive wear on the two outermost gears of the gearbox. The customer did not want to have the line shut down any longer than necessary, so new gears were ordered and the line was kept running until gears arrived.
When new gears arrived, the gearbox was opened to remove worn gears and find root cause of the problem. During investigation, it was found that the free shaft had been previously repaired, and repair on the keyway poorly done. The previous repair failed with a large piece of the keyway fractured which caused severe pitting on gear mating surface of the shaft.
The shaft was removed, and a clean and weld was done on the broken area around the keyway. It was then turned down to create a proper mating surface with the driven gear. Unfortunately the pitting was too deep, and to get a smooth mating surface it had to be turned down too far, and the gear no longer fit properly in the housing. It was then welded up everywhere so it could be turned down to proper dimensions.
Once repair was complete, everything was reassembled and final check was performed. All tolerances and runout looked good. It was filled with oil and started, with no issues.
Project Log
