The Leinen lathe features a two-speed (1:1 and 1:8) reduction gearbox that can be operated while the machine is running, utilizing a multi-disk oil-bath clutch.
We disassembled the gearbox to inspect its overall condition. Due to years of neglected maintenance, the reduction unit had a very thick layer of oil sludge and deposits inside. Fortunately, the clutch disks were still in good condition, though the shaft seals were a bit worn.
The image below shows all the individual components of the reduction unit after disassembly:
To dismantle the assembly, we fabricated a couple of custom pin spanner wrenches to remove the retaining nuts:
We carefully cleaned away all the dirty oil deposits and replaced the two shaft seals with new ones. The new seals were frozen beforehand to shrink them slightly and ease the installation process. These were exact replacements for the original parts from Simrit, purchased through INDICOM. Here is the gear case after cleaning:
The aluminum motor pulley was slightly damaged, which appeared to be the result of a poor repair job in the past. David Arnau welded it for us, and after welding, we machined it back to its correct profile on our other lathe.
Additionally, the flat belt pulley that transmits power to the lathe spindle was unevenly worn. We mounted it on our large vintage lathe and turned it to restore a true, correct profile.
With those repairs completed, the reduction gearbox was ready for reassembly. We put it back together, ensuring all the mating surfaces and joints were properly sealed. This is the final result:
