Hello.
I have an old problem, only partially solved, and I am asking advice to solve it completely.
Old electronic instruments (also old radios) often had knobs equipped with a reduction drive. We are speaking of very low speed and low torque miniature planetary drives, built like a ball bearing with the ball cage connected to the output shaft.
After many years of service, the grease inside tend to leak out and the drive start to slip, in the beginning in some positions, then everywhere. Inspection don't show any evidence of wear, so, fill it again with the proper grease will almost surely result in a complete recovery.
...but this is "the problem". Which grease? I tried four kind of greases with bad results (green lithium soap NLGI 3 for automotive bearings, black lithium soap and molybdenum disulfide NLGI 2 for homokinetic joints, white lithium and zinc oxide NLGI 2 for gearshift control linkages, brown copper NLGI 2 "antigrip"). They make the ball slip better, instead of have the right friction to move the output shaft.
Finally I had some success with a chinese XY-2, transparent silicone based damping grease (no data on viscosity)... drive work, but not "like new", and the damping grease, while it's sticky almost like the original grease, flows (albeit slowly) outside the drive through spaces while the original didn't at all.
What was inside there originally? Residuals of the grease are brown caramel color, or brown/dark green, and so sticky that you may think it's glue...
Thank you for your help and best regards,
Andrea.
I have an old problem, only partially solved, and I am asking advice to solve it completely.
Old electronic instruments (also old radios) often had knobs equipped with a reduction drive. We are speaking of very low speed and low torque miniature planetary drives, built like a ball bearing with the ball cage connected to the output shaft.
After many years of service, the grease inside tend to leak out and the drive start to slip, in the beginning in some positions, then everywhere. Inspection don't show any evidence of wear, so, fill it again with the proper grease will almost surely result in a complete recovery.
...but this is "the problem". Which grease? I tried four kind of greases with bad results (green lithium soap NLGI 3 for automotive bearings, black lithium soap and molybdenum disulfide NLGI 2 for homokinetic joints, white lithium and zinc oxide NLGI 2 for gearshift control linkages, brown copper NLGI 2 "antigrip"). They make the ball slip better, instead of have the right friction to move the output shaft.
Finally I had some success with a chinese XY-2, transparent silicone based damping grease (no data on viscosity)... drive work, but not "like new", and the damping grease, while it's sticky almost like the original grease, flows (albeit slowly) outside the drive through spaces while the original didn't at all.
What was inside there originally? Residuals of the grease are brown caramel color, or brown/dark green, and so sticky that you may think it's glue...
Thank you for your help and best regards,
Andrea.