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Schaublin 135 Variable speed pulley issue

bladesmith5

Aluminum
Joined
May 11, 2005
Location
New York
I am looking for advise on my newly acquired 135 lathe. I purchased it as non working because the variable speed drive pulleys were froze up but I read that was a common issue. By the time the machine made it home on its 2 1/2 hour trek the pulleys had freed themselves up. After reading several posts I drained the oil tank, cleaned the screen, replaced all the copper seals for the oil lines , filled with fresh oil and ran the machine for 1/2 hour. Prior to running I also did a really good cleaning of the inside around the motor compartment as it was filthy with oil, swarf from belt , ect. I had placed fresh paper towels on top of motor and around the base to determine if any leaks still existed and all looked good. But then I noticed the belts were once again coated in oil so I am guessing the oil is being fed from the hoses on the back of the pulley shaft and bypassing the seals on the pulleys.
So my big question is do I just remove the pully assembly and replace the seals on the pulleys or go to a plan B. The owner of the machine said he replaced the seals and pulley bushings about 10 years before so I'm not sure if he put in correct seals, didn't clean up any possible burrs on shaft ect. Plan B for me is to eliminate the oil system completely (just for the variable speed unit) and either machine the pulleys to accept permanently sealed ball bearings or add grease fittings for the existing bushing setup. so I don't have to deal with this again. I appreciate any help, thanks, Barry
 

marcsO

Cast Iron
Joined
Mar 24, 2020
Location
SURREY
Barry I have a 135 which I am 'cleaning up', I have a thread running on this forum too.

I have heard many comments around the oil feed system which seems to regularly dump oil on the belts and at close to £200 for the main belt its an expensive issue. I have not run mine up yet but looking at the mess in the area around the motor etc and the condition of the belt already in there I suspect mine too has a leak.

I'm considering a Festo upgrade which will require re-designing the oil feed system but as you suggest replacing the pulley bearings with sealed bearings could be an option, after all bearing technology has come a long way in 60 years when these machines were built. Will watch you plans with interest and please post pictures of the process along the way and if you are doing any machining of new parts then I would be keen to join a wish list for the parts you make.

Marc
 

bladesmith5

Aluminum
Joined
May 11, 2005
Location
New York
I will let you know what plan I will follow once I have the system apart and can determine what configuration it is, Thanks, Barry
 

bladesmith5

Aluminum
Joined
May 11, 2005
Location
New York
Schaublin 135 update

So I got the drive removed and it has the arrangement of lip seals on the outer sides of the fixed 1/2 of the sheaves and O Rings on the inner sliding sheave so after consulting with a nice chap in Australia I’ve decided to follow his advise. As mentioned I think the o rings will just fail again so I am going to machine the inner sliding pulley sides where the O rings are to accept dual lip seals like on the outboard pulley edges. I guess my only concern is keeping the new seals in place while that inner pulley slides back and forth when speed is adjusted so I am also thinking of machining in a groove for a snap ring to keep the seals from sliding out of the machined bosses. I’m happy to hear others thoughts on this fix. I guess this is plan A, hopefully a good plan, thanks, Barry
 

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bladesmith5

Aluminum
Joined
May 11, 2005
Location
New York
A better picture of the O ring seal on the sliding sheave that I want to machine out to allow for the lip seals
 

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marcsO

Cast Iron
Joined
Mar 24, 2020
Location
SURREY
Barry good to see progress, I guess the plan is still to use wet lubrication via the pump feed rather than a sealed set up with races/rollers etc? Do you feel the rotational and sliding action these seals need to endure is ideal and the outcome will hold up? Thinking about the oil pressure too, the pump naturally delivers the oil under pressure up to the bearings and then on to the gearbox so maybe the pressure is also contributing to the issues of failure - I'm no lathe engineer but watching your progress with interest.

Marc
 

bladesmith5

Aluminum
Joined
May 11, 2005
Location
New York
The problem with changing to bearings and eliminating the oil system is that there is not enough room on the carrier tube to bore to fit them. I was hoping to do that as that would definitely be the better option. In speaking with someone who completed this option of changing to lip seals, he indicated that the machine has been in daily use for the past year with no seal failure or oil bypass. He indicated that the pressure is very low on the seals as the oil has an exit hole to drain back into tank. I am getting good at taking this mechanism apart so many times so if it doesn't work then I will re engineer an entire sheave assembly or just eliminate it completely and put in a VFD! Will provide updates when seals arrive and I start machining. Thanks, Barry
 

marcsO

Cast Iron
Joined
Mar 24, 2020
Location
SURREY
Good summary as not had the parts out yet as its all new to me, may be in touch when I get to this job in a months time!

VFD control impacts power does it not? I understood that at lower rpm's the torque drops quite significantly when running motors via a VFD, it was a topic discussed on the Hardinge forum when I converted my HLV to VFD and have to say did notice issues with grunt low down especially when thread cutting.

Looking forward to the 'tutorial' .......

Marc
 








 
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