Oil leakage from the gearbox axis

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Oil leakage from the gearbox axis

Postby Fedor » 25 Nov 2018, 16:39

Hello Everyone!

Some time ago, I noticed a drop of black liquid on the floor under the powerchair after an overnight stay and charging. After a small investigation, it became clear that it flows along the axis from the gearbox of one of the motors. At the moment I have no opportunity to replace them all. I greased the axle with thick grease and it helped for a couple of weeks. This morning I noticed a small drop of oil on the floor again. It drips only after a long wait. For example, after the whole night. And I will not say that it is a lot - 1-2 points.

Here is my motor, at least very much like it. This is a four-pole 350w AMT-Schmid SRG05 (picture below).

As far as I understand the axis is surrounded by a bearing or a gasket, I do not know how to properly name it. Apparently the reason for this? It is unlikely that the axis itself could rust - the motor is 4 years old.

Is there any way to replace this part? I do not understand how to do this, because there is a lot of oil inside the gearbox.

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Re: Oil leakage from the gearbox axis

Postby hank » 25 Nov 2018, 17:54

Replace with new oil seals on hubs/wheel shafts.
Should have numbers stamped on seals to re order.
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Re: Oil leakage from the gearbox axis

Postby Fedor » 25 Nov 2018, 18:15

hank wrote:Replace with new oil seals on hubs/wheel shafts

Thanks for the answer, but how to do it? In the gearbox a lot of oil. How then to fill it? I don't see the place on the gearbox for changing the oil after i replace seals.
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Re: Oil leakage from the gearbox axis

Postby Burgerman » 25 Nov 2018, 18:51

Theres no oil in it. You pack it with grease as you assemble.
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Re: Oil leakage from the gearbox axis

Postby Fedor » 25 Nov 2018, 19:05

Burgerman wrote:Theres no oil in it. You pack it with grease as you assemble.

But I can not replace the seals without disassembling the gearbox, or am I wrong?

How to remove this thing around the axis (wheel shaft)?
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Re: Oil leakage from the gearbox axis

Postby Burgerman » 25 Nov 2018, 19:07

Some you can, some you cannot.

Same as photograph? Stick a screwdriver under it and lever it out. Be warned seals dont often fail unless bearing also has failed. Taking it apart allows you to properly check it out, clean, re-grease, and reassemble.
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Re: Oil leakage from the gearbox axis

Postby Fedor » 25 Nov 2018, 19:31

Burgerman wrote:Same as photograph? Stick a screwdriver under it and lever it out. Be warned seals dont often fail unless bearing also has failed. Taking it apart allows you to properly check it out, clean, re-grease, and reassemble.

Yes, I have the same AMT as in the photo. I use ottobock b500.

I did not know that the seals can be pulled out from the outside. Thanks for the advice. And why can a gearbox-greases flow through it? Replacing the seal will help? Does this happen sometimes? I have this for the first time.
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Re: Oil leakage from the gearbox axis

Postby Burgerman » 25 Nov 2018, 19:52

Seals dont usually leak unless the bearing is also failed. But it is possible.

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Re: Oil leakage from the gearbox axis

Postby Fedor » 25 Nov 2018, 20:03

Thank you BM. I will write to the dealer with this problem and if he will offer to buy a new motor or a similar marketing shit - try to fix it myself.
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Re: Oil leakage from the gearbox axis

Postby Burgerman » 25 Nov 2018, 20:05

Its thin metal, I use a pointy screwdriver and a hammer. To remove. And a few careful hammer taps to replace new one.

This guy does it in a more complicated way...


youtu.be/h6IX3ocOpDk
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Re: Oil leakage from the gearbox axis

Postby Fedor » 25 Nov 2018, 21:03

Very useful video. Thanks. Not as easy as it sounds.

As far as I understand it is better to do it when the motor is removed from the powerchair.
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Re: Oil leakage from the gearbox axis

Postby ex-Gooserider » 27 Nov 2018, 02:18

If the motor is not showing other problems like unusual noise or grinding, I am not sure it is worth messing with... Remember the wisdom of the British bikers - "It's not leaking, just marking it's spot" :P

Probably a job that would need pulling the motor just to get good access, and it carries some risk of damaging the bearing under the seal (don't poke to far into the motor) especially if it isn't a job you've done before...

I would definitely class it as a task that is nice to do, but that offers little benefit...

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Re: Oil leakage from the gearbox axis

Postby Fedor » 27 Nov 2018, 03:54

It seems the motor works as before, except for leakage. I would not do this if it could have been avoided. Do not quite understand what decision you think is right?
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Re: Oil leakage from the gearbox axis

Postby Burgerman » 27 Nov 2018, 03:57

Me, I would change it. With motor in the chair. But I have swapped them on card, bikes, and chairs before so to me its pretty simple. Can do it with a sharp screwdriver and a hammer in minutes. And tap in a replacement. If it isn't bothering you then tie a cloth around it and it will soak up and grease/oil so it doesn't end up on carpets etc.
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Re: Oil leakage from the gearbox axis

Postby Scooterman » 27 Nov 2018, 09:08

Burgerman wrote:. Be warned seals dont often fail unless bearing also has failed. .

Ooh I wonder if that's the reason why my scooter oil seal failed. I bet it is, I'm sure I can sometimes here a noise somewhere near rear off-side wheel? I doubt if changing a bearing is very easy. :thumbdown:
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Re: Oil leakage from the gearbox axis

Postby Burgerman » 27 Nov 2018, 09:12

Usually very easy. And cheap. But you gotta take it apart.
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Re: Oil leakage from the gearbox axis

Postby Fedor » 27 Nov 2018, 14:52

Burgerman wrote:Usually very easy. And cheap. But you gotta take it apart.

Do you mean to disassemble the gearbox? I saw a lot of videos with this, it seems there is nothing complicated, I do not understand only one thing. The gearbox has a lot of grease. When disassembling it will leak. How to fill it and close the gearbox at the same time?
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Re: Oil leakage from the gearbox axis

Postby Burgerman » 27 Nov 2018, 15:28

You just coat the parts. Assemble.

Heres one I cleaned, then re greased and reassembled earlier just like TV! Not the same but similar. As you can see, replacing bearings is simple. All 4 swapped here. And this gearbox not meant to come apart, so was riveted together. My drill removed those...

Seals are easily pushed out of empty casings.
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Re: Oil leakage from the gearbox axis

Postby Fedor » 27 Nov 2018, 16:15

This means that a black liquid grease can be easily replaced with a thick grease where it is needed? Replace and lubricate the bearing, replace the seal. And it's all? Very interesting.

The dealer told me that they do not repair the motors. Only replacement entirely. Moreover, the manufacturer forbids them to get inside. What insanity. Replacing the seal or bearing for $20? No. People should buy the entire motor for about $500. This is despite the fact that the government is constantly looking for where to save money on people with disabilities.
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Re: Oil leakage from the gearbox axis

Postby Burgerman » 27 Nov 2018, 18:15

They do generally wear out and get tired, inefficient, develop backlash, weak magnets, worn out brakes, brushes, commutator and worn cush drive rubber coupling as a unit though. So it not normally worthwhile repairing a single part. Unless a bearing fails prematurely or something.

Grease should be clean. If its black its full of metal or corrosion or something.
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Re: Oil leakage from the gearbox axis

Postby woodygb » 27 Nov 2018, 23:17

If its black its full of metal or corrosion or something.


https://www.youtube.com/watch?v=I7qp5vZLEos

The reality is that oil and grease products come in a rainbow of colors and shades, including white, gray, black, silver, blue, green, red, purple, and every variation of brown, from golden honey to dark, earth tones. Manufacturers typically color these products for their own purposes. Unfortunately, there’s no formal industry standard or convention regarding their choices, with the exception that most food-grade greases tend to be white.


https://www.efficientplantmag.com/2016/ ... brication/
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Re: Oil leakage from the gearbox axis

Postby Burgerman » 27 Nov 2018, 23:51

Interesting. But still, I doubt its meant to be black. If only because it would be super messy if it got on a carpet or something. Saw one that was sticky non runny dark red grease. All the rest I ever took apart were natural very light brown/yellow colored. Much like that picture above. Clear/clean if thin on your fingers.

But anything is possible I suppose!
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Re: Oil leakage from the gearbox axis

Postby ex-Gooserider » 04 Dec 2018, 04:00

I have seen black greases, or close to it... Particularly ones with a lot of Molybdenum Sulfide content... One was the lube specifically intended for the sprocket nose on the bars of my chainsaws....

I could see a seal failing due to getting hair or other crap stuck in it, but would think of it as unusual - otherwise I agree that if a seal is leaking there is probably an underlying issue that should be fixed as well...

Most every chair gearbox I've ever heard of uses a heavy non-flowing grease, and while some of those will separate a little bit, if there is a lot of leakage, I'd also be wondering if there is water or other contaminants in it - has this motor been swimming, or otherwise operated where water could get into it?

However I probably wouldn't mess with it if ALL it was doing is leaking a bit...

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Re: Oil leakage from the gearbox axis

Postby Fedor » 16 Dec 2018, 16:17

After some difficulties, I was able to see the markings on the seal. There is: tto d774 1 SC 25 47 7

As I understand it the size is 25x47x7
Brand is TTO (taiwan)

But what does d774 and SC mean?

And another question. I do not understand at all different brands of seals. Which is better? I found on aliexpress similar, but they will be good?
https://aliexpress.com/item/10pcs-TTO-2 ... 89054.html

Can you help me make the right choice? Amazon and ebay are good too.

In any case, thank you all again for the answers and help. I really appreciate this forum and all of you.
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Re: Oil leakage from the gearbox axis

Postby woodygb » 16 Dec 2018, 16:30

Standard Oil Seal = SC
Any brand should be fine.
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Re: Oil leakage from the gearbox axis

Postby Fedor » 16 Dec 2018, 18:25

Thank you, Woody. I found a specification for different types of seals: https://www.francejoint.com/standard-shaft-seals/

SC – standard version.
TC – with additional dust protection.

I think TC will be better?
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Re: Oil leakage from the gearbox axis

Postby ex-Gooserider » 18 Dec 2018, 03:35

Fedor wrote:This means that a black liquid grease can be easily replaced with a thick grease where it is needed? Replace and lubricate the bearing, replace the seal. And it's all? Very interesting.

The dealer told me that they do not repair the motors. Only replacement entirely. Moreover, the manufacturer forbids them to get inside. What insanity. Replacing the seal or bearing for $20? No. People should buy the entire motor for about $500. This is despite the fact that the government is constantly looking for where to save money on people with disabilities.


It isn't a total factor, but it MAY make financial sense for a dealer to replace rather than repair because of the time and expense of paying a tech to do the repair...

Remember that if we do the job ourselves as a DIY project, our 'labor' cost is ZERO (unless we could have been doing something that paid, in which case our cost is whatever we gave up doing in order to make the repair...)

However for the dealer to repair it, means he has to pay a tech pull the motor, then to tear the motor apart, diagnose the problem, get the parts in, rebuild the motor and so on... Then later (another service call?) put the motor back in... In the meantime you are stuck with a dead chair... OTOH swapping the motor saves all the repair time, and gets you back up in the shortest possible time... (more customer satisfaction....)

Because of this equation, it encourages the motor makers NOT to make parts available, because that lowers THEIR costs not to have to catalog all the parts and have to deal with orders, shipping etc....

This is part of the reason why it can cost as much for one bolt from a chair manufacturer as a box of bolts from a hardware supplier... It costs essentially the same amount to take the order, pull the parts, package, ship etc. for one bolt or 100, and the price charged has to cover all those expenses in addition to the actual part...

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Re: Oil leakage from the gearbox axis

Postby Fedor » 18 Dec 2018, 20:40

ex-Gooserider wrote:It isn't a total factor, but it MAY make financial sense for a dealer to replace rather than repair because of the time and expense of paying a tech to do the repair...

Remember that if we do the job ourselves as a DIY project, our 'labor' cost is ZERO (unless we could have been doing something that paid, in which case our cost is whatever we gave up doing in order to make the repair...)

However for the dealer to repair it, means he has to pay a tech pull the motor, then to tear the motor apart, diagnose the problem, get the parts in, rebuild the motor and so on... Then later (another service call?) put the motor back in... In the meantime you are stuck with a dead chair... OTOH swapping the motor saves all the repair time, and gets you back up in the shortest possible time... (more customer satisfaction....)

Because of this equation, it encourages the motor makers NOT to make parts available, because that lowers THEIR costs not to have to catalog all the parts and have to deal with orders, shipping etc....

This is part of the reason why it can cost as much for one bolt from a chair manufacturer as a box of bolts from a hardware supplier... It costs essentially the same amount to take the order, pull the parts, package, ship etc. for one bolt or 100, and the price charged has to cover all those expenses in addition to the actual part...

ex-Gooserider


Well. I know that the dealer has a certified service technicians. For example, they test batteries and do much more. I do not think that replacing the seal is such a difficult and expensive task. It will not be much longer than replacing the motor.

However, in my country there are not so many customers of such powerchairs (i think). And even fewer those who have a problem similar to mine with seal. At the same time, I think that a lot of such powerchairs are being bought by the government for people with disabilities. So, it is more profitable for the manufacturer/dealer not to repair anything, but to replace the parts entirely, because government pay for it. Nothing personal, just business.
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Re: Oil leakage from the gearbox axis

Postby Burgerman » 18 Dec 2018, 22:44

Well. I know that the dealer has a certified service technicians. For example, they test batteries and do much more.

I doubt they do. It takes 20 hours to fully discharge a battery to measure its capacity even if you have the equipment to do that. So 40 hours for two. And then 16 hours to fully recharge them. So thats realistically 3 days. And then when they measure say 61Ah from a 70Ah battery, is that a pass? Or a fail? Even after doing all that the answer is, a personal opinion. And there is NO WAY to do that faster. They then need to test impedance once fully charged and compare to spec. And again, decide what is "acceptable"... I doubt that the time required to do all of this is worthwhile. It would cost as much in labour as the battery is worth. Even if they knew how.


I do not think that replacing the seal is such a difficult and expensive task. It will not be much longer than replacing the motor.

Seals seldom are the thing that has failed. Seals generally fail only when a bearing behind the seal is faulty. So after the tech has wasted time traveling, swapping a seal, and then going home, the seal fails again. Then he has to disassemble the gearbox and change a bearing. Rinse and repeat. Then its noisy because the rest of the gearbox has wear. Its just not viable unless you do the job properly and strip the whole thing. And even then a new motor is cheaper than the labour, even if parts are available because they generally wear out as a unit. It may be viable for you to mess about with a seal alone and see if that fixes it permanently because your travel time and labour, and return and fix it again when it turns out to still be a problem, is free.
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Re: Oil leakage from the gearbox axis

Postby Fedor » 18 Dec 2018, 23:18

Burgerman wrote:I doubt they do. It takes 20 hours to fully discharge a battery to measure its capacity even if you have the equipment to do that. So 40 hours for two. And then 16 hours to fully recharge them. So thats realistically 3 days. And then when they measure say 61Ah from a 70Ah battery, is that a pass? Or a fail? Even after doing all that the answer is, a personal opinion. And there is NO WAY to do that faster. They then need to test impedance once fully charged and compare to spec. And again, decide what is "acceptable"... I doubt that the time required to do all of this is worthwhile. It would cost as much in labour as the battery is worth. Even if they knew how.

I say this because I spoke with a technical man working at the dealer. According to him, they have a special stand for testing batteries and they use it, for example, when checking the warranty and diagnosing various problems. How they interpret further the data I do not understand. I think, apart from the time-factor, there is no difficulty. We do about the same with PL8. Or not?

Fedor wrote:Seals seldom are the thing that has failed. Seals generally fail only when a bearing behind the seal is faulty. So after the tech has wasted time traveling, swapping a seal, and then going home, the seal fails again. Then he has to disassemble the gearbox and change a bearing. Rinse and repeat. Then its noisy because the rest of the gearbox has wear. Its just not viable unless you do the job properly and strip the whole thing. And even then a new motor is cheaper than the labour, even if parts are available because they generally wear out as a unit. It may be viable for you to mess about with a seal alone and see if that fixes it permanently because your travel time and labour, and return and fix it again when it turns out to still be a problem, is free.

I understand, it makes sense. It all depends on the individual case. It is interesting to know what they are doing with broken motors? If they get to them.
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