Gearbox issue

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Gearbox issue

Postby snaker » 10 Sep 2018, 01:46

Yesterday I felt the right wheel was abnormal while running. I asked a cousin check if there was anything wrong. He found that the gearbox on right motor lost the rubber cap and a little oil leaked out. I have another failed gearbox and can reuse its cap as a replacement. But I worry that oil might have leaked out too much or water got in the gearbox. Is that a problem? Or do I just need to clean the hole and fit another cap?

img.jpg
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Re: Gearbox issue

Postby Burgerman » 10 Sep 2018, 02:00

Pic is so close I cant tell what we are looking at! :cussing
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Re: Gearbox issue

Postby snaker » 10 Sep 2018, 02:13

Here is the cap on the left gearbox.
img2.jpg
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Re: Gearbox issue

Postby Burgerman » 10 Sep 2018, 02:24

Looks like a single stage gearbox with a shaft at the top thats driving the main gear wheel with a helix. The thing you are looking at is one of two bearings. The one visible looks like a rusty and dirty sheilded steel ZZ bearing. The gearbox is full of grease you cant have really lost any. Just replace the rubber plug. Stick some grease in there first. The bearing or any of the bearings, could be bad. Or the two large bearings could be bad. Or the motor bearings, and or the rubber motor coupling/cush drive could be bad. As can the brushes, armature, magnets, commutator, or anything else. If theres a fault they need taking apart to find it.
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Re: Gearbox issue

Postby shirley_hkg » 10 Sep 2018, 02:26

Can't think with or w/o that cap would cause gearbox a noticeable operation to user .

If still leaking , bearing is lubricated and not dry yet .
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Re: Gearbox issue

Postby Burgerman » 10 Sep 2018, 02:37

Heres the parts, removed from a similar gearbox. What you are looking at in your image is the bearing on the metal shaft at the end away from the cush drive. Towards the rear of the picture here. As you can see, I replaced with rubber sealed and greased for life.

USED-f3.jpg
USED-f3.jpg (11.63 KiB) Viewed 2014 times


And a pic of it all grease packed and returned to the cleaned gearbox. This was a quick gearbox rebuild.

USED-f7.jpg
USED-f7.jpg (17.3 KiB) Viewed 2014 times
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Re: Gearbox issue

Postby snaker » 10 Sep 2018, 02:55

That cap fits very tightly on the gearbox. I still do not figure out how it could go off the gearbox :cussing

My dad is struggling to remove the cap from the failed gearbox. He is still stuck, have not found out a way yet :evil:
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Re: Gearbox issue

Postby Burgerman » 10 Sep 2018, 02:59

If a bearing has failed the shaft could push that plug out. It is forced backwards and forwards as you go forward and back. Ifa bearing dies, it can physically move...
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Re: Gearbox issue

Postby snaker » 11 Sep 2018, 01:46

BM, can you suggest my dad a way to remove that cap from the gearbox? He gave up after a day struggling :fencing

P1010790.JPG
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Re: Gearbox issue

Postby shirley_hkg » 11 Sep 2018, 02:04

Looks like a screw-on cap , like back cover of a watch . Turn to remove it .

Confirm it by looking into your chair's gearbox that lost a cap .
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Re: Gearbox issue

Postby snaker » 11 Sep 2018, 02:39

It is not a screw cap. There is no thread in the hole.
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Re: Gearbox issue

Postby ex-Gooserider » 11 Sep 2018, 03:15

I would agree, especially if the motor hasn't been used in horribly wet environments - the bearing is sealed so it shouldn't be letting water or other crap in, or oil out... The plug is mostly cosmetic.

However if the bearing has failed, it can leak in both directions, and as BM said the shaft could possibly moved enough to push the plug out... Regardless of how the plug got lost, it's being missing should make NO difference to the way the motor works... (if what's under it is bad, that's a different story)

It is a far from foolproof diagnostic, but I would try getting both wheels off the ground and try moving them in all directions by hand with the power off, in both drive and freewheel modes... There should be NO detectable play in any direction other than turning. You will probably feel a small amount of backlash or 'slop' when turning the wheel back and forth, but not a lot. Also both wheels should have about the same amount of slop. Spin the wheels in both directions in 'freewheel' mode, they should both make about the same sounds... Any crunching, grinding, gritty sounds are probably bad...

If both wheels are about the same and seem 'normal', then you might not have a problem, if they are different then you do, and further investigation is needed....

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Re: Gearbox issue

Postby woodygb » 11 Sep 2018, 08:16

snaker wrote:BM, can you suggest my dad a way to remove that cap from the gearbox? He gave up after a day struggling :fencing

P1010790.JPG


I'd suggest drilling a small hole in the middle of the cap ... screwing in a self tapping screw and jacking off the cap .

The small hole can be repaired with a dab of silicone.
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Re: Gearbox issue

Postby dewaj » 12 Sep 2018, 04:34

I remember seeing something like this before where such a cap was installed in a split case. Tried to remove the cap or put it back in without any luck at all. Turns out the cap had a circumferential ridge about midway across that fit a channel in the case and the only way to remove or install without destroying anything was to take the case apart, put the cap in one half then put the case back together again. Totally different application but a similar gearbox design. In our case, there was nothing but the cap to keep the shaft from popping out of the case.
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Re: Gearbox issue

Postby snaker » 12 Sep 2018, 08:50

By some how that cap still went off and ... lost :worship :worship :worship

It seems impossible to pull another cap out from the failed gearbox. I now use a custom rubber plug (stopper?) to seal the hole. Not sure if it could last :cussing
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Re: Gearbox issue

Postby Burgerman » 12 Sep 2018, 09:43

It will be fine it doesent do much. If you were to fit a sealed bearing it wouldnt matter if it never had a cap.
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Re: Gearbox issue

Postby ex-Gooserider » 18 Sep 2018, 04:10

It might not be intended to be removed - at least not without destroying it. I've seen places where they will bore a hole through a casting in order to machine things like bearing seats more easily, and then put a plug in the end of the hole that they aren't using which is never intended to come out...

You might be able to get it out by disassembling the gearbox so that you can drive it out from the inside....

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snaker wrote:BM, can you suggest my dad a way to remove that cap from the gearbox? He gave up after a day struggling :fencing

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Re: Gearbox issue

Postby Burgerman » 18 Sep 2018, 13:12

Take it apart.
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