magnetic brake makes grinding noises

[Pierro]

Hello,
I'm currently having the following problem with my Optimus 2:

It's related to the electromagnetic brake on the motor. Since I always hear a slight grinding noise when driving, I opened the cover yesterday and discovered that the brake isn't fully opening. After driving a few meters, the noise diminishes and then disappears completely. The noise is only a very slight grinding noise. Look at the photo:

Where can I adjust the brake so that the grinding noise goes away? Is that even possible?

Does anyone know what these two LEDs (circled in red) are for?

Thanks and best regards

[Burgerman]

When the brake has NO power, or the chair is off, then the brake is ON.
When you want to move then the brake is supplied with either 12V or 24V and that turns it odd. It uses a spring to hold it ON so the chair wont move. It uses an electromagnet to pull and lift the brake OFF so you can move.

If the programming is incorrect these things happen.

If that brake is a 12V brake, and you feed it 24V (programming) then initially it works fine. Then the wire coils melt and it starts to short out and fails to lift the brake off. Now as you drive it is partly on, and wears out the friction surfaces.

If that brake is a 24V brake, and you only send it 12V. Then it doesent fully turn off as you move. So now it drags, heats up, destroys the friction material...

So is it possible that this brake has been used at the incorrect voltage?

In any case, you will need to replace it if its damaged.

[Pierro]

Thanks BM.

The brake is 24V – I've never changed it.

This really faint grinding noise only occurs at the beginning of the ride and soon stops. It's probably something to do with heat. And only when driving forward. There's no noise when reversing. very strange.

I'm also not sure why there are two LEDs at this exact spot (behind the motor). Nobody can see them.

Maybe they're not LEDs, but temperature sensors, and maybe they belong in the two opposite round openings? I'll have to take another look and see if they fit there.

[Burgerman]

No idea what those LEDs do. More importantly I dont think they ARE LEDs. They look like some type of screw cap that joins cut wires...
It may be bearings, brushes, or a huge build up of carbon or corrosive scale that is inside the motor. Not a brake?

Suggest that you remove the 4 brush caps. Remove the 4 brushes. Examine carefully for burning, uneven wear, chips, other damage. Use a light to look at the commutator and see if its clean and undamaged. Should be copper/light brown otherwise like new. And then use an air line and blow out any dust or rust in each hole. Then replace each brush back the EXACT SAME WAY and in the same position, as it came out. Unless worn or damaged. And then get new ones.

[martin007]

Experience tells me that when a brake makes strange noises it is close to failure...

How old is the brake / powerchair?

[Pierro]

I'm not sure if the noise is coming from the magnetic brake or directly from the motor.

To show you the noise, I've just uploaded it to YouTube. I hope the link works:
https://youtu.be/v2FcfhR5sME

Regarding the "LEDs": Could it be that there are sensors that belong there (yellow markings) and perhaps measure the motor revolutions?
I know I can't avoid it, so I'll jack up my Optimus again and take a look myself.

[Burgerman]

Noise doesent sound very serious.
Could be motor brushes running against commutator, rubber cush drive, motor bearing noise, or the brake dragging very slightly.

Those things are wire joiners...
That metal tube is just a "roll pin" used to lift the brake off.

[Pierro]

Noise doesent sound very serious.
Could be motor brushes running against commutator, rubber cush drive, motor bearing noise, or the brake dragging very slightly.

Thanks, BM. So I don't need to worry too much at the moment? After just a few meters of travel, the noise goes away.

I plan to buy new brushes and install them sometime in the winter, when the chair isn't being used much.

Those things are wire joiners...
That metal tube is just a "roll pin" used to lift the brake off.

Ups, I guess my imagination was running wild.

[shirley_hkg]

I think they are wire nodes of the microswitch linked to the freewheel lever.

[martin007]

That noise is a small thing...

[martin007]

A question Pierro.

What material is your living room floor made of?

[Burgerman]

TREE WOOD by the look of it.

[Pierro]

A question Pierro.
What material is your living room floor made of?

I think it's laminate. Very durable.
Our living room is regularly used as a workshop.

[martin007]

Have you had laminate flooring for a long time?

Can it handle the powerchair?

[Burgerman]

Laminate flooring can be good, bad, and everything in between. It depends on type, quality, how well and how it is actually installed.

You live in spain. Where ceramics are common and very hard wearing. They just dont wear out!

I prefer large ceramic tiles, polished concrete, marble or conglomerate marble etc. It is eas to clean and lasts forever. Or carpet tiles... So you can swap out any that are stained or worn. And leave the rest.

[martin007]

You live in spain. Where ceramics are common and very hard wearing. They just dont wear out!

Parquet flooring is in fashion in Spain.


My house has terrazzo floors.

> https://en.wikipedia.org/wiki/Terrazzo

[Burgerman]

Thats what I am talkin about.

[ex-Gooserider]

Unless you actually see those "LED" things lighting up, I'd be pretty sure they aren't LED's... To my eye, they look like a crimp style wire connector I've seen on a lot of different products. (basically a crimp on wire nut...)

I largely agree with much of the diagnostic suggestions others have made. One other thing I'd be tempted to look at is that cable and lever setup on the end of the motor. I'm guessing that it is the mechanism that releases the brake when you go into freewheel mode... I'd make sure it releases the brake fully when you go into freewheel, but be loose when in normal driving mode. Probably it isn't a problem, but doesn't hurt to rule it out...

ex-Gooserider

[Pierro]

One other thing I'd be tempted to look at is that cable and lever setup on the end of the motor. I'm guessing that it is the mechanism that releases the brake when you go into freewheel mode... I'd make sure it releases the brake fully when you go into freewheel, but be loose when in normal driving mode.

ex-Gooserider

because you just mentioned it...

When I set the freewheel lever to push mode and push the chair, the noise is still audible. However, I've already tried adjusting the tension of the Bowden cable to increase it, but that didn't work.

thanks to everyone who helps me

[Burgerman]

When you release the brake manually, with the lever it does "exactly" the same as operating it by powering it. So it just lifts the brake off when you move. So it will make exactly the same sound.
There MUST be some free play in that cable or it will partly release pressure on the brake causing it to slip when it should be locked on.

That sound can be many things...

Remove the brake.
That ring of bolts marked with a red stripe of paint.

Now push it or drive it and see if that sound goes away. If it does the brake is the cause. If it doesent the motor is the cause.
Now replace it!

[Pierro]

That sound can be many things...

Remove the brake.
That ring of bolts marked with a red stripe of paint.

Now push it or drive it and see if that sound goes away. If it does the brake is the cause. If it doesent the motor is the cause.
Now replace it!

Thanks BM, that sounds like a possible solution.

Will the magnetic brake come off easily, or do I have to overcome the force of the magnet? I've never done that before.

How old is the brake / powerchair?

My Optimus2 is only 4 years old and has 3.872 kilometers on the clock.

[Burgerman]

It comes off very easily. It must remain electrically connected or you will get an error.

At that mileage it may be the motor brushes, dust, worn commutator, cush drive rubber, etc. Or just the brake dragging a little.