Author Topic: Treadmill PMDC motor  (Read 212 times)

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Offline j.a.mcguire

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Treadmill PMDC motor
« on: November 24, 2019, 12:47:48 am »
Hi there,

My treadmill motor began emitting quite a lot of smoke after about 40 mins of continuous use.  Today I took it apart, it's a 180V 8A PMDC motor rated at 1.5/2.25HP. 

When I took the motor out of the treadmill, a lot of small clumps of resin fell out of the end of the motor. I've yet to disassemble it to inspect the guts but, is it likely that I will be able to repair this myself, or is the fact that its overheated in the first place signifying a short across the windings i.e. the varnish on the windings themselves have likely failed so I would have to get it rewound?

I suspect it's irrepairable, but I will take a look, however I was looking for a cheap replacement and there are a number of similar motors on Aliexpress. 

I was tempted to get a beefier unit that might hopefully tolerate my abuse, so I thought if I went for a 3HP motor it would last longer as I wouldn't be using it to its full capacity?  I had been looking at the following for example:

It's pretty expensive though at £200, and my treadmill was only £365 anyway, and has lasted around 1.5 years, I'm not convinced this is economically viable.

That aside, the 3HP motor is actually rated at 15A versus the original 1.5HP motor's 8A rating, is it possible for me to install a 15A PMDC motor into my treadmill without replacing the controller board which supplies the DC power?  I'm hoping that since it's using PWM to supply the motor that it might have a self-limiting current capability, or will a bigger motor likely blow the board?
« Last Edit: November 24, 2019, 12:50:19 am by j.a.mcguire »

Offline schmitt trigger

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Re: Treadmill PMDC motor
« Reply #1 on: November 24, 2019, 01:00:50 am »
I would think that if a motor winding shorted out, that the motor controller could also have suffered damage.

I would open the controller and inspect it for damage. You don’t want to purchase an expensive motor only to find that the controller is also kaput.

Offline BurningTantalum

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Re: Treadmill PMDC motor
« Reply #2 on: November 24, 2019, 10:48:03 am »
These motors are not long lived, and they are of poor quality to start with. I have a treadmill that has had at least 3 motors retro-fitted. The current one failed due to a poor termination where the winding wire is crimped into one of the commutator segments. I managed to clean the copper and resolder it. The resultant dynamic imbalance was annoying so I soldered the diametric opposite segment to rebalance it. It failed again a few months later- a different segment that I resoldered. I think I have done at least 1/3 of them now and it seems to have settled down.
The main reason for overheating is drag on the belt due to lack of lubrication. The machine needs a good spray of silicone fluid at regular intervals- I mean a quarter of a can at least. The best way is to fit an extension on the spray tube and spray between the deck and the belt whilst the machine if running- easiest if the machine is lifted up to the 'store' position.
My experience is that treadmills, along with other types of home gym equipment, are well over-represented on the scrap heap at the local dumps so there should be no need to spend much on a replacement. They can be a fiddle to remove so take spanners and allen keys etc. The motors have a few variants including the shaft size.

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