Tongxin Kit 'where And How'

[flecc]

Presumably with a different controller the Powacycle motor could be given more Amps too? For all I know that might fry it but I can't otherwise see why it couldn't be done. The Austrian chap who sells kits on ebay once told me that the different spec motors were basically the same but it just depended on what power you got the controller to give them.

Yes, most motors can have more stuffed into them, though for efficiency and range it's better to use the designed job. Designing in the extra capability with adequate safety margins is where the extra size and weight comes from of course, but if small and light is wanted, over-running a lesser model is a good ploy.

Some of the motors in the model world have incredible outputs from tiny sizes, but unfortunately their noise outputs are just as incredible usually.
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[john]

Rip?

A lifetime of engineering instinct tells me the drive system is a rotten design anyway, but doubtless someone will tell me how wrong I am again.
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Your instincts may be correct Flecc, but most of the issues I had appear to be more down to quality control.

When I first opened the motor I was surprised at the roller drive. I'd not come across such a design before and wondered why it did not slip. I was also concerned that there didn't appear to be any take-up of wear.

However, having dismantled 3 motors now, I believe that the force between the rollers means that there is no way that the motor could produce enough torque to cause a slip. It may be that tension in the outer gear ring is enough to take up any wear. I know that there have been reports of slip, but I have not heard any being confirmed by dismantling the motor, which is necessary. Those reports may be down to a broken gear ring or slipping freewheel or gear components significantly out of tolerance at manufacture.

So I wouldn't write of the design just yet. I had hoped that after my early model failed, TongXin might have improved there quality control. Sadly that doesn't seem to be the case and it may be too late for that company now. However, I would say that it could be worth other companies looking at a similar design. They would need to get manufacture and testing right from the start though!

 

[Jeremy]

Like you, I believe that QC seems to be the major problem. As I understand it, Tongxin is a university-based company, so the focus is on innovation, rather than production engineering.

I think the design is sound, provided the tolerances are maintained. The wear rate of roller bearings (which is really all this is) is extremely low. Car wheel bearings, for example, run under pre-set pre-load as sealed units for virtually the life of the car. I think that the roller drive system has the potential to last several tens of thousands of miles before wear becomes a problem, if engineered properly.

I've no doubt that if a good quality-engineering company took on the Tongxin design then the reliability issues would be resolved quickly.

Meanwhile, mine is going to start getting a serious work out now. I was involved in a nasty car accident yesterday, so am temporarily minus a car.

Jeremy

 

[flecc]

Yes, I fully agree that QC is a problem with much that we receive now.

I'm sure if the Tongxin design was made by Heinzmann or the like, it would be a better prospect for long term use, but it's not, so I tend to warn as I find, real world situations that people buy into rather than what can be.

I can only go by US reports of drive slip, mostly on large wheel applications. However, I still don't like the principle and am not so sanguine about long term prospects, especially given the manufacturing source and aforementioned QC problems.

Sorry to hear of your accident Jeremy. I hope you were not hurt in any way.
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[Jeremy]

I wasn't physically hurt at all, but the pedestrian runner who ran across the dual carriageway right in front of me is in a very bad way. I can honestly say that the sickening sound of a fellow human being coming through the windscreen is one that I'll never forget though.

Seeing the effect that a motor vehicle can have on the human body has been a pretty traumatic experience. I'm only thankful that I was going relatively slowly; a few miles an hour faster and the outcome would almost certainly have been fatal.

Jeremy

 

[flecc]

A horrible experience Jeremy, but thank goodness that pedestrian's foolishness didn't have a worse outcome.

Nothing I can say other than sincerely hope you are able to move on without dwelling on such a disturbing event.
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[john]

Heck Jeremy, I am really sorry to hear that for both of you.

Not sure what else to say. Perhaps you'll let us know how the pedestrian gets on.

 

[Jeremy]

I've just heard from the police that the runner is semi-concious, but stable. The good news is that he is likely to pull through, albeit with a very lengthy stay in hospital. The doctors are hopeful that the surgery to save his foot has been successful, but won't know for sure for a few days yet.

Apparently he's not in a fit state to give an account as to what happened, and may never be able to, apparently. His parents seem to be at a complete loss as to why their son was running across a busy dual carriageway, they always believed that he stayed on the footpath. I can't begin to imagine how they feel.

My car, which isn't yet three years old, may well be a write-off, apparently, which gives an idea of the severity of the impact. The only thing that contacted it was this poor chaps body.

Jeremy

 

[john]

After four mechanical motor failures in a little over a year's use I think it may be time to throw in the towel .

Make that five motor failures