Reduction Gearing

Apr 05, 2016 27 Replies

Hi all,



What's the simplest way to gear a 4,000rpm motor down to 2rpm without going in for a ready-made gearbox? (this is a DIY group, after all!) Would I be best off opting for a sequence of spur gears, or would a worm/ wheel arrangement be better - or a combination of both - or something else altogether? This needs to be something I can machine at home with the usual workshop machinery, so nothing too exotic requiring, say, bevel gears (for example).


Worm drive probably

Small worm+large spur.

Don't worm gears waste energy in friction? I've wondered that since I had a Meccano set.

Bill

In message , Cursitor Doom writes

Given that Meccano has already been mentioned, would Meccano gears solve you problem? No end of used options available via eBay and various online dealers, or new reproductions by Stewart Borrill :

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of course. All gears do, with worm drive you get one stage of moderate efficiency rather than several stages each of better efficiency. Which is the winner?

Re the OP, would belt drive not be easier than milling one's own gears? And in some cases a microwave turntable motor might do, typically 3rpm.

NT

Sounds like the wrong starting point to me; that's a shedload of gearing. CPC do a 230v 3rpm synchronous motor.

Depends very much on what load its driving. Worms are quite good, but do wear quite badly if under load. Brian

Ripple counter and stepper motor.

I'm assuming you mean a 'multi-stage' pulley system? If single stage and (depending on the power required and hence belt size etc) with an input pulley of 100mm diameter the output would have to be 200m in diameter!

We don't know what sort of size the OP's motor is to know how easy it might be to replace.

Cheers, T i m

Couple of windscreen wiper gearboxes ganged together?

What sort of energy level involved?

I have a single phase motor gearbox set salvaged from a bulk milk tank (stirrer) looking for a home. Output 12rpm from memory.

2000:1 is a hell of a reduction for any mechanical system. How critical is the 2rpm, and how efficient does it need to be? How much power is being transmitted?

Have you considered using the motor to drive a generator and then using the generator to power a low speed motor?

I've used spit motors from old cookers. Typically 4 rpm AFAIR.

quite :)

we don't know much about anything, the OP was woefully short on details, so a useful answer is at best hit & miss.

NT

I certainly did this myself, to drive a mirror ball suspended in the school hall. A little Proops motor, a few of my Meccano gears, plug it into a spotlight circuit, and all was well.

Some 40+ years later, just before the building was demolished, I revisited and spotted the timber planks I positioned to support the motor assembly were still in place above the suspended ceiling.

Chris

Start with a slower motor.

Straight cut gears aren't used much on cars where the engine runs at that sort of speed as they are noisy and wear even when in oil.

A 100 tooth worm and a 20 tooth worm sounds like a good start.

An esp8266 and a stepper?

+1, no point commenting without more information.

Hence the unmistakeable sound of a car reversing.

Well f*ck off, then. Mark the thread as "ignore" and move on. Sheesh.

We get quite a lot of new or occasional posters on this group who are genuinely looking for information, but for whatever reason do not really specify the problem, leading to threads running off in what turn out to be inappropriate directions, once the actual problem is described.

There are other posters who like to post inflammatory ideas just to provoke flame wars. That's fine, we all know who they are and can ignore them or participate according to our inclinations.

CD comes somewhere in between. This *seems* to be a genuine enquiry looking for solutions, in which case he ought to know very well that the options depend on the scale, and also any other constraints such as space, weight, or price. Without knowing these, there is little point offering solutions.

And the value of your contribution is?

They are noisy, but don't wear out anymore than helical cut types. It was the act of changing gears that caused the damage - before synchromesh arrived.

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