By continuing to use this site, you agree to our use of cookies. Find out more
Forum sponsored by:
Forum sponsored by Allendale Jan 24th

Stuart dynamo rotation

All Topics | Latest Posts

Search for:  in Thread Title in  
br06/02/2021 17:30:12
824 forum posts
7 photos

Can a Stuart dynamo be run in either direction to provide the required output ?

Thanks

Bill

Edited By br on 06/02/2021 17:30:34

john fletcher 106/02/2021 17:36:23
754 forum posts

I've never seen a Stuart Dynamo, but if the brushes are angled no as they would chip off the leading edge in reverse. If they are straight, I can't so a problem other than the polarity of the terminals. John

br06/02/2021 17:45:03
824 forum posts
7 photos

Thanks reply John

Brushes are straight in lne with each other ie 180 degrees apart and run parallel to the dynamo base ie when stood on its base the terminals are parallel to the platform it sits on

Hopefully explained ok but can post a picture if it helps.

Bill

Thomas Cooksley06/02/2021 17:56:08
55 forum posts

HI, I am not familiar with the Stuart dynamo but you should be able to do it. It depends on the excitation. Reversing the direction will reverse the polarity of the output. You may need to build up the remnant flux in the field coils in the opposite direction to make it work. Tom.

not done it yet07/02/2021 07:10:28
6504 forum posts
20 photos

Dynamos are dynamos. We always ‘flash the field coils’ on vehicle dynamos when changing polarity or fitting a different one.

John Haine07/02/2021 09:30:50
4403 forum posts
261 photos

The spare parts list mentions a magnet which suggests a PM field., in which case it will happily run either way but polarity will reverse.

br07/02/2021 09:37:43
824 forum posts
7 photos
Posted by John Haine on 07/02/2021 09:30:50:

The spare parts list mentions a magnet which suggests a PM field., in which case it will happily run either way but polarity will reverse.

Thanks John

Just what I needed toknow - most grateful

Bill

SillyOldDuffer07/02/2021 10:22:47
Moderator
7883 forum posts
1724 photos
Posted by not done it yet on 07/02/2021 07:10:28:

Dynamos are dynamos. ...

I think so too, but some DC motors have offset brushes, which improves efficiency, and running them in reverse damages the brushes. The drawing is exaggerated but if the brushes are offset as shown on the right, don't run in reverse.

brushes.jpg

Is it likely a Stuart Dynamo is designed to maximise efficiency? Probably not! Never seen a DC motor with offset brushes either, but my experience is tiny. They do exist.

Dave

br07/02/2021 10:38:01
824 forum posts
7 photos

This is the dynamo

Dating from1980 and has never been used - note the clean windings .

img_0267.jpg

John Haine07/02/2021 10:46:35
4403 forum posts
261 photos

I thought AC series wound motors can have offset brushes to improve efficiency given the inductance in the windings - and they are not reversible. DC motors uness made for a very specific application may be required to run in either direction so would not have offset brushes. Anyway this is a model dynamo to show off a steam engine, efficiency is hardly likely to be an issue!

Edited By John Haine on 07/02/2021 10:47:02

Michael Gilligan08/02/2021 23:08:51
avatar
19571 forum posts
994 photos

At the risk of inciting semantic outrage ...

The ‘Stuart Dynamo’ is an AC Generator:

.

0ca101d6-7b63-4275-8cb6-de884c4626ad.jpeg

.

**LINK**

https://youtu.be/qOZGZ__3vi8

So the brushes are in contact with slip-rings, and therefore most unlikely to be damaged by reversing the direction of rotation.

MichaelG.

Speedy Builder509/02/2021 07:03:26
2490 forum posts
196 photos

Is it a DYNAMO ? A/c current, slip rings - dynamo or alternator ???

Oops, I should have read the previous post from Michael!

Edited By Speedy Builder5 on 09/02/2021 07:05:35

Michael Gilligan09/02/2021 07:42:34
avatar
19571 forum posts
994 photos

My best guess is that the word ‘alternator’ was coined for the emerging Motor Industry, to conveniently distinguish AC dynamos from DC dynamos ... but I don’t know by whom.

Alternating Current Generator

Here’s some more info about the Stuart machine : **LINK**

http://www.stuartturnersteam.com/Machines/Bottone/Bottone.html

MichaelG.

.

Edit: __ I haven’t yet found a freely downloadable copy of Bottone’s little book, but :

https://www.si.edu/object/siris_sil_243390

and

https://www.nature.com/articles/031052a0

.

UPDATE:

https://ia800205.us.archive.org/26/items/dynamohowmadehow00bottrich/dynamohowmadehow00bottrich.pdf

Edited By Michael Gilligan on 09/02/2021 08:04:35

Michael Gilligan09/02/2021 08:33:35
avatar
19571 forum posts
994 photos
Posted by Michael Gilligan on 09/02/2021 07:42:34:

My best guess is that the word ‘alternator’ was coined for the emerging Motor Industry […]

.

A bad guess ^^^ it appears: **LINK**

https://en.wikipedia.org/wiki/Alternator#History

MichaelG.

JasonB09/02/2021 09:01:53
avatar
Moderator
21967 forum posts
2531 photos
1 articles
Posted by Michael Gilligan on 08/02/2021 23:08:51:

At the risk of inciting semantic outrage ...

The ‘Stuart Dynamo’ is an AC Generator:

.

Excuse the outrage but Stuarts also made two DC ones, which Dave may have been thinking of as Br had not shown which one he had at the time. One was small and intended to be run from the S50 and 10 series models, the other older one was more like Br's in looks

Michael Gilligan09/02/2021 09:24:04
avatar
19571 forum posts
994 photos

You don’t need to be excused, Jason ... You are a Moderator

‘though I’m not sure why you felt the need to post a link to a page I had already referenced.

MichaelG.

.

Note: The semantic outrage that I risked was that initially expressed by Speedy Builder5

... but of course he then read my post, and got the point.

Edited By Michael Gilligan on 09/02/2021 09:28:53

br09/02/2021 09:25:40
824 forum posts
7 photos

My dnamois from the 1960's not 1980aspreviosly stated ,It had been discontinued by then.

It has slip rings and generates AC.

Some info that has been kindly sent to me is below:-

 

Alternating Current for direct lighting. It will not run as a motor nor charge Accumulators.

Height 3-inches, Length Overall 4-inches

Output
-
At 2,500 r.p.m. two 4 volt 1 watt lamps
At 3,000 r.p.m. four 4 volt 1 watt lamps
At 5,000 r.p.m. eight 4 volt 1 watt lamps

This dynamo has been specially designed to be driven by the Stuart Mill Engine, No.10, "Sun" and other small engines

Bill

 

Edited By br on 09/02/2021 09:26:01

noel shelley09/02/2021 12:45:07
995 forum posts
19 photos

AC can be easily be rectified by fitting a simple bridge rectifier to give DC ! Noel

br09/02/2021 12:54:37
824 forum posts
7 photos
Posted by noel shelley on 09/02/2021 12:45:07:

AC can be easily be rectified by fitting a simple bridge rectifier to give DC ! Noel

They are clever little things

I fitted a 240v dc motor to my U3 back along and had to fit one of these chaps,

AC is two wires in, DC is 2 wires out and all in a little case that is about 25mm square by 12 mm deep, excluding terminals sticking out,. All very clever.

Bill

SillyOldDuffer09/02/2021 13:24:28
Moderator
7883 forum posts
1724 photos
Posted by Michael Gilligan on 08/02/2021 23:08:51:

At the risk of inciting semantic outrage ...

The ‘Stuart Dynamo’ is an AC Generator:

So the brushes are in contact with slip-rings, and therefore most unlikely to be damaged by reversing the direction of rotation.

MichaelG.

Just out of curiosity does it have brushes at all? Is it really a Magneto, i.e. the armature spins a permanent magnet rather than an electromagnet powered by slip rings? The warning about not removing the armature without bridging it suggests a permanent magnet to me. Doesn't matter: Magneto or slip ring alternator, it should generate rotated in either direction.

Etymology is interesting. From the Greek word for force δύναμη. Dynamo appeared in 1882 as a contraction of Dynamo-machine, itself a contraction of Dynamo-electric-machine which dates to 1862.

Current electricity was originally called dynamic electricity and we still call the other sort Static Electricity.

There's nothing in the dictionary to suggest a dynamo produces DC rather than AC, so I guess the distinction between Alternator (AC) and Dynamo (DC) is technical English and came later.

Dave

 

Edited By SillyOldDuffer on 09/02/2021 13:25:55

All Topics | Latest Posts

Please login to post a reply.

Magazine Locator

Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!

Find Model Engineer & Model Engineers' Workshop

Support Our Partners
Warco
cowells
Eccentric July 5 2018
walker midge
emcomachinetools
JD Metals
rapid Direct
Eccentric Engineering
Subscription Offer

Latest "For Sale" Ads
Latest "Wanted" Ads
Get In Touch!

Do you want to contact the Model Engineer and Model Engineers' Workshop team?

You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.

Click THIS LINK for full contact details.

For subscription issues please see THIS LINK.

Digital Back Issues

Social Media online

'Like' us on Facebook
Follow us on Facebook

Follow us on Twitter
 Twitter Logo

Pin us on Pinterest