mk1-forum.net

A friendly international forum for people interested in the tuning & modification of classic BMC vehicles
It is currently Tue Feb 18, 2020 3:59 am

All times are UTC [ DST ]




Post new topic Reply to topic  [ 6 posts ] 
Author Message
 Post subject: Rotation of heater motor
PostPosted: Wed Feb 12, 2020 1:50 am 
Offline
User avatar

Joined: Thu Apr 18, 2013 1:45 am
Posts: 331
Location: Melbourne, Australia
A member of the Ausmini forum is asking about the rotation of the motor in the Smiths metal cased heater. Regardless of which way he connects the two wires, negative and positive, the motor spins the same way.

I checked the Smiths plastic cased heater in my 1970 Cooper S and find the rotation reverses when I swap positive and negative leads.

Are there any electric motor specialists on here that can comment? Was a different type of motor used in the Smiths heater during its life?


Top
 Profile  
 
PostPosted: Wed Feb 12, 2020 7:26 am 
Offline
User avatar

Joined: Thu Apr 18, 2013 1:45 am
Posts: 331
Location: Melbourne, Australia
I see the person with the query has posted here so feel free to ignore my post - viewtopic.php?f=3&t=27731


Top
 Profile  
 
PostPosted: Wed Feb 12, 2020 11:23 am 
Offline

Joined: Fri Jul 19, 2019 9:40 pm
Posts: 4
Thanks for putting this out there. We must have been posting at the same time.

In terms of resolving my issue - the picture Bill added on the Aus forum showed the same direction as my heater motor turns so it has become somewhat of a moot point. Having said that, I’m still interested in the answer as to why the motor only turns one way.


Cheers, Paul.


Top
 Profile  
 
PostPosted: Wed Feb 12, 2020 1:06 pm 
Offline
User avatar

Joined: Thu Jun 24, 2010 5:28 pm
Posts: 790
Location: London UK
If the motor had permanent magnet stator, it will be reversible by swapping power connectiions.

More powerful motors have an electromagnetic stator (like a starter motor) so always turn the same way, no matter the polarity.

I assume your heater is the latter.

If your motor and fan was fitted in the other end of the heater box it would go the right way wouldn't it ?


Top
 Profile  
 
PostPosted: Fri Feb 14, 2020 7:49 pm 
Offline

Joined: Sun May 29, 2011 10:44 pm
Posts: 47
I think these motors are series wound motors so the field and armature windings are in series. Changing the polarity of the dc power source has no effect, much the same as your starter motor if you change from positive to negative earth which doesn’t spin the other way. I think you have to swap either the field or armature polarity but not both in order to change direction.


Top
 Profile  
 
PostPosted: Sat Feb 15, 2020 11:20 am 
Offline
User avatar

Joined: Thu Apr 18, 2013 1:45 am
Posts: 331
Location: Melbourne, Australia
Which Smiths heaters in their range had what type motor? Is it a metal heater versus plastic heater thing, or a date change?


Top
 Profile  
 
Display posts from previous:  Sort by  
Post new topic Reply to topic  [ 6 posts ] 

All times are UTC [ DST ]


Who is online

Users browsing this forum: Google [Bot], Nev and 15 guests


You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot post attachments in this forum

Search for:
Jump to:  
cron
Powered by phpBB® Forum Software © phpBB Group
Localized by Maël Soucaze © 2010 phpBB.fr