Wheelchair Motors

Hi,
Can someone please explain why wheelchair motors are rated at 24V yet have a 12V brake? Is there a reason for the difference in voltages?
Cheers,
Michael
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Michael,
Maybe they wire the brakes in series?
Jeff.
--
Jeff Shirley
snipped-for-privacy@mindspring.com
  Click to see the full signature.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Well that's what I thought but surely you would want to ensure that both brakes have the correct voltages dropped across them?
Michael
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

a
Can you give an example or link we can look at? Others on here probably already know the answer but I for one would like to see exactly what you are talking about - to satisfy my own curiosity.
Thanks ! JCD
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Well I'd rather not since I saw it in a currently active eBay listing and I don't think it would be fair on any prospective bidders. That said every set of motors that come up on eBay I find have the exact same thing - and even the pair I have are the same.
I was wondering if it was something to do with power consumption...lower voltage = lower heat dissipation and thus longer running life.....
Michael
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload
Michael wrote:

The brakes on the electric wheelchair motors I took apart were deadman brakes. Applying power dis-engaged them. When the drive is turned off, the brake power gets turned off too, so an un-energised chair doen't roll. The poster that suggested that the brakes were in series got it. There is no fine control to balance, so exact voltage drop doesn't matter.
If you remove the brakes from the motors, it's a great place to put optical encoders for odometry or closed loop motion control. there is even a nice little cover!
Bob
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Polytechforum.com is a website by engineers for engineers. It is not affiliated with any of manufacturers or vendors discussed here. All logos and trade names are the property of their respective owners.