On Thu, 05 Feb 2015 20:27:22 -0800, Larry Jaques
wrote:

On Thu, 5 Feb 2015 21:16:21 -0600, "Terry Coombs"
wrote:

Larry Jaques wrote:
On Thu, 5 Feb 2015 19:04:40 -0600, "Terry Coombs"
wrote:

Baron wrote:

Fine, try this link:-
http://www.homemodelenginemachinist.com/showthread.php?t=23130


Nice ! Made me go out and look at the wiper motors I have . Got one
old one that's reversible , but I'm not sure how it's wired , has a
good worm

That's likely a window motor rather than a wiper motor, Terry. It
should work well!


set in it . It has one black going to the field coils , a red and a
green , one to each of the two brushes . The other is a sealed motor
, newer and only 2 wires - looks to be a PM motor . I can't remember
if this is the that one has a stripped gear on the worm , that might
have been the one with the fried commutator that I tossed .

Grab the output shaft with a pair of channellocks and energize. You'll
know in a hurry if it's bad. g

No , it's definitely a wiper motor , still had the arms to drive the wipers
and the park switch in the assembly when I got it . I just can't remember
how it was wired , or why I disassembled the motor part . That might have
been because I was trying to figure out the wiring .

Maybe the extra wire was the hot park lead? I've never seen a
reversing wiper motor, but older motors had discrete windings for
extra speeds. Clare, you?
Hideaway wipers on seventies era GMs reversed to tuck the wipers in
under the trailing edge of the hood. Any Permag motor with an isolated
ground can be reversed. Actually ANY permag motor can be reversed by
simply reversing the polarity - positive ground runs backwards from
negative ground. In some applications that is do-able, in others not.

I forgot about the 2 speed GM motors - they had wound feilds up until
1980-ish - power was fed to the motor all the time and the switch
grounded the motor - it had series and parallel feilds and a built in
20 ohm resistor. One part of the switch grounded the park/run relay
wich fed power to the armature and shunt feild through the series
feild. On high speed the shunt feild was grounded through the feild
weakening resistor, and on low speed the resistor was shorted out,
full feilding the shunt, causing the motor to run slower with
increased torque.

On the more common multispeed permanent magnet motors a shifted brush
is often used for the second speed. You have your "common" or live
brush, one 180 degrees from it, and one about 120 degrees off-set. for
a 2 speed motor.. Not sure if anyone makes a 4 brush 3 speed PM motor
or not.

Resistors are still used for speed control on some PM motors and I
would be surprised if electronic speed controllers are not in common
use today. I don't work on cars everyday any more so not sure what
"state of the art" is today.