windshield wiper motors for robot drive motors ?

I bought a few at the local junkyard (car salvage) a few years ago for
$10-$15 each.  Prices may vary.  Ebay might not be the best place to buy
these; I imagine their weight makes shipping expensive.

Pros:  High torque, durable design.  Mine had a few terminals; you could
use them to select different speeds.  Run on standard 12v.  Cheap.

Cons:  Somewhat awkward lever arms.  Moderately high current
requirements.  Rather slow since they're geared so heavily.  Hard to get
"standard" parts.  No encoders.  Used.

- Daniel

Most windshield wiper motors are pure crap for robotics. They're made to
turn in one direction, and many exhibit a 20-25% speed loss in the other
direction. They're loud and inefficient; neither problem is too critical
for an automotive application, but important for mobile robotics.

But they're cheap.

-- Gordon

Thanks Gordon, just the kind of info I needed.
I figured they would be slow, but had no idea about the reverse speed issue.
Glad I haven't bought any yet!

P.S. Do you get any spam using your "NOSPAM" address? ( I'd like to switch
to that form but I got hit so bad on some newsgroups a year ago that I am
now gunshy. )


"Gordon McComb"

If in doubt, give spamgourmet.com a try.  They've been reliable for the
couple years I've used them.  Only adds a delay of a couple minutes per
email.

- Daniel

I used an unspammed address for so long it doesn't really matter, but I
figured it can't hurt in trying to avoid even more. For a while I was
getting upwards of 600 spams a day, from harvests of my e-mail on Web
sites and on newsgroup postings. I still get >200/day.

-- Gordon

My first robot used 12v windscreen motors and indeed the motors
did run faster one way than the other.  However I have another
robot base which uses 24v windscreen motors and they appear
to work fine in both directions. I don't know about their efficiency
but they are powerful enough to move furniture, crash through
walls and burn out the tyres if the robot base hits a wall without
any stop button.

As for noise I liked them because compared with a high geared
motor they make hardly any noise at all. The electronic control
was too expensive however as they did use a lot of watts and
the base had to be out of welded steel to hold the weight of
the motors and batteries.

When I tried some light weight motors from a kids battery driven
car the noise of the gears was horrendous.  I was going to use
a toy tank base as a cheap robot platform until I heard the noise
and realised I and the wife would be driven mad with that thing
moving around the house.

-- John

An alternative is car headlight motors, I used a couple I pulled from a
Toyota Celica, worked great.  They even have a knob on the shaft for raising
the headlights manually if the motor failed.  I attached a shaft encoder to
this and got great feedback.

Don't what their duty cycle is like though, they might overheat if used
really heavily.

-Will