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### Topic: Connecting strange wiper motor, help selecting diodes (or other suggestion) (Read 13231 times)previous topic - next topic

#### be80be

#15
##### Nov 25, 2012, 08:35 pmLast Edit: Nov 25, 2012, 08:37 pm by be80be Reason: 1
If the wiper motor draws 25 amps it's bad almost any of the never use over a 15 amp fuse and 10 amps in newer cars is the normal.
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Current. The minimum required current for the motor is 1.6 amps at 70 rpm, 0.9 amps at 41 rpm (and 4 amps if you elect to run it at 106 rpm, see note on the next page). These current ratings are for the motor spinning with no load. As you add mechanical load, these numbers can increase dramatically, doubling or even tripling under a heavy load. (When testing for torque, I found the motor to draw close to 14 amps in a stalled condition.) This factor must be taken into account when selecting a power supply. Since the motor will only use what it needs when it comes to current, it's best to provide a source with a higher current rating than you think you might need. I would recommend a 5 amp or greater supply to handle most circumstances.

And most stuff you find on the net say a 5 amp supply will run most any of them there not a power house of a motor
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Contrary to what some believe, the wiper motor does not oscillate back and forth, it rotates continuously in one direction like most other motors. The rotational motion is converted to the back and forth wiper motion by a series of mechanical linkages. Here's a page that shows how this works in a car http://auto.howstuffworks.com/wiper1.htm

This type of motor is called a"gearhead" or "gear motor" and has the advantage of having lots of torque. My unscientific test (using one wiper motor and a torque wrench) found that at 12 volts, on high speed, the motor has 13.5 pound-feet and on low speed, has 17.5 pound-feet of torque.

#### NickPyner

[ As seen the output shaft of the typical motor in the video is at a right angle to the axle of the DC motor inside it. My motor has the output shaft (after reduction gears) parallel to the DC motor axle. I

You are right to draw attention to this, and the picture.

So, are you sure it is a wiper motor? It certainly doesn't look like one, and questioning that will not only go quite some way to explain  why you are having so much trouble with it, but also eventually explain any surprises you might get when you finally succeed - or fail.

I have never worked on a Japanese car but I don't imagine them to be any different.  I don't recall any wiper motor not having a right angle drive i.e. a worm drive. There are three glaringly obvious reason for wiper motors to use worm drive.

1. It substantially increases the torque available from a small cheap motor

2. It reduces the speed to what is needed for the job i.e. not very fast and a hell of a lot slower than what a DC motor normally delivers.

3. 1 and 2 above are achieved with just two components - the worm, integral with the motor shaft thereby not actually qualifying as component, and the large gear wheel. The alternative is a multi-component gear train - with the attendant cost, space, and reliability issues.

Further, that motor looks pretty big for a wiper motor.  Further still, I see talk of 25A but I have never known a wiper requiring anything bigger than  a 15A fuse, and that is quite often shared with something else. And while you are at it, window motors are the same, for the same reasons - with the added advantage that the worm drives fits in the door better.

I think it is sort of actuator. I have no idea what for. Actuators on cars are usually vacuum. The most interesting thing about it is that your neighbour can't remember what car it came off (if it actually came off a car). You could find that your best solution is to go to a junk yard and procure what is definitely a wiper motor - one that is actually connected to wipers.

#### be80be

It's a wiper motor I've seen one just like it on a old chevy dump truck. It's old like me.

#### Aqualize

Thank you all for your responses.
be80be seems convinced it is a form of wiper motor. I have only what heard and pieced together. It comes from a man that fixes cars at home, he said it was a wiper motor that he'd gotten from a scrapyard. On a older car I can't think on any use for such motor (slow turning, high torque) except for the wipers.
I'm going to continue assuming it is a wiper motor. Anyway if a wiper motor of similar size seems nowhere near using 25A I hope I can feel calm with my motor controller and those diodes I bought.

Well I'm not convinced by the wiring suggested by be80be (from when I tested it with trial end error) I will print it and bring it with me next time I go there and have a chance to study it more.
And the reason I don't keep it here where I live is that the intended use is as a motor for turning the steering wheel on a tractor, which is at my parents home and travel there by bus and train and is not so keen on carrying this motor back and forth. The tractor has hydraulic assisted steering (otherwise I don't think it would be enough to turn the steering wheel). But that is a subject for another thread which I hope to start if this projects gets going.

#### NickPyner

OK. The penultimate, or possibly ultimate question:

Looking at pic028, you have a bit of white cable to estimate the rpm. Did you just see that cable move momentarily, or did you see it rotate continuously in both directions?

#### Aqualize

OK. The penultimate, or possibly ultimate question:

Looking at pic028, you have a bit of white cable to estimate the rpm. Did you just see that cable move momentarily, or did you see it rotate continuously in both directions?

It moved continuously (no stuttering) for as long as I wanted it to be by having the wires in contact with the connection points. By shifting connection points I could make it go the other way. But they moved in different speed. Lets say 80 rpm and 150 rpm. That they moved in different speeds makes me think that there isn't any "low" and "high" connections, changing direction makes the high and low.

#### NickPyner

#21
##### Nov 27, 2012, 03:22 pmLast Edit: Nov 28, 2012, 02:04 am by NickPyner Reason: 1

That they moved in different speeds makes me think that there isn't any "low" and "high" connections, changing direction makes the high and low.

That's as good an explanation as any, but it may be reversing just to park.

The reason why I asked the question is that I'm sure the bit of cable  isn't wrapped round an "output  gear", it's a spline. It looks exactly like the spline for a screenwiper arm, hence my question.  If the shaft rotated about a thirty degrees and then reversed, the motor is almost certainly a windscreen wiper motor but not off a car. It's off a train or a bus, hence the size. You often see buses with the wipers going but obviously not connected and thus must have a motor for each.  It could still be a wiper motor but, if that is the case, it obviously has a large and vital part missing, the reciprocating gear. Fortunately it is not too vital for you, but the bit that connects to the spline would probably be useful. It could have been that the motor originally drove a hydraulic pump, which might have been nice for your purpose(!)

#### Aqualize

That they moved in different speeds makes me think that there isn't any "low" and "high" connections, changing direction makes the high and low.

That's as good an explanation as any, but it may be reversing just to park.

The reason why I asked the question is that I'm sure the bit of cable  isn't wrapped round an "output  gear", it's a spline. It looks exactly like the spline for a screenwiper arm, hence my question.  If the shaft rotated about a thirty degrees and then reversed, the motor is almost certainly a windscreen wiper motor but not off a car. It's off a train or a bus, hence the size. You often see buses with the wipers going but obviously not connected and thus must have a motor for each.  It could still be a wiper motor but, if that is the case, it obviously has a large and vital part missing, the reciprocating gear. Fortunately it is not too vital for you, but the bit that connects to the spline would probably be useful. It could have been that the motor originally drove a hydraulic pump, which might have been nice for your purpose(!)

That's an interesting thought. Wiper motors for tractors work similar to how you describe it for other bigger machines (the arm is connected to the wiper motor directly and the motor changes direction).

Well the lack of speed makes me doubt it would be used to drive a hydraulic pump. The tractor hasn't hydrostatic steering (orbitrol). First I was thinking of affected the hydraulic valve on the servocylinder but gave up that. I think it is tightly built together so connecting some electronic valve (which I don't have and they are expensive) may not be possible. Bicycle gears of appropriate size and chain connecting the steering wheel and the electric motor is a way I think this will work, thanks to the power steering. An older tractor we have is without that I know that for such task this little motor wouldn't be enough.

But to sum it up we are waiting for me to take another look it with multimeter and wires, having a printed copy of the wiring diagram I got and see if it corresponds or not. And after that I think I will build it together as I thought with 4 diodes, smaller fuse on the motor controller and an Arduino for a bench test run. I know for sure I will visit the parents around Christmas, we'll see if I go earlier. So don't hold your breath until then!

#### Aqualize

[...]

[...] It could still be a wiper motor but, if that is the case, it obviously has a large and vital part missing, the reciprocating gear. Fortunately it is not too vital for you, but the bit that connects to the spline would probably be useful. [...]

As I don't have this piece my idea use the bicycle gear, somehow centered and then use the welding machine to permanently attach it.

#### Aqualize

So it is Christmas time and I have a chance to experiment with the motor again. And the connection works as intended!
So now the two input cables, when reversed polarity also reverses direction of the motor. Those 4 diodes was the key.
I will post pictures of the whole thing when I also get the arduino to drive it via the HB-25 controller. What I've done now to test the motor is to connect it to my modded computer PSU (banana sockets on top of it for easy access).
I don't know if I'm doing it wrong with the HB-25 but I will experiment on a small DC motor I have tomorrow.

#### Aqualize

I thought maybe a video showed it better
Using the servo library I got it to work. I hooked it up to read input from the Y axis of the joystick shield.
I measured the amperage between the PSU +12V and HB25 controller's positive connector, when the motor runs at full speed with no load it uses ~2.5A. Peaks higher, especially if changing direction suddenly.

So thanks everyone for the help, the objective I needed help with by starting this thread has been archived.