66-67.5 Wiper Motor - Triple Brush Voltage/Current Flow?

[Curtis]

Yes, a long title.

I'm finishing up a harness set and was checking to make sure the wiper motor works okay. As is usual with me I get to wondering about how it is wired. Unfortunately I did not finish my education in electronics and turned to mechanical so my knowledge of motors is limited.

So the motor is a 3 brush motor. It has 12v going in and a low brush out and a high brush out. I searched and searched about 2 speed motors and how they work and did not find all that I wanted. Found that it probably has two winding.

I have attached a diagram of how the motor is wired at low speed. Power goes to both the high and low brushes. Combined this gives you a slower speed. What I found was in fact this motor can be a 3 speed motor. If you hook power just to the low then it goes pretty slow. Hook power to both as it is wired in the car then it goes a little faster. And last hooked just to the high speed brush wire you get the faster speed.

So what is my point/question? I'm wondering why it runs at the slower speed with both brushes hooked up? I'm supposing it has to do with resistance or the number of winding. Anyone here know?

The diagram has the flow highlighted with green and yellow with a dashed red line.

Thanks.

datsun_wiper_layout_66_67 low speed.pdf

[Curtis]

In looking at the armature it appears it may have two winding. I'm wondering if the two changing polarities for the low and high as it turns mediates the speed?

[fj20spl311]

I have always been interested in wiper motor swapping and design, but never followed up on it.
I did a little internet search and discovered that Volvos circa 1967 used either Compound DC Motor with Field Windings or a PM DC Motor.
Ours sounds more like the Compound DC Motor with Field Windings and I know they are not a PM DC Motor.
Might be a place to start.

[Curtis]

The round can is a PM motor, just has magnets glued to the case.

[fj20spl311]

I never notice anything sticking to my spare, I stand corrected.
The Volvo article had a lot about the PM motor also.

wiper motor design

[Curtis]

Here's the case with the magnet and the armature.

IMG_2343[1].JPG

IMG_2344[1].JPG

[Curtis]

I bought a 2 pole, 4 position rotary switch. Soldered on some leads yesterday and hooked up the wiper motor. Got it to work as a 3 speed.

Slow speed about 40-41 strokes per minute.
Middle speed which is the stock slow speed is about 44 strokes per minute so not much difference.
High speed is about 51 strokes per minute.

Today was a long day spent in Vancouver, B.C. Leave at 5:30am and got back about 8:30pm Judged too many matches.

[shifty]

Is the park switch hooked up to the windings? I know that some wiper motors are stopped by putting +12 volts to both “poles” to force it to stop quickly.

[Curtis]

Is the park switch hooked up to the windings? I know that some wiper motors are stopped by putting +12 volts to both “poles” to force it to stop quickly.

It parks with the low.