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Mini Wiper Motor
RobBrown - 5/11/02 at 06:46 PM

The wiper motor I have seems to travel too fast for the park switch to kick in.
I have replaced the park switch, thinking it was broke, but still have the same problem.
I have also checked out the lump (technical term) on the drive wheel, but it looks ok (no wear on it at all).

Any ideas


theconrodkid - 5/11/02 at 07:00 PM

sounds like you wired it up wrong and its on fast speed,if not check the ramp that activates the switch,that may be worn.


RobBrown - 7/11/02 at 12:28 PM

I have checked that I have wired it up to the slow connector, rather than the fast one.
The ramp seems to be in good condition.

If I am able to slow the motor down a bit then the park switch will work. I could do this with a resitor in series with the permenant 12V feed.
Do you know where I could get a resistor suitable.

Cheers
Rob


theconrodkid - 7/11/02 at 06:02 PM

i cant see how the motor is spinning toooooo fast,it uses an extra brush to speed it up so if wired up right should only go at slow on pos 1,still a mystery


stephen_gusterson - 7/11/02 at 07:40 PM

you can get a power resistor from farnell

www.farnell.co.uk


however, you need to know the current drawn by the motor to work it out.


Lets guess at 6 amps at 12, and you want to slow it down


Ohms law is V = I x R

so V
---- = R
I


12v / 6A = 2 ohms.

Thats the resistance of your motor in that case.


if you used a resitor of around 0.47 ohms, then you would reduce the voltage at the motor to about 80%.

Use a 0.68 ohm one and it will fall to 70% ish.


At these kinda power levels you need a resistor of about 25 watts. The aluminium clad ones are nice - but bolt it down to some metalwork as a heat sink.


If you need pointing at a specific component, let me know



atb


steve


sg_frost - 17/3/03 at 01:44 AM

make sure the park is wired right, mini wipers are bastards to wire correctly, its all to do with the way the contacts act in the switch. Are you testing it on the car or on a bench, the resistance of the wipers on the screen could slow it enough.


RobBrown - 17/3/03 at 01:02 PM

Originally I was testing this on the bench, and the motor seemed to race away.
Fitted the scuttle and wiper assembly to the chassis this weekend and wired it in to the rest of the loom. I can tell that it has slowed a little.
I have not fitted the screen and wipers yet, so would hope that, as you say, the resistance of the blades on the screen is enough to slow it down a bit more (enough for it to stop when it should do).