Faster Motor (Bosch Exxcel1200)

Many thanks for that.

I did some measuring of the motor/drum pulleys and scribbled a few numbers down on a piece of paper....but halfway through I forgot exactly what I was trying to work out (I managed to prove that a 1400 spin speed machine spins at....1400 rpm).

And then it occured to me that it would be far easier just to turn the blooming machines on and count the revolutions of the drums during a wash.

So, with the aid of a torch and a stopwatch I found out that I'd been fooled...and that the 1400 Exxcel washes (30 degree cycle) at 54 rpm while the 1200 does so at 46 rpm.

There's some slight difference in the diameter of the drums (15 1/2" on the 1400, 15" on the 1200), but by this time I'd figured that the difference wasn't worth worrying about and that my pants won't get mullered in the wash.

What the final spin speed of the 1200 is now is anybody's guess - but having read the article about spin speeds I'm none too bothered.

Cheers,

Steve

Washing machine motors are controlled by a board. They have to be. If you take any washing machine motor and put pure uncontrolled voltage into it, it will spin like a jet turbine. I've seen this with the sensor on the motor shaft removed. This sensor reports back to the control board the revs of the shaft, so the power can be adjusted accordingly. It doesn't just give the same set voltage everytime the machine spins or washes, because it simply wouldn't work. A full drum is not going to spin at the same speed as an empty drum unless power can be increased. The motor will be turning at near enough the same speed as the old one but obviously the pulley wheel sizes will influence the overal drum rotation speed because they are essentially gears. So, if you put a motor rated at 2000 rpm spin (just as an a silly example) into your machine, the spin speed will be reduced to 1200 by the board because the revs are monitored and controlled from there. Taking it the pulley sizes are the same of course.

Sure thing, there'd have to be some sort of controller otherwise all the speed changes for and during the various wash programs would have to be done via gears...which would make the machine rather complicated...and heavy (though possibly more fun). But the slightly larger pulley on the 1400's motor seems to suggest that that speed control module (in itself) is the same across a given range of machines, and that the relatively minor change in top spin speed is done via gearing. It would make sense from a cost perspective - and the speed differences in the 30 degree wash cycles seem to tie up nicely with the relative difference in motor pulley diameter.

The sensor/load/power relationship makes sense - when I take the 1200 motor apart I'll have a look for it.

Cheers,

Steve

Hoover used to fit the same module or programmer to 800, 1100, and 1200 spin machines and the same motor. Instructions were to cut this link for 1200, cut this one for 1300 etc. The faster spin machines had a smaller drum pulley too.

Well, I stripped the 1200 motor down today to give it a bit of a service - and while I was there I had a good look around for the speed sensor. Couldn't find one. Apart from all the usual wires and connectors the only other item of note was a temperature sensor.

If there's one at all I'd imagine it'd be on the drum casing somewhere...unless they're getting feedback from the motor in some other way.

Cheers,

Steve

The speed is controlled through monitoring the small tacho coil and magnet at the end of the motor where the motor plug is. As the armature turns, the magnet revolves and the control board can count the revolutions.

Aha! That would be the odd-looking 'doughnut' just before the rear bearing. I wondered what that was for...and now I know!

Cheers,

Steve