An Electric Car Motor

Ain't She Sweet!

Yes, this motor is a beauty.

While playing one of Bach's two part Inventions the other day, I heard my washing machine give out a huge groan. I had left it on, rolling about while I played the piano. On concluding my playing, I went into the kitchen to find a pall of smoke and a rubbery smell.

That night, I bought a new washing machine and set the old one aside. It made me recall a conversation I once had at the Aluroll smoking shelter where I had started vocally dreaming about building may own car and car factory. Aluroll's driver, Gwyn Jones, said that Tesla cars run on washing machine motors. So, here was my chance to get hold of one and test it out.

The motor I got out, a big ball of metal with bits of flex cable dripping off it, like a skull and spine from a corpse, now sits on my desk. It is a Selni universal motor which can be run off AC or DC, and is wired in series from any power supply. Speed is governed by the simple expedient of giving it more or less voltage. It will run off 230V 50Hz AC, or any amount of DC, using 2.5Amps for 1400 RPM.

 

Shown to the right is a universal commutator motor speed controller which I put together today to make it work. At the bottom of this post you will find a schematic of the motor wiring up, though not of the speed controller, which can be got from Velleman.

Washing machine motor

The sound of electricity

The video above provides some audio-visual information, which I will now elucidate with some prose. When the motor is hooked up to a controller, it should idle gently as we see. Turning the potentiometer, the motor voltage rises. A standard washing machine motor will also have a couple of terminals which link to the odometer. I have linked these to my multimeter, which reads the AC voltage odometer outputs. When the motor is given a load, such as my hand grasping at the spindle, the controller (which is Triac based) sends it more amps, and it buck away from me. So, in theory, it should respond well if the load (say, a car drive chain) demands it. That is, the motor does not simply slow down and stop - it draws more current.

Note, if you don't use a motor speed controller, the universal motor will still move - but it will keep moving until it reaches unbearable speeds and, well, I haven't driven it far enough to kill it yet. But you do need to clamp it down if you simply attach it to the mains.

The Lunar Rover

I have obviously not inserted this motor into a car. It wouldn't move a car. Besides, washing machine motors aren't the devices put into Tesla vehicles. That's just silly.

But, universal motors were used on the Apollo mission lunar rovers. According to the Haynes manual for that vehicle (Lunar Rover, 1917-1972 (Apollo 15-17; LRV1-3 & 1G Trainer)), Haynes Publishing, Yeovil, 2012), each wheel had its own 36V DC universal commutator motor of the kind on my desk. See the manual next to this paragraph. Each motor represented about 1/4 horsepower. Each motor had a 80:1 ratio transmission unit and was directly attached to the wheel hub.

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