Hi D'geek
these were sold to anyone looking for a really strong durable machine that saved water. They would have been used on farms in arid areas with many employees using the machine. Some time in the late seventies my Sister had just got her drivers license, so She, her boyfriend, our younger sister and I all went on a five day holiday around our state, staying in overnight vans in caravan parks (trailer parks). At one place they had one of these King Size twins powered from a coin-in-slot power point. There were no instructions up, you had to figure it out for yourself. We managed OK, that was the last time I ever saw one of these.
Your description of what they should have done sounds like you have just designed the Hoover Keymatic.
The other ones were somewhat more conventional, in that they had a rubber pinchvalve controlling the tub outlet; single pump driven by the wash motor, whenever it was switched on the wash action operated, you could not "spin only" because the single pump was operated by the wash motor. Two controls - on/off switch and pump valve. No timer at all, it runs as long as it is switched on. The other machines had a lid over the spinner, with a cable operated brake on some and a hopeless solenoid operated brake on others.
Most versions only had one motor - the spin motor, with a v-belt to drive wash action and pump. The one I had was a two motor version, the only one I ever saw.
I already have a garage full of machines and yet there are several more machines I really want to collect but I have no more room, so I must be very selective about more acquisitions.
Chris.