washer motor shaft question

[grizzly]

Warning, dumb question area ahead, read on at your own risk...

Q. On a washing machine motor that has a mechanical pump attached directly to the motor, what keeps the motor's shaft from spinning the pump impeller during the agitate cycle?

- Is it that the shafts coming out the top and bottom aren't necassarily running at the same time, which is controled by the timer? Or do both the transmission shaft and the pump shaft always spin if the motor is running?

- Or maybe is it that when the motor is running the the agitate direction, the pump doesn't pump, but it does pump if the motor is running in the spin direction.

- But that can't be, because a lot of washers seem to drain for a while, before they start spinning. I'm confused.

Ok, one more question about pumps. What keeps water from slowly draining during the fill and/or agitate cycle? I mean why doesn't the force of gravity slowly pull some water down since both the pump and the drain are  underneath the tub? I mean, it wouldn't be as fast as when the pump is running and impelling, but surely some has to come out, but it doesn't, and I don't know why.

I'm thinking of a Whirlpool direct drive while thinking of this, if that helps any.

Thanks!

[Pegi]

The impeller inside of the water pump is cupped one way, when it is agitating it is rotating against the back of the cups for recirculate, during drain the pump reverses and can then pump the water out......the end of the drain hose being higher than the water level in the washer keeps the water from draining during fill and agitate...lay the drain hose down on the floor and see how much water the washer will hold.....

[Scottthewolf]

When the motor runs in agitation, the motor runs in the opposite direction of the drain and spin cycle, so the pump is forcing the water back into the tub. If you can see inside the tub during agitation, you will see bubbles at the tub outlet , it's the same principle of taking a drinking straw and blowing into a glass of water.

[grizzly]

Thanks Pegi & Scotthewolf! So the shafts are both always spinning at the same time, and in the same direction, when the motor is running then. I see.

I'll warn ya now, my initial questions are probably gonna be these fundamentals type deals. I can figure out how to change a part, but I want to have a good grip on the basic laws of appliance physics too.

I swear on my pet hamster's grave that I will NEVER be a mere parts changing monkey.