Washing Machine Agitation


Washing machines used to agitate back and forth. Now they agitate only in one direction. Is someone able to explain why? I posted this in what I considered relevant forums and they told me it was too simplistic for them to bother with. So, I’m trying here.

edit: I don’t have a front load washer, mine is top load. And it only agitates in one direction. I do appreciate your answers and they make sense to me. But I still don’t get why a top load washer would do the same thing. (It is high efficiency, it’s just not front load. I’m not fond of those.) And I put Engineering because it’s the only flair that seemed to fit.

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I’m not a laundry engineer or anything … but I think it’s cause the newer front load machines are high efficiency ie. use less water.

The older top loads used a lot of water and the agitator whirlwinded all the clothes as they were submerged. The newer ones don’t fill up so have to continuously rotate the clothes through the water that sits in the bottom.

Think about the way a front-loader works. Imagine a shirt laying against the bottom of the tub. As it rotates, it will eventually fall to the bottom, but the side that was originally against the outside is now on top. Next, imagine the chaos that a bunch of clothing causes as it falls – some fall soon, others later. Pure randomness. Lots of interference, and almost no water or soap. Much more efficient.

Next time you do a load of wash, keep the lid open while it swishes & watch the circulation. If it’s not over crowded, the clothes should circulate from the bottom, up the outside, across the top, and down the center.

The curved fins on the center piece make the water move.

(Thank you for the award. Totally not necessary, but appreciated.)

Single direction is much simpler for the drive and much less wear on the machinery. Going back and forth puts cyclic loading on everything and is generally a giant pain in the butt to engineer.

So the question isn’t “why don’t they agitate anymore?”, it’s “why did they agitate in the first place?”

And that goes back to how washing machines started…which was to imitate human washers, who move stuff back and forth on a washboard because humans can’t do rotary motion. Old washing machines imitated that.

On top of that, if you’re going one direction and get unbalanced while washing (I.e. heavy) the forces on the bearings are *huge*. Oscillation means you don’t need to worry about getting unbalanced. This is still and issue in the spin cycle but it’s much less bad after the water has been drained out.

Modern washers have sensors and computers to detect imbalance and can stop/reverse/protect themselves. But that wasn’t possible until we had economical electronic controllers for washing machines.

Once we figured out the right arrangement of fins, speeds, drums, and controls etc. to give clean clothes without oscillating, that’s what we did.