Demise of impeller dishwashers

[brucelucenta]

Impeller dish washers were what most of the machines were up until the 60's with a few exceptions. I know that Kitchenaid was the only one who always had a spray arm type dishwasher from early on. Was that the reason all the others could not make their dishwashers with spray arms back then? Just curious for the delay in doing so. I do remember seeing a D&M type dishwasher right before the transition to spray arms that had an impeller in the bottom and a round roto rack with the sprayer under it that made it rotate while it washed the glasses and cups on the top rack. I thought it odd at the time, but I guess that was the best they could do until the patent ran out. Right after that they made spray arms for the bottom instead of an impeller. I do remember that the impeller models were difficult to load and lighter weight things would get knocked around in the bottom. But then some of the spray arm ones were so powerful that happened too. I am curious if it was because Kitchenaid had a patent on the spray arm in dishwashers. I am assuming it must be, but not really sure if that is why.[this post was last edited: 7/1/2016-06:14]

 

[turquoisedude]

I don't know if it was patent that kept the impellers in dishwashers for so long, I think it may have had more to do with the design of the machines.   I guess that trial and error led manufacturers to believe that the impeller was the most practical way to propel water around the wash tub at the time; I am surprised at how well an impeller actually does at moving water!  

 

 

 

[cornutt]

I imagine that the impeller design was cheaper to build, since it seems to have fewer parts. What I remember about the impeller designs, though, was that they were all noisy and fairly rough on the dishes. I've seen a couple of videos of impeller machines running with a transparent top, and you can see what happens. The idea is that the impeller is supposed to supply a continuous spray of water. But what tends to happen instead is that all of the water in the sump gets tossed in the air by the impeller all at once; there's a big upward wave of water and the impeller runs dry for a moment. Then the water cascades back down and the impeller scoops it all up and tosses it again. There's a rhythmic noise of whooshing and thumping, plus dishes getting banged around by the forceful waves of water.

I would guess that the noise wasn't as objectionable back in the days when most houses had kitchens that were somewhat remote from the rest of the house and could be closed off after dinner. Since the late 1960s, though, the tendency has been for the kitchen to be open to the living area, which makes it more important that the dishwasher be quiet, and the spray-arm designs are generally quieter because they don't have those big waves of water being tossed in the air. Another thing that might have kept the impellers going for a while was that a lot of the earlier spray arm designs (other than the KitchenAid) did a poor job of washing the things in the upper rack. It was not too uncommon to have to re-wash glasses and cups that came out of those machines dirtier than they went in.

 

[foraloysius]

That things came out dirtier than they went in, was that perhaps because there was no filter? Or were there dishwashers with an impeller that had some sort of filter or macerator?

 

[launderess]

Our own of late and most happy memory WestyTopLoader

Shows us why and how impeller dishwashers left much to be desired:



More about those dishwashers here:

http://www.automaticwasher.org/cgi-bin/TD/TD-VIEWTHREAD.cgi?22140

Basically impeller dishwashers were a crap shoot; each load would wash differently depending upon such factors as placement of items, what was being washed, and so forth.

Unlike spray arms, there is no real direction of water with impellers; water is simply shot up and out from the bottom of tub to land where it may, or may not.

Without recirculating systems the same water (often laden with muck) was flung about leaving things coated with yibbles.

 

[warmsecondrinse]

Thanks for the info and links. Looks very cool and a lot of fun, but am not sure I could handle a 'crap shoot' for a daily driver.

 

Jim

 

[cuffs054]

Launderess, what is the strong looking spray at the back of the tub? It doesn't seem to move like the rest of the water.

 

[launderess]

Have no idea

Am not an expert on those dishwashers, am sure someone will come along sooner or later and explain.

Perhaps simply could be a result of how the dishes are loaded.

Looking at a vintage advert for a Kenmore version apparently there were baffles placed inside the tub to direct water.

http://www.automaticwasher.org/TD/AWJPEG/VINTAGE/2009/5-6-2009-13-21-44--dishwashercrazy.jpg

Looking at the size of impeller and motor on that GE it likely could move water quite forcefully.

http://www.automaticwasher.org/TD/AWJPEG/SANDBOX/2009/dishwashercrazy++8-11-2009-09-22-37.jpg

 

[tolivac]

Remember the impeller dishwashers as a kid.Wo onto the unfortunate peice of flatware or small dish that fell thru the impeller guard and into the spinning impeller!The impeller suffered,too broke or the blades severly nicked.The item was broken or bent!When this happenes you get a sound you don't forget.Figure the appliance parts places kept a steady stock or replacement impellers.

 

[brucelucenta]

In some of my first memories of the new house we moved into when I was about 5 or 6, we had Turquoise GE appliances. My mother insisted on having a built in dishwasher which was a GE drawer type machines with a metal impeller on the bottom. We moved from that house when I was in the 3rd grade, so I really don't remember that much about it other than that. I know she used to rinse everything off before putting it in and never put pots and pans in it for some reason. The house we moved into from there had a GE with a spray arm. She never did wash her pots and pans in the dishwasher until I started doing it when I was older and we had replaced the GE with a Maytag in the 70's. Needless to say, it did a superior job to the GE. The reason I thought that maybe Kitchenaid had a patent on the spray arm was because of that D&M dishwasher made for Kenmore with the impeller at the bottom and the upper spray that made the round rack rotate as it sprayed under the glasses, something different than Kitchenaid. I do know that right after that model they went to a spray arm in the bottom too.

 

[turquoisedude]

I'm somewhat (OK, completely...) biased about impeller-wash dishwashers.  I grew up with a Westinghouse-built one and I guess what I learned as a brat was how to load it properly.   When the '56 GE was installed down in Ogden, it was like a trip down memory lane.  At first, I was paranoid about food scraps so I rinsed everything before loading.  I abandoned that practice fairly quickly... LOL  I do admit that I will give really messy dishes a scrape before loading and although I wash pots and pans in the GE, I know darned well that anything baked on isn't going to come off in a typical cycle.  

 

I remember the first time I saw my ol' GE run - it seemed pretty darn powerful to me!

 



 

There is one fairly obvious weak point, however - the middle of the dishwasher.  Notice how the spray goes around this and never really sends water right down.  Yet, the cutlery basket of the  '56 GE is in the middle and stuff gets clean IF properly loaded.  GE made the right decision to move the cutlery basket to the front part of the upper rack when the metal bow-tie impeller machines debuted in 1957.   And yes, even I have to admit that my '57 Mobile Maid does better on cutlery than the '56.   But I'm still biased... LOL 

 

[tomturbomatic]

KA was not the only one to always have a wash arm. Waste King always had a wash arm.

Early impeller machines COULD be made without a drain pump, if installation permitted a gravity drain and if a drain pump was needed, it could be powered by a small intermittent-duty motor. Building a pump powerful enough to actually wash dishes was an expensive proposition. Hobart was positioned to have the pump building technology and know how to put that methodology in home machines, even if their other technology lagged behind.

GE's change to the bow-tie impeller machines was the bridge between old-style impeller machines with a separate drain pump and the development of a pump that could develop power and run continuously. At first, the main motor ran the pump and then reversed to run the drain pump. Later the pump assembly was used to run the Power Shower. Among other things, durable seals had to be perfected so that leaking pumps did not take out motors. Part of the reason that the bow-tie impeller machines were so good was the powerful pump that got rid of food soil by grinding it. Pump technology advanced by that point that anyone who wanted to make a serious dishwasher looked to wash arm type construction at least for their TOL machines.

And, BTW, only a seriously under-filled impeller machine would throw water and them have to wait for it to return to the sump. Water, by its very nature does not act like that with an impeller in a sump, although you can get surging similar to that in a pump type dishwasher when there is not sufficient water to keep the pump intake covered at all times. I saw it happen with a big ass machine in a hospital kitchen. You can hear it as older KA machines fill and the pressure builds in relation to the amount of water available for the pump.