Legends of Dishwashing: The Maytag Reverse Rack

[potatochips]

Continuing on with the legends series is the Reverse Rack Maytag. I remember the first time I ever laid eyes on this machine in digital form was on this very website. The ads, brochures, and personal machines captivated me with its unusual racking, promised loud noises, aggressive wash action, promised Maytag reliability, and near limitless capacity made this machine larger than life. The first time I ever seen one in the flesh was at the Habitat for Humanity restore, a WU301, and it was then I realized this machine is truly legendary.

 

[potatochips]

Opening the door reveals its most apparent quirk. Not the only quirk asI feel that's what this machine is, quirky. The racks are reversed, cups go on the bottom, plates up top. In the patent for this style of racking, which orginiated in their top load machines, Maytag states this is a great way to maximize space by compartmentalizing the racks for specific items. Incase you missed it, yes Maytag patented this design.

One thing to note is how I've loaded this machine. More on that later.

http://https//patents.google.com/patent/US3402975A/en?q=dishwasher&assignee=maytag&page=6

 

[potatochips]

The second quirk is the motor and pump set up. It's belt driven?! In the 1974 patent for this, Maytag states that not only will motor placement offset the need for a counterweight in portable machines, it discussss how the motor placement being belt driven maximizes space. It's my belief that motor technology at the time from Maytags supplier wasn't good (small) enough to support a direct drive machine, and thus, a belt driven solution.

The belt provides an excellent D-D-D-D-D noise until the flat spots created by the pullies is smoothed out after an initial start. And believe me, with this machines capacity, the belt will sit long enough to create this vibration.

In the later production models, the WUx04, the belt drive system was replaced by a direct drive motor.[this post was last edited: 10/28/2017-06:49]

http://https//patents.google.com/patent/US3906967A/en?q=dishwasher&assignee=maytag&page=3

 

[potatochips]

At the heart of the machine is the pump. This design was originally patented in 1967, and although the pump pictured is from a 1996 DWU9962, the overall philosophy remains the same. Maytags philosophy is to strain large particulate that's about 3/8" size by a coarse strainer for which the owner can clean from the bottom of the dishwashers sump. Whatever passes through the coarse strainer is met by the micro-mesh filter, and this is where the real genius begins.

You can see the micro mesh filter in the photo below, and wash water is drawn through it by the wash impellers auction. This effectively strains the wash water like a dryer lint screen. Unfortunately, whatever is captured by this screen has the potential to clog the micro-mesh screen which would reduce washing performance entirely by starving the suction of the wash impeller.

The genius is that plus shaped part that has little clearance between itself and the micro-mesh screen. This is the backwash arm. On reverse rack machines there are only two backwash arms, Maytag changed this to four when they redesigned their whole lineup in 1991. The backwash arm is what the spray arm attaches to so it will rotate with the spray arm. As wash water leaves the discharge of the pump, a small amount is diverted to the backwash arm to pass through small slits that blast clean wash water on the micro mesh filter, effectively blasting off what goo was filtered out. The goo will naturally find its way back, only to be blasted off again and again by the backwash arm, effectively keeping it in suspension.

Similar to Whirlpool machines, when the motor reverses to drain the wash impeller still produces pressure, so the backwash arm will still function when the machine drains, and because the drain impellers sucttion is after the coarse filter and before the micro mesh filter, everything held in suspension goes down the sewer.

This design lasted in various improved states until Maytag was bought by Whirlpool.

There is no hard food disposer like in Whirlpool or GE machines.

The design is most certainly unique and effective. It's very rare to find any kind of residiual evidence of goo on any dish or utensil.

 

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Because of the micro mesh filters effectiveness of filtering goo, small diameter jets are used all over the spray arms. Small diameter jets allow for focused sprays of high pressure wash water. In the patent linked, Maytag claims this pump design moves thirty five gallons a monute of water.

The small holes have one apparent disadvantage. IF, and it does happen, things make it though the micro mesh filter. They can clog the spray arm holes. But since there is forty seven of them, the detriment isn't noticed right away.

The rhythm of these spray arms is so melodic, it could put anyone to sleep. You can hear their fast wooshing action.

Maytag did advertise that they were the only one to have a full upper wash arm, but this was much needed as it sprays DOWN on to the cutlery and dishes. The cutlery is on the top rack, above the detergent dispenser, so there is no risk of cutlery pitting from the soap.

http://https//patents.google.com/patent/US3491780A/en?q=dishwasher&assignee=maytag&page=1

 

[potatochips]

The reverse rack is one of two legendary machines that feature fan assisted drying. I never use heated dry, and In Whirlpool or GE machines it's a rare sight to see items (aside from plastics) that have a little drop or two of water after an air dry. With fan assisted, those little drops never ever happen. Because of this marginal difference, I believe fan assisted drying is a gimmick. I've played around with enough non fan assisted machines which have al proved great success.

HOWEVER, Maytag made a real serious attempt as the nozzle curves, meaning the air will sweep along the entire bottom of the machine near the heating element before traveling up and out the vent.

The only real distinct advantage of fan assisted drying is the ability to use your dishes right away when the cycle competes as they're not piping hot. But that's not really a problem.

Gimmick. [this post was last edited: 10/28/2017-02:35]

 

[potatochips]

Alright, alright. Down to the business here, the most legendary QUIRK. The racking.

It's very often I run out of dishes before the machine fills up, which is what was happening in the first photo.

A GE is hard to master, and if you can figure it out and load it right, you can load anything. A Whirlpool power clean is open season, there is no special secrets to loading it which makes it the most versatile. But the reverse rack? Oh, there is a specific spot for cutting boards. Specific spot for large plates,
Small plates, bowls, cups saucers. Everything has a place, and that place is very easy to find. Very very clear and apparent where everything goes.

The cutlery basket has a sealable compartment that's big enough to fit things like mason jar lids or baby bottle nips. And the lid on it has large enough slots so it can still hold cutlery. Genious.

If you go wild, Bobloads are SURE to happen with amazing results and capacity. These machines truly hold the most. It's shameful to not run it full, but sometimes you don't have that option as you're out of spoons.

 

[potatochips]

Because the lower spray arm has a GE like wash tower, things can be loaded on the top rack that require wash action from the bottom. In a frantic attempt at finding space, it sometimes can become a catch all for odd items.

 

[potatochips]

The bottom rack is very versatile, even though a slot is cut out of it to make room for the aforementioned wash tower. Casserole dishes and mixing bowls will fit in any order. Cups and mugs can be tightly packed as there are no tines in the back half of the rack.

Medium sized plates, or bowls can also be loaded in the bottom rack too.

Oh, and you bet there are things loaded underneath that metal roasting pan. Versatility.

 

[potatochips]

Noise is a real thing. Although it's not the loudest machine, GE is, it ranks second with Whirlpool during the wash, but loses points as you can blatantly hear the spray arms do their thing. The drain, well if you think Whirlpool was loud pre-tuning weight. This thing sounds very very loud. Offensive drainer.

Options and features? Well just like their "this is a washing machine and this is all you get" attitude towards laundry appliances, there are no special features here. Just different ways of presenting those features. Just a knob, a knob and buttons, a knob and more buttons, only buttons, All controlling the same things.

Heated dry on or off. And temperature boost on or off. Rinse and hold. That's it. And depending on the machine, how the temp boost option works is different. The greatest disadvantage of these machines is that they rely off a hot incoming water, so pre heating the water by running the tap is a must. BOL machines have no temperature assist, MOL to TOL machines may have it either timer controlled or thermostatically. Either way, a temp boost option will extend the main wash by 13 minutes, and Some machines have the heat on at all portions of the cycle, some it's on all portions but thermostatically controlled. There is no uniformity here.

The cycles are ahorter with less water changes. A mainwash is just a prewash, wash, rinse, conditioner rinse. Whereas GE, WP, and KA have different ideas.

[this post was last edited: 10/28/2017-02:39]

 

[potatochips]

The holy grail is the computer controlled WU1000, but like its anologue cousins, it doesn't have anything spectacularly fancy in terms of options and features.

Parts, aside from belts, are hard to find and the lack of a true thermostatic hold or high temp rinse, meaning the reliance on hot incoming water is this machines only true disadvantage.

It is also the only machine where you can easily level the back legs on a built in install. A use once feature, but a feature that shows every single detail (aside from water heating) was thought of.

It is a Bobloading dream as you will purposely dirty things just so you can load it. It will always clean superbly. It will always amaze and confuse house guests, and it will always end up being 3/4 full before a wash is desperately needed. These are amazing machines, and if you don't own one, go find one. They're legendary.

 

[johnrk]

Thanks So Much!

A real enjoyment to read, and learn. I remember looking at these a couple of times for a couple of homes way back when. Never bought one, I was a KA buyer. But I came close because of that fascinating rack system. I never knew about the internals, and you explained them so even I can understand. Thank you very much-

 

[Ultramatic]

Thanks Kevin!

 

 

You just answered a ton of questions! Greatly appreciate the time and effort you had put into this series.

 

[peteski50]

Maytag ReverseRack!

Kevin thank you so much for posting. These DW's were exceptional cleaners and held tons of dishes. I have a friend that had a more basic wu300! A real powerhouse! I used to load her DW quite a bit! Everything always came out spotless and gleaming! Her water was scalding, so their was never a problem. The better models had the water heating - from what I read the Power Boast kept the heater on all through the cycle and heated the main wash to 140 degrees. The Temp Boast heated the main wash to 140 degrees! The Sani Scrub on the electronic model did increase the cycle time by 13 minutes but no thermo hold to my knowledge! This was where Kitchenaid and GE had the advantage over Maytag at the time where all their models can utilize 120 temp! They were extremely noisy especially during drain! They sounded like the old Hotpoints (pre GE Models)! I did always wonder if the more TOL models were more quiet? That reverse rack was one DW I really enjoyed loading and Never being disappointed with the results!
Peter

 

[countryguy]

I had the model 1 below the top of the line all pushbutton model. I purchased it new in 1991 and used it until 2007. It was a great machine, cleaned everything without pre-rinsing but as stated, it was loud. The pics were taken in 2007 just before I replaced it with a Kitchen Aid.

Gary

 

[potatochips]

John and Louis, thanks for the great comments!

Gary, that's a beautiful direct drive machine. Yours has adjustable racks up top, right?

Peter, I have a Jenn-Air clone of a WU1000, and it, although insulated, is not too quiet. The drain still sounds like a jet engine. The water heating regime was strange! I can post the info I have in The Book Of Maytag from the dishwasherus section when I get home from work next week. I think the neat thing is that on higher end models like you said, regardless if it has a thermo hold or not, heating is on ALL portions of the cycle. Pre-wash, wash, rinse, and conditioner rinse are all heated.

 

[peteski50]

Maytag ReverseRack!

Gary - I have this documentation from 1988 - your model looks like the wu702! Kevin yours seems like the wu902! They are both so awesome! I want to try to attach my documentation! If you can read the fine print it explains the differences in the water heating options!

 

[gusherb]

I love my 1983 portable RR I picked up at the Habitat for $50. I was so excited about it I don't even know how I got it home and all the way down the basement stairs without any help or a dolly once I learned they weigh over 200 pounds.

Since mine lives in the basement it only comes out to play on Thanksgiving and sometimes Christmas. I dump everything in a plastic tote bin and carry it on downstairs, pack it full and stand there hypnotized by the rhythmic sound of the wash arms, and that wonderful industrial sound of the huge motor those machines have, I especially love the deep sound the motor makes on startup.
Everything always comes out sparkling clean with no prior rinsing, and bone dry.

 

[peteski50]

Maytag ReverseRack!

I knew a few people that had them but the only one I operated at my friends house many times was the wu300 from 1981. It was awesome loading and you can really pack it full! Never ever disappointed with the results! With no prerinsing! These maytags never had a true pots&pans cycle like whirlpool & GE with extended wash periods! On this wu300 it had heavy wash and about 1983 or so the newer models changed it to pots&pans which was really no different than the heavy wash cycle it replaced! One of the appliance stores that I was in contact with in the early 80's said that when they sold maytags they sold mostly this model at that time! They had that plastic demo in the store filled with water that demoed the reverse rack as most of us are familiar with! Quite impressive! But most of the sales still went for kitchenaid and GE at the time!