Top Load Washing Machines

(Est. Reading Time: 6 min)    

How many of you have top loading washing machines? I have one. It has issues, too.

Wait a second, this has nothing to do with software engineering! Hold on, no, I promise that is does.

I've had my particular washing machine for about 4 years now. We had to get a new one at the worst possible time, and paid dearly for it. If you all remember back after the COVID-19 vaccine came out, everything was starting to go back to "normal", except the supply chain. Appliances were really hard to come by, and choices were slim.

Fast forward to a little over a year ago, to the months right after getting laid off from my job at ViaSat. A load of some blankets is in the washing machine getting cleansed, and the washing machine starts blurting BEEP BOOP every 5 seconds with "UR" on the LCD. To the uninformed, that means "your load is unbalanced" in Samsung speak. Unbalanced load? Isn't that part of the job of the washing machine, to keep the load balanced while it's doing its job? This is the first time a washing machine ever told me I had to correct the "balance"  of my own load of laundry.

My instincts in this situation always starts with asking myself: is this something I can fix? So, I "YouTube'd" it. Yes, every repair person said it was easy to do, just a few screws to undo for access, and just replace the dampening rods that have a tendency to go bad. Not to mention, these dampening rods were $70 or more for the set of 4.

Seeing the repair people explain the solution on YouTube really triggered my engineer brain, and I got frustrated. Why would Samsung use flimsy thin rods and weak springs to hold the weight and balance a heavy wash basin with heavy soaking wet fabric at high speeds and great centrifugal force? It just sounds like bad design. I really didn't understand why swapping out the rods changed anything, and how they could even keep a load balanced to begin with.

Do some deep breathing. Take a step back. Its not so black and white.

Just like in software engineering, sometimes we have to work on other people's designs, and deal with the problems in those designs. That's actually just engineering, in general. This washing machine design is no different. An inexperienced engineer will look over a design they don't understand, make some fair assumptions, and claim it needs to be scrapped and redesigned. A seasoned engineer will want to learn WHY it is designed that way, and derive a more efficient and effective solution based on that understanding.

One way we can understand a problem better is to learn how its put together, and then come up with theories on how it can be fixed. So, I studied the internals of the washing machine and I theorized that these thin dampening rods were subject to warping, or the springs in the spring assembly were getting worn and are not as springy anymore. Because the un-balanced load appeared to move the basin horizontally, I suspected applying springs from the basin housing to the frame at the top in every corner would dampen the horizontal movement, thus balancing the load better than the original solution.

This theory didn't pan out, though. It was a $10 experiment, and it failed, but why? Because there is more happening in the original solution.

Looking deeper, it turns out that this particular design for top loader washing machines has been around for decades. It wasn't just a Samsung design. The flimsy dampening rods are even a somewhat universal design seen across brands. They would be interchangeable if it wasn't for the differences in how long the rods are or what type of connections the rods have at the top or bottom.

My theory was disproven, and I was wrong. Actually, most of the time when an engineer has to solve the problems someone else's engineering solution created, they groan a lot and make confident claims that they know a better way. The reality is, the original engineers that came up with the solution designed it that way for a reason. It wasn't just a "cost-cutting measure". It's a complex orchestration of industry design standards, conformity with repair and maintenance protocols, and the balance of cost, weight, efficiency, and effectiveness.

Let's think about how a washing machine works. Dirty laundry and soap is placed into the machine, and the machine needs to automate cleaning the laundry with the soap. Water has to be pumped in, soap get introduced, and the tub contents need to get agitated around to make the soap get all sudsy and start to work. Then the tub needs to drain, and fill back up with water a couple times, to rinse all the soap out. Last, the tub needs "wring out the load", which it does by spinning really fast.

The washing machine is an innovation for doing laundry through automation, freeing up our time to do other things while it does its work. Before washing machines, it sucked to do the laundry. Even if I wanted to design my own machine, I'd probably over-engineer it. But overtime, and many lessons learned, that design will get better and better. That what the appliance industry has typically done, well, until now.

Right now, cost-cutting is cheapening our appliances. Plastic. These major appliance companies are taking these awesome engineering designs, and replacing parts of it with plastic. Sometimes plastic is better. Sometimes, like in this case, its a bad idea to use plastic, but its cheaper. It isn't just Samsung using plastic in the wrong places. Whirlpool, Maytag, LG, GE, and just about all the other brands are also using plastic to cut costs.

Please now refer to my sad diagram of a top load washing machine I made in Microsoft Paint:

There is a mechanical engineer screaming at their computer right now, looking at that.

This is what is causing all the unbalanced washing machine right now:

First, the dampening rods are not bending, and the springs are not wearing out. No, at the top of the spring assembly is a little plastic cap, and it job is to protect a dense little plastic-y foam plug. Its this little plug that actually dampens the movement. Its also getting worn out from, guess what, movement, causing it to not dampen movement. In this picture below, its the white ring in the middle. Making this out of plastic means it actually wears out from dampening motion.

One solution is to fill up the space around the plug with suspension grease. Another is to replace the plug with a foam plug you can punch out of a yoga mat or similar and coat it in suspension grease. Both of those may work, or may not, because there is one other issue that can cause balance problems. When all the dampening rods stop working, overtime, the off-balance loads start to make the basin wear against the axle assembly a lot more.

The axle is thick metal, and its not going to bend. However, the assembly that joins the basin to the axle is plastic. The plastic isn't such a bad design, because it seals better than metal with less friction, and you want to keep the water from the basin housing from leaking. However, they are making the whole assembly plastic now. Most of it used to be metal, because plastic wears down was faster in this application. That's because an unbalanced weighted tub rocking back and forth on a connected axle shift causees the axel to apply frictional pressure against the assemply. 

This can be fixed by taking the basin and housing out, and replacing the plastic bushings with metal ones, but it's a lot more involved repair process, though, still not that complex.

This is what a plastic axle hub and bushing look like. A plastic clamp (the U shaped thing) holds it all together with 6 small screws. This thing screams wear and tear.

A metal axle hub resists the wear, and if you do the work to replace the axle hub assembly, you might as well put in something that isn't going to wear out in a few years.

We know that a brand new washing machine can hurt the pocket book, and sometimes its worth it to just hire someone to fix a broken one, or replace it. But if you really want to see if its something you can tackle yourself, just watch a YouTube video like this one to get an understanding of what is involved and if you are up to the task.

But if you are a software engineer, *ahem* an engineer, and you need to learn how a solution was engineered, keep this in mind: it has a reason to be designed that way, but it doesn't always mean its the best design. If you take the time to learn why it is the way it is before altering it or dismissing it, you find that you can make more thoughtful, practical suggestions and improvements that save everyone the trouble of you just building it all over your way.