About 20 years ago, I bought a new refrigerator from Sears. Since Sears sells a ton of refrigerators, you would expect the engineers to know how to design an effective, long-lasting motor.
After about six months, I started to hear the freezer fan blade hit its housing. One of the things I like about Sears's products is that a parts list is usually provided. You can order the parts at a reasonable price and repair it yourself. I found the parts list and ordered a new fan motor. So far, so good.
When the parts arrived, I disassembled the freezer ductwork and removed the old motor. It was like one of those old record player motors with only a rotor surrounded by laminated iron and an A/C coil. The fan was attached to the shaft. I couldn't believe what I was seeing. The motor and fan assembly had only one bearing. Was it placed between the fan and the rotor? No!
This horizontal shaft motor had the only bearing on the end of the shaft opposite the fan. This bearing bore the entire torque from the weight of the rotor and fan, a direction it wasn’t designed to accommodate. It looked like a felt-filled bearing with a brass housing. How could this get through design, development, and manufacture? Somewhere along the way, someone must have said, "This doesn't make any sense." Apparently not.
The new motor placed the bearing between the rotor and the fan. Someone finally figured out the faulty design.
This entry was submitted by Rob Youngberg and edited by Rob Spiegel
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The analogy with record-player motors is very apt. I've restored a bunch of turntables, and the motors tends to not have been designed with long life in mind. Nor are they designed to provide reasonable torque, which is something you'd think would be a requirement. Like so many other things, the prime design requirement seems to have been, make it cheap. So typically the bearings don't maintain lubrication all that well and they get gunked up pretty quickly, reducing torque, and so the motors can't turn the platter. Not as bad as your one-bearing Sears refrigerator motor, but not great design either.
Alexander, as I understand it low torque is actually desirable for a turntable. The low torque combined with the rotational inertia of the platter + record forms a low-pass filter that IIRC reduces wow and flutter.
On appliance quality in general, this is why I've learned to buy based on quality and reliability and not just on price. Manufacturers have to build what sells. Buying based only on price forces any manufacturer that wants to stay in business to shave off just as many pennies as the other manufacturers, and (no big surprise) product quality suffers. You (hopefully) get what you pay for. I try to find product reviews on e.g. Amazon and Consumer Reports and avoid buying junk, so manufacturers lose business by building too junky products.
Wow, that is really creative!! The long standing, centuries old (The ancient Egyptians even figured this out) standing tradition of having TWO bearings per motor was improved upon and cost reduced. McMaster has that bearing for $0.29.
Multiple bearings virtually eliminate the excessive moment load currently being placed on the journal bearing.
Two ABEC-5 bearings cost around $7.50. So they saved 14 bucks making the refrigerator.
Personally I would be willing to pay an extra $14 to have these on my refrigerator...
Well, I have a GE refrigerator and I can not find a single design flaw. Ice maker, ice crusher, water dispenser, all have worked perfectly for 3 years...
I have a Whirlpool and there are some condensation weirdnesses that I can't figure out. My crisper drawers slowly fill with water. Everything else works fine. So I drain the crisper drawers once a month and everything is fine. But it's not right. The fridge is seven years old.
There is normally a tube running from the bottom of the freezer compartment to the drip pan under the fridge. It provideds a path for water during the defrost cycle of the freezer. If the tube is clogged, the water will enter the fridge and pool in the bottom or the crisper drawers. The tube is probably hidden under the freezer bottom tray. Remove the tray (tools probably required)and run a piepiece of wire through it to open the line. You may have to let the fridge manually defrost if the tube is plugged w/ ice
In a case like this I often wonder if a basic design FMEA had been performed. How often do we see something so simple slip through the design process? Often I wonder if work like this was actually done by a design engineer or if it was done by someone that wasn't really qualified to design a part like this. Engineering is a profession and when designs like this are used in products I believe it gives the entire industry a black eye.
We all like to bellyache about how poorly made our fridges (or stoves, washers, or other white goods) but I wonder what the reality is like for the engineers on the other side of the fence? I sure would like to hear from someone who did their time designing this stuff to find out what the reality is. Do they put stuff out knowing that it will fail? Do they do a warranty cost benefit to using parts they know may attract a lot of warranty costs? And balance this against the potential bad reputation that the product name will attract if too many failures get noticed? I think that the Manufacturers calculate this stuff to the last penny. Which puts to shame any sales blather about quality in manufacturing. The true maximum profit sweet spot must be to produce something less than quality, at a sticker price that sells, and accept the monkey derision?
If you are (or has been) one of those engineers, I'm sure you have a point of view that many of us would love to hear!!!
I work in design engineering so I can let you in on a few secrets:
Factor in the cost of the part + cost of assembly (often more than the part itself), multiply by x thousands units, a small cut in the individual cost of an assembly translates to big dollars.
Using an off-the-shelf part originally designed for a different part is a big reduction in NRE.
Parts are designed for a specific life-time, not eternity. 20 years is beyond the typical lifespan of a household appliance.
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