Sears / Kenmore Progressive Vacuum Cleaner: Motor FAIL

After seven years, our Sears / Kenmore Progressive vacuum cleaner gave off a horrible screech and an intense smell of electrical death, prompting me to tear it apart.

It’s easy to find the two front screws holding the top in place, although you’ll need either a bendy or offset screwdriver to remove them:

Sears Progressive Vacuum - front case screws
Sears Progressive Vacuum – front case screws

Pull up hard on the cord retraction plunger to remove it, revealing the two rear screws:

Sears Progressive Vacuum - rear case screws
Sears Progressive Vacuum – rear case screws

Extract the wires and motor control PCB from their niches:

Sears Progressive Vacuum - motor assembly overview
Sears Progressive Vacuum – motor assembly overview

Prying the latch in the middle of the rear panel (over on the right) releases the motor assembly, which you can then wiggle-n-jiggle upward and out:

Sears Progressive Vacuum - extracting motor assembly
Sears Progressive Vacuum – extracting motor assembly

Disconnect the wires, peel off various foam bits, and extract the motor from its carapace. Measure the blower diameter and cut a suitable plywood clamp for the bench vise:

Sears Progressive Vacuum - custom motor clamp
Sears Progressive Vacuum – custom motor clamp

I loves me some good laser cutter action, even when the plywood crate the laser came in doesn’t have much to recommend it:

Sears Progressive Vacuum - failed plywood clamp
Sears Progressive Vacuum – failed plywood clamp

I vaguely recall reading the purple tinge comes from the bromine vapor used to dis-insect the wood during manufacturing, before shipping it halfway around the planet.

One area of the commutator looks like it’s in bad shape:

Sears Progressive Vacuum - as-found commutator
Sears Progressive Vacuum – as-found commutator

Clean the commutator bars in the desperate hope it’s just random crud, even though that seems unlikely, then connect a widowmaker cord to the motor terminals:

Sears Progressive Vacuum - widowmaker line cord
Sears Progressive Vacuum – widowmaker line cord

Use a Variac to spin the motor at a (relatively) low speed while watching the brushes and commutator:

Sears Progressive Vacuum - commutator sparking
Sears Progressive Vacuum – commutator sparking

Now, that is not a nominal outcome.

The cleaned commutator again shows signs of distress:

Sears Progressive Vacuum - scarred commutator
Sears Progressive Vacuum – scarred commutator

Indeed, measuring the resistance across the line cord terminals shows a shorted winding: 0.0 Ω with the brushes aligned on the bars just antispinward of the scars.

So the motor is definitely, irretrievably dead.

Extracting the brushes shows the arcs have eroded their spinward edges:

Sears Progressive Vacuum - eroded motor brushes
Sears Progressive Vacuum – eroded motor brushes

The dark smudge on the windings seems due to internal problems, rather than just the arcs, because the wiring crossing between the commutator and the smudge remains clean:

Sears Progressive Vacuum - charred motor windings
Sears Progressive Vacuum – charred motor windings

One can buy a used motor assembly on eBay for about $40, with no assurance it doesn’t also have a shorted winding.

Dang, now I gotta make more adapters for whatever vacuum comes next …

11 thoughts on “Sears / Kenmore Progressive Vacuum Cleaner: Motor FAIL

  1. I disassembled a lower cost Eureka vacuum and found that the motor housing was all finest-kind plastic. Not fiber reinforced, just clear plastic. OTOH, Eurekas tend to die with broken hoses, and dealing with the beater drivetrain is annoying.

    We’re getting a few year’s* use out of our house vacuums. Switched to Bissell, but the first one of that brand broke the tab keeping the upright portion in place. It got demoted to the shop, but the replacement was as close as we could match. When I find the round-tuit, I’ll puzzle out the broken tab.

    I never was fond of the auto-retract cords. Much less hassle doing it by hand…

    (*) Between pumice dust and dog hair, it’s a challenge, but the Bissell is fairly easy to clean.

    1. We’re likely to go with another canister vac, if only because the place has no carpets.

      Surprisingly, despite the lingering death of Sears, one can still buy Genuine Kenmore Vacs.

  2. In the spirit of the blog, encase the dead motor, stator and rotor and all, in resin. Then slice into neat elliptical coasters (You wouldn’t simply do a straight equatorial cut through the motor, would you?) for further talking points while consuming those hot winter drinks.

  3. I finally bit the bullet and bought a fancy Míele vacuum. They’re nominally expensive, but I just happened to show up near closing on a slow day and they were extremely motivated to make a sale. I got a nice Solaris for $475 and it’s well designed and durable. I vacuum all sorts of things I probably shouldn’t, and I’ve clogged the hose a couple of times, but all the hose fittings easily come apart to retrieve such things. The only issue I’ve ever had with it was the cord retractor broke after a few years. They replaced it with the new stronger design and it has given no trouble since.

    1. Our Young Engineer once said she used a Snow Crash idiom in a meeting, whereupon a (much older) attendees exclaimed “You read Snow Crash?”

      I was so proud of my parenting …

    2. Makes note to pick up Snow Crash once the Kindle recovers from yesterday’s buying surge. :)

      I rather liked Neuromancer when I read it mumble decades ago.

      1. It is perhaps a satire of cyberpunk novels. One of my favorite chapter endings after a setpiece bar fight: “… after that it’s just a chase scene.”

        And I’ve always wanted a can of Liquid Knuckles in my pocket, although it’d surely be illegal in most jurisdictions.

Spam comments get trashed, so don't bother. Comment moderation may cause a delay.

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s