I have a GE DDE7208 dryer with a 5KH26JJ motor. When the motor is
stationary, the centrifugal switch energizes the start winding along
with the run winding. When I depress the starter, the motor hums but
does not turn even with the belt off. That points to a bad motor, but I
want to be sure.
Winding resistances are 3 and 4 ohms. That doesn't prove the insulation
is holding up at 120 VAC, but if there were a leak so bad that the motor
wouldn't turn even unloaded, wouldn't the overload protector break the
At 2 amps DC, there are only 6 mv across the centrifugal switch, so the
contacts appear to be fine.
Bearings have no slop or noise but more friction than some motors I've
seen. It takes 0.7 inch-pounds to get the shaft moving.
What could be wrong?
My experience with motors is that under normal operation windings don't
fail. Usually the problem is with the "stuff" surrounding the
magnetics. Switches, capacitors, bearings, clutches, etc. Make sure
everything is clean and lubricated. The motor may not have much
starting torque so compromised bearings mare be a problem. Can you
safely give the motor a bit of help when starting to verify or rule this
Thanks. The switch I push to start gave a consistent hum, but I could
check it with a couple of amps to be sure the voltage drop is tiny and
That leaves friction. The 0.7 inch-pounds I measured would be
equivalent to 1 pound of pull on the belt. That doesn't sound like
much, but maybe it was higher before I removed the motor to measure.
One website said removing the motor and vacuuming the dust can sometimes
reduce friction enough to get it working again.
I started the motor several times a few days ago because I was removing
items a few at a time. There was no starting trouble. I wonder if
whatever lubricates the plain bearings got a little gummier since then.
Should I try to lubricate the bearings? I have WD-40, sewing-machine
oil, and motor oil.
That looks like the solution. I measured the friction again, wrapping
the string around the shaft at the blower end, and got 0.5 inch-pounds.
Last night I wrapped the string around the pulley, which is probably
All that friction made me think they were plain bearings. That seems to
be wrong. It's an open-frame motor, so I think I can apply a tiny bit
of "small motor" oil without making a mess.
... Well, I applied a little oil, spun it, and found that the friction
had risen to 5.5 inch-pounds. Now it's back down to 5. It looks as if
something is funny in the bearings, and the oil may do the trick.
Good idea. I wish I'd thought of it before I removed the motor. If the
motor doesn't work when I put it back in, I'll try turning the drum.
Somehow I'll need to press the door interlock and the start switch as I
turn the drum.
Above, I meant .55 and .5 inch pounds. It's going much lower if I pull
the cord two or three times in a row, but higher if I let the shaft sit
a couple of minutes. Maybe the oil needs time to work.
On the red side of the power plug, the side that supplies the motor, I
have about 0.8 ohm, and it varies when I move the cord. I guess a tug
years ago, and countless cycles of heating current, and perhaps
oxidation, have damaged it. Maybe when I hit the start button, the cord
resistance was high enough to severely limit starting torque, and the
cord was big enough not to get hot instantly.
Much of the motor friction was coming from the plastic ring that throws
the motor switches when it stops. Without springs pushing that ring,
the motor feels like roller bearings when it turns.
No. The bearings had a little more friction than I've felt on some 1/4
hp electric motors. Not knowing why the motor didn't turn when I
pressed the button and whether this much friction was normal, all I
could think to do was get a number by pulling a cord.
Isn't 3-in-1 like 5W motor oil without additives?
I want to cut open the old power cord. I'll bet there a lot of broken
copper strands. I wonder how many dryer cords get like that. I wonder
if they are a fire hazard.
For whatever reason, the three in one oil I've had dries out after a while.
I think it's different.
Broken strands. That's why they have so many strands. So one or two can
break, but the rest keep carrying electric. They break in different places
along the cord.
I used Marvel Lubricating Oil. Its recommended uses include small
motors, but I don't know if 1/4 hp is what they mean by small.
Apparently the bearings were doing fine, so it would have been better to
leave them alone. I don't think enough Marvel got into the bearings to
wash away any original lubricant.
That seems to happen with things like headphone cords. I think
oxidation can keep current from flowing from one strand to another. In
that case you replace the cord or the headphones.
I found no broken strands in the dryer cord. Apparently it was a bad
connection in the molded rubber plug.
Clean the berrings with a shot of brake cleaner, Gumout spray, or other
areosol solvent. Let it dry throroughly, specially if the spray is
flammable. The proper lube is something like ND 30 (non detergent). Failing
that, 10w30 should give you years of service.
WD and sewing machine oil are totally not suited. They dry and get gummy.
Some portions of the motor housing or end caps may have "warped" enough
so the outer surface of the rotor will get pulled into mechanical
contact with the inside of the stator when magnetic fields are present
and then "stick there".
Can you try powering the motor and rotating the pully carefully by hand
and see if it seems "stuck" when power is applied?
Can you disassemble the motor and see if there are any "rub marks" on
the outer surface of the rotor?
I've encountered this phenomena a couple of times over the years.
Let us know what you find,
The frame is riveted. Before reassembly I tried looking between rotor
and stator to see if there was dust. The spaces looked even.
After reading your post, I plugged it in and pressed Start. It started
every time. I think maybe oxidation in the damaged stranded wire at the
plug kept the motor from starting, and wiggling the cord has reduced
resistance for now. I'd better get a cord before I try drying laundry.
I have a rattle now. Investigating, I found about 5mm endplay for the
drum. Maybe that's normal. The rattle seems to be coming from the
sheet metal behind the drum, where the heating elements are mounted.
Opening the unit will be much easier this time!
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