I have a 3 phase Yale 1/2 ton hoist. It has an electric brake with a
solenoid, whose job is to pull away the brake lever when 230VAC is
supplied to it.
The problem is that it does not do it. Instead of steadily pulling
away, it constantly jerks the lever, but never far enough to the end
point where it is supposed to be pulled away. So, the brake is not
disengaged as the hoist operates. I am glad that I noticed that.
I tried pulling on the lever by hand when the solenoid was engaged. I
noticed that if I help the solenoid and pull away the lever to the
end, jerking stops completely, but if I slowly let go of the lever and
it returns to the brake position, jerking resumes.
I am thinking that perhaps this solenoid has two separate coils,
pulling and holding one, and the holding one is not working or not
It may have two windings on one coil. I deal with solenoids like that
all the time. The first strong winding pulls it in then opens a "end of
stroke" switch so it doesn't burn up. Then the second weaker winding is
just strong enough to hold it and can stay energized without burning up.
If the second weak winding is broke, you get a chattering action.
That would be a "Pick and Hold" solenoid. The "Pick" is the strong
winding with the switch, and the Hold would be the weak constant
And the Pick might not be able to pick without the Hold being
energized too, so it buzzes and doesn't open all the way. Or it's
bouncing on the end switch - hard to tell without looking.
Check the connections - If it's two separate windings, there might be
a loose lead.
--<< Bruce >>--
Or it's actually a DC coil and there is suppose to be a diode in
series some where ?
If there isn't any large amount of debris from what you think is
a dragging brake pad, I would leave it alone. It could be a design
feature to simply release the pad to allow them to slip freely and not
create a gap between the disc. This would allow for the quickest
engagement of the pads when the hoist is deactivated and thus less
mechanical slip jerk.
I suppose it could be a AC coil with at shaded ring tip in the
core, if that is the case, there should be some sign of over heated
coil wire that would indicate a few shorted turns, if you can see them.
Also, do do make coils with embedded diodes.
Sigh. As usual, Maynard (AKA: jamie) misses the point. It takes more
than a diode in series to convert an AC solenoid into a DC solenoid.
You also need a filter capacitor or you are trying to operate it on a
half cycle of the AC waveform, giving you 230 * .707 or 162.61 volts
which is 50% of the power of a full cycle. With the filter capacitor
you get 230 * 1.414 or 325.22 DC
You can't have a sense of humor, if you have no sense.
On Sun, 13 Nov 2011 11:47:07 -0600, Ignoramus22978
Yup, it's just a standard box solenoid, probably Dormeyer they make
zillions of them - and all crapped up inside that end-bell. If it was
something fancy it would look it.
Take it apart and clean up all the sliding and metal surfaces, a
little dab of Lubriplate white grease on the moving pole pieces inside
the solenoid, and hit it with some clear-coat to stop the surface rust
on the metal parts - and stop leaving it outside in the rain.
You do NOT want to pull an "Honest Al Babin" and start painting all
over the insides. You want to see if something is starting to crack.
--<< Bruce >>--
That solenoid requires that the pole pieces be in contact. Then it will
hold (strongly). If it can not close completely, it will vibrate. Not
much of a puller, but a big holder.
Check to make sure it can pull in fully and that the poles are not
cruded up. It looks like it only needs some cleaning and TLC.
There is only one coil. You get what you see.
You don't need to listen to me at all, if facts bother you then just
please put me on your ignore list, I wouldn't want to be responsible for
causing you any pain and agony.
It's a shame the simple minded can't see past their nose.
I didn't look at the picture before how ever, that solenoid needs replacing!
Between the corrosion, most likely in the wire too, the laminates
are most likely bad!
THat part of the equipment should be well closed to keep it much
cleaner than that!
I know of an area of our work place where a whole bunch of new
solenoids are stored just for that hoist! We no longer have hoist
of that type in operation. The solenoids are kept on hand for R&D
material until they run out, they also make good look bolt retractors.
On Sun, 13 Nov 2011 09:21:30 -0600, Ignoramus22978
Clean off the corrosion before blundering forward. It's likely that
the jerkiness is cuased by corrosion or rust on the moving parts of
the solenoid. I suggest you tear it apart, clean off what can be
easily removed, use a wire brush on everything else, coat is with some
kind of sealer (clear acrylic), and make sure everything moves easily
and correctly before reassembling. If that's too much, it looks like
the solenoid can be removed with 4 screws and a cotter pin, so start
Jeff Liebermann firstname.lastname@example.org
150 Felker St #D http://www.LearnByDestroying.com
That amount of surface rust and corrosion INSIDE a cover
indicates it's been wet, or in a wet location.
That's a disc brake and should dis-engage when the hoist
is in operation.
Do you have the wiring diagram for this hoist?
I know that label reads, "Caution dual voltage" as an
indication it "might be wired for a different voltage than
what you're using.
Despite all the random guessing, I'm assuming that is a
very simple straight forward coil that pulls the release
on the disc brake.
If that coil is set up for 480 volts and you're putting 240
across it, it IS going to buzz and chatter. It will do that
without any missing diodes, open coils, hidden switches or
two sets pull & hold windings.
If that coil is set up for "dual voltage" it should have
more that two wires connecting to it. Or there should be a
control transformer somewhere else in the housing to supply
the correct voltage to a single voltage coil. Or a dropping
resistor (not likely) to allow a 240 coil to be used on 480.
And the instructions, as such, should have the connection
for both voltages and everything you have to reconnect listed.
Ok, so what is the original coil voltage suppose to be? 230 or 480?
You do know that many of those types of devices that allow you to
rewire uses the same coil for both voltages? Normally the coil is
spec'd out for 230V AC.. which will work in either case, it's just
where you connect the wires to.
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