Hoist brake solenoid buzzes/fluckers instead of steadily pulling

[Ignoramus22978]

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 engaging?

Any idea?

thanks

[Tony Miklos]

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.

[Jamie]

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.

Jamie

[Ignoramus22978]

[Michael A. Terrell]

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

[BQ340]

There would be more than 2 terminals on it if it had multiple windings.

MikeB

[GeorgeD]

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.

[Jeffrey Angus]

Looks like your typical washing machine part. And yes, lots of hold power when the pole pieces touch.

Serious case of corrosion there. No telling how much surface crud on the sliding parts.

Of course, but we still have to listen to Maynard's view of multi- windings and embedded diodes.

Jeff

[Jamie]

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!

P.S.

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.

Jamie

[Jamie]

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.

Jamie

[Jeffrey Angus]

How ironic.

Jeff

[Jamie]

Yeah, isn't it?

Hope you enjoy your dilemma..

Have a nice day.

Jamie

[Tony Miklos]

I don't see the wires. How many wires does the solenoid have?

[Jeff Liebermann]

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 cleaning there.

[Bruce L. Bergman (munged human]

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 winding.

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.

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[Bruce L. Bergman (munged human]

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.

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[Ignoramus22978]

I bought it at auction.

I have never seen this hoist run.

At my place, I have 240v 3ph only. (well, I have a transformer that I could wire to get 460v, but it is sitting in the corner right now).

i

[Ignoramus22978]

Well, what I know is that I did measure voltage at the solenoid terminals, and it was 230v.

i

[Jeffrey Angus]

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.

Jeff

[Jamie]

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.

Jamie