Hoist brake solenoid buzzes/fluckers instead of steadily pulling

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.

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

Here's a picture.

i > I have a 3 phase Yale 1/2 ton hoist. It has an electric brake with a

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

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

MikeB

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.

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

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

Have you thought of contacting the manufactirer?

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

How ironic.

Jeff

Yeah, isn't it?

Hope you enjoy your dilemma..

Have a nice day.

Jamie

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

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.

"Michael A. Terrell" fired this volley in news:2-qdnbSWuLmrfyLTnZ2dnUVZ snipped-for-privacy@earthlink.com:

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Michael, it's even less than that: Full-wave single-phase rectified AC has an area under the curve of .707*Vpeak. Half-wave has half THAT area. If you filter half-wave, and draw no current from the cap, it charges to peak V-in.

Filtered - either half-wave or full-wave - the DC voltage never rises above peak, regardless of draw, unless you use a doubler circuit. A full-wave rectifier (with or without filtering) is not a doubler.

Lloyd

How is 230 * 1.414 a doubler? It is a simple rectifier & filter for the input voltage. Of course you have the forward drop of the rectifier, and it will be less than that if the filter is too small. You don't need a full wave bridge, or millions of old line operated radios would have never worked. They were a simple rectifier & a 160 VDC electrolytic, usually around 30 µF.

OK, I kind of suspected that also (based on my past diesel generator experiences).

What else do you expect from 'Skippy - V2.0'? He also thinks Electret microphones are crystal microphones, and that you can easily change the bandgap in LEDs to adjust the color. He's a real, no class clown on sci.electronics.design.

I put some penetrating oil on the screws, I will get it off and clean thoroughly. Thanks.