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Discussion Starter #1
It's always leaped into action when the pressure plate triggers it and then bounces up and down before settling halfway down. I thought that's how they were supposed to work intill I looked on YouTube and saw others that stay down. Any adjustments or repair strategies?

 

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Discretely adding a slight amount of weight near the end of the gate may help keep it lowered. Also, a lower voltage or a 10 watt, 10 ohm wire wound resistor would help slow down the lowering gate.
 

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What voltage are you using to activate the gate?

There's a solenoid in the gate housing; a plunger surrounded by a coil. In the off position, the plunger is fully down surrounded by the coil. When power is applied the plunger jumps up and hits a cog on the gate's axle to force the gate down. Continuing power keeps the plunger up (and the gate down). But only if it's getting enough voltage. Else the solenoid won't be able to keep it's plunger in the fully up position (and the gate fully down).

After that, Doug's suggestion may work. But if the plunger can't keep itself fully up and you add enough weight to keep the gate down, the gate may never go back up.
 

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Discussion Starter #4
The video shows it at 14v but 10v is the same only slower. 19v same same. I've tried adding weight but any weight at all results in it staying down. It seems to me that maybe the plunger isn't staying projected. The others I see on youtube seem to go down firmly and stay down as if held mechanically. Hmmmm
 

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The video shows it at 14v but 10v is the same only slower. 19v same same. I've tried adding weight but any weight at all results in it staying down. It seems to me that maybe the plunger isn't staying projected. The others I see on youtube seem to go down firmly and stay down as if held mechanically. Hmmmm
Maybe the solenoid's coil is "dying". Or some poor internal connection. I presume you checked the connections leading to the gate - that all 14 V is getting cleanly to the gate's terminals underneath.

It's not hard to remove the guts, two screws underneath. That may offer some insight. You can power it outside the gate to see if it stays fully up. But be aware, powering the solenoid outside of the gate will shoot the plunger out of the coil. There's no mechanism in the solenoid to limit the plunger's travel. You'll have to do that manually (finger?)

The gate itself is well balanced. The plunger's own weight is far more demanding to keep it fully up.

There are replacement parts available if you get that far ...

Gate.png
 

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Press down on the Contactor plate under the tracks by hand and see if the gate stays down. If it does, it may need adjustment to activate with a lighter load by turning the thumbscrew.

Larry
 

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Typically the coil and or plunger become warped from repeated use. Your video shows the plunger 'sticks' and then shoots up at which point the gate bounces down. The coil or plunger is binding though and the plunger doesn't have full travel so it can't hold the gate down.

You need to disassemble and free up the plunger for full travel. If you have no success with that you'll have to replace the coil, plunger or both.
 

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Press down on the Contactor plate under the tracks by hand and see if the gate stays down. If it does, it may need adjustment to activate with a lighter load by turning the thumbscrew.

Larry
+1. The OP should test that. But the light stays on in the halfway position. That's why I'm thinking the coil may be losing some power.
 

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Typically the coil and or plunger become warped from repeated use. Your video shows the plunger 'sticks' and then shoots up at which point the gate bounces down. The coil or plunger is binding though and the plunger doesn't have full travel so it can't hold the gate down.

You need to disassemble and free up the plunger for full travel. If you have no success with that you'll have to replace the coil, plunger or both.
If I understand you ... The initial plunger boost to it's halfway point propels the gate all the way down; by the gate's own momentum. But the plunger sticks halfway so it can't keep the gate down.

What puzzles me is this. Cutting power allows the the gate to go back up. So the plunger isn't "stuck". It just can't travel further than halfway.
 

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Discussion Starter #10
I was holding the pressure plate down so I know it had constant power. I think the notion of the plunger getting stuck matches the symptoms. The gate propels down from momentum nut the balance raises it up until it hits the partially extended plunger. Thanks for the diagram. I'll tear it down. Pity, Dad bought it used back in the 60's, been this way the whole time. Thanks everyone.
 

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Discussion Starter #11
The solenoid and plunger are fine. The 252-4 cam is loose on the axle. It looks like it's actually broken. Not surprising but I have to admit it's a disappointingly frail design for something that suffers such violence at such a great frequency.
 

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Discussion Starter #12
EPILOG: A dab of superglue on the axle and cam stopped the cam from spinning on the axle and improved performance greatly. We'll see how long that will last. Thanks for the help.
 

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The solenoid and plunger are fine. The 252-4 cam is loose on the axle. It looks like it's actually broken. Not surprising but I have to admit it's a disappointingly frail design for something that suffers such violence at such a great frequency.
Yep. I have one where the cam was shattered. And two more recent purchases that need to be tested.

Replacements are available but there seems to be different cams depending on year that may be an issue buying the correct replacement.

I have a tiny electromagnet on order. I'm hoping the magnetic pull will slowly lower the gate in a realistic manner. The only issue is it needs to be under the gate itself, maybe embedded in the layout platform Have to see when I get it.
 

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Discussion Starter #14
That sounds interesting. I hope to see a post about it when you do it. The axle replacement looks difficult.
 

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That sounds interesting. I hope to see a post about it when you do it. The axle replacement looks difficult.
Not that bad when I looked at it (though I didn't do it). I did punch out the axle and put it back in - pretty easy but sans the cam. Replacing the cam may be a little harder. It has to be inside the housing when the axle is put back in.

A couple of other thoughts ...

Glue a small, light spring to the top of the plunger to minimize the shock to the cam on activation. And experimenting with minimum voltage required to activate the gate to reduce the plunger's force.
 

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Lionel 252 Crossing Gate on Reduced Voltage - Video

The minimum throttle voltage on conventional transformers varies between 5 and 7 volts depending on the model. In this test, I used a Marx basic transformer. As shown in the video, the minimum voltage is ~6.6 V. The reduced voltage preserves the gate's internal CAM from the violent impact of the solenoid's plunger when using accessory voltage of 14 V - 16 V. And a more realistic gate lowering is achieved.

The next test will use a AC-DC adjustable regulator. Upon activation (contactor, isolated rail) the regulator will use track power as it's voltage source . It will then supply the gate with a fixed voltage regardless of the track voltage. And that fixed voltage can be adjusted to suit the specific gate / desired activation speed.

 

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I will say that almost all the older accessories work best at diffrent voltages. This will change depending on your wiring set ups and how well the item is maintained. I used to have some stuff on a variable output so i could ajust depending on the accessory. This was more important on some of the more complicated activated things. I had the voltages writen on the controllers arount the layout. Glad your gate works well now.
 
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