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Level crossing gate mechanisms - 4mm


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Stow Park and Blankney and Metheringham have wheel operated gates. There are two gates only and they are arranged to just miss each other in the middle of the carriageway. The crossing is at a skew which helps of course.

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  • RMweb Gold

Somewhere on RMWeb Captain K posted images and detail of how he motorised his. A PM might bring it back?

Sadly, as I have had to tell Gordon, it wasn't about motorising the gates, I think it was simply photos of the four gate level crossing on Callow Lane, which I am also scratching my head about how to motorise...

 

Given my aversion to electrics, it may well end up with some kind of rod and crank mechanism for manual operation - that's how the two level crossings on Bleakhouse Road are operated.

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It's at times like there when the demise of Meccano really sinks home. It would have been really easy back then - a worm, a clutch and a chain drive.

 

And furious cranking from behind the baseboard.

 

 

 

 

 

CRANKING!

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Sadly, as I have had to tell Gordon, it wasn't about motorising the gates, I think it was simply photos of the four gate level crossing on Callow Lane, which I am also scratching my head about how to motorise...

 

Given my aversion to electrics, it may well end up with some kind of rod and crank mechanism for manual operation - that's how the two level crossings on Bleakhouse Road are operated.

My apologies Capt. Could have placed a bet on it being you. Still someone around these parts did it - IIRC (which I obvious;y don't) - it was buried deep in a layout thread. Just like many interesting gems that seem to get lost or go unnoticed and so difficult to find again. Almost certain to be an earlier incarnation of RMWeb. There were photos of the beneath board mechanism and operated by in track loco detection.

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I have some little chips somewhere that have been programmed to operate a pair of servos to open and close the two gates on a level crossing one after the other when you flick a switch. Here is the crossing that I motorised.

 

post-7495-127333657443_thumb.jpg

 

You will just need the chip, a bit of Veroboard, a 5V power supply (4x AA batteries will be OK), an on/off switch and the two servos.

 

PM me if you are interested and I will work out a price for the chips.

 

post-7495-127333484749_thumb.jpg

 

This is a picture of three of them on one board to operate the level crossing, a slow motion point and a semaphore signal. They will do barriers as well of course.

 

Here is a picture of the servos and linkages.

 

 

post-7495-12733379769_thumb.jpg

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Suzie,

 

Thank-you for your offer.

That has spurred me on to draw out my gate plan full size.

In its current configuration the gates will pass each other, so it looks like four servos working as two pairs.

The gates over lap each other when closed across the track.

 

Am I right in thinking that your circuit limits the servo movement to 90+ degrees with the posts acting as stops,

and the thin wire loops acting as omega loops absorbing the over run?

 

Gordon

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In its current configuration the gates will pass each other, so it looks like four servos working as two pairs.

The gates over lap each other when closed across the track.

 

Am I right in thinking that your circuit limits the servo movement to 90+ degrees with the posts acting as stops,

and the thin wire loops acting as omega loops absorbing the over run?

Gordon

 

 

Servo movement is nominally 180 degrees, so the levers in the linkage have to adjust the movement to 90 degrees (or whatever is required if the crossing is slewed). The servos have been used at full travel to make the movement as smooth as possible over 1000 steps. You will need a very good quality servo to track that smoothly though.

 

You should not need the omega loops if you do it properly, but this was a first attempt five years ago and it was all a bit floppy, so I used the omega loops to create some very slight tension to hold the gates shut. It is important not to stall the servos (they typically draw 900mA when stalled and everything gets hot!), you can only use the stiffness of the gear train to hold the gate in place. If you use fast servos there is a little bounce programmed in as the gate slams into the post.

 

 

Depending on how good you are at making linkages you may be able to link the servos to more than one gate, but it will be easier to use four servos.

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Hi

I have used a switch pilot servo drive unit from esu, it can drive up to 4 servos and is easy to configureits dcc comatable and also has a manual function to open and close the servos if your not wanting dcc control try the MERG unit easy to put together and also controls up to 4 servos you will need a set up box with this but not the esu one as its set using the cv settings on your dcc hand set

willpost some pics off both units tomorrow.

 

JOHN.

(Lincoln Central)

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...if your not wanting dcc control try the MERG unit easy to put together and also controls up to 4 servos you will need a set up box with this...

 

Just for clarification, the MERG Servo4 unit will work with or without DCC. The setup box is not needed if you use a a serial cable and a small windows application to set it.

 

Nick

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  • 2 years later...

Here's an overlapping mechanism for crossing gates constructed in brass donkey's years ago. Came from an old railway mag that I might still have.

 

Pete

post-14904-0-27944000-1342717754_thumb.jpg

post-14904-0-62689200-1342717768_thumb.jpg

post-14904-0-99884300-1342717782_thumb.jpg

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