[si1881]

I am currently trying to construct an operating gate for a private siding - I have the gate which has a pivot long enough to go through the baseboard but have drawn a blank on any kits or mechanisms designed to allow operation of the gate to turn through about 90'.

I was wondering if anyone knows of such a device or where any plans on constructing your own simple set up could be found? I am a bit loathed to try and invent something that may well already exist!

My current thinking is if not - would it be possible to adapt the kind of mechanism/motor kit that is available for the Peco turntable fitted with micro switches to allow the motor to stop when the gate reached its open and closed points.

I have tried trawling the net for devices for level crossing gates etc but apart from modern style lifting barriers there seems to be a gap in the market.

Any ideas would be gratefully received.

 

[dwb]

Have a look at using a Fulgurex motor. One of the Forum's advertisers - DCC Supplies - has information on it. You can get to it via this link

The Fulgurex has a linear motion. You can traslate that to a rotary motion by mounting your gate on the hinge point of a crank and driving the end of the crank with the Fulgurex.

Others will recommend Tortoise and there's no reason why you shouldn't check them out as well.

David

 

[ozwarrior]

Hmm. Good question and reply. There's a guy at my club that might just make use of that idea.

 

[Sol]

Have a look at British Railway Modelling magazine, page 62 of the Sept 2007 issue for an article on a mechanised level crossing.

 

[Gordon H]

Standard (and cheap) R/C Servos are the obvious way to achieve such a motion. The only awkwardness is the need to generate a suitable control signal for them, but this can be done with a bit of simple electronics, usually involving a 556 dual timer chip or similar. I am sure such circuits could be found with a simple web search. MERG produce kits for operating this kind of mechanism (see http://www.merg.org.uk). Item 21 on the kits page.

 

[mikeg]

Whynot use memory wire with a crank, it has all the required strength and is easy to install. It can be used for signals as well. Do a google search and you should fine a few sites. One of a dutch layout uses it for all the points, but I am not sure if the site is still current as the chap has had to move and the layout dismantled.

hope this helps

mike g

 

[poliss]

Can't it be done using meccano parts?

 

[dwb]

QUOTE Standard (and cheap) R/C Servos are the obvious way to achieve such a motion

I keep hearing about servos (eg in ESU SwitchPilot sales material) but I know little else about them. I presume they must be cheap and plentiful to those "in the know", but I'm not. Where can I find out more?

Thanks
David

 

[John Webb]

David,

R/C servos are small DC motors in a plastic case containing a gearbox which links the motor to some form of actuator such as a crank, T-piece or a linear actuator. The internal electronics sets the actuator at a particular position dependent on the signal sent by a transmitter in the form of a variable length pulse. (Usually between 1 to 2 milliseconds long, I recall - so a pulse 1.5ms long would put the actuator in its mid-position.)
The servos are used in model aircraft, boats and vehicles. Some railway modellers in the larger gauges use them to remotely control live steam locos. A model shop selling R/C models can show you what the servos are like. They are smaller than most point potors and quite quiet compared to a lemanco, fulgerex or similar device. They are also rather cheaper, no doubt due to the quantities produced.

It surprises me, on reflection, that no-one has marketed these commercially with appropriate remote electronics to operate railway points.
Regards,
John

 

[dwb]

Thanks for the information John. It's certainly a good question why no one has made a pitch for model railway business. Indeed many shops selling model railway kit also sell RC kit in another department but they don't cross sell? (Does this make me sound like Gary?

David

 

[PaulRhB]

I'd recommend a Tortoise and angle crank simply wired up to a switch to reverse polarity. Simple and reliable.

 

[mikeg]

DWB there is a company who do the servos and control equipment for model rail use, there was an aticle in one of the mags a few months ago but can't remember which one. You have to buy a setup unit with the first unit but then that can be used with any number thereafter. It was not all that expensive for the servos but the unit was I think about £40 or so, and it was thought by the contributor that for a club this could be bought and then hired out to memebers who wanted to use the system, so reducing the cost; seemed like a go idea!

regards

mike g

PS I still think memory wire is the cheapest option!

 

[dwb]

QUOTE DWB there is a company who do the servos and control equipment for model rail use, there was an aticle in one of the mags a few months ago but can't remember which one. You have to buy a setup unit with the first unit but then that can be used with any number thereafter. It was not all that expensive for the servos but the unit was I think about £40 or so,

With the number of points I have to motorise, the upfront cost would be covered over the lifetime of the project. I'm intrigued by the need for such a thing.

David

 

[dwb]

I've done some preliminary research on RC Servos.

First there's the cost, the cheapest seem to be about £8 and come from Futaba; is that correct?

They are generally powered by about 5v DC and need a pulse to activate them. This is best done with a dedicated interface board. As a MERG member I could make use of the kit mentioned by Gordon.

The activation time is generally less than 20ms so they are pretty quick.

The downside for my application is that there doesn't appear to be an auxilliary switch for switching point frog polarity which I prefer on my live frog points and is essential for live frog slips, crossings and three way points.

So for me, a Fulgurex which comes with two changeover switches is a better fit for changing points.

David