Drawbridge build attempt

[Madman]

stainless steel is fairly corrosion resistant, if you can find bronze hinges let me know... You can buy loose pin brass hinges so that the pin can be pulled completely...
http://www.ebay.com.au/itm/Quality-Door-Butt-Hinge-SSH70-L-70x50x1-6mm-Loose-Pin-Stainless-Steel-/271278305073?pt=AU_Building_Materials&hash=item3f29726f31

If you are prepared to spend alittle more, go to a builder's hardware supplier. Pretty much anything is available. It so happens that I was looking for more solid brass barrel bolts for use as turnout controls. I found a whole bunch of marine hardware, which is solid brass plated with chrome or nickel. As I mentioned in another post, I am a carpenter and in my forty plus years in the trade, I installed an amazing array of hardware on doors. We relied on a couple of very knowledgeable hardware suppliers. Whenever we hit a roadblock, they would come to the rescue with stuff I didn't know existed.

 

[Madman]

?? You have Obama in your fridge ??

Dang, I thought it was a tight fit

 

[Madman]

OK, so I did more work on the drawbridge.  Got the hinge thing straightened out.  Even made a temporary lifting mechanism, albeit manual.  I want to study an electric lifting device a bit more before I dive into it.  There is still alot of cleaning up to do like grinding all of the sharp edges and painting.

 

[Tim Brien]

Dan,
what about a reversible rotisserie drive motor for a barbeque. There are numerous inexpensive examples on Aussie eBay so no doubt models should be available in the States.

 

[Madman]

Dan,
what about a reversible rotisserie drive motor for a barbeque. There are numerous inexpensive examples on Aussie eBay so no doubt models should be available in the States.

Thanks Tim. I'll look into those.

 

[Madman]

So in the interim since my last post, I dove into the motorized pool.  When you walk away from a project, it gets much more clear when you return to it.  The motor arrived that I will be using.  It`s a powerful, 12 volt, geared motor.  I repositioned the pulleys and wrapped the 1/16" aircraft cable around each one twice.  I`ve also added a counterweight.  The bridge moves up and down using a small Makita cordless drill.  The drill is temporary.  I am waiting for a coupling so that the 12 volt motor can be installed permanently.  Some photos below.  Photo #27 shows two springs.  I wanted the bridge to raise to a plumb position so that when I have to work on the layout I would have a full 36" clearance.  However, the counterweight will hit the railhead before that happens.  So in order to finish the raising manually, I had to keep the cables taut.  Otherwise they would foul around the pulleys. 

 

[trammayo]

Looks like your on the road to success Dan. That motot/gearbox looks quite nifty too.

 

[Madman]

Those motors are on Ebay. Most, if not all from China. I'm not helping our trade balance am I?

 

[trammayo]

Those motors are on Ebay. Most, if not all from China. I'm not helping our trade balance am I?

I wouldn't feel guilty Dan At least you can buy other things G Scale related from within the U.S. Everything I buy has to come from the U.K., mainland Europe, China or (even the U.S.A).

 

[Andrew Foster]

I`ve been otherwise occupied lately, and missed the start of this thread. My own approach to bascule design is to use an elevated trunnion bearing, the height being set by the highest rolling stock that will use the line, plus the usual clearance standards. The structures are aluminium alloy, with stainless steel and engineering plastic hardware - they last for ever outdoors. The counterweight is concrete and the power source is a small gearmotor using a chain drive. It needs very little power, due to the overall balance of the moving structure.

If you are interested in more about how we do this, drop me an e-mail and I`ll help you if I can. It`s not a sales pitch - we don`t do a G scale bascule!

Andrew

 

[Tim Brien]

Andrew,
now that is nice. Does the bridge open vertically? It looks like the counterweight would contact the rail before the bridge deck was vertical.

 

[Andrew Foster]

Thanks, Tim! Yes - it really does open vertically and clear the track, and I`ll see if I can do a better job of attaching a picture this time.

Andrew
[attachthumb=1]

[attachthumb=2]

 

[Tim Brien]

Andrew,
many thanks. That is indeed a marvellous structure and apart from the absence of a large sector gear plate, it replicates the prototype well.

 

[Andrew Foster]

Tim - when you mentioned the sector gear plate, is that the quadrant plate used in the Scherzer rolling bascule bridge? In effect, it`s a simplified rack and pinion arrangement, but very elegant, particularly in the way it is driven:

We looked at this for the GME bascules, but decided that the cost would be too high; also that outdoors there would be trouble with leaves and such blowing into the roller track - hence the decision to go with the trunnion type. If I was designing a new one in a larger scale, though, I would probably find a way to use the true Scherzer design - it really does look much better.

Andrew

 

[Madman]

Thank you Andrew. Those photos are excellent. I think I got it by the third one

 

[Tim Brien]

Andrew,
yes that is correct. I can see the simplicity of the chain drive method though for reliability.