Garden Railway Forum

I am installing a lift up (as opposed to lift out) bridge to allow access to the centre of the loop.
It will be hinged at one end and aligned at the non hinged end with lift out rail clamps.
I am concerned that at the hinged end the rail on the bridge will foul the rail on the base when the bridge is lifted.
Has anybody done something like this and are there any tips/suggestions that could be passed on?

There are various types/shapes of cranked or offset hinges available which do exactly what you need. Mainly intended for things like windows to allow the to swing back fluch into the frame but work equally well horizontally as vertically. I used them for railway flaps in front of doors and windows many years ago, when we built a railway line round their bedroom for my young sons, many years ago.
It's too long agao for me to remember exactly what I used but a search on ebay and/or amazon should find plenty of options.

I haven't done it, but if you have the hinge axis above the railhead then there will be no issue with the bridge rails fouling the fixed rails.

You have seen my bridges.
The 'trick' is to have the hinge pivot ABOVE the top of the rails.

These pics are of my alum bar rail, but I did have a bridge with normal rails at Ti-tree, (now demolished and no pics.)
My 'hinge' is just a few bits of steel with 1/4" bolts - rough and ready but been there for 25 years!

Note that I used 'outriggers' to align the rails as the rough hinge had a lot of play. Easy with the alum bar, but it's not hard to do with normal rails - I just ground the foot down to the width of the head and soldered some 2mm brass on.
I used the same method at the 'lifting' end to align the rails automatically.

The Rylston Light Mark 1 had a complicated aluminium through-truss lift-bridge, but the mechanics were simple as per the previous posts with the hinge pivot just above the rail top level, the only thing I would add would be to think about expansion and contraction. I fitted mine on a cold day and then couldn’t close the bridge when I wanted to run it on the first nice sunny day!

Newbie mistake, I then worried (after trimming the rails) that the gap would be too great on cold days, but suprisingly that seemed to be ok. I have no science/maths to offer but a tight fit on a hot day seemed to be just right; but the bridge was under the shade of a Leylandi weed.

Other may offer better advice about the optimum gap but it can be an issue if not planned for. It might be worse in a sunny spot.

The bridge worked well, but as time went on It bothered me that such a grand design was out of keeping of the RLR, so was scrapped and has not been reserved for mark 2.

Andy

Never done a lift up bridge for the garden, but similar to the above, it hinged portable layouts, the hinges are higher that the highest fixed point to allow the items to "swing" away from each other, your bridge should be no different.

Thank you all for the suggestions.

I have 2 options;
1. hinges on top of the bridge seems to be the norm
2. and one suggestion where the hinge is below the bridge.
Bit more thinking/planning to be carried out

Either should work. The 'below' option will be potentially less visually obtrusive but more complicated to implement, I think.

I agree with Philip, the hinge below does look good, but could be complicated, but if you have the skill *and i am sure you have) go for it.

Like the under-bridge solution, would like to see the development of this bridge. Looks like it would work.

Andy

This will be no problem for Ben Hur constructions.

I went with a hinges under the bridge option using this suggestion. I have started building the hinge area and it is working out well so far.
I am using gate hinges The gap needed to allow opening is not really that wide it is slightly wider than the thickness of the board. The bridge will be made out of hardwood reinforced with steel angle.
To get a level, the hinges will be recessed into the mounting block.
The lower part of the hinges will be cut off to remove the piece protruding into the walkway. This is part of Stage 2 of the build and details will be put on my blog in due course.

This certainly looks a robust build

Jimmyb wrote: ↑Wed May 20, 2020 6:05 pm This certainly looks a robust build

Wait till you see the MkII version it is getting bigger than the Sydney Harbour Bridge.
Wood goes and steel is a replacement

GAP wrote: ↑Mon May 25, 2020 10:35 am

Jimmyb wrote: ↑Wed May 20, 2020 6:05 pm This certainly looks a robust build

Wait till you see the MkII version it is getting bigger than the Sydney Harbour Bridge.
Wood goes and steel is a replacement

WOW can’t wait to see that.

Pictures of the mounting block made from "C" Purlins and the new more robust hinge.

Type of Purlin pieces used The mounting block New hinge

I built the bridge supports out of aluminium box section to reduce the weight so SWMBO can open it, if I made it out of hardwood it would be to heavy for her.
The whole bridge will be made out of aluminium.
Some pictures of the supports an hinges also showing mounting block attaching bolts.

After some testing of the track alignment, the supports will have to be re aligned but that is all OK as it is just a simple re-drill of 2 of the 3 hinge mount holes and re attach.
This will allow the track to run straight across the opening with curves either side.

A question was asked on another forum about the pivot height and when I revisited it I found that when track is attached to the supports there is a yawning gap that just does not work.
I have built a proof of concept jig to test the opening method and so far it appears that the secrets to having the hinge below the track is the angle of the cut made to the track, 45 degrees as opposed to vertical seems to work the best with no fouling.
So it is back to the drawing board for this little project.

Bridge Design MkIII proof of concept jig has been built and the design has been tested with positive results.
As previously stated the secret of the opening is the 45 Degree cuts in the rail which allows the moving rail to drop away from the fixed rail without fouling.
The moving arm of the hinge is level with the baseboard and the gap that the rail folds into is not real wide.
The error I made with the MkII was that I put the bridge support on top of the hinge and when the rail was added the gap was just unworkable as the support folded into it, the bridge support will now be level with the top of the hinge and will not fold into the gap.

So now the bridge construction can now begin following the concept principles.
Closed Open Close up (closed) Close up (Semi Open)