Help with a bridge past shed door...

[Realistic_build_Speed]

Hi all, this is my first post on what looks like a really great site.
 

Need some help please... I’ve been working on and off for the last 5 years (!) on a railway in a shed for my Dad. It’s in 00 gauge as that’s what he’s collected all his life.

He’s got parkinsons now so modelling is hard for him and I’m doing what I can to help.

 

Main problem is he wants two loops but the shed isn’t huge so we have to cross directly in front of the door, span of circa 1.2metres. Helpfully it opens outwards.

 

I came up with a few ideas for a bridge and the one that’s lasted longest has a pair of horizontal locating dowels at one end and vertical clamp down magnets at the other. It’s still a bit fiddly but he’s used it successfully to date. Sadly this is now becoming too tricky.

 

I’ve looked at various hinge types and   poured over google then ordered a few speculatively to try, but this hasn’t worked out well before. I’m sure we’re not the only people to be faced with this problem.

 

Can anyone share any bright ideas? Must be intuitive, robust and with no small parts....

 

Thanks in advance!

Alan

[JDW]

The simplest solution would probably be to hinge the bridging section at one end, assuming it is not scenic and doesn't have anything other than flat track on it. Accurate hinges, such as piano hinges, mounted on the top surface of the board would be the most simple, if its a non scenic section, otherwise mounted to the end of the bridging board and the end of the baseboard, providing the frame is suitable.

At the other end, a strong batten for it to rest on when down, making sure its at exactly the right height to give a level board. I'd probably put a couple of locating dowels in the top of the batten and bottom of the bridge board to make sure it stays perfectly aligned. 

To hold it in the raise position, I'd just use or make a simple hook, attached to the wall or roof of the shed, to hold the board when raised.

[mdvle]

Marty McGuirk built a swing bridge for his new Central Vermont layout that looks reasonable simple and durable.  Pictures can be seen on his blog - https://centralvermontrailway.blogspot.com/2019/10/swing-gate-v10.html and  http://centralvermontrailway.blogspot.com/2019/12/end-of-year-progress-report.html

[Harlequin]

Hi Alan,

 

You didn't say why your previous attempts at using hinges didn;t work out but a hinged bridge of one form or another (swing or lifting) is the obvious solution.

 

Alignment of tracks at the hinged end should be reliable. You just need to do something non-fiddly to align the tracks at the landing end. Something like a lever with a good handle on the top that you grasp and push or pull in a large positive movement. I’m thinking that lower down it would produce a smaller movement to drive an alignment bolt into a socket to both set the horizontal position of the bridge and to hold it down if it’s a lifting bridge.

 

Edited January 13, 2020 by Harlequin

[Robert Stokes]

I'm guessing that, unless the shed is really large, the tracks will have to curve as they cross the bridge. It is best if the ends of the lifting flap are cut at right angles to the tracks or as near to this as possible, especially at the opening end. There is no reason why the lifting flap has to be rectangular. I think you will find that, if the tracks are cut at a sharp angle, then derailments will be more common.

 

Another thing to keep in mind is how wide the lifting flap has to be. It need not be the whole width of the doorway. You will probably find that a gap of about 60cm is enough to get through easily. The shorter the lifting flap the easier it will be to get it to work properly. Of course this won't be an easy option if it is already made.

 

It is precisely because of the difficulties with a lifting flap, that I have raised the height of my layout in a shed, to the point where I can duck under a fixed fitting of  tracks across the doorway.

 

Robert

[Phaeton]

4 minutes ago, Robert Stokes said:

It is precisely because of the difficulties with a lifting flap, that I have raised the height of my layout in a shed, to the point where I can duck under a fixed fitting of  tracks across the doorway.

For somebody with Parkinson's this is still likely or impossible to achieve, @Realistic_build_Speed likely to be not easy, but could you take a photograph of the system as it is at the moment, it may give the collective a better idea to come up with a solution. My B-I-L has quite severe Parkinson's so I do understand the issue maybe a little more, but I think the hinge method has to be the way forward. Then with a rope to pull to lift the section up, this needs to be accessible from both inside & outside of the shed, ideally a motorised lift so all he has to do is press a switch to get it to lift & comeback down.

[Robert Stokes]

1 minute ago, Phaeton said:

For somebody with Parkinson's this is still likely or impossible to achieve.

 

Yes, I realise that. I wasn't advocating it for the OP, just explaining why I had abandoned a lifting flap.

 

Robert

[Realistic_build_Speed]

Thanks for all the responses!

 

Firstly, JDW, the bridge is not scenic, it’s just the simplest, cheapest way of filling the gap between the rest of the otherwise U-shaped layout. I’d like to make it scenic (e.g. make it a girder bridge) but time and skills are not on my side. Instead both sides will have a scenic break before the bridge then into a station. One side has an elevated flyover into a single track branch terminus LBT (?) which is not connected to the loops. The other side has a 4-platform station (one for the elevated branch) and service area/sidings which use up the space inside the loop. There is no fiddle yard as such. 

 

Robert’s points are all valid. The bridge is *just * long enough so that the track across it is completely straight, but this results in an infeasibly tight inner loop curve on the side with the single track station. Only stock with two axles, or two axles per articulated bogie (e.g. DMU or an HST) can navigate this curve safely. I was planning to rework it with some radius 3 settrack as I think that’ll just about fit - with the transition from straight to curved being at the bridge / board interface. Failing that I’ll have to get creative and have the curve extend onto the bridge as suggested. 

 

Dad loves Coronation(?) class locos (4-6-2) which haven’t a hope of getting round the inner loop in the current build (0-6-0 Jinty can’t). Not sure the big locos will handle radius 3 any better than the current build but if not the join will have to go on the bridge - or they’ll have to be kept to the outer loop.

 

Re Harlequin’s hinge question - the baseboard is 5mm plyboard over a 25x50mm wooden batten frame. The edges are not that sharp / precise - just as it came from B&Q. As such when anything is screwed into the wood very near the edge it doesn’t seem to have much strength, preferring to break apart into splinters. For that reason I’d shied away from piano hinges before as they seem quite fine and either have to attach very close to the edge or are so chunky that I doubted the track would ride over them. Perhaps it’s time to look again at elevating the track so it rises over the hinges?

 

The second concern was “how will the track ends come together with hinges?” With the dowels one end the bridge “buts up” along the running axis and is therefore guaranteed to locate properly, and come out again without the rails snagging each other. With hinges I was concerned that I’d have to leave a huge gap at that end to ensure the rails didn’t catch as the sections moved past each other.

 

The other end drops in once the dowels have located - so it’d be the same with the existing arrangement or a hinge. To validate the concern though, the non-dowel end has snagged a couple of times and I’ve had to repair or replace the track on each occasion. The dowel end has a copper plate screwed into the board with the track soldered to it. That has proven resilient so I will convert the rest to the same as arrangement once I have a concept that works.

 

I had actually seen the swing bridge before, but I’ve struggled to envisage how it would work with the space we have available. It’d need to be a heavily compressed version and I’m not sure I have the woodworking skills to make it happen, or to make it robust and reliable. I’ll measure up again though to be certain.

 

Motorised would be fantastic and a hinged concept (in either axis) would facilitate that immeasurably. The current concept is beyond mechanisation. That being said we’d both settle gladly for a lift-to-open-then-let-gravity-close-it system.

 

I don’t have pictures with me now but will take plenty next time I’m up there (it’s a c2hr drive door to door hence the glacial progress in the last half decade!).

 

Thanks again all!

[Robert Stokes]

The way to use hinges and have negligible gap between the track ends, is to mount the hinges (two small types with one each side of the tracks) so that the middle of the hinge axis is just above the top of the rails. If you draw a side view diagram of the situation you should see how the system works to stop the track ends clashing. I hope this helps.

 

If the tight curve is at the opening end then take a larger radius curve onto the lifting flap but make the end at an angle as I mentioned earlier. This also means that you can make the gap a little wider for easier access.

 

Robert

[Phaeton]

Just another thought you don't say where your father is, but maybe try a local modelling club, if you supply the tea & biscuits you might get a couple of folks to come over, look, provide some suggestions & possibly if you offer to make a donation to the club build fund give you a hand.

[Harlequin]

Hi Alan,

 

Thanks for the explanation. As Robert says, mount the hinges on blocks either side of the track to bring the axis of the hinge just above rail height. Those blocks can be glued and screwed through to the wooden battens underneath the plywood deck to make a solid construction.

You'll need to chamfer the frame at the landing end so that it doesn't foul the baseboard as it lifts.

 

Unlike Robert, I wouldn't be concerned about the track crossing the joins diagonally, even while curving. If the alignment is good, if everything is solidly fixed and the gaps in the rails are small, it's unlikely vehicles will derail. The bridge would then be simpler to build becasue the ends would be square.

 

To get good alignment and small gaps in the rails, lay the tracks across the bridge and across the joints, solder the rails to copper clad PCB either side of the joints and when you're sure it's all solid then use a thin slitting disc to cut the rails.

 

Edited January 14, 2020 by Harlequin

[DCB]

To steal Harlequin's idea and sketch, I had this issue.  Two lifting sections one of which lands on the other. I adopted a just a bit higher than rail level hinge solution but the hinges wouldn't stay put, the constantly  worked loose.   Problem one was the door hinges I used had too much slop, and the second was I didn't get them quite in line, third they were screwed through the baseboard surface gradually compressed loosening the hinges.   .   The cure took a long time to work out. For years we tried not to lift it and crawled under, but in a Eureka moment I found car bonnet hinges.   Flat metal plates with a shouldered bolt through.   Screwed  to the sides of the lifting flap and baseboard  with short fat stubby screws its massively engineered and has almost no play at all. It works in the plane intended with less load than the Car bonnet applies,  Ordinary domestic door hinges work at right angles to their intended orientation.

From above the hinge is about an inch long, against about 3" for a small door hinge but stands an inch or so higher.  See my scrawl on Harlequins beautiful drawings.     I will look for pics of the lifting section and its hinges

Edit, the pics now posted, not as good as I hoped, will do some more next time I'm home.  One with Jinty was done when I sold it on eBay shows it on the upper lift section, the bridge, just passing the hinge which is inside the abutment .  The other shows the lower lift section with multiple tracks taken 5 years ago shows the hinge without its usual concealing bit of scrubby bush. It has needed no attention at all in 5 plus years.

Edited January 14, 2020 by DavidCBroad

[Realistic_build_Speed]

Fantastic input, thanks all.

 

I’d debated the car bonnet hinges before, I thought there’d be quite a lot of play...? Did you use any particular make David? As an aside, I have that same Jinty... 

 

For some reason offsetting the hinge centres never occurred to me. Genius and so simple / elegant a solution once it’s pointed out... This has given me a lot to think about and to try out.

 

By “thin slitting disc”, are we talking Dremel-like devices? I have an angle grinder but it’s not exactly the correct scale...

 

So grateful to you all for taking the time to help out. It’ll mean a lot to him if we can crack this and move on once and for all from bridge dramas!

 

Edited January 15, 2020 by Realistic_build_Speed
Spelling

[Stubby47]

I have a curved loop on a small 4x 2 layout that folds to give a complete circle.

I've used fire door hinges to ensure zero movement in the alignment.

 

Also agree to raising the axis of the hinge above the rail height.

 

Stu

[DCB]

2 hours ago, Realistic_build_Speed said:

Fantastic input, thanks all.

 

I’d debated the car bonnet hinges before, I thought there’d be quite a lot of play...? Did you use any particular make David? As an aside, I have that same Jinty... 

 

The hinge has almost no play at all, just a few thousanths of an inch  The principle is a shouldered bolt passing through a coupe of steel plates, maybe 1/8th" 3mm or less  thick. I think mine came from a Ford Focus but there are a wide variety of other suitable scrap cars in my local scrap yard.  For the upper bridge I drilled some steel plates to suit some shouldered bolts.  Push Bike chain ring bolts might make suitable pivot bolts if you make your own hinges.

Edited January 15, 2020 by DavidCBroad

[DCB]

Duplicate.

Edited January 15, 2020 by DavidCBroad

[Realistic_build_Speed]

At last, a chance to get to the shed and take a few pictures... 

 

Unfortunately as you can see it has been partially disassembled since my last visit following a breakage while trying to release the bridge. It really needs to be flawlessly effortless to operate.

 

Next time I get up there I’ll measure up properly. Had my son clawing at me this time wanting to drive the trains...

 

Three photos below. First shows the landing area, with a magnet facing upwards to clamp the bridge down. Black marks show where the wooden sides of the bridge (used for both strength and to ensure nothing falls off) rest when it’s positioned. Track is offset as he originally wanted three tracks over the bridge. Second shows the end Where  the dowels mount into the wooden baton. Third just showed the bridge stores on some hooks.
 

 Would really like to have it hinges but as you can see it’s really close to the shed door as Dad wants the longest trains here can possibly fit.. 

Edited March 2, 2020 by Realistic_build_Speed

[APOLLO]

 

Have a look here - scroll down a bit for my post & photos. I used Paste table hinges for the lifting bridge. Hope this helps.

 

https://www.rmweb.co.uk/community/index.php?/topic/64295-wright-writes/page/1128/

 

Brit15

 

 

 

[RJS1977]

Thinking a little bit more "outside the box".......

 

Could the bridge be attached to the door, so that as the door opens, it moves out of the way, and when it closes, it lines up again?

 

You would need to cut the board join off at an angle at the moving end of the door, and possibly at the hinged end as well. 

[DCB]

If you have the height you can set the hinges back as shown in my doodle. 

It does make the deck longer.   The pivot needs to be exactly horizontal and at right angles to the deck to make life easy

I use steel strip AKA car bonnet hinges.

The upper bridge in my photo above has this set back hinge feature hidden in the bridge abutment

[Realistic_build_Speed]

So! The end result. Taking on board the suggestions here and aided by the fortuitous presence of a folding wallpaper table we have the attached...

 

Elevating the hinges was the missing link. Works a treat and we have a tight, well-controlled interface at each end which is basically foolproof. Bridge is either up (and deliberately must be held that way while you pass under it to ensure no trains try to fly) or its down and instantly operable.

 

 Thanks everyone for the ideas!

 

Edit: actually only have a photo of the trial fit. It’s now reinforced, aligned and y’ know, has rails on it.... Light was fading when the action shot was taken but we have two operable loops and City of Nottingham christened it with a rake of BR Maroons.

Edited March 14, 2020 by Realistic_build_Speed
Photo fail

[DCB]

Looks good. I never thought of pasting table hinges,   Good tip,  You could use the rest of the table for framing.   I have a weighted flap which comes up to block off the tracks when the bridge is up.  I posted about it on this forum

see  Train Protection Barrier By DavidCBroad, July 29, 2018 in Layout & Track Design

Basically its a bit of string over a pulley to a clock weight which pulls the flap  up as the lift section rises. Prior to that locos had been caught in mid air and a couple of locos bit the dust, a  Gaiety 57XX which bounced   and was undamaged and a Mainline/K's Dean goods which didn't and wasn't.  The lift section has a catch which holds it vertical, bit of shaped plywood.  I will get pictures

Edited March 14, 2020 by DavidCBroad
Added info

[Realistic_build_Speed]

Thanks David. I deliberately didn’t put in a latch as I’m worried it’ll get left up as things start moving. A DMU and a really nice 2-6-2 Tank Engine already had incidents....

 

I like the weighted flap idea and am also looking into an electrical interlock which would cut power and light up a warming lamp or similar. Ideally it’d set all signals to danger but I think that’s be a long term r&d piece!

[RJS1977]

One way of preventing trains from falling off (on the 'free' side) when the flap is raised would be for the last couple of feet of the track approaching the gap to be fed through door bolts from the flap itself.

 

[Realistic_build_Speed]

The other way I was considering was feeding the layout with power via the bridge, such that when it’s raised it’s impossible to move any trains..