Transition into (and out of) a gradient....?

[Zerogee]

A question to Those Wot Know, about track entering and leaving a gradient section (simple adhesion track, no racks involved).....

I am installing a moderate (about 3.5%) gradient to connect my ground-level track to a section on raised bed areas; the gradient will be laid in ballast on top of solid blocks, as can be seen in this pic:



The unconnected 6' length of AML track illustrates where the track will run up the gradient, and at the top end of the ramp there will be an LGB girder bridge carrying the track over to the raised bed that can be seen at top right of the pic.
This pic shows the bridge end more clearly (note that bridge positioning is not final, it is just placed roughly in position here):



My question is, does anybody have any advice for managing the vertical transitions into and out of the gradient section? I want to avoid sharp vertical bends in the track at top and bottom of the slope.
At the bottom end there is probably about 18" between the point that can be seen on the very left of the first pic, and the start of the incline - what I want to avoid is any tendency for the point itself to twist due to the upward slant as the track enters the gradient, and also obviously to minimise any derailing risks - and then the same as the line levels out at the top to cross the bridge.

I am generally clamping all track joins everywhere on the line, but what I had thought was possibly having the vertical transitions made up of several short pieces of track (like 150mm half-straights?) joined only by the push-on fishplates, but with each such joint bridged by soldered wire jumpers for electrical continuity (after successfully soldering the power cables to the track last weekend, I'm no longer put off by the thought of soldering directly to the track!)....... would that allow sufficient vertical flexing of the track to avoid any potential problems?

All advice and ideas gratefully received, so over to you chaps.......

Jon.

 

[stockers]

I was using plastic decking which gave a slow smooth transition. I simply stood on the rails to encourage them to bend a bit, using the decking as a template to stop anything going too far. On your blocks, you may need to be a bit more careful. How about using a thin plank as a template and bending off site.

 

[G-force1]

The track should be a curve viewed from the side. A sudden change of grade (up or down) is a prime place for derailments, as the stock will tend to 'ski' over the change.

 

[wandgrudd]

Jon,

thats the way i did on my rack section but have also just gently bent the track as well on other areas.

 

[JimmyB]

My gradients are 1:25, and I try to use a 4 foot length of track to transition the gradient. When i have had temporary fixing the sudden change at the tops of the gradient have proved to be problematic.

 

[Hutch]

When I had noticeable grades, (last house), I used the infamous "BELLY BEND" for transitions.
It worked there.

 

[korm kormsen]

since in our scale(s) there is always a problem with avayable space, keep your transitions short.

let me explain, taking JimmyB's numbers.
a grade of 1 in 25 results in 1.2 cm per foot.
the mentioned transitions of four foot each can be computed with half that elevation. (the middle between 1.2 and zero) we have twice 2.4 cm (4.8cm) using eight foot length.
for a simple under-over situation we need an elevation of 24cm.
24 cm minus 4.8 is 19.2 cm ... divided by 1.2 is 16.
we then need 16 one-foot pieces of track plus the twice four foot transitions. that makes 24 foot of straights (curves need more) to get a track above the other.
that was the good news.

now the bad news:
on the other side you need the same length of graded track (including transitions) to come back down on the bottom of facts.

so...
if you put a one foot long bridge in the middle, you build yourself a nice 49 foot up'n down piece of track. (in case, that it shall be a roundy rounder add another five foot for the R1 curves on both ends.) that are sixteen and a half meters!

Jon,
my councel would be, make the transitions as short, as your longest car is long.
the only important thing is, that no wheels are lifted so high, that the flanges raise above the railheads.
your idea with short pieces of track and fishplates is spot-on. 100 mm pieces would be even better.

steeper than 3% (one in 33) should be left to short trains with powerfull locos.


one goes up 6% (one in 16.7), the other goes down 6%.

http://kormsen.info/landscape/bilder/steigung22.JPG

 

[phils2um]

My max grade is also 3.5%, 1 in 28. That is not really such harsh a gradient. I used both 1.2m straights and 1.5m flex LGB track leading into and out of the grade. No bending was required. The track naturally followed my transitions which were done by eye. If it looks good it should be OK. I would avoid multiple short sections at any cost as they have no chance to create a smooth transition. They wont bend. There will just be a kink at each joint.

Phil S.

 

[beavercreek]

Although my gradient climbs about 3 feet in 40 feet (maxing at about 1:10), the beginning transition is nice and gentle.
The incline does start before a wide curve which then feeds into a long 'straightish' run up to the summit (near where the climb peaks at about 1:10).

So a I used a 2ft straight length together with a 20ft diameter curve and then a 5 ft straight to begin the gradient.

I screwed the 2 ft straight together with the wide curve to a length of thinnish plywood, then propped up on one end and very very carefully applied pressure (with weights or rocks) until I got the vertical 'curve' that I wanted.
I also did the same to the 5 ft straight. Even though the plywood wants to return to its 'flat' state, the track has the bend in place and it is unscrewed before letting the plywood spring back.

I then screwed the track down (into wooden stakes buried to just below ballast level) at various places (every 20 inches or so) to maintain the vertical curve
12 years on, that section has never caused a problem for any loco (oh dear I have summoned up the 'pride before a fall' demon).

 

[Rhinochugger]

Yes, transition is necessary, but it will depend on what locos and stock are going to be operating - long locos and bogie stock will require a more gentle transition - vehicle overhang, coupler heights all being relevant. A long loco or wagon / coach van easily demonstrate the issues, but you then have to remember the cantilever action on the coupling that sticks way out past the axle, or bogie pivot point

 

[Zerogee]

Thanks for all the replies..... but...... I'd hoped that one method might be shown to be more successful than the other, instead I reckon it's about 50-50 between those who advocate using multiple short lengths, and those who go for a long length with a gentle vertical curve in it.....
Guess I'm just going to have to pick one or the other and give it a try..... eeny, meeny, miny, mo... oh hang on, we're not allowed to do that one any more are we?

Ta anyway, chaps!

Jon.

 

[ebay mike]

Jon, how about putting a few vertical hacksaw cuts in the track (rail) - not all the way through, but enough so that a small upward bend can be made. It would obviate the soldered jump wires work. The spacing would be up to you, but if it was up to me I'd make them quite wide in the first instance. If not successful at first attempt you can always put more cuts in.

 

[Zerogee]

An interesting thought, Mike.....

Jon.

 

[ebay mike]

Further to the above the top transition could be accomplished by cutting into the 'foot' of the rail to avoid a gap which might cause wear to the wheels. Come to that you could do it with the bottom transition too.

 

[dunnyrail]

Have to say the only time I have worried about a transision on grades was with the Rack System I installed on the Ruschbahn. Going to a less than 1:10 grade you really do need to think about it. But I do love Stockers solution if putting the boot in, nice one Alan.

 

[stockers]

No need to cut the rail - it will curve with a little encouragement.

 

[Rhinochugger]

No need to cut the rail - it will curve with a little encouragement.

The size of your feet I'd say that's big encouragement

 

[KentKeith]

Don't want to sound old clever clogs but some how I got the transition by slowly changing the gradient and somehow it worked:



Didn't do any track bending or cutting or make any calculations. Like most of the work done in the garden it just sort of happened.

Since installing the above rack line the terminal area on which I was pictured kneeling has been raised by a couple of blocks and today I was removing the rack line so that I can redo the transition onto the rack:




I'll let you know how I get on!!

 

[korm kormsen]

Thanks for all the replies..... but...... I'd hoped that one method might be shown to be more successful than the other, instead I reckon it's about 50-50 between those who advocate using multiple short lengths, and those who go for a long length with a gentle vertical curve in it.....
Guess I'm just going to have to pick one or the other and give it a try..... eeny, meeny, miny, mo... oh hang on, we're not allowed to do that one any more are we?

Ta anyway, chaps!

Jon.

both work well.
only difference is, that it is nearly impossible to undo upward- or downward bents in the rail. (thinking of future re-use)

 

[beavercreek]

both work well.
only difference is, that it is nearly impossible to undo upward- or downward bents in the rail. (thinking of future re-use)

If, using my plywood method to bend the track, you do the reverse...ie bend the plywood so that it matched more or less the bend in the track, screw the track to it, then let the plywood spring back go to its flat state (maybe with a little extra encouragement) it will bring the track back to nice and flat again