Point Rodding - some questions

[LNERGE]

[LNERGE]

Compensation doesn't have to be a precise science. A foot or two out wont make a jot of difference. It should be possible in most cases to plant compensators arm to arm under the rodding run but provision must be made for greasing etc by special nipples or other means to keep things lubricated.

 

[The Great Bear]

Compensation doesn't have to be a precise science. A foot or two out wont make a jot of difference. It should be possible in most cases to plant compensators arm to arm under the rodding run but provision must be made for greasing etc by special nipples or other means to keep things lubricated.

 

 

Thank you for the pics, helpful, and the comment: realise now that a bit of leeway ok. Should have realised that.

[TheSignalEngineer]

Taking into account the rodding lengths and crank actions it is unlikely that two compensators would come in exactly the same spot. They would be staggered so that the downset joints didn't conflict with the compensator arms.

 

In the case of a heavy route I have seen several instances of compensators fitted opposite each other, as in the picture above, so that one was towards the cess and one towards the bank.

[The Stationmaster]

A way of doing it (even includes a proper Reading pattern comp crank in the foreground ) when there are 3 comps close together, note the common Western practice of fitting the cranks to ironwork between the concrete beds.  (apologies for tardy reply - I've been on hols, again).

 

[The Great Bear]

A way of doing it (even includes a proper Reading pattern comp crank in the foreground ) when there are 3 comps close together, note the common Western practice of fitting the cranks to ironwork between the concrete beds.  (apologies for tardy reply - I've been on hols, again).

 

Interesting picture, thanks Mike. No need to apologise about delay or having a holiday. Not sure to what extent I am going to model these, that's a little while away.

[RedgateModels]

in case some have missed my blog here's a couple of links

 

http://www.rmweb.co.uk/community/index.php?/blog/534/entry-14124-rodding-board-one-done/

 

http://www.rmweb.co.uk/community/index.php?/blog/534/entry-14071-rodding-rodding-everywhere/

 

and now the signal wires

 

http://www.rmweb.co.uk/community/index.php?/blog/534/entry-14190-signal-wires-pulleys-and-horses/

[The Great Bear]

Well, progress on the layout is such that finally getting around to adding the rodding. Straight away I'm realising it's not straightforward either in planning or execution.

 

First bit of first run

By quirk of geometry, if (big IF) I have understood correctly what to do the compensator would be right next to the crank, is that alright? (Edit - is that what it shows in your second photo, Mike, on the run coming down from the top of the photo?)

 

Alternatively, would the arrangement below work instead. I think the run under the track effectively becomes the compensator?

 

(Looking at photos of the real thing the run which continues to the trap point on the siding was in the 6 foot and not running along the cess, but the point was further away from the box.I need to remember for crossovers and this one to have the push-pull such that the points move in the right direction together.)

 

There will probably be some more questions - sorry - until I've got the hang of this.

 

Thanks

 

Jon

[Grovenor]

 

the compensator would be right next to the crank

If you can arrange for a crank half way along the route then the compensator is not needed as the crank can be used to change push to pull. The essential thing is that half of the run should be in push and half in pull.

For a crossover you treat each section of the run seperately, ie from box to first turnout has to be half push half pull, then the sectiion from first turnout to the second turnout also half push half pull.

Regards

[The Stationmaster]

Jon

 

Looking back at that picture I can only just see a comp in it, almost at the very top of the view - I suspect what you are seeing is a crank and not a comp.

 

As Keith has said what it is all about is equalising the amount of pull and push in a rodding and don't forget that cranks can be arranged to reverse the direction of movement so that a pull on one side creates a push on the other side - so taht would always be the first port of call for equalising push & pull in a rodding run. 

[The Great Bear]

Jon

 

Looking back at that picture I can only just see a comp in it, almost at the very top of the view - I suspect what you are seeing is a crank and not a comp.

 

As Keith has said what it is all about is equalising the amount of pull and push in a rodding and don't forget that cranks can be arranged to reverse the direction of movement so that a pull on one side creates a push on the other side - so taht would always be the first port of call for equalising push & pull in a rodding run. 

 

 

If you can arrange for a crank half way along the route then the compensator is not needed as the crank can be used to change push to pull. The essential thing is that half of the run should be in push and half in pull.

For a crossover you treat each section of the run seperately, ie from box to first turnout has to be half push half pull, then the sectiion from first turnout to the second turnout also half push half pull.

Regards

 

 

Keith, Mike - thank you, starting to make sense...

 

I think, hopefully, the below takes on board what you have said? I'm not sure about the stuff immediately in front of the box, though here they cross only signal wires. Or is the run from the box to the point short enough, 8¹/₂ yards, not to have to worry about expansion?

 

 

Thanks

Jon

[Grovenor]

Looking pretty good to me, you might find this worth a read.

Regards

[The Stationmaster]

To be honest I've never seen rodding like that Jon )well not on the Western anyway.  Trying to think back to point ends that near the 'box - if you make the rod coming out of the 'box push you will get, presumably 52mm of push then 8+15+20 (=43) of pull which over that sort of fairly short distance would I suspect be sufficient to avoid problems.  The leading off rod from a GW 'box is very easy to arrange to either push or pull simply by reversing the crank under the 'box and it's not unusual to find cranks both ways round under a frame.

[The Great Bear]

To be honest I've never seen rodding like that Jon )well not on the Western anyway.  Trying to think back to point ends that near the 'box - if you make the rod coming out of the 'box push you will get, presumably 52mm of push then 8+15+20 (=43) of pull which over that sort of fairly short distance would I suspect be sufficient to avoid problems.  The leading off rod from a GW 'box is very easy to arrange to either push or pull simply by reversing the crank under the 'box and it's not unusual to find cranks both ways round under a frame.

 

Thanks, Mike. That's a lot simpler.

 

How the crank in the 6', turned around to reverse the push to pull, fits with the other ones doesn't look straight forward, a different shaped crank might fit, I guess? The cranks shown are a bit diagrammatic, may try and draw up in more detail.

 

Quite how I'm going to build this detail is another matter...

 

(The bit in front of the box I'm going to cover and not model, so if what's drawn is amiss it won't bug me.)

[Grovenor]

You do need to look carefully at how you are going to get those 6 rods through the sleeper bays.

What's the significance of the stagger in the track between the box and 37A point end?

Regards

[The Great Bear]

You do need to look carefully at how you are going to get those 6 rods through the sleeper bays.

What's the significance of the stagger in the track between the box and 37A point end?

Regards

Good point, thanks - there's only so much I can do on the pc; I've realised as well the ground signal for the point is a bit in the way here too.

 

The stagger is draughting error, bodge in XtrackCAD when I first drew the track plan. Not there in "reality"

[The Great Bear]

Some experimentation with rodding and the cranks as discussed above in my layout thread here http://www.rmweb.co.uk/community/index.php?/topic/26456-marlingford-begbrooke-point-rodding-experiments/?p=2194317

 

A few things need refining the test was a much to see if I could build what's been discussed here. Answer - yes, more or less and hopefully more practise will improve things.

[The Great Bear]

I have some new bits to try to model the rodding, 3d printed stools. More of that anon on my layout thread.

 

In the meantime, to work out what to model, I'm struggling to find good / colour pictures of round rodding, almost all even when searching for GWR bring up the latter channel type. I can see that the channel stuff is on I shaped concrete blocks it looks like, for older round rodding what would this be on? (I'm trying to work out, what if anything to put under the 3d printed stools and would this be visible, depends on the ballasting I suppose.)

 

Also I can't clearly see in photos the detail for where the take off to a crank for a crossover, where the longitudinal rod continues on to the other point. Is it a lug on the underside of the rod driving the crank underneath?

 

Thanks

 

Jon

[Grovenor]

The supports for the A frames will look pretty much the same whether it is for round or channel rodding. Most of the support is buried, rather like an iceberg. Visibly it will be a timber or concrete plank, or in some cases cast iron stools that hold the A frames directly and will hardly be visible at all.

 

With channel rodding the link for the first turnout of a crossover is indeed a lug on the underside of the rod, the lug bolts into place with T bolts in the same way as the fishplates so you see the bolt heads on the top. Not sure if round rodding used lugs but the alternative is to use wide jaw rods to connect to the crank so two rods connect to the crank, one over the other.

Regards

[The Stationmaster]

I have some new bits to try to model the rodding, 3d printed stools. More of that anon on my layout thread.

 

In the meantime, to work out what to model, I'm struggling to find good / colour pictures of round rodding, almost all even when searching for GWR bring up the latter channel type. I can see that the channel stuff is on I shaped concrete blocks it looks like, for older round rodding what would this be on? (I'm trying to work out, what if anything to put under the 3d printed stools and would this be visible, depends on the ballasting I suppose.)

 

Also I can't clearly see in photos the detail for where the take off to a crank for a crossover, where the longitudinal rod continues on to the other point. Is it a lug on the underside of the rod driving the crank underneath?

 

Thanks

 

Jon

The GWR used concrete supports for rodding roller assemblies although I'm not entirely sure what the might have done before have their own concrete works but it looks as if the stools might have been cast iron (the Western never seemed to use wood - probably on the grounds that it eventually rotted).  A good photographic source is Noodlebooks 'Great Western Infrastructure 1922-1934' - some of the captions are distinctly shakey (and occasionally downright wrong) but the photos are superb and well reproduced.

 

Lugs were definitely used to take drives off round rodding runs which continued on to another function but I don't know of this was the only way in which it was done.  All the pin joints, as with channel rodding, were blacksmithed from stock parts on site so some variation was possible.

 

http://www.crecy.co.uk/great-western-infrastructure-1922-1934-stations-signalling-track

 

There might be something among this lot - but there is an awful lot of it and even if you know the drawing or stick number the next problem is finding a  copy of it as many Reading drawings were dumped.

 

http://www.signalworks.co.uk

http://www.signalworks.co.uk/draw1.pdf

[The Great Bear]

The GWR used concrete supports for rodding roller assemblies although I'm not entirely sure what the might have done before have their own concrete works but it looks as if the stools might have been cast iron (the Western never seemed to use wood - probably on the grounds that it eventually rotted).  A good photographic source is Noodlebooks 'Great Western Infrastructure 1922-1934' - some of the captions are distinctly shakey (and occasionally downright wrong) but the photos are superb and well reproduced.

 

Thank you, Mike, for reminding me that I have that one . I even managed to find it straight away in the shed. Whilst the subject of a lot of the photos are signals, point rodding appears in a lot of photos too.

 

A quick scan through suggests the majority of supports (at the time of the photos) to be something darker than the surrounding ballast, looks like metal or wood. Showing this, I particularly like the photo of Bathampton on pg 25 with the rodding running down the middle of ex broad gauge 6' plus, like I'm proposing in part. The picture of Yeovil Pen Mill on page 30 again shows something darker supporting the rodding and, hailing from that town, is of interest to me, a reminder how much more interesting the railways used to be there before my time . (The same could be said of a lot of places, of course...)

 

There are some photos eg one at bottom of page 11 of South Harefield Halt showing new rodding where the supports are paler than the ballast, so concrete I assume.

 

So this evidence matches your and Keith's thinking

 

By the way a couple of links I found this afternoon for anyone else's reference, the first being Keith's own site

 

http://www.norgrove.me.uk/resources/rodding.htm

 

http://www.tventon.freeserve.co.uk/pointrod.htm

 

Thanks again, Mike and Keith

 

Off to model this later...

 

Jon

[The Great Bear]

Bingo! Looking at my collection of photos of Kidlington again, there's one dated 1954 clearly showing round rodding in the up cess south of the signal box on concrete supports. Whether this is the original rodding (box and track layout dated from 1890) or was later replacement and if so when that was done I know not. What to model may boil down to what's easiest, then!

[The Great Bear]

One thing I've realised I haven't taken account of in my planning of the rodding is the detail of the facing point locks and the position of any locking bars, if present.

 

From reading past questions I have had answered and also articles in Model Railway Constructor February and March 82, acquired for this purpose, I believe locking bars are required on the facing points unless covered by track circuits to prevent release with a train on them? In the diagram below, in the equivalent real layout at Kidlington, track circuits were provided at 6, 38 and 40 and 8, 44 and 45. In reality the first three of this list were the other side of the accommodation bridge. I am surmising that track circuits were provided for these signals because the bridges/distance would obscure view of train standing at these signals from the box?

 

 

So, assuming my thinking is right, FPL 28 doesn't need a locking bar but the others do. Which then leads to the question of how these might be arranged and the rodding linking to them. I've gleaned some ideas from the MRC articles but the points where the FPL is for two close together points looks a challenge as they aren't far enough apart to get the bar (40'?) in. Take for example 34...

 

(Confusingly the above screenshot is rotated 180 degrees from the signalling diagram and the lever numbers in the above are wrong, they don't match the signal diagram anymore having reversed that to suit my operating position and how my lever frame arranged.)

 

Is what I have shown for the locking bars plausible? And what to with 23 on the end of the double slip?

 

How much of this I model I am debating as a lot of the area above is under the road bridge, so like a lot of my questions, they are as much for my education as for the model-making.

 

Thanks

 

Jon

[Grovenor]

 

(Confusingly the above screenshot is rotated 180 degrees from the signalling diagram and the lever numbers in the above are wrong, they don't match the signal diagram anymore having reversed that to suit my operating position and how my lever frame arranged.)

It would greatly help making comprehensible suggestions if you first got your diagrams into synch with what you are actually building.

If track circuits are provided then the area around the doubleslip/scissors would be a prime candidate as two track circuits would get rid of 6 problematic facing point lock bars.

Regards

[The Great Bear]

It would greatly help making comprehensible suggestions if you first got your diagrams into synch with what you are actually building.

If track circuits are provided then the area around the doubleslip/scissors would be a prime candidate as two track circuits would get rid of 6 problematic facing point lock bars.

Regards

My apologies, Keith, I will revise them as suggested to make them clearer