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Rubbing posts/strips on the Shroppie Bridges


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9 minutes ago, magnetman said:

To be fair there would be no need for the grooves to be added because the original used to make the mould would already have the grooves in it. 

 

A potential reason for the original items being removed could be because they were cut in half and became useless. 

 

 


but they were clever types in them foundries,

and the grooves on the original could easily have been filled with clay/sand  whatever if using it as the pattern to reproduce a full/clear iron guard. 
 

 

 

Edited by beerbeerbeerbeerbeer
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Yes but the theory under discussion is that some of these items have been put in at a later date for authenticity. A bridge guard with rope no grooves would look less authentic than one with grooves. 

 

Of course the ones with fewer grooves could be replacements for those which were cut in half. 

 

 

 

 

It is also possible these items were originally made with small grooves in them to pick up the towing line. If they had been thinking about it rollers migjt have been better. 

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Tow ropes would pick up grit from the towpath and they would then create grooves in anything they rubbed against, either stone or cast iron. Tow ropes would need to be changed about every six weeks because of wear. Cast iron was used because it was much cheaper to produce the guards than in wrought iron or later steel. Numerous grooves were worn because each boat and each horse would be a different height, so the tow rope height would vary, These rope guards were provided at places where tow ropes were likely to rub, so mainly bridges. The arch was the main location because the bridge hole was much narrower than the canal either side, so the 80 foot long tow line would rub on both faces of the bridge on the tow path sides.

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1 hour ago, beerbeerbeerbeerbeer said:

If we accept they’re genuine, (which they most likely are), there’s been no offer of an explanation so far, other my guess work earlier in the thread, why this set of guards on the lower Shroppie are so well used/worn in comparison to others on the system. 

 

 

 

Some were fitted much later than others, Have you looked closely to see if there is a Best before casting date on them 

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15 minutes ago, beerbeerbeerbeerbeer said:

but why are the Shroppie ones so obviously and distinctively different from anywhere else on the system?

Because they were put there by a different canal company from those that owned and ran the rest of the system. Back in the day when there were a large number of separate canal companies each had their own operating and maintenance depots staffed by local craftsmen. Lock gates, paddles, lift and swing bridges and other bits and pieces, including bridge rubbing posts, were manufactured at the local depot, and were different from those made and used by other companies. And on the longer canals with several maintenance yards the standard designs varied along the canal length.

The relative uniformity of such kit seen today is as a result of the canals coming under more centralised control, firstly in some cases under railway ownership, and later with nationalisation. Since then BW and CRT have rationalised their maintenance and repair practices. 

When I started boating there was much more variety of lock gate and paddle gear styles that has now been largely lost. Take a look at photographs taken in the 60s and 70s by enthusiasts like John Gagg and you will some some of the things that have now gone. Fortunately bridge rubbing strip are pretty permanent, and with the end of horse towage, aren't getting more wear and tear, so many have survived in the same state as they were 50+ years ago.

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1 minute ago, beerbeerbeerbeerbeer said:

why have those guard irons worn so excessively?

Because of heavy traffic on the Shroppie during its heyday.

 

1 minute ago, beerbeerbeerbeerbeer said:

they’re relatively new to other irons on the system

Not necessarily. Wooden ones have long rotted away, wrought iron and steel ones would be thinner, so more likely to be cut through and replaced, whereas the heavy cast iron ones on the Shroppie have survived with deep scoring but otherwise little changed from when they were installed.

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Ok, thanks,

feeling I’m slowly getting an answer,

 

And there were once wooden guards?

 

(not necessarily on the Shroppie but generally speaking)

22 minutes ago, David Mack said:

Because of heavy traffic on the Shroppie during its heyday


but there was heavy traffic elsewhere ?

Edited by beerbeerbeerbeerbeer
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46 minutes ago, beerbeerbeerbeerbeer said:

Yes, I understand all that,

but it doesn’t answer the query, does it?

 

why have those guard irons worn so excessively?

 

they’re relatively new to other irons on the system ?
 

 

I don't think the question is why they were so worn, it's whether the ones still out there are all genuinely worn original ones or replicas of a heavily worn set which looked nice. Or maybe a mixture...

 

If they all have the same groove pattern, they're replicas. If they're all different, they're originals. The only way to sort this out is photos... 😉

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30 minutes ago, beerbeerbeerbeerbeer said:


tell me why any are so worn?


A couple of possibilities.

 

Shroppie bridge holes are very narrow. Surprisingly so for an otherwise heavily engineered canal. That possibly means the tow rope was pulled round them at a tighter angle and therefore a larger component of perpendicular force. I noted some guards on GU today that were much less worn. They were in much more generous bridge holes.

 

Another possibility is the metal they were cast with. If enough heat is generated through friction in one event then the crystalline structure can change and become susceptible to wear in way that is wasn’t previously. While I’m not sure how this might happen on a canal it’s how excessive wheel slip affects railway rails.

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1 minute ago, Captain Pegg said:

Shroppie bridge holes are very narrow. Surprisingly so for an otherwise heavily engineered canal. That possibly means the tow rope was pulled round them at a tighter angle and therefore a larger component of perpendicular force. I noted some guards on GU today that were much less worn. They were in much more generous bridge holes.


that was kind of my proposal earlier in the thread,

 

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On 06/12/2023 at 10:02, magnetman said:

 

The one pictured above has a very distinct pattern right at the top end. That would be an interesting area to compare. 

Easier than trying to compare the whole thing as the brain would tend to get overloaded. IMG_20231206_100400.jpg.5621afef119848d40b41cd7a3d9a3650.jpg

 

This is the bit which needs photographing. 

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Rope material and type also an interesting factor. Maybe a 4 strand line would tend to pick up more dirt than a 3 strand line and thus cause more abrasion damage. 

 

 

 

And boats passing each other. There would be a give way procedure. 

 

Oh to be a bystander ! 

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My very far away pictures of other ones don’t seem to show the same wear. I specifically took the one shown close up  as it struck me as being well worn and picturesque.
 

My other photos are of bridges or surrounds in general, so close ups aren’t brilliant at all. 😕
 

Another point is many bridges on the Shroppie are  of fairly soft sandstone so wear would be far worse than the more usual brick bridges, so guards needed to be sturdy things perhaps? 
 

The one thing that seems a bit odd is the wear really is quite low down in some places on the bridge near Pendleford. Why would that be ?  
 

IMG_2023-12-12-085604.thumb.png.ab3b92d50ef4a005e1e53e8b5ced1b72.png

 

IMG_2023-12-12-085541.png.5f41f85fb07d9477ee8667a3d8d64039.png

 

The two at Knighton 


IMG_2023-12-12-085453.png.4d705cb5c5b504eda3a3334d31976562.png


IMG_2023-12-12-085513.png.e92adeac2ea46df27d1900e1aa385d2b.png

 

Apologies for poor quality 


and the  bridge near Pendleford showing low ish IMG_2023-12-05-193632.thumb.jpeg.3c6c46e80232c3352adb7856df2f2310.jpeg wear too? 


 

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Boats which had slowed or stopped starting up again with longer ropes to prevent risk of horse falling in under the bridge? 

 

Some of the wear must be related to the passing protocol. They can't just go in reverse there must be an arrangement at bridges. 

 

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