Odd hole under bridge.

[Graham and Jo]

There are a pair of matching circular fittings under bridge 95 at Braunston. It is the turn over bridge just before the puddle banks. It also has slots for stop planks and a set of planks.  Any idea what these metal fittings did or still do? 

 

Cheers Graham 

[beerbeerbeerbeerbeer]

Elsan?

[LadyG]

On the Chesterfield (Brindley 1777) some bridges (nice brickwork) have concrete coping stones with two iron posts about six inches high and two feet apart, not sure if it is all bridges. 

 

Edited September 13, 2023 by LadyG

[magnetman]

Maybe there was an idea to put gates there to protect the rest of the canal from the embankment collapsing..

 

 

 

 

 

[Graham and Jo]

1 minute ago, magnetman said:

Maybe there was an idea to put gates there to protect the rest of the canal from the embankment collapsing..

 

I do wonder if it is something todo with the proximity to the embankment. It was damaged by bombing in the war.  Cheers Graham 

 

1 minute ago, magnetman said:

 

 

 

 

[Derek R.]

Fire suction hoses?

[magnetman]

2 hours ago, Graham and Jo said:

 

Damaged during the war

 

I'm sure I've seen gates protecting embankments in other places. They are not typical gates in that they don't have balance beams or paddles but there are definitely some about. 

 

This one on Limehouse cut/Lee navigation is interesting I think it was part of a tidal control gate system but it does show that this sort of gate will not necessarily have the same kind of hardware one would find on a normal lock gate. 

 

I assume there is a physics thing happening and the gate closes itself as the water evacuates either by damage or because of tidal influence. 

 

 

Old gate near Bromley by Bow. 

 

 

 

 

So if there were gates at the iron bridges at Braunston then if the embankment was broken open perhaps these gates are subjected to some sort of hydrodynamic forces and close themselves thereby protecting the rest of the pound which if my memory is right extends all the way to Hillmorton top lock. 

 

Just a theory !

[Ken X]

These flood gates are on the Worcester and Birmingham Canal just up from Salvage Turn.  Plenty of other examples around the network.

 

[Graham and Jo]

The gate idea makes sense. I guess there is a corresponding socket at the bottom. 

 

Cheers Graham 

[Jen-in-Wellies]

6 minutes ago, Graham and Jo said:

The gate idea makes sense. I guess there is a corresponding socket at the bottom. 

 

Cheers Graham 

How would the gate be removed for repair/replacement? It wouldn't be getting the usage that a lock gate would, but the oak will still deteriorate in water. After several decades, getting it out would mean removing all the ironwork at the top first, rather than just knocking the locking wedges out of a collar, as on a lock gate. Maybe they thought this was fine for a flood gate, but it seems strange to use it, when collars were a common technology, at similar cost and complexity to install.

I've not paid much attention to the remaining gates, most of which are in very decrepit condition to know what was the common way of locating them.

[Graham and Jo]

1 hour ago, Jen-in-Wellies said:

How would the gate be removed for repair/replacement? It wouldn't be getting the usage that a lock gate would, but the oak will still deteriorate in water. After several decades, getting it out would mean removing all the ironwork at the top first, rather than just knocking the locking wedges out of a collar, as on a lock gate. Maybe they thought this was fine for a flood gate, but it seems strange to use it, when collars were a common technology, at similar cost and complexity to install.

I've not paid much attention to the remaining gates, most of which are in very decrepit condition to know what was the common way of locating them.

I thought it a bit odd when I looked at it. You obviously need to drop a post of some sort into the hole but the brick arch on the offside would make that difficult.

 

Cheers Graham 

[magnetman]

It does look odd for a gate support. 

 

Maybe something completely different like a white painted wooden post which is there to remind boat steerers that they are joining another canal with potential for conflicting traffic. 

 

 

Old fashioned version of a stop sign. 

 

Wooden post to protect the bridge from impact damage? 

 

It would be interesting to know if there is a corresponding fitting in the canal bed. Not enough room to get a long post into there. 

 

 

 

Might there have been a height barrier there to prevent damage to the rather low bridges further on towards Napton? 

 

I know wide boats can get through that bit but there are one or two very low bridges if you did have a large wide craft from further south. 

 

I could imagine a wooden structure imitating the profile of that bridge a bit further on. 

[Graham and Jo]

I have a vague feeling that there is another one at the bridge at the other end of the puddle banks. I will have a look when I go back past in a few days. 

 

Cheers Graham 

[Ken X]

I had a bit of a look at these photos and there appear to be a void to the left of the hole in the far bank.

 

 

There also appears to be a partial cup or bearing visible through the hole in the near bank.

 

 

My current guess is that a flood gate could be constructed with stub top and bottom pivots.  The top stub pivot would be short enough to be pushed under the steel plate and up with the gate tilted.  The gate would then be lifted slightly to allow the gate bottom stub pivot to drop into a socket on the canal bed.  The gate would be contained in the recess by placing a square plate with a shallow socket in the underside over the top pivot. The gate could be swung either automatically by the flow or possibly manually by a vertical bar if the flow was too slow.  Course I could be talking complete rubbish. 😄

[magpie patrick]

22 hours ago, Graham and Jo said:

 

Cheers Graham 

 If you look at this picture you can see that the coping stones on the left are over a cavity, whereas the ones on the right are not. This lends credence to the gate idea

 

6 hours ago, Jen-in-Wellies said:

How would the gate be removed for repair/replacement?

 Conjecture, but maybe the gate had a hole on the top into which a spindle was inserted once the gate was in position. Take the spindle out the gate would come away quite easily

 

Of course getting the spindle out after fifty years is another matter...

[Graham and Jo]

6 minutes ago, Ken X said:

I had a bit of a look at these photos and there appear to be a void to the left of the hole in the far bank.

 

 

There also appears to be a partial cup or bearing visible through the hole in the near bank.

 

 

My current guess is that a flood gate could be constructed with stub top and bottom pivots.  The top stub pivot would be short enough to be pushed under the steel plate and up with the gate tilted.  The gate would then be lifted slightly to allow the gate bottom stub pivot to drop into a socket on the canal bed.  The gate would be contained in the recess by placing a square plate with a shallow socket in the underside over the top pivot. The gate could be swung either automatically by the flow or possibly manually by a vertical bar if the flow was too slow.  Course I could be talking complete rubbish. 😄

I see what you mean by the recess. A closer examination is required. I will be back there on Saturday I think.

 

Cheers Graham 

[magnetman]

38 minutes ago, Ken X said:

I had a bit of a look at these photos and there appear to be a void to the left of the hole in the far bank.

 

 

There also appears to be a partial cup or bearing visible through the hole in the near bank.

 

 

My current guess is that a flood gate could be constructed with stub top and bottom pivots.  The top stub pivot would be short enough to be pushed under the steel plate and up with the gate tilted.  The gate would then be lifted slightly to allow the gate bottom stub pivot to drop into a socket on the canal bed.  The gate would be contained in the recess by placing a square plate with a shallow socket in the underside over the top pivot. The gate could be swung either automatically by the flow or possibly manually by a vertical bar if the flow was too slow.  Course I could be talking complete rubbish. 😄

It does look like a quoin for a gate heel post in the lower image. 

 

It is also possible that as these were emergency gates the casting at the top was put in when the gates were already installed and locked them in place. Over time the gates probably disintegrated and were removed but as they were never meant to be used there would be no need for collar straps and other hardware associated with moveable lock gates expected to be opened and closed dozens of times a day 

 

Fit and forget. I reckon its a war thing. 

 

 

Edited September 14, 2023 by magnetman

[Chris Lowe]

There doesn't appear to be a gate recess for any stop gate to swing into

[magnetman]

It looks like there is room under there but would need checking on site. 

 

 

 

 

The gate would not need to be above the waterline. 

 

The object would be to close if the embankment breaches. Its about not losing all the water in the pounds either side. You could lose 6 inches of water and nobody is going to worry about it but if it is all lost you have no canal. 

 

So in this sense submerged gates made of elm or a wood which likes being underwater would make sense.

 

 

 

 

 

It looks like there is a recess to the left of the hole. 

People will tend to think a lock gate must by definition protrude well above the waterline but that isn't necessarily the case in this particular situation.

 

 

I reckon there definitely were gates there. 

Edited September 14, 2023 by magnetman

[Graham and Jo]

There is a picture of the bomb damage here and you can just see the bridge in the top right. 

https://collections.canalrivertrust.org.uk/bw192.2.80.2

 

Cheers Graham 

[Graham and Jo]

We have just crossed the puddle banks again and there is a similar structure at Bridge 97 at the west end of the embankment. The cut out for a gate is more obvious. It is facing away from the embankment too which supports the flood gate idea. 

 

Cheers Graham 

[Ken X]

Cool.  Wish I was a bit closer I'd quite enjoy poking about. 

 

If they were fitted, I bet they closed with a bit of a thwap when that bomb drained the canal. 😳