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Query about balance beam ends


Leo No2

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I have been sent the attached image of what is purported to be Rickmansworth Lock in about 1915 and the question that was posed is what are the round objects (and their purpose) on the end of the lower gate balance beams.

 

Edited to change image type from PNG to JPG

 

 

post-16597-0-78147200-1479819207_thumb.jpg

Edited by Leo No2
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interesting

another photo they look like wheels

 

 

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if you go to this link http://postcardsthenandnow.blogspot.co.uk/2013/10/rickmansworth-hertfordshire-batchworth.html in 1913 there was only one on the right beam

 

were they added to help balance the gate, like adding an extra weight

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I would suggest the towing line was run round them as a boat aproached the lock from above so the horse didn't have to walk down those steps to pull it into the lock.

Only one on the towpath side would be needed if that was the case. On the L&LC, at staircase locks like Bingley, they did have a pulley for this reason, but only on the towpath side. This photo from the Waterways Archive shows one of them.

gallery_6938_1_171120.jpg

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Isn't the clue in the name 'balance beam' ?

I don't know, is it?

 

The term 'balance beam' refers to the beam itself rather than things added to it.

 

As in the photo posted by Pluto, not everything added to a a lock balance beam is there to assist with its 'balance' but may have another purpose.

 

There is a cleat clearly visible on the beam in his picture too, what would you suggest that is for?

Edited by MJG
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You naturally assume that the balance beam is there to balance the weight of the gate, kind of so obvious that it doesn't need questioning but apart from the gates that are operated by boatmen in the UK you almost never see them. Great big dock gates (OK some are hollow and partially float) never have them and all over the French, Dutch, Belgian system I can't remember seeing any and even if the gate is some ancient thing it has a toothed rack attached to the gate which is operated by a vertical winding thingy. A pedant would want to call them pushing beams or some such thing but as far as balancing anything goes they don't seem necessary.

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You naturally assume that the balance beam is there to balance the weight of the gate, kind of so obvious that it doesn't need questioning but apart from the gates that are operated by boatmen in the UK you almost never see them. Great big dock gates (OK some are hollow and partially float) never have them and all over the French, Dutch, Belgian system I can't remember seeing any and even if the gate is some ancient thing it has a toothed rack attached to the gate which is operated by a vertical winding thingy. A pedant would want to call them pushing beams or some such thing but as far as balancing anything goes they don't seem necessary.

Not if there is a mechanical means of opening the gate but I would suggest that without the balancing effect of the beam it wouldn't be possible to operate lock gates manually. The beam does of course also provide a lever arm to aid the manual operation and a convenient surface to push against.

 

 

Weight...;)

Judging by your emoticon that must be a clever response. Problem is I don't understand it.

 

JP

Edited by Captain Pegg
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Pluto will know far more about this than me, but in principal "balance beams" both balance and lever the gate, a short heavy beam is less effective than a longer beam of similar weight, whilst a long, lightweight beam is less effective than a shorter heavy one. "Balance" beams are not the only bit of the gate involved in the balancing of a gate, the angle of the heel post and the distribution of weight within the gate will make a difference too.

 

A number of french canals originally had balance beams, some still do, such as the canal d'Ille et Rance in Brittany. Drawings for the Canal du Midi show balance beams were originally fitted there. Beams are less effective as locks get bigger, the few locks in England that are large and have balance beams (e.g. Bristol Avon) are often hard work because however well balanced they are there is still a lot of gate to move. On feature of the Frenh canals is that generally the gates are much lighter than ours (and also much less robust)

 

There are gates that are manual and don't have beams, some on the Stort used to have ropes (they may still have, I haven't been for a while) but they were very difficult to get closed - it is possible but a winding mechanism makes life easier

 

As for the original picture, I have no information but wonder of it's an iron ring, shrunk onto the end of the beam cartwheel-style either to add weight or protect the end of the balance beam

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There is a cleat clearly visible on the beam in his picture too, what would you suggest that is for?

The cleat could well be for a line of the fore end when you need to hold a boat as far forwards as possible. A butty in a lock the rudder is vulnerable so you take a line off to keep it on the gate.

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Judging by your emoticon that must be a clever response. Problem is I don't understand it.

 

JP

But anything added to it will affect the balance which is why it seems an unlikely place to mount anything of significant size weight for any other purpose.

Does that help??

 

Just a bit of gentle leg pulling BTW....

Edited by MJG
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I don't know, is it?

 

The term 'balance beam' refers to the beam itself rather than things added to it.

 

As in the photo posted by Pluto, not everything added to a a lock balance beam is there to assist with its 'balance' but may have another purpose.

 

There is a cleat clearly visible on the beam in his picture too, what would you suggest that is for?

Cleats like the one illustrated at Bingley were fitted to all L&LC gates, though I think the only ones surviving are on River Lock at Leeds. They were used to hold the boat forward in the lock so you didn't hang up on the sill, or get the rudder caught between the gates.

 

On balance beams, it has always seemed strange that they are so much more common in the UK than elsewhere. I am currently translating an Austrian book, published in 1817, which looks at European canal engineering around 1800, and which may explain more about how lock construction was understood at the time. The author had visited England in 1795, and the book does include some details of lock construction in Birmingham.

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There are gates that are manual and don't have beams, some on the Stort used to have ropes (they may still have, I haven't been for a while) but they were very difficult to get closed - it is possible but a winding mechanism makes life easier

 

Cowbridge Lock on the Witham Navigable Drains is or was opened and closed by pulling on chains. No balance beams when we passed through.

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I felt certain I had seen an exact explanation of what the plates on the end of the batchwoth Lock balance beams actually were, and that they were formerly som other bit of canal furniture used for that purpose.

 

However if I did, I sure as hell can't find that explanation now.

 

Also I can't immediately find a picture of any other Grand Union lock having them, although I feel I have seen such pictures in the past.

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