Floating Bridge out again!!!

Accepted.

Could anyone imaging Alan Sugar continuing to employ those buffoons? The public sector workers who are responsilde or this shambols should have been sacked..
 
Seajet said:
How the hell does one ' snap ' one of those chains ?!
Click to expand...

To be clear, it's not one of the main chains across the river that has snapped, but one of the ones holding up the ramp.

I still don't know how they managed it, but I'm sure the ramp supports are a lot lighter than the main chains.

Pete
 
prv said:
To be clear, it's not one of the main chains across the river that has snapped, but one of the ones holding up the ramp.

I still don't know how they managed it, but I'm sure the ramp supports are a lot lighter than the main chains.

Pete
Click to expand...

This is the second time one of the ramp lifting chains has broken. Last time they were all replaced partly by wire cables with, afaik, only the end section remaining as chain. I believe it is actually the wire cable section that has failed this time, at least that was what was said in one of the first reports.

I suspect the problem is the snatch loads that the chains/ cables are subjected to.

When the ramp is raised the slack in the chains is wound in and then without pausing the ramp is lifted. One might expect a system where once the slack has been taken up it pauses and then restarts with "a soft start". Think how the crane lifting your boat operates. Firstly all the slack in the slings etc is taken up then the actual lift starts gently........ at least it does if you have a good crane operator.

Also if you watch as they approach the shore. they lower the ramp, I guess so that they can see from the stupidly placed central control cabin. When the lowering stops with the ramp fully extended horizontally it does so abruptly. If you watch you can see it " bounce" on the lifting chains.
 
Seajet said:
All you need is a good run-up and a ski-ramp, forget the chat about tunnels or bridges ! :)

https://www.flickr.com/photos/73614187@N03/43292843314
Click to expand...

Right way up? What a wuss. This is how it's done:

mYHi8Ee.png


Geek trivia: That was the first movie stunt to be checked and set up using mathematical modelling beforehand, rather than "that looks about right"
 
I'm thinking Mr J Daniels may have been involved in the calculations, if not he should have been.

Anything would be better than the present setup, apparently designed by Homer Simpson.
 
VicS said:
This is the second time one of the ramp lifting chains has broken. Last time they were all replaced partly by wire cables with, afaik, only the end section remaining as chain. I believe it is actually the wire cable section that has failed this time, at least that was what was said in one of the first reports.

I suspect the problem is the snatch loads that the chains/ cables are subjected to.

When the ramp is raised the slack in the chains is wound in and then without pausing the ramp is lifted. One might expect a system where once the slack has been taken up it pauses and then restarts with "a soft start". Think how the crane lifting your boat operates. Firstly all the slack in the slings etc is taken up then the actual lift starts gently........ at least it does if you have a good crane operator.

Also if you watch as they approach the shore. they lower the ramp, I guess so that they can see from the stupidly placed central control cabin. When the lowering stops with the ramp fully extended horizontally it does so abruptly. If you watch you can see it " bounce" on the lifting chains.
Click to expand...

I believe that one of the reasons for changing over to partial wire cables was that there were complaints from the neighbours about the noise made by the original chains running through the 'crane' section when the ramp was lowered or raised particularly during late night operation.
 
VicS said:
I suspect the problem is the snatch loads that the chains/ cables are subjected to.

When the ramp is raised the slack in the chains is wound in and then without pausing the ramp is lifted. One might expect a system where once the slack has been taken up it pauses and then restarts with "a soft start".
Click to expand...

A two-stage takeup like that would certainly be kinder on the gear, but I'd have hoped that the margin of safety would be enough not to need it...

Assuming the motor isn't being directly controlled by a human being beyond pressing a "ramp up" button, taking in the slack then pausing at the right point and restarting softly might require slightly more sophisticated control gear than initially fitted. But there is certainly kit out there that can do it; a few months ago at work I encountered an Elmo Golden Oboe (their product names are notorious :) ) that I think could be programmed that way.

Pete
 
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