Slip coaches & Slipping Distant signals

[Andy873]

Cowley, thanks for re-directing me to this thread, really is interesting - there's a lot for me to read and digest.

Thanks again, much appreciated!
Andy.

 

[Irascible]

Every now and then I idly speculate on battery-powered slip coaches & what might have been ( although you would of course need an extra driver, or at least enough of a driver somewhere then ). Slip operations are really fun as a lot of quirky things are, but so much faffing around to retrieve the slipped coach & do something with it. 5 mins of battery self-propulsion to attach itself on the back of the local would have cut that so much...

 

[randyrippley]

Every now and then I idly speculate on battery-powered slip coaches & what might have been ( although you would of course need an extra driver, or at least enough of a driver somewhere then ). Slip operations are really fun as a lot of quirky things are, but so much faffing around to retrieve the slipped coach & do something with it. 5 mins of battery self-propulsion to attach itself on the back of the local would have cut that so much...

Imagine. Converted MLVs as slip coaches

 

[pdeaves]

Heath Robinson did a slip coach cartoon (see https://www.alamy.com/stock-photo-v...w-heath-robinson-consternation-105390516.html). I'm pretty sure he did a 'reverse slip' idea, too but if the cartoon I picture in my memory was him it seems not to have made the many images online. It involved the carriage to be collected at the top of a ramp dangling a string down to catch the express as it shot past underneath.

 

[zwk500]

The solution to return slip workings is clearly a combination of Travelling Post Offices and Ski lifts.

 

[Cowley]

Cowley, thanks for re-directing me to this thread, really is interesting - there's a lot for me to read and digest.

Thanks again, much appreciated!
Andy.

No problem. It really is a fascinating subject.

 

[edwin_m]

The solution to return slip workings is clearly a combination of Travelling Post Offices and Ski lifts.

I may have imagined it, but I think I read somewhere the big rubber doughnut on the front of Danish IC3s and similar units was intended to allow trains to couple while in motion.

If that's true, I suspect whoever said it hadn't thought it through.

 

[Tester]

I may have imagined it, but I think I read somewhere the big rubber doughnut on the front of Danish IC3s and similar units was intended to allow trains to couple while in motion.

If that's true, I suspect whoever said it hadn't thought it through.

Uncoupling!

If you aren't aware of it you may find interesting post #31 in.....

It was twenty years ago today...(The contract for the Danish IC4 was signed)

One of the most amazing things about the IC3/IR4 family is that they uncouple on the move (just like slip coaches of yore!) the first time I saw it happen at Frederica station I thought a major incident had happened! There is no physical reason why any train with an autocoupler couldn't do...

www.railforums.co.uk

 

[Gloster]

I may have imagined it, but I think I read somewhere the big rubber doughnut on the front of Danish IC3s and similar units was intended to allow trains to couple while in motion.

If that's true, I suspect whoever said it hadn't thought it through.

No, there were never plans to couple the IC3 when in motion (which produces an image of two trains chasing each other as used to be depicted in old silent films). The trains can uncouple on the move, but this is more of an additional advantage of the bellows: their main purpose is to provide a relatively smooth exterior when sets are coupled.

 

[edwin_m]

Thanks both, I must have mis-remembered the bit about coupling. Even with a big squishy bellows trying to couple on the move would be incredibly dangerous, not least because you'd have to disable the signalling system that's doing its very best to keep them apart.

 

[Pigeon]

Heath Robinson did a slip coach cartoon (see https://www.alamy.com/stock-photo-v...w-heath-robinson-consternation-105390516.html). I'm pretty sure he did a 'reverse slip' idea, too but if the cartoon I picture in my memory was him it seems not to have made the many images online. It involved the carriage to be collected at the top of a ramp dangling a string down to catch the express as it shot past underneath.

Haha, my own pils coach idea was kind of the reverse of that - the rear coach of the express sticks a hook out the side to catch the loop of string being hung out the other side of the pils coach waiting in the platform. Sprung trailing points to take it out. The string is wound around a big drum geared to a flywheel, in multiple layers so the effective diameter of the drum reduces as the string is pulled off; this means the pull on the string is light at the moment it is first caught, to prevent a massive jerk, and gets heavier the more string is pulled out, accelerating both the flywheel and the carriage itself. When the whole length is pulled out, the flywheel carries on rotating and begins to wind it up the other way, transferring energy from the flywheel to further accelerate the carriage. The various masses and gear ratios are worked out so that there is enough momentum in the flywheel to pull the carriage all the way up to the main train just as the flywheel comes to a halt, at which point the autocoupler engages. You have a quite small battery and motor as backup in case it doesn't quite make it and needs a bit of extra winding for the last few metres, and a hand crank as further backup in case the battery goes flat.

 

[Lloyds siding]

The article linked in post #6 says that portions several coaches long were slipped.

Above that they ran several portions as independent trains. It also says that 3 up trains slipped portions at Reading, the 8.30 Plymouth and the 8.20 Weston-super-Mare and the 8.30 Weston. Maybe like the up WCML trains used to stop at Watford Jn to set down for the N suburbs.

As I understand it the London-Southport train consisted of two carriages at the rear of the train to Liverpool Lime Street, for several years in LMS days these were slipped to arrive at Edge Hill, where a small tank engine would attach, reverse out of Edge Hill to join the Canada Dock Branch for access to the Liverpool-Southport line at Bootle Junction. In latter days the coaches were detached once the train had reached Lime St.

 

[Irascible]

Haha, my own pils coach idea was kind of the reverse of that - the rear coach of the express sticks a hook out the side to catch the loop of string being hung out the other side of the pils coach waiting in the platform. Sprung trailing points to take it out. The string is wound around a big drum geared to a flywheel, in multiple layers so the effective diameter of the drum reduces as the string is pulled off; this means the pull on the string is light at the moment it is first caught, to prevent a massive jerk, and gets heavier the more string is pulled out, accelerating both the flywheel and the carriage itself. When the whole length is pulled out, the flywheel carries on rotating and begins to wind it up the other way, transferring energy from the flywheel to further accelerate the carriage. The various masses and gear ratios are worked out so that there is enough momentum in the flywheel to pull the carriage all the way up to the main train just as the flywheel comes to a halt, at which point the autocoupler engages. You have a quite small battery and motor as backup in case it doesn't quite make it and needs a bit of extra winding for the last few metres, and a hand crank as further backup in case the battery goes flat.

This is brilliant, I love it some interesting gyroscopic effects to work through though.

Does sound the sort of principle that's been used somewhere or other.

 

[Rescars]

There is the London and Blackwall way of dealing with the slipped coaches of course. Namely, slip the relevant coaches at every intermediate station when going outbound, then clamp them all to the haulage rope and tow them back at the same time to the terminus, so you can reassemble the train there for the next outbound trip. It does require cable haulage, is hardly express in terms of speed and makes travelling between intermediate stations a nightmare, but it was decidely ingenious for the1840s. There is an explanation of this way of working on Wikipedia - I am sure others can point to better ones elsewhere.

 

[Western 52]

Out of interest, does anyone know of any slip working that still takes place anywhere outside the UK? Or were slips just a UK thing?