How do NR remote control de-icer wagons work?

[Sun Chariot]

Today, on the southern half of Portsmouth Direct Line, an "out and back" Class 3 working, from Totton Yard. Photos attached
The two Network Rail wagons appear to be remote control for de-icer fluid.
Flickr has a photo - attached - the description mentions a Snow and Ice Treatment Train.

My questions to a knowledgeable person -
1) how do these wagons normally operate?
2) if the wagons operate as part of a bigger consist, then - as today's Class 3 working only had the remote control wagons - what was the purpose of that particular working?

Thanks in advance.

 

[Adrian Barr]

I think that is the normal formation for a Snow and Ice Treatment Train (SITT), with two "remote control" wagons.

In your screenshot from flickr, the back tank (small square-shaped thing) is labelled "fuel filler" and the front tank is labelled "de-icing fluid filler." The caption mentions the "motor on it chugging away" which means the nearest tall module is probably a diesel generator (appears to have a little black vent coming out of it). The other tall module probably has pumps and other control machinery in it.
The writing on a de-icing tank is visible more clearly in this photo (zoom in, on the left): https://www.flickr.com/photos/tigertim1950/24953799186/
They would only need to apply a thin film of de-icing fluid, unlike the high-pressure jet of water from an RHTT, so the tanks are a lot smaller (the sandite module on an RHTT is also a sort of box).

There's a Network Rail page which mentions these trains:
https://www.networkrail.co.uk/runni...al-track-treatment-and-weather-support-fleet/

The MPV and SITT both scrape ice off the conductor rail head (the top of the conductor rail) and can spray the rails with hot liquid anti-icer that prevents ice sticking to the conductor rail head.

I assume the SITTs work similarly to the autumn railhead treatment trains (RHTTs), with a dedicated operator in the cab turning the flow of de-icing fluid on and off or switching it from one side to the other to match the location of the conductor rail in different places.

In this shot of an RHTT, the wagon appears to be connected up to a jumper cable on the loco. I don't think this is being used for multiple-working of the locos; as I understand it the cable is being used as part of the control system operating the sandite equipment and water tanks (although I could be wrong).
https://www.flickr.com/photos/the_prisoner/51647847801/

From the photos I've seen, I don't think this arrangement is used on the SITTs, so perhaps the "remote control wagon" is literally that - operated by remote control from the operator's handset, or maybe a laptop, connected wirelessly.

I'm making a few assumptions here, so maybe someone can clarify or correct the technical details.

 

[Sun Chariot]

They would only need to apply a thin film of de-icing fluid, unlike the high-pressure jet of water from an RHTT

Many thanks for that clear, comprehensive insight. Makes perfect sense.
The de-icer treatment didn't appear to be in operation, when I saw it run northbound and southbound. It might have been treating the third rail further north than Havant area (e.g. on the two climbs to Buriton, across the South Downs).

Certainly it seems less messy than the Rail Head Treatment for leaf mulch, if this shot (taken last autumn) is anything to go by!

 

[43096]

In this shot of an RHTT, the wagon appears to be connected up to a jumper cable on the loco. I don't think this is being used for multiple-working of the locos; as I understand it the cable is being used as part of the control system operating the sandite equipment and water tanks (although I could be wrong).
https://www.flickr.com/photos/the_prisoner/51647847801/

It's plugged in to the standard red diamond multi-working socket on the loco and the bufferbeam on the wagon, so unless the locos have been modified my reading is that it is just through control to the rear loco - the wagons are fitted with various through multi-working cables and sockets. My understanding is that the RHTT equipment (at least on the loco-hauled vehicles) work by remote control.

 

[wickham]

These might be different nowadays, but the old Southern Region Deicing units had a system whereby the fluid was spread on the side where the conductor rail was simply by the shoe lifting and opening a nozle. However, they usually ran with an "opperator" on board (a depot fitter) just to oversee opperation. If a fitter was not avaliable the units would be sent out on automatic, but this could present problems, such as nobody to turn off the flow at reversing points (!!) and nobody to oversee that all was working as it should.

 

[Sun Chariot]

... the old Southern Region Deicing units had a system whereby the fluid was spread on the side where the conductor rail was simply by the shoe lifting and opening a nozle

The 930 (ex-HAL ex-SUB) de-icer units used to fascinate me.

I can dimly recall the southern snow of the very early 1980s, where Kent's suburban EPBs were hastily hooked to classes 33, 47 and 56, to keep services going whilst the third rail was iced up.

 

[Adrian Barr]

It's plugged in to the standard red diamond multi-working socket on the loco and the bufferbeam on the wagon, so unless the locos have been modified my reading is that it is just through control to the rear loco - the wagons are fitted with various through multi-working cables and sockets. My understanding is that the RHTT equipment (at least on the loco-hauled vehicles) work by remote control.

That makes more sense now that you point it out! My technical knowledge is limited and I think my mind was wandering off to some fanciful adaptation of the completely unrelated TDM system used for push/pull operation on some of the BR passenger locos. I don't think there are any special loco mods involved with RHTT working, except for some locos fitted with tripcocks to work on the outer reaches of the LUL Metropolitan line, if they still do that.

I was trying to think why they would want to have the locos working in multiple on an RHTT, given they are so lightweight and that top and tail working normally just involves a loco being dead or idling on the rear.

One possibility is that having both locos working should reduce wheelslip, by having less power applied to each axle (2 locos accelerating on half power instead of one on full power for example). The RHTTs (at least the ones working the circuit off Peterborough) seem to visit the wheel lathe at Roberts Road quite often during the sandite season, perhaps because they spend most of their time on routes with poor adhesion, which by definition haven't been treated yet because they are in front of the wagons doing the treatment.

I can dimly recall the southern snow of the very early 1980s, where Kent's suburban EPBs were hastily hooked to classes 33, 47 and 56, to keep services going whilst the third rail was iced up.

This video gives a good demonstration of why you would want to get rid of ice on the third rail...

Video: BR in the 1990s Woking Station on 8th February 1991 After Heavy Snowfall | Channel: spompeytransportvideo

 

[Sun Chariot]

Near-zero temperature forecasted tonight:

The Snow & Ice Treatment Train - led by a distinctive former European example - returns from its Portsmouth Direct Line duties and approaches the junction with the West Coastway.