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Bubble cars - Class 121 / 122

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xc170

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Spent a few hours at the Ecclesbourne Valley today at the Multiple Memories, it featured the resident Class 122 and a visiting 121.

Apart from different builders and the 121 having a headcode box, are there any other differences between the two classes?
 
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alexl92

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Spent a few hours at the Ecclesbourne Valley today at the Multiple Memories, it featured the resident Class 122 and a visiting 121.

Apart from different builders and the 121 having a headcode box, are there any other differences between the two classes?
I've always wondered this and done research and never been able to come up with a clear answer. Apparently some 122s ran with a trailer coach or something like that? But I've never been able to find any specific info.

Would really appreciate if anyone could enlighten us!
 

hexagon789

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I've always wondered this and done research and never been able to come up with a clear answer. Apparently some 122s ran with a trailer coach or something like that? But I've never been able to find any specific info.

Would really appreciate if anyone could enlighten us!

Both 121 and 122 had driving trailers, these had cabs at one end only and were originally used as loadings required. The 121s were originally built to replace the GWR-built railcars and were concentrated more out west in the likes of Plymouth, Cardiff, Bristol etc; the 122s were originally based in London and Birmingham on the Western Region.

As time went on the 121s in particular seem to have become more widely spread across the BR regions, the Scottish Region even having a few it used on the Dundee-Arbroath stoppers for a period in the 1970s.
 

theblackwatch

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Both ran with a trailer sometimes. Class 122 cars 55000-55019 (without the headcode boxes) were built by Gloucester Railway Carriage & Wagon Co, as were supplementary trailers 56291-56299. The Class 121s came later and were built by Pressed Steel, 55020-55035 with trailers 56280-56289.
 

CarltonA

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I went to the Battlefield Line a few years ago and they were running a bubble car together with another DMU car which I thought at the time was actually powered but only had one cab. I may be wrong on this and perhaps it was a driving trailer as detailed above. Would it be possible to have multiple working with half a DMU and a bubble car? Strangely the traincrew were both wearing Chiltern Railways hi-vis vests. Sorry for drifting a bit OT.
 

hexagon789

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I went to the Battlefield Line a few years ago and they were running a bubble car together with another DMU car which I thought at the time was actually powered but only had one cab. I may be wrong on this and perhaps it was a driving trailer as detailed above. Would it be possible to have multiple working with half a DMU and a bubble car? Strangely the traincrew were both wearing Chiltern Railways hi-vis vests. Sorry for drifting a bit OT.

For first generation units, very possible and often happened. I've seen quite a few pictures of Scottish Met Camm units formed with extra power cars tacked on or a power car and intermediate trailer.

The great thing about the Blue Square multi working, plain twin-pipe vac brakes and buffer and hook couplings was it enabled great flexibility in forming trains. Something I'm sure Ayr depot was grateful of after the fire gutted several units.
 

theblackwatch

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Class 121 'bubble' cars often replaced an out of service Class 117 power car on Reading based sets which worked out of Paddington. Similarly, Tyseley's Class 122 bubbles were also regularly used vice other power cars on services around Birmingham.
 

CarltonA

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Interesting, I'd never noticed that happening and I spent a fair bit of time going between Slough/Padd in the eighties. I believe that parcels vans had been at one time been attached to "Bog Units", another thing I don't remember seeing. Sorry again for the drift into nostalgia.
 

hexagon789

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Interesting, I'd never noticed that happening and I spent a fair bit of time going between Slough/Padd in the eighties. I believe that parcels vans had been at one time been attached to "Bog Units", another thing I don't remember seeing. Sorry again for the drift into nostalgia.

Parcels units and 'bubble cars' seemed to be not infrequently used as spare power cars on the London Midland and Western Regions.

The railcar website has a few photos and some information pertaining to this.
 

pdeaves

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Nothing to do with differences between classes but I hope you fill forgive this here. I well remember when I was little waiting at a crossing near Criccieth for a train to pass... that happened to be a single 'bubble car' unit towing a solitary four wheel freight van. It never crossed my mind to take a picture, I just gawped - one of life's big regrets!
 

RPM

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Nothing to do with differences between classes but I hope you fill forgive this here. I well remember when I was little waiting at a crossing near Criccieth for a train to pass... that happened to be a single 'bubble car' unit towing a solitary four wheel freight van. It never crossed my mind to take a picture, I just gawped - one of life's big regrets!

They could handle a trailing load. Back in the late 90's during the fuel crisis Chiltern Railways ordered a trainload of reserve diesel fuel which sat in the branch siding at Aylesbury for several weeks. Eventually the tanker vans were moved into the depot for emptying, one at a time - hauled by a class 121 bubble car.
I have photos of bubble car 55024 shunting a Wrexham & Shropshire coach and DVT around Aylesbury depot, using only one engine, back in 2009.
 

STEVIEBOY1

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I do like those older DMUs, also the Class 110. (Not sure which class it was, but I travelled on a single car DMU on the KWVR a couple of years ago, the doors were in the middle, I think it spent it's working life in East Anglia, I also enjoyed a single unit DMU about the same time on the Weardale Railway, which is a good line too. (I think it, the line, is in the process of being bought by a new operator?)
 

Taunton

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The great thing about the Blue Square multi working, plain twin-pipe vac brakes and buffer and hook couplings was it enabled great flexibility in forming trains. Something I'm sure Ayr depot was grateful of after the fire gutted several units.
I know it's annoying when someone comes along with points like this, but Ayr was about the one depot where this didn't apply, as the Swindon-built cross-country units which were the bulk of its allocation were the White Circle coupling code, built with some air pipe differences for a reason which seems never to have been given.

Having said that, I once took a Glasgow-Ayr service which was a normal 6-car Swindon unit, plus a 3-car Glasgow area Derby Blue Square unit at the back. I always wondered how that was done, and discussed it here a few years ago only to be told it was not possible; that I had mis-identified it; that I had not noticed the rear unit was not coupled and was left on the buffers at Glasgow, etc. All wrong.

The Blue Square system was, I understand, devised for BR under subcontract by Walker Bros. of Wigan, who also did various other diesel unit components, and even a few narrow gauge complete cars. The previous Yellow Diamond system, also theirs, was much the same, apart principally from the engine starting sequence, and could have been readily converted without too much rewiring, but that was never done.

Incidentally, regarding the Gloucester bubble cars, the predecessor 1940s GWR single units (cars number 17-38) they replaced were also built there under subcontract from Swindon, as were the Gloucester cross-country units as well. Gloucester RCW were a longstanding subcontractor to Swindon, I believe the construction drawings were issued by Swindon, and even the correct BR shade of green paint was sent up by the Swindon stores.
 

hexagon789

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I know it's annoying when someone comes along with points like this, but Ayr was about the one depot where this didn't apply, as the Swindon-built cross-country units which were the bulk of its allocation were the White Circle coupling code, built with some air pipe differences f

I know the 126s weren't compatible, but I specifically mentioned the Ayr depot fire in my example, which occurred after the 126s were withdrawn ;)
 

hexagon789

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Didn't the Ayr line go straight from 126s to electrics?

No. The last 126s went in 1983, and it bumbled along with 101s, 104s transferred from England, a few 105s from Norwich for a period in 1986 when the 107s had to be temporarily withdrawn, 107s, 116s and some 120s (some running with 101 centre cars) until late-1986.

The full electric service didn't come in until January 1987.
 

61653 HTAFC

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I do like those older DMUs, also the Class 110. (Not sure which class it was, but I travelled on a single car DMU on the KWVR a couple of years ago, the doors were in the middle, I think it spent it's working life in East Anglia, I also enjoyed a single unit DMU about the same time on the Weardale Railway, which is a good line too. (I think it, the line, is in the process of being bought by a new operator?)
That KWVR unit will have been their early railbus, built in (then) West Germany for trials in East Anglia. Wickham also built a few similar vehicles I believe.

I don't think they were ever given a class number.
 

High Dyke

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That KWVR unit will have been their early railbus, built in (then) West Germany for trials in East Anglia. Wickham also built a few similar vehicles I believe.

I don't think they were ever given a class number.
They don't seem to have been given numbers. Info here: http://preserved.railcar.co.uk/DRB.html

Mention of the Wickham unit prompts me to look for the photo I've got of it at the Old Dalby research centre. That particular unit was always a departmental unit, none of the original passenger units have survived.
 

Mat17

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Having said that, I once took a Glasgow-Ayr service which was a normal 6-car Swindon unit, plus a 3-car Glasgow area Derby Blue Square unit at the back. I always wondered how that was done, and discussed it here a few years ago only to be told it was not possible; that I had mis-identified it; that I had not noticed the rear unit was not coupled and was left on the buffers at Glasgow, etc. All wrong.

Now I'm not technically minded at all, so please forgive any misunderstanding here, but I summise and nothing more. My understanding is that indeed White Circle and Blue Square systems were wired up differently and thus incompatible and so they couldn't work together in multiple. Could it be however, that the Derby unit was simply hauled 'dead' as a tail-load only coupled with the shackle? I'm just not sure how the braking etc. would be dealt with, I assume isolated and released on the rear unit which would have to be locked out of service? Surely this could be a possible explanation, afterall units could and did rescue other failed units. Whether this is possible with different control systems (isolated or otherwise) I am very much uncertain. Certainly at a ratio of 6:3 with regards to braking, 2/3rds of the train would have operative brakes and thus it would have enough brake force to stop safely.
 

davetheguard

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Class 121 'bubble' cars often replaced an out of service Class 117 power car on Reading based sets which worked out of Paddington. Similarly, Tyseley's Class 122 bubbles were also regularly used vice other power cars on services around Birmingham.

Class 121's also worked on their own on the Henley on Thames branch. They were rostered to work it on Sundays in the Summer; there were no trains on the line on Sundays in the Winter. (During the week, it was 3 car 117's which were full in the rush hour with people standing in the Guard's van).
 

SteveyBee131

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Now I'm not technically minded at all, so please forgive any misunderstanding here, but I summise and nothing more. My understanding is that indeed White Circle and Blue Square systems were wired up differently and thus incompatible and so they couldn't work together in multiple. Could it be however, that the Derby unit was simply hauled 'dead' as a tail-load only coupled with the shackle? I'm just not sure how the braking etc. would be dealt with, I assume isolated and released on the rear unit which would have to be locked out of service? Surely this could be a possible explanation, afterall units could and did rescue other failed units. Whether this is possible with different control systems (isolated or otherwise) I am very much uncertain. Certainly at a ratio of 6:3 with regards to braking, 2/3rds of the train would have operative brakes and thus it would have enough brake force to stop safely.
I could be wrong, but I think the braking systems were standard vacuum at this time. I think it was the transmission which was the main reason for problems. Likewise I'm not well blessed with technical knowledge though, so may well stand corrected!
 

hexagon789

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I could be wrong, but I think the braking systems were standard vacuum at this time. I think it was the transmission which was the main reason for problems. Likewise I'm not well blessed with technical knowledge though, so may well stand corrected!

They could assist in emergency, but if it was a loco assisting then only the vacuum train pipe could be connected, not the release pipe.

The White Circle cars also had buckeye couplers which were used in all normal operations, the conventional coupling gear was only lightweight and designed for shunting not for haulage so any such use would've been only in emergency.
 

randyrippley

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I thought the white circle and blue square systems were identical. The different code was simply to stop sets with torque converters working with sets using SCG auto gearboxes???
 

hexagon789

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I thought the white circle and blue square systems were identical. The different code was simply to stop sets with torque converters working with sets using SCG auto gearboxes???

That's was done with the hydraulic 127s which were re-coded red triangle to stop them being used with blue square units.

White circle itself is actually two systems, that fitted to the 79xxx cars (Edinburgh & Glasgow) was based on the older yellow diamond system, that fitted to the 126s (Ayrshire units) was based on blue square. Modifications had to be made to the 126s to enable them to work with the 79xxx cars. White circle cars could not run with any other types because each power car produced it's own control air supply and the wiring was also different.
 

High Dyke

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Interesting, I'd never noticed that happening and I spent a fair bit of time going between Slough/Padd in the eighties. I believe that parcels vans had been at one time been attached to "Bog Units", another thing I don't remember seeing. Sorry again for the drift into nostalgia.
Also, in later years a number of passenger units were converted for use by the Parcels sector. Most notably the Derby built Cl.114 units - which had roller shutters fitted to ease the loading of the trains. I've also seen Cl.105 (Cravens) and the Cl.120 (Swindon) units on parcels workings. I've attached one of the purpose built Cl.128, seen here passing Roade (WCML) in 1990
 

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High Dyke

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They don't seem to have been given numbers. Info here: http://preserved.railcar.co.uk/DRB.html

Mention of the Wickham unit prompts me to look for the photo I've got of it at the Old Dalby research centre. That particular unit was always a departmental unit, none of the original passenger units have survived.
As promised. An undated shot of the Wickham unit at Old Dalby test centre. Whilst I didn't think to take a picture of the neglected stock next to the 'Wickham', judging by the shape that could be the Drewry Railcar (RDB998901), previously associated with the Woodhead route.
 

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STEVIEBOY1

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As promised. An undated shot of the Wickham unit at Old Dalby test centre. Whilst I didn't think to take a picture of the neglected stock next to the 'Wickham', judging by the shape that could be the Drewry Railcar (RDB998901), previously associated with the Woodhead route.

Yes, that is very similar to the unit I travelled on at the KWVR as mentioned above.
 
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