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Dapol Class 21/29


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There are shots of a class 29 in Diesels & Electrics on 35mm Vol 1. The tunnel shot does sound a bit Maybach but by my betting the pacing shots filmed from a moving vehicle are genuine and if so, class 29’s definitely had turbo scream, but not to the extent of HST’s, which stands to reason given that the Valenta is a later development than the Ventura. Unfortunately basing the sound on recordings stood next to an engine rather than being stood next to a loco isn’t always right as has been mentioned. A 12 cylinder Sulzer engine at full power just sounds like it’s revving fast with turbo whistle inside the engine room but outside its very different with the exhaust gasses blasting out.

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53 minutes ago, Baby Deltic said:

There are shots of a class 29 in Diesels & Electrics on 35mm Vol 1.


Very true but *all* the “....on 35mm” productions were over dubbed with library recordings - the proprietor of Video 125 (who produced them) told me so at Warley several years ago.

 

BTF films were full of sound bloopers - “Points and Aspects” has Maybach powered 20s (and a 47!) at Carstairs, ”Merry go Round” has a class 56 sat whistling to itself to name but 2 examples!

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1 hour ago, Holmesfeldian said:


Very true but *all* the “....on 35mm” productions were over dubbed with library recordings - the proprietor of Video 125 (who produced them) told me so at Warley several years ago.

 

BTF films were full of sound bloopers - “Points and Aspects” has Maybach powered 20s (and a 47!) at Carstairs, ”Merry go Round” has a class 56 sat whistling to itself to name but 2 examples!

They used Peter Handford recordings for some if the clips but I think the 29 pacing shot would be too difficult to dub convincingly, plus the sound changes with gradient, distance and obstacles such as terrain between the track and road. Also it was shot for a movie (Ring Of Bright Water) so it’s highly likely it was shot with sound.

 The tunnel clip does have genuine echo.

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20 hours ago, Phil Bullock said:

 

As a general principle you can apply full power to a hydraulic transmission at standstill - as a torque converter has no direct mechanical connection energy not transmitted from the impellor to the turbine and hence to locomotion via the cardan shafts and final drives is converted to heat and dissipated via the cooling circuit.  Misuse of any transmission will cause problems however and bent cardan shafts in Hymeks (the most powerful single engine/hydraulic transmission set installed in UK) were not unknown.....

 

You cannot apply full power to an electrical machine at stand still for long however as without motion the armature and field coils are permanently in circuit until the motor starts to rotate and will function as resistors and generate heat for which there is no immediate direct dissipation - melt down would follow. Current limiters in control circuitry are required to restrict this risk.

 

Furthermore individual axles cannot slip on a bogie with hydraulic transmission as they are all directly connected by cardan shafts - not the case on a diesel electric with individual traction motors - so a hydraulic can theoretically better utilise its tractive power although sophisticated control circuitry on later diesel electrics helped alleviate this issue.

 

Heres D1015 demonstrating hydraulic starting power ... the dip in engine sound as the converters fill still makes my spine tingle

 

https://www.youtube.com/watch?v=5FDC0JFNqAI

 

Can recommed a visit to Kidderminster Diesel Depot when one of the Wizzos is up on the jacks to get a good view of hydraulic power trains.....

H

 

 

Thank you for that excellent explanation. Crystal clear too! I love the way a big diesel engine under load roars before the loco starts to move. Spine tingling indeed. Interesting snippet about the Hymeks, which, I think, were the most reliable of the diesel hydraulics.

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On 20/12/2019 at 17:57, MM1991 said:

I believe the Class 29 with discs was D6123, but it had the other Class 29 external modifications - AFAIK.  However the 21's did live long enough to be seen on B/G mk1's

 

MM

I have seen a picture of D6122 hauling a rake of B/G coaches with a MK2A behind the loco.

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Help needed from 21/29 experts!  I’m getting an all-green Class 21, and want to renumber it as one of the D6110-19 Stratford allocated series. What alterations - if any - will I need to make to the loco?

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4 hours ago, Baby Deltic said:

I have seen a picture of D6122 hauling a rake of B/G coaches with a MK2A behind the loco.

That would be interesting, I dont think I've seen that!  

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5 hours ago, Baby Deltic said:

I have seen a picture of D6122 hauling a rake of B/G coaches with a MK2A behind the loco.

Ah but was it D6121 in disguise by this point ?

did it have vents above the cab windows ?

 

popular myth has this as an ID swap, but at a minimum it swapped cabs with D6121, following an accident. In Barry scrapyard the class 21 there saw its paint fade and revealed both D6121 and D6122 as numbers.

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42 minutes ago, adb968008 said:

Ah but was it D6121 in disguise by this point ?

did it have vents above the cab windows ?

 

popular myth has this as an ID swap, but at a minimum it swapped cabs with D6121, following an accident. In Barry scrapyard the class 21 there saw its paint fade and revealed both D6121 and D6122 as numbers.

It was D6122 running under the wires on the WCML. I think it would have been D6121 by this point because it had a MK2 immediately after it so it would probably been about 1968 just before withdrawal.

 

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22 minutes ago, Baby Deltic said:

It was D6122 running under the wires on the WCML. 

If the RCTS havent seen that picture, I think they would be very interested to see it.

https://www.rcts.org.uk/features/diesels/loco.htm?id=diesels/D6121

mk2’s were introduced from 1964, same year as the cabs (at a minimum) were ID swapped between D6121 & D6122.

D6122 was known as a bit of a works queen in  1964 & 1965 with many “on works” sightings, it became a bit camera shy thereafter, its release until it headed south in 1967... so 18 months to fill the gap at which it suddenly became active.

 

D6121 seemed to be reliable, however suddenly lost its eyebrows in the same time period.. then disappeared to return as a class 29.
 

1967 D6122 (now suddenly with vent cabs from D6100-21 batch) was heading to the Southern region for testing, Dead at this point.

finally in Barry D6122 started showing D6121 numbers also.

 

so it could be an important picture you have, as 64-67 isthe period of interest, and being seen with a Mk2 puts it right there.

 

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21 minutes ago, adb968008 said:

If the RCTS havent seen that picture, I think they would be very interested to see it.

https://www.rcts.org.uk/features/diesels/loco.htm?id=diesels/D6121

mk2’s were introduced from 1964, same year as the cabs (at a minimum) were ID swapped between D6121 & D6122.

D6122 was known as a bit of a works queen in  1964 & 1965 with many “on works” sightings, it became a bit camera shy thereafter, its release until it headed south in 1967... so 18 months to fill the gap at which it suddenly became active.

 

D6121 seemed to be reliable, however suddenly lost its eyebrows in the same time period.. then disappeared to return as a class 29.
 

1967 D6122 (now suddenly with vent cabs from D6100-21 batch) was heading to the Southern region for testing, Dead at this point.

finally in Barry D6122 started showing D6121 numbers also.

 

so it could be an important picture you have, as 64-67 isthe period of interest, and being seen with a Mk2 puts it right there.

 

I'm aware of the 6121'2 debate. A works Plate found near the loco has proved that it was 6121 at Barry.

 

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28 minutes ago, Baby Deltic said:

I'm aware of the 6121'2 debate. A works Plate found near the loco has proved that it was 6121 at Barry.

 

Not necessarily... its proved the cab was from at some point fromD6121.

 

 

 

D6121? at Barry 1976

 

D6121 was a converted class 29, with Headcodes upon withdrawal..

Class_29_D6121_(8392450774).jpg

 

But the engine sold to Woodhams, and widely documented and photographed heading to the SR and hence barry was D6122... Without headcodes, but with ventilators..

NBL Class 21 D6122

 

The question is.. was D6121 (a somewhat documented workhorse) ID swapped with D6122.. a knackered works queen that had a bump, prior to D6121 becoming a class 29 conversion...

 

or did St Rollox take the cabs off D6121 and stick it on D6122 at the time of its bump to get it back out of the works, and hence D6121 getting a repaired now exD6122 cabs but now with headcodes fitted  as part of its conversion to a class 29.

 

Personally, having seen lots of class 25 cabs hanging around and seen in preservation class 25’s bearing several numbers, I am of the school of thought that economics comes first.. get the loco out of the door by taking good bits off one coming in... as D6122 was hanging around longer than it should, taking cabs off D6121 gets it back in traffic... then fix the cabs off D6122 and put them on D6121.

 

The thought of a loco like D6121 coming in for overhaul, presumably at time of an exam required, being shoved back out of the door with new numbers, without overhaul is risky, especially if something goes wrong down the road, especially on a class known for going wrong.

 

 

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41 minutes ago, adb968008 said:

Not necessarily... its proved the cab was from at some point fromD6121.

 

 

 

D6121? at Barry 1976

 

D6121 was a converted class 29, with Headcodes upon withdrawal..

Class_29_D6121_(8392450774).jpg

 

But the engine sold to Woodhams, and widely documented and photographed heading to the SR and hence barry was D6122... Without headcodes, but with ventilators..

NBL Class 21 D6122

 

The question is.. was D6121 (a somewhat documented workhorse) ID swapped with D6122.. a knackered works queen that had a bump, prior to D6121 becoming a class 29 conversion...

 

or did St Rollox take the cabs off D6121 and stick it on D6122 at the time of its bump to get it back out of the works, and hence D6121 getting a repaired now exD6122 cabs but now with headcodes fitted  as part of its conversion to a class 29.

 

Personally, having seen lots of class 25 cabs hanging around and seen in preservation class 25’s bearing several numbers, I am of the school of thought that economics comes first.. get the loco out of the door by taking good bits off one coming in... as D6122 was hanging around longer than it should, taking cabs off D6121 gets it back in traffic... then fix the cabs off D6122 and put them on D6121.

 

The thought of a loco like D6121 coming in for overhaul, presumably at time of an exam required, being shoved back out of the door with new numbers, without overhaul is risky, especially if something goes wrong down the road, especially on a class known for going wrong.

 

 

The fact that D6122 has eyebrows at both ends when pictured at Barry proves that it was more than a cab swap with D6121 unless there was damage at both ends of the loco after an accident. Why would they go to the trouble of swapping both cabs? My betting is that for some reason, possibly a cock up or some sort of administrative reason, the loco’s swapped identities or that D6121 was selected to become a 29 and problems were found, but to save a lot of beaurocratic BS, they dragged in D6122 and converted it instead then quietly swapped the numbers to cover their tracks.

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1 hour ago, Baby Deltic said:

The fact that D6122 has eyebrows at both ends when pictured at Barry proves that it was more than a cab swap with D6121 unless there was damage at both ends of the loco after an accident. Why would they go to the trouble of swapping both cabs? My betting is that for some reason, possibly a cock up or some sort of administrative reason, the loco’s swapped identities or that D6121 was selected to become a 29 and problems were found, but to save a lot of beaurocratic BS, they dragged in D6122 and converted it instead then quietly swapped the numbers to cover their tracks.

I saw sites like this with great frequency in works visits as a kid...

 

Class 25 Cabs Derby Works

(Flickr url, not mine).

and another...

Class 25: 25192 Derby Locomotive Works

 

 

 

if you need access to the internals, take off the cab.

I cant imagine those cabs went on the same locos they came off.

 

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2 minutes ago, adb968008 said:

I saw sites like this with great frequency in works visits as a kid...

 

Class 25 Cabs Derby Works

(Flickr url, not mine).

 

if you need access to the internals, take off the cab.

I cant imagine those cabs went on the same locos they came off.

 

There’s no doubt cabs were swapped. There were locos with headcode boxes at one end and not the other where cabs had been swapped at one end, but it still raises the question that if D6121 received a cab off off D6122, why did it have eyebrows at both ends?

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9 hours ago, Baby Deltic said:

There’s no doubt cabs were swapped. There were locos with headcode boxes at one end and not the other where cabs had been swapped at one end, but it still raises the question that if D6121 received a cab off off D6122, why did it have eyebrows at both ends?

Both cabs swapped...

 

I’ve just shown you both cabs off 25192.. yet it went on another 8 years, so highly likely there’s at least 4 cabs out there with 25192 on. I once saw a 31 in Manchester Victoria, then went home that night to look at the same number on the cab side I had in my shed.

 

Think of it from a welders point of view, you’ve got to remove to cab doors and fill the void, then cut and shut a headcode panel... are you going to do it standing on a plank across two buffers, with a drivers desk hidden behind the plate fully connected and potential to burn something behind what your about to cut...weighing the best part of your body weight.

 

or standing on the workshop floor removed cab in front of you and with all those internals behind it safely away able to work from both sides.

 

Now your part of a production line with a target and a knacker in front of you... remove those cab, work on them, remove the cabs of the incoming, refit the first already done, then start work on the others for the next loco... you’ve just saved days off that job.


i would look at railphotoprints site of 21’s.. many cabside numbers show evidence of partially modifying a digit on the numbers... brighter/darker digits, misaligned digits etc.

 

take 6132 for instance..

https://www.rail-online.co.uk/p463703822/h11A0378F#h1ddc29b3

 

This has been Railway practice for nearly 2 centuries, why would it not exclusively apply to these two ?

 

if nothing else from a modelling perspective, you can renumber a 21 by only removing 1 digit and leaving it mismatched in placement, font and colour density making it a junior modellers dream to renumber.

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10 hours ago, adb968008 said:

Both cabs swapped...

 

I’ve just shown you both cabs off 25192.. yet it went on another 8 years, so highly likely there’s at least 4 cabs out there with 25192 on. I once saw a 31 in Manchester Victoria, then went home that night to look at the same number on the cab side I had in my shed.

 

Think of it from a welders point of view, you’ve got to remove to cab doors and fill the void, then cut and shut a headcode panel... are you going to do it standing on a plank across two buffers, with a drivers desk hidden behind the plate fully connected and potential to burn something behind what your about to cut...weighing the best part of your body weight.

 

or standing on the workshop floor removed cab in front of you and with all those internals behind it safely away able to work from both sides.

 

Now your part of a production line with a target and a knacker in front of you... remove those cab, work on them, remove the cabs of the incoming, refit the first already done, then start work on the others for the next loco... you’ve just saved days off that job.


i would look at railphotoprints site of 21’s.. many cabside numbers show evidence of partially modifying a digit on the numbers... brighter/darker digits, misaligned digits etc.

 

take 6132 for instance..

https://www.rail-online.co.uk/p463703822/h11A0378F#h1ddc29b3

 

This has been Railway practice for nearly 2 centuries, why would it not exclusively apply to these two ?

 

if nothing else from a modelling perspective, you can renumber a 21 by only removing 1 digit and leaving it mismatched in placement, font and colour density making it a junior modellers dream to renumber.

I'm not disagreeing with you and I'm well aware of BR works practices and I have many books in the collection showing class 25 cabs and others severed from scrappers ready for  reuse. But all NBL built diesels used aluminium extensively in their construction. The cabs were fabricated from aluminum with heavy use of castings to save costs, therefore corrosion damage warranting cab replacement should not have been an issue, unlike steel cabbed loco's like class 25's whose cabs were salvaged and stored for fast repairs. I know BR bought a few extra cabs from the manufacturer in London just in case of collision damage because their fabrication was pretty specialist with them being aluminium with all the custom castings. If the cabs were swapped due to accident damage its highly unlikely D6122 would have been subsequently repaired given the fact that many of the class were already in store including some other damaged ones. There must be an accident report to corroborate the accident theory if they were swapped due to a loco sustaining damage at both ends?

 

I cannot see why BR would go through the trouble of swapping both cabs on a loco for whatever reason then repair the donor on a class which was unreliable and half in store already. Surely they would have dragged one of the stored ones out of Kittybrewster or wherever to cannibalise it, not cannibalise and then repair a loco which was still in pretty good nick and probably still a runner. My theory is the loco's completely swapped identities for reasons unknown other than accident damage or cab replacement. 

 

 

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i think your still missing the point... D6121 was converted from a class 21 to a class 29...

that included removing discs, removing the cab nose doors, weld sealing & plating, cutting a horizontal hole to accomodate a riveted in Headcode box. Further it including relocating the wipers, and modifying the horn grills, it wasnt just a repaint, Probably also some cab internals...the cab was substantially modified.. doing all that standing on a wooden platform standing on too buffers is cumbersome, slow and dangerous... doing it with a spare cab on the shop floor in advance and swapping it is much easier..but as you say spare cabs not being as common as the class 25.. you take from the christmas tree.. long term non-runner D6122 as your source.


similarly there was no reason to suspect that 21s didnt have a long future ahead of them in 1964.. they were being converted to class 29’s. Painting over a number as an elaborate scam would fall apart as soon as it reached St Rollox shed.. the power unit hours, the locos mileage would mismatch.. indeed anything subject to exam would be off right down to tyre thickness..any inservice failure could easily read the power unit number and the balloon would go up... then even a depot clerk could read the pu number, worksplate and QED St Rollox would be had for falsifying reports.

 

Something occured, but i’m not convinced it was a 4965 incident, the circumstances were different, 4965 was unlikely to ever go anywhere than Swindon, and 4965 was due to be scrapped soon anyway. And the part most susceptible to any investigation was its boiler..not its frames and it was a good boiler that precipitated it, not a bad one. D6121 left St Rollox and went to Inverurie straight after. Reports show D6122 in both works on the same day.. indeed 3 places (as it was parts & whole) in Inverurie.  The scam theory requires both works to be complicit, centres around a component (the cab) not the most important.. its electricals.

 

Is there any record of which class 21’s were rebuilt at St Rollox, I understand not many, above D6122 however is only 7.. of which we are debating 1.. D6123 was done at Colchester, so if none of the other 5 were at St Rollox .. then to me that would close it down.
 

something happened, I grant that, without evidence its unknown, but I prefer to go path of least resistance & good intentions before believing in UFOs, its a debate which I am sure benefits interest in sales of Dapols D6121.. if they were to do D6122 in the future I’m certain that would do ok too.

 

 

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2 hours ago, adb968008 said:

i think your still missing the point... D6121 was converted from a class 21 to a class 29...

that included removing discs, removing the cab nose doors, weld sealing & plating, cutting a horizontal hole to accomodate a riveted in Headcode box. Further it including relocating the wipers, and modifying the horn grills, it wasnt just a repaint, Probably also some cab internals...the cab was substantially modified.. doing all that standing on a wooden platform standing on too buffers is cumbersome, slow and dangerous... doing it with a spare cab on the shop floor in advance and swapping it is much easier..but as you say spare cabs not being as common as the class 25.. you take from the christmas tree.. long term non-runner D6122 as your source.


similarly there was no reason to suspect that 21s didnt have a long future ahead of them in 1964.. they were being converted to class 29’s. Painting over a number as an elaborate scam would fall apart as soon as it reached St Rollox shed.. the power unit hours, the locos mileage would mismatch.. indeed anything subject to exam would be off right down to tyre thickness..any inservice failure could easily read the power unit number and the balloon would go up... then even a depot clerk could read the pu number, worksplate and QED St Rollox would be had for falsifying reports.

 

Something occured, but i’m not convinced it was a 4965 incident, the circumstances were different, 4965 was unlikely to ever go anywhere than Swindon, and 4965 was due to be scrapped soon anyway. And the part most susceptible to any investigation was its boiler..not its frames and it was a good boiler that precipitated it, not a bad one. D6121 left St Rollox and went to Inverurie straight after. Reports show D6122 in both works on the same day.. indeed 3 places (as it was parts & whole) in Inverurie.  The scam theory requires both works to be complicit, centres around a component (the cab) not the most important.. its electricals.

 

Is there any record of which class 21’s were rebuilt at St Rollox, I understand not many, above D6122 however is only 7.. of which we are debating 1.. D6123 was done at Colchester, so if none of the other 5 were at St Rollox .. then to me that would close it down.
 

something happened, I grant that, without evidence its unknown, but I prefer to go path of least resistance & good intentions before believing in UFOs, its a debate which I am sure benefits interest in sales of Dapols D6121.. if they were to do D6122 in the future I’m certain that would do ok too.

 

 

 

What is a 4965 incident? 

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In my view there is no evidence come to light anywhere that any Class 21/9 had a cab change, 6127 had been out of service years, there was two cabs there that could have been re-used, also I believe 6125 never ran again after serious cab damaged, again a spare cab available there but for some reason 6122 did get it,s cab repaired and one assumes that 6121/2 just swapped numbers.

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It is very common knowledge that 25s swapped cabs with indecent frequency, but that does NOT prove the same was true for 21s or any other class for that matter, did 20s swap cabs, or 37s, 40, 47s etc?

 

I think D6121/D6122 did something similar to D5005/D5025-

https://www.derbysulzers.com/24025.html

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