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The mighty Class 74 (some questions!)
- Thread starter Harlequinuk
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Sun Chariot
Established Member
The photo I found, was definitely a JA
Big Jumby 74
Established Member
HA ?
Sun Chariot
Established Member
Oh yes - I always get my HAs and JAs mixed!
The post 1974 core Rep working cycle in the basic off peak pattern was from
Waterloo Down 91 Weymouth
Bournemouth Up 91 Weymouth
Waterloo Down 92 Bournemouth
Bournemouth Up 92 Bournemouth
Waterloo
So, Up from Bournemouth, after the TC were attached to the Rep, each combined 4Rep/8TC remained together to Waterloo on a 91, then a 92 to Bomo and back complete train, then the next 91 Down to Bomo, where the Rep detached. Repeat.
Before the pedants dive in and start listing exceptions, of course start of day, end of day, morning peak, evening peak, weekends, etc etc had numrous variations.
Pre 1974 was a little different in that the 91s were bi hourly and the 92s hourly, i.e. 3 trains every 2 hours, but they were still hourly to Weymouth - the bi hourly Weymouth 91s alternated with a bi hourly Weymouth 92.
Harlequinuk
On Moderation
Does anyone know of a Frank 'Mad Monk' Matthews? Been reading he had a reputation for pushing a loco , and holds the unofficial speed record in a 74?
hexagon789
Veteran Member
I seem to recall mention of him, the nickname rather sticks, on rmweb or possibly another forum.
He was indeed reputed to have got (IIRC) 120mph out of a 74...
D6130
Established Member
Was he a Waterloo (ex-Nine Elms) driver?
hexagon789
Veteran Member
The book ‘The twilight of Southern steam’ by Don Benn contains a few references to Frank Matthews, which suggest that he wasn’t averse to working locomotives extremely hard. Sadly, the same book refers to his death in a collision between two engineering trains at West Brompton on 29 July 1989 (accident report available on the Railways Archive website). The report refers to the driver involved as ‘T Matthews’, but Don Benn seems to know the Nine Elms drivers involved in the end of steam on the SW main line well, so I have no reason to think he would get such an important detail wrong.
I believe he was based at Waterloo at the time of the accident.
I believe he was based at Waterloo at the time of the accident.
Thread reopened for @Harlequinuk to add to
Harlequinuk
On Moderation
Hey all, got a request. Been reading that the original `clean sheet` design for the Class 74 was aiming to have a much larger and more powerful engine (possibly a paxman V12), to make it a true type2 on diesel to complement the type 4 electric power , and was wanted by W.J.A Sykes before the government shot him down. Apparently it was also discussed by A. Hawes at the IEE in 1975?
I don`t suppose anyone has anything concrete, maybe a schematic or 2?
I don`t suppose anyone has anything concrete, maybe a schematic or 2?
D6130
Established Member
IEE ?
Sun Chariot
Established Member
Institute of Electrical Engineers?
D6130
Established Member
Thanks! Should have thought of that - or Googled it - but it's still a bit early in the morning for me!
Hard to believe it would fit
Harlequinuk
On Moderation
It was a clean sheet design, not a rebuild of the 71 ; however the government of the day (and the mandarins at Southern), wanted to reuse the 71s out of traffic, so the plans wernt progressed. Instead the paxmann V6 was fitted instead . https://steamindex.com/jile/jile50.htm WJA Sykes wanted a far more powerful design to handle boat trains, as the 600 bhp `HA` was underpowered.
I'm pretty sure the late A.T.H.Taylor (who's experience stretched from 10201 & co through DEMU and D6500s and all EDLs) told me the proposed engine was the Paxman 12YJXL i.e. the V12 from the same model range (per D830 and the D6100 rebuilds) as the 6YJXL used in 74s (and 14s); that would make it 1300 hp in direct proportion or 1350 hp at its contemporary BR traction setting.
I suspect it was space reasons led to V6 not V12 in the 74s as rebuilt and not the new design - not so much engine size space but cooling capacity - you need double the radiator size, double everything and there was not much space in a 74 as it was.
The Paxman YJ "Ventura" range
was very highly thought of by BR engineers unfortunately arrived too late to be of much use in BRs diesel fleet. It can be thought of as the lineal predecessor to the Valenta (RP200) indeed the early Valentas were designated Y3J (mk3 YJ).
There were also V8 and V16 versions from Paxman but BR did not take either; only one V16 traction example was built, for export, and no traction V8; the V16 ad V8 were however much used in marine and power generation.
I supposed the V8 might have been looked at for EDL and in proportion would have come out at 867 hp; have never seen evidence to that effect.
I suspect it was space reasons led to V6 not V12 in the 74s as rebuilt and not the new design - not so much engine size space but cooling capacity - you need double the radiator size, double everything and there was not much space in a 74 as it was.
The Paxman YJ "Ventura" range
Paxman Ventura (YJ) Diesel Engines
Paxman History - Applications and Despatches of Paxman Ventura Engines
www.paxmanhistory.org.uk
There were also V8 and V16 versions from Paxman but BR did not take either; only one V16 traction example was built, for export, and no traction V8; the V16 ad V8 were however much used in marine and power generation.
I supposed the V8 might have been looked at for EDL and in proportion would have come out at 867 hp; have never seen evidence to that effect.
Harlequinuk
On Moderation
I believe there was another consideration - the use of the booster/generator. Instead of having a system ala HA, the engine simply replaced the flywheel, which of course was another reason the V6 was anaemic , it had to drive an additional series of moving parts before power got near the motors. Which would explain the 315 bhp at teh rails from a 650 bhp paxman (where the EE 4pot in the 73 made 388 at the rail from 600 bhp). I think i read the cooling group would be more akin to a 47 to cool the V12 Paxman?
D6130
Established Member
Shame....there were 19 nearly-new Paxman Ventura V12XJYL engines available when they scrapped the 29s.
I am saying it was A that determined B, you are saying B determined A.
The booster sook up that space (and weight) that could otherwise have been used for a bigger engine. That comes before power output of the whole drive line because without that set (taking up space and weight) the output power would be different. The underlying reason for the small engine is space and weight with the set .
ITYF if you scroll back it was me who pointed out (see msg 27) in this thread the power at rail values.
47 original was 2750 hp which is double that of the 12YJ at 1300/1350 hp => the cooler group for the V12 Paxman would be half the size of that in a 47.
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No, the booster set was removed to make space for the diesel engine. There wasn't any room for anything bigger
Shame....there were 19 nearly-new Paxman Ventura V12XJYL engines available when they scrapped the 29s.
Not sure BR worked like that.
It can equally be suggested there were already a number of the V6 YJ engines from early D9500 withdrawals maybe not actually withdrawn in 1966/67 but already in store pending disposal. Yet the 74s had new engines. While it is true BR sold many D9500s into industry that needed to keep their engines, I suspect they generated far less cash from selling 11 complete D9500s than buying 11 new engines,
err what did the engine drive if it were not the booster set then ?
74s retained booster but now electronic controlled
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Yes I seem to have been
I reported my post and requested it be deleted before you posted
I think you are confused.
The booster set is a motor generator set on a common shaft, with a flywheel on that shaft in a 71; the 74 did not have the flywheel, just the m-g set.
A 74 in FWO weighed 84 tons - the correct figure being in the BR Diagram 740AX not what is in wikidripplepedia and often copied. The flywheels was removed to keep weight down.
== Doublepost prevention - post automatically merged: ==
ok got it now we were posting in parallel hence the further confusion