Diesel mixed pairs

[russ p]

This came up on the thread about class 15s and Whitemoor and mention of a baby deltic multi'd up with a 15 something which i knew was possible but never seen a picture of or even mentioned before. 

The historical stuff to me is more interesting but as I type this im actually travelling back passenger having worked an intermodal train from York to toton with a class 88 and 68 in multiple so it still happens today 

[HGR]

It's mainly an issue of load-sharing.

 

Some of the early classes, particularly the pilot diesels, had control systems that limited their multiple working capability to others with the same arrangement of equipment, so sometimes only within their own class. This automatically ensured compatibility within the group.

 

Blue Star is an example of an attempt at a 'universal' multiple working capability. It basically relies upon using the regulating air pressure to control all coupled locomotives so the engine output of each is in proportion 0% to 100%, so all locos produce the same percentage of their rated output. The output of a diesel engine is limited by the speed it is run at, so the regulating air pressure controls engine RPM through (in most cases) a mechanical governor. The load regulator of each loco then takes care of loading up the diesel to its fullest for the set RPM. So load is shared according to rated power output of each loco.

 

The success of any combination of different classes in multiple then brings other factors into play, field diverts being the usual culprit. As these are generally taken and reverted at particular set road-speeds, there can be instability if the train is running around about the cut-in or cut-out speed of one of the locos. Accelerating quickly through the divert setpoint speeds will generally be OK, but climbing slowly through the critical speed(s) or slowing on a rising gradient can cause surging and/or transient overloading / unloading on one of the locos. Some pairings seemed to be more susceptible to this than others. Some classes are prone to this even when working between members of the same class. 37s for example can get a good fight going once one decides to go for divert, evidenced by the varying exhaust clag and outbursts of thunderous noise and mightily uncomfortable ride up the front end of the train as the engines over / underload.

 

 

[russ p]

Different sub classes of 37 also divert at different speeds.

37s and 20s work well together,  I had a very enjoyable run from Skegness to Derby some years ago with this combination 

I have seen  quite a few different pairings of blue star locos but never red circle locos..

When DRS had the 47s fitted with the DRS version of blue star we've had 20/47 or 37 combos 

[Teabag]

I have seen pictures of 33s and 24s paired in the early days of the 33s before the SR had electric heated coaching stock - the 24s providing steam heat.

Also seen a picture of a 33 and 73 in Blue on a parcels turn - both running, judging by the exhausts.

 

Teabag

[keefer]

In the '60s, used to have cl.27+20 on Glasgow-Fort William sleepers. The 20 had a through stream pipe to avoid having to turn the locos.

Edinburgh-Inverness trains often had cl.24+26.

In general, up to about 1975, the WTT specified cl.24 and/or 26 together as they had the same power & top speed.

Likewise other trains diagrammed for cl.25/27.

In NW England in the '80s there was a regular BOC working that was cl.40+25

(There's an old thread on RMweb somewhere about this sort of thing)

Edited May 4, 2021 by keefer

[Rivercider]

In the 1988 Working Manual the instructions were:

With two locos in multiple except when specific loads are published then the following instructions apply.

 

Two locos of the same class in multiple to be twice the load of the single loco, provided it does not exceed the highest load for any single loco on the route.

For two locos of different classes, in multi or tandem, to be the load of the most powerful loco plus half the load of the less powerful loco, but not exceeding the highest load for any single loco on the route,

 

cheers 

[stovepipe]

Euston - Stranraer overnight service was due to be piloted from Ayr by a 20, but was often a 27, with a 47 as the main engine. Similarly the Padd - Penz sleeper was 50+31 over the Devon banks, in earlier times the summer saturday day trains were piloted by 22s with Warships and Westerns.

[pH]

10 minutes ago, keefer said:

Edinburgh-Inverness trains often had cl.24+26.

As in:

 

BRCW Type 2 D5343 and Sulzer Type 2 D5127 at Newtonmore 6 August 1962

[russ p]

14 minutes ago, keefer said:

In the '60s, used to have cl.27+20 on Glasgow-Fort William sleepers. The 20 had a through stream pipe to avoid having to turn the locos.

Edinburgh-Inverness trains often had cl.24+26.

In general, up to about 1975, the WTT specified cl.24 and/or 26 together as they had the same power & top speed.

Likewise other trains diagrammed for cl.25/27.

In NW England in the '80s there was a regular BOC working that was cl.40+25

(There's an old thread on RMweb somewhere about this sort of thing)

 

The 40 +24 or 25 seemed a common if unusual pairiin the other West in the 70s and 80s

[daveyb]

In 'Diesels out of Kings Cross' there are few shots of a 15 or 16 paired with 30/31 hauling rubbish on the GN Hatfield / Luton branch to Blackridge tip near Wheathamstead

[russ p]

I know they weren't used much but were the bellows in locos fitted with connecting doors standard or was each class different? I understand only the CO-BO still has them fitted

[Johann Marsbar]

You occasionally saw 31+37 combinations on Freightliners...

 

 

I think everything featured in that photo has gone now, including the school buildings!

 

[Johann Marsbar]

I forgot this one as well....

 

 

 

[HGR]

Wasn't the power of 'larger loco plus half that of the smaller loco' applied for tandem worked pairs of any sort - mixed or same class ? For multi worked Blue Star pairs or triples it was simply totalled up. It may have been a NE or LMR regional thing maybe ? Seem to remember seeing an instruction about reducing the load of freight trains if the locos had a failure of the MW gear. Do remember putting a loco 'inside' to remedy defective MW - the pair worked OK coupled the other way round.

 

[caradoc]

On 03/05/2021 at 00:34, russ p said:

37s and 20s work well together

 

For a while in the 1980s a 20 plus 37 combo worked Ayrshire coal trains. 

 

16 hours ago, Teabag said:

Also seen a picture of a 33 and 73 in Blue on a parcels turn

 

And in the 70s a 33 plus 73 combo worked MGR coal trains to Didcot Power station. 

 

[Tom Burnham]

47 plus 45 pairs were usual on the Toton to Northfleet cement works MGR coal trains. I believe the Class 45 didn't have slow speed control.

[Rivercider]

In the hydraulic era it was quite common for a class 22 and class 42/43 to work together in Devon and Cornwall.

 

I have a few photos of mixed pairs.

As mentioned by keefer I understood that class 24/26 and 25/27 pairings were more common,

but on one of my rare visits north of the border we enjoyed a class 26/27 combo out of Inverness.

27003 and 26034 wait to depart from Inverness on the 10.48 service to Aberdeen, 08568 is the station pilot. 18/6/83,

 

cheers

 

[Johann Marsbar]

I had 26 037 + 27 037 on a Far North service from Inverness in June 1985 whilst on a 2 week All-Line Rover....

 

 

After posing the question elsewhere about this, it seems this working may have been a "fix" for someone, given the loco numbers involved and the fact that the previous year when I was there it was wall to wall 37's.......

[russ p]

4 hours ago, HGR said:

Wasn't the power of 'larger loco plus half that of the smaller loco' applied for tandem worked pairs of any sort - mixed or same class ? For multi worked Blue Star pairs or triples it was simply totalled up. It may have been a NE or LMR regional thing maybe ? Seem to remember seeing an instruction about reducing the load of freight trains if the locos had a failure of the MW gear. Do remember putting a loco 'inside' to remedy defective MW - the pair worked OK coupled the other way round.

 

 

I remember as a secondman on the potash trains out of boulby if the railhead conditions were bad taking the jumper cable out and shutting the reg air pipes as 20s seemed to be better driven singularly 

[keefer]

4 hours ago, Tom Burnham said:

47 plus 45 pairs were usual on the Toton to Northfleet cement works MGR coal trains. I believe the Class 45 didn't have slow speed control.

Correct, and adding the 47 meant the trains were a bit quicker through the crowded commuter lines.

[divibandit]

Morning,

I've just found this thread.

In theory is it possible for Blue Star fitted Claytons to work in multiple with Blue Star fitted Class 29s? 

 

Steve

 

[russ p]

1 minute ago, divibandit said:

Morning,

I've just found this thread.

In theory is it possible for Blue Star fitted Claytons to work in multiple with Blue Star fitted Class 29s? 

 

Steve

 

 

It certainly is and may have taken place. I'm sure the preserved Clayton was originally red diamond but has been rewired blue star 

[divibandit]

Hi Russ,

Yes they were originally Red Diamond, while the 21/29 was originally Red Circle. I haven't worked out whether the re-engined ones were rebuilt as Blue Star.

 

Steve

[russ p]

6 minutes ago, divibandit said:

Hi Russ,

Yes they were originally Red Diamond, while the 21/29 was originally Red Circle. I haven't worked out whether the re-engined ones were rebuilt as Blue Star.

 

Steve

 

Hi Steve 

For some reason the locos that were rebuilt as 29s were all red circle which to me seemed a strange decision. 

I've never seen any pictures of the master controllers in the NBLs to see if the two different systems had different controllers . There is some brief footage of a 29 one on ring of bright water

The red circle ones had ten notches and blue star variable although 31s do have a couple of notches on the controllers as do 25 I seem to recall 

[divibandit]

That's a very strange decision!

Well, I guess Rule 1 will have to apply, lol.

Thanks Russ,