Class 20's being driven cab first

[popeter45]

Is that not the Class 18 as described above?

thats a top cab so cab see both ends vs a full size locomotive but only one cab at one end

 

[norbitonflyer]

I don't recall ever seeing a pair running cab to cab, but nose to cab (ie both facing the same way) was not unknown when they were in regular service.

Class 18's centre cab and low bonnets is essentially the same layout as some BR types- notably Classes 07, 14 and 17. The full height bonnet and single cab was only ever used by Classes 15, 16 and 20 - and of course the standard shunters (classes 08-13). Of these, only classes 15 and 16 had bonnets at each end.

As well as cost saving they were built in an era when single cabbed locos (i.e steam) were the norm. Would a class 20 type layout meet current safety requirements if being introduced today? The class 18s have a central cab with much lower bonnet either side.

The single cab was part of the Type A (later Type 1) pilot scheme specification laid down by the British Transport Commission, along with no steam heating and a power output of up to 1000hp. The single cab and absence of a boiler saved weight, not only of those components themselves, but because a shorter frame was needed to support them.
Pilot scheme Type Bs (later Type 2s) had two cabs and steam heating, and especially the D6100 (class 21) and D5900 (class 23) which had little if any more power than a class 20, were very poor performers. (The class 22 had the same engine as the Class 21, but a lighter hydraulic transmission)

 

[XAM2175]

As well as cost saving they were built in an era when single cabbed locos (i.e steam) were the norm. Would a class 20 type layout meet current safety requirements if being introduced today? The class 18s have a central cab with much lower bonnet either side.

Can't speak for here but I know it's still officially permitted in Australia (and on much longer locomotives to boot), though in recent times it's actively discouraged except for shunting and other short-distance/low-speed moves.

 

[Taunton]

In the USA the cab position at the three-quarters point, with "long hood" and "short hood" became standard in the 1950s for the bulk of the standard Road Switcher main line diesels, like a D8200/8400. Then the height of the short hood was reduced from full height, to give a forward view from the whole cab, and most railroads moved on to this, some even rebuilding the older ones the same way.

However, a few major railroads had never operated their diesels short-hood-forward, and did so the other way round. The Norfolk & Western and the Southern (and indeed the merged Norfolk Southern company at first) were principal users of such locos, running long-hood-forward. With the incidence of level crossing accidents in the USA, it was long felt to be a safety issue for loco crews having the cab exposed more than minimally at the front - mainstream USA operators commonly have quite a number of units in the shops at any time for substantial repair after such events.

 

[Magdalia]

The single cab was part of the Type A (later Type 1) pilot scheme specification laid down by the British Transport Commission, along with no steam heating and a power output of up to 1000hp. The single cab and absence of a boiler saved weight, not only of those components themselves, but because a shorter frame was needed to support them.

The whole Type A/Type 1 saga is one of the biggest, if not the biggest, wastes of money of the Modernisation Plan.

There were three Type As is the Pilot Scheme: the EE D80xx, BTH D82xx and NBL D84xx.

why were they designed like that, with a thin cab one end and not with cabs both ends?

Cheaper to fit one cab rather than two.

As well as cost saving they were built in an era when single cabbed locos (i.e steam) were the norm.

It is important to remember what the Type As were originally for. In the mid 1950s nearly every rural branch line had a daily pick up freight which brought coal in and took agricultural produce out. The Type As were to replace steam on these workings.

In particular it was important to save weight to get a low axle load to give the locos a very wide route availability.

Quite the opposite, the 20 is designed for driving with the cabbed (no.2 end) leading, but the cab does feature dual controls. In fact in BR days I believe a secondman was required when driving 'nose first' to assist with signal sighting.

No, the EE Type 1 is designed for driving in both directions.

If I remember correctly from their first year of introduction, photos generally showed them single unit, and running long-nose-forward on both passenger and freight (and when lined up well polished to show dignitaries). Little driving difference to a steam loco of course.

On branch line trips the loco would be driven from one end on the outward and the other on the return, unless the traincrew bothered to turn the loco on a turntable at the end of the line.

English Electric did a range of exports, eg to Australia, with the cab at the three-quarters position, and long and short noses, just like a USA road switcher or D8200/8400.

While the D82xx and D84xx locos had the three quarters position, the EE Type 1 had the cab at one end. This was one of it major drawbacks and why BR stopped orders after D8128. They then disappeared down the Clayton and Paxman rabbit holes, both of which were designed to provide good all round visibility for working branch line trip freights.

Following the failures with the Claytons and Paxmans BR came full circle eventually going back to the EE Type 1 for 100 more locos. I have not yet worked out what use BR thought it had for these in the post Beeching world.

The use of EE Type 1s in pairs as a surrogate Type 4 only really starts in the late 1960s, around the time of the final elimination of steam. Almost by accident BR found that pairs of EE Type 1s, coupled nose ends together, were ideal on heavy unfitted freight trains. In particular a pair of EE Type 1s were far superior to an EE Type 4 because the pair of EE Type 1s had 70 tons of brake force compared to 51 tons on an EE Type 4.

 

[RJ]

I don't want to create a new thread for this so i'll ask here.

In pairs Class 20s always travel cabs outer, but has anyone ever seen a pair operating with bonnets outer? I'm sure it must have happened at least once over their long careers though never seen photographic evidence!

It has happened on the mainline this side of the millenium!

 

[12LDA28C]

No, the EE Type 1 is designed for driving in both directions.

Ok, I'll rephrase - the normal method of operation is No. 2 end (cab) leading, or would you disagree? I'm well aware that a single loco often appeared nose-first, particularly in Scotland but a single loco was not sufficient for hauling a decent load and pairs were almost always coupled with cabs outwards.

 

[Magdalia]

the normal method of operation is No. 2 end (cab) leading

Not when the locomotives were new.

a single loco was not sufficient for hauling a decent load

When the locomotives were new there was no intention to use them to haul a decent load on main lines. In the early days the EE type 1s were primarily used singly on trip freights and branch line pick up freights, which were lightly loaded. It is very rare to find a picture of a pair before the end of steam.

pairs were almost always coupled with cabs outwards

I agree with this bit, but it only happened to a significant extent after the end of steam, and the closure of many branch lines after Beeching. It was at that point that the EE Type 1s were repurposed to operate in pairs as a surrogate Type 4 with lots of brake force.

The second build locos, with headcode panels, and delivered in 1966-68, saw very little of the original method of operation, especially the D8144-99 batch that went new to Toton.

 

[Sm5]

When I was a lot younger I remember class 20’s regularly running singularly bonnet first. I never saw many running cab to cab, but running bonnet to cab was also fairly common.

I think early 1980’s it seemed 20’s were deemed under powered for modern trains and settled on bonnet to bonnet coupling and running in pairs being the norm.

 

[dubscottie]

A single 20 running bonnet first was very common in the east of Scotland until the demise of Speedlink. Trip workings to Rosyth Dockyard etc.
They had to have a brakevan when running like that as the guard was not allowed to travel in the same cab as the driver.

 

[Lewisham2221]

Wasn't part of the "limited visibility" design on these, as well as things like 37's with a bonnet and relatively small windows, to replicate the view from the footplate of a steam locomotive, thus making the transition from steam to diesel slightly easier for the crews, or is that just a myth?

 

[norbitonflyer]

The second build locos, with headcode panels, and delivered in 1966-68, saw very little of the original method of operation, especially the D8144-99 batch that went new to Toton.

Although they were fittted with headcode panels at both ends, suggesting that running bonnet first in main line use was envisaged.

 

[12LDA28C]

Wasn't part of the "limited visibility" design on these, as well as things like 37's with a bonnet and relatively small windows, to replicate the view from the footplate of a steam locomotive, thus making the transition from steam to diesel slightly easier for the crews, or is that just a myth?

Never heard that before. The Class 20 was possibly derived from steam locomotive design hence the single cab but locomotives with a 'nose' like 37s, 40s, 44-46s, 55s were so designed to prevent the driver being able to see straight down onto the track in order to reduce the effect of 'sleeper flutter' at speed until it was ascertained that the effects of this phenomenon were not as severe as first thought.

 

[Lewisham2221]

Never heard that before. The Class 20 was possibly derived from steam locomotive design hence the single cab but locomotives with a 'nose' like 37s, 40s, 44-46s, 55s were so designed to prevent the driver being able to see straight down onto the track in order to reduce the effect of 'sleeper flutter' at speed until it was ascertained that the effects of this phenomenon were not as severe as first thought.

That's the one. I knew it was something along those lines

 

[cce]

EE Type 1s were repurposed to operate in pairs as a surrogate Type 4 with lots of brake force.

Out of interest, how did this compare in terms of running costs to something like a 40?

 

[Taunton]

Wasn't part of the "limited visibility" design on these, as well as things like 37's with a bonnet and relatively small windows, to replicate the view from the footplate of a steam locomotive, thus making the transition from steam to diesel slightly easier for the crews, or is that just a myth?

I don't think so.

Diesels came early to the USA, of two types, the "road locos", with fully streamlined bodies, often in multi-unit sets, with the cab just facing forward, and "switchers", low speed locos, cab at one end but a narrow main body allowing a view both ways, when shunting back and forth.

The road locos were a handful on occasions when they needed to shunt backwards, so a development (I think the Alco RS-1 was the first, just before WW2) was the "road switcher", combining the two approaches. The early multi-unit streamliners were kept as fixed formations, for various reasons, some didn't even have proper couplings within the unit, just a bar, while road switchers made it easy to vary the formation as required. And some railroads, as mentioned above, chose to run them normally "long hood forward". The cab at the three-quarters point allowed the main diesel to be in the long hood, and various accessories in the short hood.

I experienced the issue with classic F-unit streamliner road locos when riding on Canada's "Super Continental" in the 1970s. At Hornepayne, Ontario, middle of the forest, in the small hours, the diner developed a hot box and had to be got out of the middle of the train and detached into a siding. Absolute pitch dark outside, brakemen down on the ballast swinging lanterns, engineer only able to face forwards, four units with doubtless variable throttle responses, it proceeded with a series of shouts and jolts until the finale, propelling the two halves of the train back together, which we hit at about 5mph with the power on, surely waking everyone up in the whole train!

 

[Magdalia]

Out of interest, how did this compare in terms of running costs to something like a 40?

I have not seen anything that examined that. Intuitively a pair of class 20s would have higher running costs than a single class 40 but that's probably more than offset by the increased payload. With heavy unfitted freight trains running at low speed the maximum weight carried is determined by brake force not horse power.

 

[norbitonflyer]

I have not seen anything that examined that. Intuitively a pair of class 20s would have higher running costs than a single class 40 but that's probably more than offset by the increased payload. With heavy unfitted freight trains running at low speed the maximum weight carried is determined by brake force not horse power.

A Class 40 weighs 135 tonnes, two class 20s weigh 146 tonnes. Moreover, all eight axles are powered, so traction will be better than the 1Co-Co1 Class 40, in which two of the eight axles are unpowered.

 

[Taunton]

A Class 40 weighs 135 tonnes, two class 20s weigh 146 tonnes. Moreover, all eight axles are powered, so traction will be better than the 1Co-Co1 Class 40, in which two of the eight axles are unpowered.

Am I not correct that the Class 40 unpowered wheels are not braked either?

 

[Magdalia]

Class 40 unpowered wheels are not braked either?

Yes that's correct, hence the lower brake force.