Class 40 hauling ETH (air con) stock ? ! ?

[Richard Scott]

I have heard more than one ex-driver say they felt a good 45 had the edge over a 47

Heard that too (Gloucester drivers used to rate 45s and think they signed quite a few types).

 

[hexagon789]

Heard that too (Gloucester drivers used to rate 45s and think they signed quite a few types).

Just looked at the diagram book and the entry for 47s states full engine output is available to 77mph, but for a 45 the figure is 82mph. Perhaps that's at least a partial explanation as to why 45s had a slight edge?

 

[Shaw S Hunter]

I have heard more than one ex-driver say they felt a good 45 had the edge over a 47

Depends on the route. 47s were much better at low to medium speeds but had almost nothing left above 80mph. 45s, with all that extra weight, accelerated more slowly but the electrical set-up did indeed mean they had more oomph at higher speeds. Hence the 45/1s did well on the MML but were hopeless on TP(N) compared to 47s.

 

[hexagon789]

Depends on the route. 47s were much better at low to medium speeds but had almost nothing left above 80mph. 45s, with all that extra weight, accelerated more slowly but the electrical set-up did indeed mean they had more oomph at higher speeds. Hence the 45/1s did well on the MML but were hopeless on TP(N) compared to 47s.

I would also perhaps argue the 47s were perhaps a slightly better all-rounder, more of a mixed-traffic jack of all trades while 45s were better cruising on passenger trains at sustained 80-90mph running speeds.

 

[Cowley]

I think the Crompton Parkinson electrical equipment fitted to the 45s was considered to be extremely good and fairly bombproof compared to the Brush gear on the 46s.
There’s plenty of performance logs showing 45s cracking 100mph back in the day.

 

[Richard Scott]

Depends on the route. 47s were much better at low to medium speeds but had almost nothing left above 80mph. 45s, with all that extra weight, accelerated more slowly but the electrical set-up did indeed mean they had more oomph at higher speeds. Hence the 45/1s did well on the MML but were hopeless on TP(N) compared to 47s.

The 47s used were mostly series parallel machines, I believe, which seem to get power down quicker than all parallel machines. 45s being all parallel take a while to get going but once on the move go like the preverbial off of a shovel! Also a 45/1 only around 13-17 tons heavier than a 47/4 so not as much extra weight as you may think. Those 5 stages of field weakening don't half make a difference too.

 

[CW2]

It was rumoured that certain Longsight class 40s had been deliberately downrated for ease of maintenance. The idea of downrating something that is already overweight and underpowered is madness, but such "local initiatives" were not unknown. I recall 40029 was one of those affected, and was a complete gutless wreck.

 

[70014IronDuke]

Depends on the route. 47s were much better at low to medium speeds but had almost nothing left above 80mph.

I'm sorry, but this is nonsense. A Cl 47/4 with 10 Mk2 air-con could, and did, attain and exceed 95 mph quite easily between Newport and Paddington day in, day out in the mid-70s. Not, eg of course, on the climb out of Severn Tunnel or through PSRs eg at Reading. Drivers between Bristol Parkway and Didcot in particular, and then on to Slough area had to continually ease off, with the controller on about half power, to avoid over speeding, on S Wales expresses. I rode on the footplate on several occasions and experienced this.

EDIT - I never personally experienced it, but let's not forget the ECML, where Cl 47s regularly deputised on Deltic diagrams and were logged mile after mile at around 100 mph as drivers worked to lose as little time as possible.

45s, with all that extra weight, accelerated more slowly but the electrical set-up did indeed mean they had more oomph at higher speeds. Hence the 45/1s did well on the MML ...

The Crompton-Parkinson electrical gear on the Cl 45s was always considered more robust and, IIRC, less prone to flash-overs than the Brush gear on the Cl 46s and Cl 47s.

This was common talk by both drivers and maintenance staff. I admit that I never saw any documented data to back this assertion up. But I suspect it did exist.

 

[edwin_m]

The Crompton-Parkinson electrical gear on the Cl 45s was always considered more robust and, IIRC, less prone to flash-overs than the Brush gear on the Cl 46s and Cl 47s.

This was common talk by both drivers and maintenance staff. I admit that I never saw any documented data to back this assertion up. But I suspect it did exist.

There must have been some reason that the 45s and not the 46s were picked for fitting of ETH.

 

[Richard Scott]

There must have been some reason that the 45s and not the 46s were picked for fitting of ETH.

They were allocated to MML trains already, I believe whereas 46s worked cross country and some ECML services? 45s were definitely more robust the Crompton electrical gear was far better than Brush, was slightly lighter, the 5 stages of field weakening allowed better acceleration and think they could produce maximum power over a greater speed range (and had slightly more power at rail in the first place).

I'm sorry, but this is nonsense. A Cl 47/4 with 10 Mk2 air-con could, and did, attain and exceed 95 mph quite easily between Newport and Paddington day in, day out in the mid-70s. Not, eg of course, on the climb out of Severn Tunnel or through PSRs eg at Reading. Drivers between Bristol Parkway and Didcot in particular, and then on to Slough area had to continually ease off, with the controller on about half power, to avoid over speeding, on S Wales expresses. I rode on the footplate on several occasions and experienced this.

That's true but earlier quote isn't too far from the truth. All type 4s started to unload at speeds between 80 and 90mph. There is a point at which the generator cannot be excited any more than it is and back emf from motors starts to overcome what the generator is producing so as speed rises the output drops. This doesn't mean the loco won't go any faster as long as it's still more than overcoming friction it will continue to accelerate up to the point this no longer happens. 45s could attain 100mph with ease, 47s could get into the 100s, had one at around 107 and 50s could get into the 110s, had one at around 115 but these were on loads of around 10 or less (in the case of the 50 with no ETH as summer on MK2 a/b stock). Did have a book with technical info as to the unloading speed of each class but can't find it. The 40s would have been limited by their lower installed power, only had one on mainline do can't comment on their performance.