GBRF class 66 re-gearing

[50002Superb]

Pictured here: https://flic.kr/p/2rHVLzz

 

[warwickshire]

I think 66671 has just passed me at Trent Junction on its way to Eastleigh.

Yes, saw 66671, on Thursday 27th November 2025, at Widney Manor, hauling a small train of rails, on the 6X01 1008 Scunthorpe to Eastleigh service, hauling the service on its own power as a solo engine for the rails made in Scunthorpe.

 

[50002Superb]

Apparently 66693 has finally left Longport today

 

[SWR450127]

66776 is now 686 as it ran yesterday on 0E72 to Donny Decoy.

 

[XCTurbostar]

66776 is now 686 as it ran yesterday on 0E72 to Donny Decoy.

Can confirm, it still carries its Joanne name plate.

 

[50002Superb]

There was previously a thread on this but it’s locked for comment and I can’t work out how to request that it be re-open which can be found here:

https://www.railforums.co.uk/threads/gbrf-class-66-re-gearing.285993/page-4

Anyway, I noted from a recent posting by @47286Dan on the Freightliner thread that some more GBRF 66/6s are now renumbered and had not seen any reference to these.

The 66s in question are:

66667
66678
66682
66695
66696

Does anyone know when these were renumbered and what they were renumbered from please?

I believe that we are still expecting the following at some point:

66664
66665
66681

Does anyone know how far they are in terms of progression and whether there are any more that haven’t previously been mentioned?

Many thanks
50002Superb

 

[JonathanH]

Does anyone know when these were renumbered and what they were renumbered from please?

Should be

66757->66667
66761->66671
66768->66678
66772->66682
66776->66686
66777->66687
66779->66689
66793->66693
66794->66694
66795->66695
66796->66696

Fairly straightforward once it is noted that 66780 to 66789 are the ex DB Cargo locomotives which aren't involved. Anything lower numbered take off 90, anything higher numbered take off 100 from the previous number.

 

[Tony2]

66685 also renumbered recently from 66775 or F231 (originally I got the two alphanumeric GBRfs mixed up but was put right!!).

I’d hoped the old thread would be unlocked as well, however this new one does the business.

I wonder why the GBRfs have gaps in the numbering when DB and HH (before export) didn’t.

 

[150249]

There was previously a thread on this but it’s locked for comment and I can’t work out how to request that it be re-open which can be found here:

https://www.railforums.co.uk/threads/gbrf-class-66-re-gearing.285993/page-4

Anyway, I noted from a recent posting by @47286Dan on the Freightliner thread that some more GBRF 66/6s are now renumbered and had not seen any reference to these.

The 66s in question are:

66667
66678
66682
66695
66696

Does anyone know when these were renumbered and what they were renumbered from please?

I believe that we are still expecting the following at some point:

66664
66665
66681

Does anyone know how far they are in terms of progression and whether there are any more that haven’t previously been mentioned?

Many thanks
50002Superb

I see they're avoiding one locomotive like the plague

 

[47286Dan]

Friday afternoon update

Just thought I’d add a list of the current ones

66667 GBHH GRAINGBRF GRAINGBRF 7 X
66671 GBEL ASHTONMGB 356C52CJ18 4 HTRBQGBRF N
66678 GBEL CLITCEMGB CLITCEMGB 6 N
66682 GBHH WHITEMOOR WHITEMOOR C N
66685 GBNB MHILL REC MHILL REC N
66686 GBNB SINFNGBRF 576O77CU18 7 * GRAINGBRF N
66687 GBHH DAVTRY GB 706O55CP18 4 DOLNDMRGB N
66689 GBHH ANGSTNWGB 886M79CK18 4 BARDONHLQ N
66693 GBHH WLSDNETGB 726O37CO18 5 CLIFFEGBR N
66694 GBHH TONB11&12 TONB11&12 5 N
66695 GBHH DRAX GBRF 174N61CJ18 0 * TYNEDK GB N
66696 GBHH HTRBQGBRF 096J84CL18 4 BRINDLGBF N

Dan

 

[50002Superb]

That’s brilliant, thanks @47286Dan - I seem to have missed a few coming out so got a few to chase now

 

[Trainz6013]

I see they're avoiding one locomotive like the plague

Just need to hope they convert 66756, doubt they will...

 

[Roylang]

Just need to hope they convert 66756, doubt they will...

As I understand it, the original order for the conversion of 47/0s to 47/4s was reduced by one to end at 47665.

Roy

 

[andy33gmail]

Tenuously if they deliver more TE and hence power at the rail at a given speed you could claim to have increased the power output, but they haven't clarified what they mean by "power".

You may get more power at lower speeds as you are unlikely to be able to load the motors to maximum at a standing start so power at 0mph will be limited to less than rated continuous power output, which is probably available from around 10mph+.

Also tenuous, but if you increase the mass the train is capable of pulling, then the result would be that more power is usefully used

(Or if you want to go full Tabloid, power is energy over time, so allowing the trains to be utilised on more services per month also increase power)

 

[Richard Scott]

Also tenuous, but if you increase the mass the train is capable of pulling, then the result would be that more power is usefully used

(Or if you want to go full Tabloid, power is energy over time, so allowing the trains to be utilised on more services per month also increase power)

Not necessarily as it would accelerate more quickly.
Power is an instantaneous reading of work done i.e. energy transferred per second (so what the machine can do every second) so not sure what you're getting at with last statement? Utilising a machine for more time increases the energy transferred, as the time has also increased the power remains the same.

 

[andy33gmail]

Not necessarily as it would accelerate more quickly.
Power is an instantaneous reading of work done i.e. energy transferred per second (so what the machine can do every second) so not sure what you're getting at with last statement? Utilising a machine for more time increases the energy transferred, as the time has also increased the power remains the same.

If the previous gearing permitted a 200,000 tonne train to be hauled, and the new gearing permits a 250,000 tonne train to be hauled. And if they nevertheless accelerate at the same rate due to the lower gearing. Then you are delivering more power

That’s more specific than what I meant, and no doubt 10x off in mass one way or the other, but that’s the tenuous claim I was making

 

[Richard Scott]

If the previous gearing permitted a 200,000 tonne train to be hauled, and the new gearing permits a 250,000 tonne train to be hauled. And if they nevertheless accelerate at the same rate due to the lower gearing. Then you are delivering more power

That’s more specific than what I meant, and no doubt 10x off in mass one way or the other, but that’s the tenuous claim I was making

Initially you would get more power at rail at lower speeds compared to installed horsepower but it will level out at a lower speed so whilst it seems you're getting something for nothing you're not. Bit like leaving a car in a lower gear, it will accelerate more quickly but you'll use more fuel overall.
You can't get something for nothing.

 

[43096]

Initially you would get more power at rail at lower speeds compared to installed horsepower but it will level out at a lower speed so whilst it seems you're getting something for nothing you're not. Bit like leaving a car in a lower gear, it will accelerate more quickly but you'll use more fuel overall.
You can't get something for nothing.

Indeed. You don’t get “more power” just the same power at different speeds because of the gearing - the diesel engine can only deliver power up to its maximum. So it is really about matching the loco’s capabilities with the requirements of the load to be hauled.

 

[andy33gmail]

You can't get something for nothing.

I understand - and again, I was just constructing a tenuous definition of “more power” that’s consistent with the headline

Both the situations I originally described allowed for usefully *using* more power, i.e. great engine utilisation

 

[Richard Scott]

I understand - and again, I was just constructing a tenuous definition of “more power” that’s consistent with the headline

Both the situations I originally described allowed for usefully *using* more power, i.e. great engine utilisation

It's a different use, move a heavy load more slowly or a lighter load more quickly. Depends what you want to do. Either way you still are only using what you have.

 

[andy33gmail]

Either way you still are only using what you have

The power output is a limit

Gearing may help you come closer to that limit (on average)

 

[Richard Scott]

The power output is a limit

Gearing may help you come closer to that limit (on average)

No it won't, your limit is efficiency of the transmission equipment, which will be no different with whatever gearing you have. All it will do is shift the speed at which maximum efficiency occurs.