59 vs 66

[Pacerman99]

Why is it the 59s can pull much heavier loads than a shed?
According to Wiki, both have 3,300hp and the 66s are actually a little heavier than the 59s. I do notice that the sheds can do 75mph compared to a 59s 60mph, but then 59/2s can also do 75mph, so surely the gearing must be similar ish. What am I missing?

 

[Rob F]

Are the 66s fitted with less powerful traction motors?

 

[delt1c]

Why is it the 59s can pull much heavier loads than a shed?
According to Wiki, both have 3,300hp and the 66s are actually a little heavier than the 59s. I do notice that the sheds can do 75mph compared to a 59s 60mph, but then 59/2s can also do 75mph, so surely the gearing must be similar ish. What am I missing?

Whilst they may look similar, underneath there are dramatic differences, the 59 was designed as a pure heavy haul for stone traffic and single 59’s replaced double headed 56’s ( which singly were of equal power). The 66’s were designed as a standard fright loco.
it’s a bit like 44’s and 45’s both similar but traction effort miles apart.
You have to go beyond just engine and weight, it is all in the gearing and how power is transmitted to the rail.
as an aside do the 59’s still hold the UK record for singly pulling the heaviest UK train under test conditions

 

[Speed43125]

59s have a higher maximum tractive effort

 

[DB]

They might look very similar, but they are actually quite different locos. Different engines, for a start.

 

[Dunfanaghy Rd]

59s have the large generator and traction motors as fitted to the parent SD40/2. 66s have smaller of each (to save weight, I imagine) which are less able to absorb heat. The ability to slog at low speed depends on the ability to shed the heat generated. Even a 59 can get hot and bothered, a Westbury driver once told me about a (ex-) colleague who got one so hot on arrival at the Quarry that no-one could touch it for an hour.
Pat

 

[ac6000cw]

59s have the large generator and traction motors as fitted to the parent SD40/2. 66s have smaller of each (to save weight, I imagine).

Correct - EWS wanted the largest possible fuel tanks to minimise depot visits for refueling, and I think also wanted the radial-steering bogies.

The '66' design was not originally intended for heavy-haul use, hence the different design compromises - geared for 75 mph, lower-capacity alternator and traction motors. The weight savings from that (and a more modern V12 engine which I assume is lighter than the older V16 in the 59's) were 'spent' elsewhere in the design.

The main thing they have in common is that they look similar - 'under the skin' they are somewhat different.

 

[Dunfanaghy Rd]

I think there was confusion among the enthusiasts and the press. It seemed as though they assumed that there was a direct link between 'Type 5' and 'heavy haul'. In reality they were a Class 47 replacement that would, and did, fill in on all the Class 37 etc. work, enabling more productive working (in theory).
Pat

 

[Deepgreen]

I imagine traction control/anti-slip equipment must make a significant difference as well as gearing, motor ruggedness, etc. Within limits, what you don't want on a heavy haul loco is weight saving - greater weight on the driving wheels increases tractive effort (within track/structure limits, obviously).

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59s have a higher maximum tractive effort

Indeed, but I think the OP was, in essence, asking how that has been achieved.

 

[delt1c]

what seems to be forgotten is the 59s were the US advert for the UK and European markets and were built to be very high standard to promote US locos sales .

 

[hwl]

The 59s used the then standard US traction motors which are big and heavy with high unsprung mass hence the RT / NR track access charges are comparatively high, so from what I understand when the 66s were being designed they wanted to minimise track access charges which they did by swapping to the EMD (Brazilian) narrow gauge traction motor design which are far smaller and lighter thus reducing the unsprung mass.

The track access charges (/km) for a 59 are ~61% higher than a 66, with a chunk of the difference being traction motor weight.

 

[alexl92]

How does a 59 compare to a class 60? It seems to me that they’re designed for roughly similar work?

 

[Pacerman99]

Thanks everyone! It seems I completely overlooked the traction motors.

== Doublepost prevention - post automatically merged: 4 Oct 2020 ==

The 59s used the then standard US traction motors which are big and heavy with high unsprung mass hence the RT / NR track access charges are comparatively high, so from what I understand when the 66s were being designed they wanted to minimise track access charges which they did by swapping to the EMD (Brazilian) narrow gauge traction motor design which are far smaller and lighter thus reducing the unsprung mass.

The track access charges (/km) for a 59 are ~61% higher than a 66, with a chunk of the difference being traction motor weight.

Thats very interesting, thanks! Any ideas how the access charges of a 60 or 70 compare to them?

How does a 59 compare to a class 60? It seems to me that they’re designed for roughly similar work?

From what I hear the 60s are a lot better when hauling at speed than the 59s. According to the Platform 5 locomotives book, a 60 has higher continuous tractive effort than a 59 which seems to explain that. The maximum tractive effort for a 59 is higher though, so I guess they may be able to haul more from a standing start. A 70 has higher tractive effort than both though in theory.

 

[43096]

From what I hear the 60s are a lot better when hauling at speed than the 59s. According to the Platform 5 locomotives book, a 60 has higher continuous tractive effort than a 59 which seems to explain that. The maximum tractive effort for a 59 is higher though, so I guess they may be able to haul more from a standing start. A 70 has higher tractive effort than both though in theory.

A Class 60 is actually better than a 59 for starting trains in low adhesion conditions, as was found out when the 59s were trialled on the heavy trains out of Liverpool Bulk Terminal. The Class 59’s creep control only functions from about 3mph, whereas the Class 60’s SEPEX based control system functions from 0mph: the problem was the 59s couldn’t get to 3mph for the creep control to become effective.

 

[ac6000cw]

I imagine traction control/anti-slip equipment must make a significant difference

It does, but only if the traction motors and main alternator are up to handling, over a reasonable period of time, the higher currents needed for the higher tractive effort that the better wheelslip/wheelcreep control can enable. The lower capacity of the motors in the 66 versus the 59 limits maximum low-speed tractive effort and the duration it can sustain it. This isn't a limitation you want when there's 4000 tonnes behind the drawbar and you're going uphill at 15 mph...

 

[Right Away]

Be careful when quoting the figures 'from the books'. For starters they don't mention at what adhesion the figures are obtained so are no good for comparison purposes, and secondly the data obtained from the various test runs differs from the quoted figures.

== Doublepost prevention - post automatically merged: 4 Oct 2020 ==

A Class 60 is actually better than a 59 for starting trains in low adhesion conditions, as was found out when the 59s were trialled on the heavy trains out of Liverpool Bulk Terminal. The Class 59’s creep control only functions from about 3mph, whereas the Class 60’s SEPEX based control system functions from 0mph: the problem was the 59s couldn’t get to 3mph for the creep control to become effective.

Comparisons from trials at the former Ebbw Vale steelworks support this. Depending on which textbook you read, the class 59 'Super Series' creep control, which uses doppler radar to compare actual ground speed with wheel rotation speed, doesn't kick in until the locomotive is moving (I have heard between 0.4 mph and 3 mph quoted). However, a 59 is better at keeping a heavy train rolling along. In line with American operating methods, the traction motors can be run 'in the red' for prolonged periods. Over the Berks & Hants route, the 'loads book' used to show (I haven't seen one for a couple of years) a class 60 as being limited to a maximum trailing load of circa 3300 tonnes compared to the 4500 tonnes permitted for a class 59.

 

[ac6000cw]

The Class 59’s creep control only functions from about 3mph, whereas the Class 60’s SEPEX based control system functions from 0mph: the problem was the 59s couldn’t get to 3mph for the creep control to become effective.

Yes, it's that sort of issue that's caused AC-drive diesel locos to become the dominant type for heavy-haul in the US/Canada/Australia etc. and bump their DC-drive sisters off to intermodal use (where power at higher speeds tends to be more important than sustained low speed tractive effort).

 

[43096]

Yes, it's that sort of issue that's caused AC-drive diesel locos to become the dominant type for heavy-haul in the US/Canada/Australia etc. and bump their DC-drive sisters off to intermodal use (where power at higher speeds tends to be more important than sustained low speed tractive effort).

It was the heavy haul requirement for Powder River basin coal services that drove development of the SD70MAC and AC4400CW types, as I recall it.

Notable too, that Freightliner’s Class 70 trial on the Mendip traffic was very successful; shame they didn’t go with them on those services.

 

[hwl]

Thanks everyone! It seems I completely overlooked the traction motors.

== Doublepost prevention - post automatically merged: 4 Oct 2020 ==


Thats very interesting, thanks! Any ideas how the access charges of a 60 or 70 compare to them?


From what I hear the 60s are a lot better when hauling at speed than the 59s. According to the Platform 5 locomotives book, a 60 has higher continuous tractive effort than a 59 which seems to explain that. The maximum tractive effort for a 59 is higher though, so I guess they may be able to haul more from a standing start. A 70 has higher tractive effort than both though in theory.

track access charges compared to a 66:
37 +52%
47 +57%
56 +63%
59 +61%
60 +36%
68 +40%
70 +69%

Everything else (not listed) is higher than the 66s too...

 

[ac6000cw]

It was the heavy haul requirement for Powder River basin coal services that drove development of the SD70MAC and AC4400CW types, as I recall it.

Correct - BN (Burlington Northern) was using sets of locos like the EMD SD40-2 and GE C30-7 on those trains, which did the job but were burning a lot of fuel in the process (due to the number of locos needed per train to get enough low-speed tractive effort). EMD and Siemens were thinking about building an AC-drive version of the SD60, BN wanted to reduce the fuel and maintenance costs of the Powder River loco fleet, so they got very interested. EMD/Siemens built four demonstrator SD60MAC locos in 1992, BN tested them, were very impressed, and ordered 350 of the more-powerful production SD70MAC version straight off the drawing board to enable them to haul the same trains with a lot fewer locos. That 'broke the mould' in the US and the rest is history...and some of those SD70MAC's have been hauling Powder River coal trains since 1993 to the present day.

The GE AC4440CW followed a short while later, and had more advanced 'inverter per axle' traction control (versus 'inverter-per-bogie' on the SD70MAC). That said, from what I've read, in real world use there isn't that much difference in performance between the two. EMD probably has a better bogie design and GE better traction control.

 

[delt1c]

track access charges compared to a 66:
37 +52%
47 +57%
56 +63%
59 +61%
60 +36%
68 +40%
70 +69%

Everything else (not listed) is higher than the 66s too...

Does that mean a 20 has a higher track access charge than a 66?

 

[ac6000cw]

Does that mean a 20 has a higher track access charge than a 66?

Yes, a 20 is just a bit below a 37.

I *think* that one reason EWS went for the radial-steering bogies on the 66 was reduced track access charges (as they are supposed to reduce rail wear in curves). But the class 66 charges are so much lower than other locos, I suspect EWS also managed to negotiate a particularly good deal on track access charges at the time...

 

[delt1c]

Yes, a 20 is just a bit below a 37.

I *think* that one reason EWS went for the radial-steering bogies on the 66 was reduced track access charges (as they are supposed to reduce rail wear in curves). But the class 66 charges are so much lower than other locos, I suspect EWS also managed to negotiate a particularly good deal on track access charges at the time...

Would be interesting to see actual track wear per class

 

[richieb1971]

Once whilst standing on Westbury's platform I chatted to a driver who said the 59 is light and day better than 66 and went into the above jargon as to why. His train pulled in with 30+ fully loaded wagons.

He said "Watch this" when he got into the cab and revved the thing high and the platform had what I would call an earthquake effect as the power went to the wheels. He panicked and let off the power. I believe the adhesion to the track wasn't good enough and the wheels slipped or something. As he was already on his merry way I didn't get a chance to ask what happened.

From a drivers perspective, isn't the 59 a much nicer loco to drive as well? Most 66 drivers don't like them at all due to their lack of A/C units and bumpy rides. A bit like driving a tin can. Some 60 drivers don't like 66's for the same sorts of reasons.

 

[alexl92]

I love that video on Youtube where a 59 hauling a stone train also propels a dead HST to clear the line. That's serious power.

 

[hexagon789]

Why is it the 59s can pull much heavier loads than a shed?
According to Wiki, both have 3,300hp and the 66s are actually a little heavier than the 59s. I do notice that the sheds can do 75mph compared to a 59s 60mph, but then 59/2s can also do 75mph, so surely the gearing must be similar ish. What am I missing?

Wikipedia is rather out with its figures,

A 59 has an engine of 3300hp gross, continuous output at rail is 2,533hp.

A 66 (same engine as the 67) has an engine of 3,200hp gross/3,000hp traction with a continuous output of 2,480hp at rail.

The design makes up for the rest of the difference in hauling capabilities as others have stated.

 

[cossie4i]

From a drivers perspective, isn't the 59 a much nicer loco to drive as well? Most 66 drivers don't like them at all due to their lack of A/C units and bumpy rides. A bit like driving a tin can. Some 60 drivers don't like 66's for the same sorts of reasons.

I drive both and prefer 59s.
When the controller is it idle they idle, unlike a 66 which revs up and down all the time.
Instant power deployment when moving away from idle unlike a 66 which takes around 5 seconds before giving you power.
59s on a whole are quieter and vibrate less but I will admit some 66s are good.
We have recently been told 59s will be fitted with side blinds A/C and new seats next year.

 

[DelW]

We have recently been told 59s will be fitted with side blinds A/C and new seats next year.

I still think of 59s as relatively new locos, it's amazing (to me anyway) that the original Foster Yeoman examples are now nearly 35 years old!

 

[ac6000cw]

I still think of 59s as relatively new locos, it's amazing (to me anyway) that the original Foster Yeoman examples are now nearly 35 years old!

Yes, five years older than the 60s.

Having a good pedigree probably helps their longevity - they are a derivative of the early 1970's SD40-2, one of the all-time classic EMD products.

Instant power deployment when moving away from idle unlike a 66 which takes around 5 seconds before giving you power.

The slow build up of power seems to be a common issue with modern big diesel engines - AFAIK it's to keep within emissions limits. It's definitely a reason why some US traincrew prefer old EMD GP40/SD40 etc. for local freight work and shunting in yards - they are much more responsive than the more modern stuff.

 

[Wyrleybart]

I drive both and prefer 59s.
When the controller is it idle they idle, unlike a 66 which revs up and down all the time.
Instant power deployment when moving away from idle unlike a 66 which takes around 5 seconds before giving you power.
59s on a whole are quieter and vibrate less but I will admit some 66s are good.
We have recently been told 59s will be fitted with side blinds A/C and new seats next year.

Presume the 16 cyl 645 is much smoother than the 12 pot, but also the class 59 structures were more custom built than the "down to a price" class 66s.
Do the 59s have EMD compressors driven of the free end of the engine like the 66 ?