QRN Locomotive Adhesion Ratios
#1
Hi all

For those interested in how a locomotive is likely to cope with high load, low speed operating environments I've killed some time and put this list together as a very loose guideline. The Adhesion Ratio should give some idea of whether a locomotive can apply all of its tractive effort to the rail without slipping. In the late steam era, a value between 4.00 and 4.50 was considered optimum, however more and more advanced adhesion packages have decreased that value considerably. The big question is where does the optimum level sit now. You might note that until the advent of the 4000 an effort was still made to keep continuous tractive efforts above 4.00. Needless to say it will be interesting to see where the UGL PH37ACMai ends up.


QRN Adhesion Ratios

Weight Starting TE Continuous TE Adhesion Ratio

2100 216,097lb 64,292lb 50,804lb 3.36/4.25

2250 242,557lb 88,121lb 58,448lb 2.75/4.15

2300 209,481lb 55,076lb 3.80

2600 238,147lb 56,874lb 4.18

2800 255,788lb 93,741lb 59,796lb 2.72/4.27

3500 242,557lb 84,300lb 58,448lb 2.87/4.15

3700 277,839lb 112,400lb 98,912lb 2.47/2.81

3800 291,069lb 118,020lb 101,160lb 2.47/2.87

4000 264,554lb 121,392lb 103,408lb 2.18/2.56

5000 388,092lb 170,623lb 131,732lb 2.27/2.95

6000 (L) 295,479lb 120,268lb 2.46

6000 (H) 308,710lb 120,268lb 2.57


Conversions – kNx0.2248x1000 = lbs
0.4535kg = 1 lb

Nickel Plate High Speed Service
#2
UGL Powerhaul PH37ACmai

Engine: GE P616, V16
Power: 2750kW 3,700-GHP

Weight: 120 Metric Tons = 264,555lbs
Starting TE: 600kN = 134,885lbs
Continuous TE: 460kN = 103,412lbs
Adhesion Ratio: 1.96/2.56

GE Transportation has successfully delivered PowerHaul Series locomotives to the UK for Freightliner who labelled it the Class 70. The UK version of the PowerHaul is somewhat different in appearance to the PH37ACmai to be built by UGL in their Australian based manufacturing facilities, though the technology employed “under the skin” is the same.

[Image: i-MxTc3SR-L.jpg]
[Image: F111RAAFweb2A.jpg]
#3
Thanks for finding that, the Aussie PH37ACmai doesn't look too bad. However that starting tractive effort looks like it will be tough to achieve for a 120tonne loco with a ratio of just 1.96 (the lowest I've ever seen). The UGL design team must be planning on using lots of sand or getting some rubber traction tyres from Powerline. Meanwhile the continuous TE will be the same as a 4000 which is interesting. In the end I suspect they may not be able to lift much more than a 4000, but once they get moving the extra horsepower should give them greater acceleration.
Nickel Plate High Speed Service
#4
(26-Nov-2011, 11:46 AM)Sulla Wrote: However that starting tractive effort looks like it will be tough to achieve for a 120tonne loco with a ratio of just 1.96 (the lowest I've ever seen).

Took the figures from a Media Release for the Australian Launch of the PwerHaul Series Locomotive at AusRAILlPLUS2011 Conference, 22 Nov 2011...Used the Base figures from the Release (Weight, Starting and Continuous TE) and attempted to copy your format for evolving the Adhesion Ratio(s)...But I must admit I thought I'd misunderstood your process when achieving the low figure of just 1.96. Please do check my figures...
[Image: F111RAAFweb2A.jpg]
#5
(26-Nov-2011, 11:46 AM)Sulla Wrote: ...the Aussie PH37ACmai doesn't look too bad.

Agreed...Very Handsome Design...
Another Version of the 'Artist's Impression....'

[Image: i-5vSkppG-L.jpg]

[Image: F111RAAFweb2A.jpg]
#6
(26-Nov-2011, 12:04 PM)BelowRadar Wrote:
(26-Nov-2011, 11:46 AM)Sulla Wrote: However that starting tractive effort looks like it will be tough to achieve for a 120tonne loco with a ratio of just 1.96 (the lowest I've ever seen).

Took the figures from a Media Release for the Australian Launch of the PwerHaul Series Locomotive at AusRAILlPLUS2011 Conference, 22 Nov 2011...Used the Base figures from the Release (Weight, Starting and Continuous TE) and attempted to copy your format for evolving the Adhesion Ratio(s)...But I must admit I thought I'd misunderstood your process when achieving the low figure of just 1.96. Please do check my figures...

I get 1.96 too, so it all adds up. I really don't know how much these ratios are used by designers these days, but I suspect they're starting to get a little neglected for the sake of compromise (trying to put more loco into a fixed axel load package). Modern traction control systems might be pretty amazing but there's still a big ugly physical world out there where it rains sometimes and the tracks go up hills. If this was a steam loco or an earlier diesel it probably wouldn't get out of the loco shed without spinning the wheels.
Nickel Plate High Speed Service
#7
Hi all, a bit of an update I've also included adhesion percentages, which is the adhesion measurement preferred these days by manufacturers. From what I can find, maximum ‘All weather’ Adhesion Percentages are considered to be - DC 25% (4.00 in ratio form), DC with Super Series 29-30% (3.33-3.45) and AC 37%-38% (2.63-2.70).



QRN Adhesion Ratio and Adhesion Percentages

...Adhesive Weight...Starting TE...Continuous TE...Ad R..............Ad %
2100...216,097lb........64,292lb.......50,804lb........3.36/4.25.....29.7%/23.5%
2250...242,557lb........88,121lb.......58,448lb........2.75/4.15.....36.3%/24.1%
2300...209,481lb.......................... 55,076lb........3.80.............26.3%
2600...238,147lb...........................56,874lb.......4.18..............23.9%
2800...255,788lb.......93,741lb........59,796lb......2.72/4.27.......36.6%/23.4%
3500...242,557lb.......84,300lb........58,448lb......2.87/4.15.......34.7%/24.1%
3700...277,839lb......112,400lb.......98,912lb......2.47/2.81.......40.5%/35.6%
3800...291,069lb......118,020lb.......101,160lb....2.47/2.87.......40.5%/34.7%
4000...264,554lb......121,392lb.......103,408lb....2.18/2.56.......45.8%/39.1%
5000...388,092lb......170,623lb.......131,732lb....2.27/2.95.......43.9%/33.9%
6000(L) 295,479lb........................120,268lb......2.46..............40.7%
6000(H) 308,710lb........................120,268lb......2.57..............38.9%
UGL...264,608lb......134,880lb.........103,408lb....1.96/2.56........50.9%/39.1%
Q.......295,479lb............................92,168lb.......3.21.............31.1%
LDP...295,479lb.......134,880lb........116,896lb....2.19/2.53........45.6%/39.5%

Conversions – kNx0.2248x1000 = lbs
0.4535kg = 1 lb


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