Some tractive effort numbers

Note that the following numbers are for Continuous Tractive Effort - the Starting Tractive Effort will be much higher but is a bogus number for anything beyond switching and starting a train. All for General Electric built locomotives:

GE 47 ton 330-350 hp with 35 mph maximum gearing (Oahu/C&TS #15/19, US Army and NFLD) = 12,000-13,000 pounds
GE 50/52 ton 400-450 hp with 40 mph maximum gearing (SP#1 and SVRR #720) = 15,800
GE C+C 70 ton 600-660 hp (US Potash and many more in South America) = 23,700
GE C+C 68 ton 730 hp (only for Venezuela) = 25,400
GE C+B+C 120 ton 1400 hp (IRCA/Columbia) = 37,600

All the above were built into the mid 1950s and used either the GE733/763 or GE747 traction motors which were self-ventilating and used double-reduction gear units, which limited the capacity of diesel-electric designs for narrow gage.

GE Shovelnose 800-900 hp (WP&Y 90 class) = 24,000 pounds (36"+)
GE U6B 540 hp = 26,500 (four axles mid-late 1950s) (36"+)
GE U10B 800-950 hp = 36,200 (meter+) or 26,400 (36"+)
GE U26C 2600 hp (Chris' New Zealand Dx class) = 54,300 (meter+) or 45,810 (36"+)

All the above used conventional "wheelbarrow mount" type axle-hung single-reduction traction motors. Note that the traction motors for meter gage or wider have a greater capacity than those capable of 36" gage. A 36" gage traction motor only has about 30" to fit between the wheels on the axle, for meter gage that extra 3-3/8" gives you an extra 10% of room for copper and insulation.

GE Dash 9-40BBW B+B-B+B 3990 hp (Brazil) = 82,497 pounds
GE ES43BBi B+B-B+B 4300 hp (Brazil) = 132,277 pounds

The two models above are currently available from GE and have been built for meter gage lines in Brazil. The 36" gage version (if there was ever any justifiable demand) would have to be less because of smaller traction motors. Note that the Dash 9 has the power of any TWO K-class DRGW engines! And the ES43 is equipped with AC traction motors and is the equivalent of three and a half K36/37 engines! Weren't the Uintah/SVRY articulateds around 42,000? And the NdeM articulateds about the same?

If the traffic levels on a narrow gage did not continue to grow over time enough to justify upgrading the infrastructure to handle heavier cars and engines, there just isn't any reason not to simply replace them with trucks.... And in North America, the NG system was so small the answer would have been simply to standard gage, except maybe the White Pass.

EDIT:

Forgot to add the GE UM6B (South Africa 51 ton 91 class for 24" gage!) These replaced the Beyer-Garretts that were mentioned. These used GE778 traction motors (only use) which were mounted through a double reduction 13.68:1 gear unit at . The SAR diagram lists these at 50kmh (30mph) maximum. Figuring TE is a little trickier. They show 86kn at 20% adhesion and 15kmh (about 8-1/2 mph). 20% adhesion would be the lowest nominal adhesion on poor rail, and 86kn converts to 19,330 pounds tractive effort which seems about the right range. They also show 395 amps at 14 kmh continuous minimum speed, which is the same as its continuous tractive effort rating. Since it all should be proportional, then the continuous tractive effort should be around 92kn or 20,680 pounds at 8 mph, but another way I can calculate it shows it as high as 24,000 pounds. And they ran these in multiple unit at least in pairs. Need one for Maine. At 51 tons they need about 42# rail minimum.



Edited 1 time(s). Last edit at 05/31/2018 04:18PM by Dan Robirds.