Class 70 power

[truckman060473]

are these new Freightliner locos supposed to be the new "king of freight" in the uk? it may be too early to ask, but do they have a tractive effort greater than that of a 59, 60 or 66? the maximum tractive effort of these locos (according to my handbook) are 506kN, 500kN and 409kN respectively.

 

[Wyvern]

From the Railway Gazette, starting TE = 534kN

 

[truckman060473]

oh right. so not a great deal higher then. suppose the limiting factor is the adhesive weight and most co-co's tend to be no more than 131 tons (as is the case with the class 60 with the larger fuel tank) due to max axle load etc

 

[ailsa]

You're quite right that the (lack of) weight of the loco is a limit to the absolute tractive effort available.

The 60 and also I believe the 70 have individual axle control of the traction motor torque, while the 66 does not. This makes a difference to the starting traction as they are better able to cope with conditions of poor adhesion. The main effect of the extra power in the 70s is to be able to haul heavy loads at higher speeds than say a 60 - as speed increases you need more horsepower to maintain the same rate of acceleration. This is due to the kinetic energy increasing with the square of the speed.

 

[Ferret]

The 60 and also I believe the 70 have individual axle control of the traction motor torque, while the 66 does not. This makes a difference to the starting traction as they are better able to cope with conditions of poor adhesion.

Apart from this morning when it reportedly needed assistance to climb Old Hill bank!!!

 

[The Planner]

Depends how much was on the back of it, anything with more than 1100 tonnes trailing needs banking up Old Hill, a 70 cant do much more from what has been computer modelled.

 

[Mystic Force]

when the iowa interstate got their new 4400HP GEs earlier this year they used them to replace a larger number of 2000HP GP-38 and SD-38 on their trains. However on their first outing the crew managed to stall it on a gradient having failed to appreciate the drop in axles. They then went to top and tailing the freight so that not all the power would be on the slope at the same time.