Re: Fate of 85/86 class

[John MacCallum <johnmac@lisp.com.au>]

> > Err,little confusion here , the 85 / 86s are nowhere near as powerful as an NR
> or indeed an 81.
> Please dont confuse as a lot of people do horsepower with pulling power.
> Horsepower is simply a measure of the power output of the main prime
> mover with a small reduction due to the non perfect efficiency of
> the rectifiers and traction motors .
> The pulling power is determined solely by the gearing ratios of the traction
> motors and by their design , ie the amount of iron in the motor, the guages of
> copper in the armature and the field coil current.
> Pulling power is measured usually in either Kn (kilo newtons or Lbs).
> 
> here are a couple of examples.(these are continous ratings)
> 81 class 75730 lbs at 19 km/h.
> 85 class 49910 lbs at 45 km/h.
> 86 class 49887 lbs at 45 km/h.
> 
> Railpages loco info has tractive effort figures for most Aus locos and its a

Err a little more confusion here!
Tractive effort and Horsepower are different but they are related.
An 86 class indeed more powerful than an 81 class as indeed an 85 class
is more powerful than an 86 class.
To compare an 81 with a 86 directly is like comparing apples with
oranges. Tractive effort is a function of traction motor current,
wheel diameter, gearing and adhesion. An 86 can pull a given load
faster than an 81 can because it has more power available. An
81 can pull more load up the ruling grade than an 86 because it has
lower gearing and more adhesive ability.

85 class and 86 class engines do indeed have a fairly complicated 
wheel slip control circuit but it is only single channel in its
operation. So where a GM fitted with super series control each axle
independent of the rest an 85/86 class can only control one axle at a
time.

Operationally high horsepower, high adhesive diesel locomotives are
more flexible than Electric Locos and that's why a lot of USA railroads
opted out of electric traction. 

i.e. You can't double stack under overhead wiring and you can't haul
as heavy loads with 1500 V DC up hills as diesels.

Pope

Alias	John MacCallum