A message from Phil Clark on Ausmodelrailways Yahoo group on 4/06/05

Hi All

Maybe this can solve some of the confusion over the slow running qualities of Proto SD7 bogies. I checked the gear ratio of some bogies today, here are the results Athearn & Austrains are 12 to 1 Proto SD7 are 14 to 1. That is for the same voltage applied to the Loco with equivalent motors, a loco with Athearn or Austrains bogies doing a scale speed of 60 KMH, a loco with SD7 bogies would be doing 51 KMH.

Remember a lot of things influence a loco speed such as bogie lubrication, tension of power pickups, motor type fitted, generally the smaller the motor the faster they run.

If constant Voltage Lighting is fitted 2.25 volts is lost to the motor, so running at 12 volts to the track will result in 12 volts to the motor or 9.75 volts to the motor depending on the type of lighting setup.

Tomorrow I will post some time for various locos do do a lap of my layout ( 50 metres) Phil C

Further to my previous email on Loco speeds, here are some comparisons over a 50 metre track at 10 volts:-

Powerline 48s,

standard mech,

(1)- 2m 10 sec;

(2)- 2m 18 sec;

(3)- 2m 18 sec;

(4)- 2m 30 sec;

(5)- 2m 20 sec;

(6)- 2m 08 sec;

(7)- 2m 16 sec;

(8)- 2m 13 sec

Standard K& M mech 

(1)- 3m 46 sec;

(2)- 3m 18 sec

49 class;   Austrain bogies / Mashima motor;       2m 32 sec

442 class; Austrain bogies / Mashima motor;       2m 01 sec

442 class; Austrain bogies / Austrains motor;       2m 12 sec

C class;    Austrain bogies / Austrains motor;       2m 04 sec

44 class;  Athearn bogies / Masima motor;           2m 25 sec

44 class;  Athearn bogies / Athearn motor;          1m 50 sec

45 class;  standard AR mech;                             2m 38 sec

BL class;  standard Bachman mech;                   1m 39 sec.

So you can see big differences between locos

Hope this helps someone

Phil C