Good evening everyone.
I was trying to explain the diesel throttle to my grandkids but realized I didn’t know enough.
When the throttle is advanced and the diesel engine speeds up what happens at the motors. In other word what is the difference in if you are in run eight and moving five miles an hour or run eight and moving 55 miles an hour? Maybe I’m not asking the question right. Do the electric motors shift speed or do they just draw more current?
Edit; I know the E. motor to axle is fixed gear. Is motor speed changed electrically or do you just back off the engine to give less current when train comes up to speed required?
[%-)]
Thanks
Lee
I knew once, now I’ve forgotten. Wanna say it acts like the transmission in a car, I do know this might attract more professionals in the Prototype Info for the modellers, and that you’ve got me intrigued.
You are on the right track-an increase in the RPM’s of the diesel engine causes the traction generator (or alternator) to produce moe voltage(and amperage) causing the traction motors to increase speed as fast as the load will allow. The one minor error in your question is that a dc traction locomotive operated in run 8 at five miles an hour will very quickly exceed the short time rating (the amount of time an overload can occur) of the traction motors and burn them out. Hope this helps.
The long and short of it…
In “Idle” or “Run Zero”, you’re not producing any power to the traction motors. “Run One” is a bare amount of power, say, 250 amps. If you’re just moving engines about, it’s about all you’ll need. I might run over the road in this depending on the territory and my train. But, get to any significant grade and you’re gonna be pulling back the throttle and starting into the notches very quickly.
“Run Two” will produce say, 400 amps. It just goes up and up until “Run Eight” and then not having any further to go.
The throttle doesn’t really control “speed”, as much as it regulates the amount of electricity that is available to the traction motors. In “Run Eight” while light engine you may see that while you are producing “X” amount of amps, you’re only drawing a few hundred to the motors due to the lack of significant loading. As you start to add cars (read: Weight and friction), you can watch the amp meter rise as more and more effort is needed. If you’re running an older DC locomotive like say a GP-18 and you’re in “Run Eight” going five miles per hour, you won’t be getting to far before you put the electrical system to ground and fry a traction motor or multiple motors.
Now for example, I’ve got my trusty GP-40 Dash II and maybe say… 8 loads on the tail. If I’m in 25 MPH territory with minimal grades I’ll probably be able to keep my train moving at speed by feathering between “Run Zero” and “Run One” the whole trip. If I approach a steeper grade, “Run Two” or “Run Three” will do the trick just find. Going over the mountain though? Five or six will do to keep her going at speed… and then full Dynamics down the other side [swg] [swg] [swg] .
Powerbraking and dynamics? We’ll get into that later. [:-^] </
Granite Railroader
Thats cool, exactly who I was looking for, an old hand. [bow]
My grandkids will think I know what I’m talking about. I appreciate your post. I understand a little about dynamics. Many years ago I worked on ground based RADAR that was a twined unit that put out 5 million watts per side. when one was on line at 5 mill. we could work on the other side at half power and dump the 500 thousand watt load into a dummy antenna.(resister)
Lee
Who you calling an Old Hand? [:-^]
…and 5 million watts? That surely beats the various 250 and 300 watt VHF and UHF radios I work on at my side job. 500k watts into a dummy loads… Now that’s enough to fry an egg on! [D)]
Granite R.R.
[swg] You could fry anything on the dummy load or in front of the antenna. the dummy was almost as big as a foot locker and had a cage all around it. We fed the antenna with a wave guide that looked like 5" gutter pipe, and had a switching device that changed the output from antenna to dummy load. This was with almost all vacum tubes.
Have a good day
Lee