I posted this on a somewhat related thread, but thought it deserved to be asked outright.
Can anyone tell me how to get the prime mover RPM to act in a more prototypical way in relation to the physical speed of the motor? I have tried the settings suggested in the manual, ie speed steps per notch, and tried various momentum settings. Nothing works.
On every prototype loco I have ever heard, when the engineer increases the throttle, the diesel engine increases in RPM to spin the generator faster, then after a short pause, the traction motors begin to turn faster. On a reduction of the throttle, the RPMs drop well before the motors start to slow, and the locomotive begins to coast, gradually slowing, unless the brake is applied.
The Tsunami almost has this completely backwards, as the model's motor responds before the sound changes both on accelleration, and decel, often causing the RPMs to remain very high, after the model has been stopped.
Can anyone offer a specific set of CV settings to correct this?
I had a simillar problem with the QSI unit in a BLI NW2, and never could get it to my satisfaction. Apparently QSI addressed the issue as the Proto SW9 is much improved and the H10-44 is very well done in this area IMO. Also IMO, LokSound has this dead on correct.
Another issue I have is that the Tsunami manual goes out of it's way to explain this, yet the decoder appears not to behave in this way, or even to be able to be configured to behave this way.
The specifc decoder is a GN1000 EMD 567.
Thanks for any help.
Hey.
I was hoping to get a reply from you, as I generally agree with your findings.
I believe I am on 28 steps, but will doublecheck. I know the throttle is on 28.
davidmbedard NO...I am refering to adjusting the 28 step speed table so your loco will not start to move until speed step 3 or 4, that way you hear the rev-up before the loco moves. David B
NO...I am refering to adjusting the 28 step speed table so your loco will not start to move until speed step 3 or 4, that way you hear the rev-up before the loco moves.
David B
So, would this mean that one would then have to re-program all the other engines in a consist (that had been carefully programmed to move on speed step one) to also not move until speed step 3 or 4?
I can see where making the adjustment to the initial engine would help the OP's issue with that engine. But how would he make an adjustment to the intermediate speed points? I guess I'm asking how would he get the engine to rev up before moving faster as the throttle was advanced from speed step 12 to 13 on a 28 speed step scale?
I wonder if you would get the desired effect by setting acceleration.
Springfield PA
After spending another two hours on this today, I am done.
They are on ebay.
All of my QSI and LokSound units perform IMO satisfactory after less than 15 min of programming.
They all start on speed step 1 at the slowest possible operation of the motor.
Strike three for soundtraxx.
Thanks David. I still appreciate your opinion.
maxman- you have a good point. It's not just about startup. I actually got to a point I could live with for startup. But stopping kept driving me crazy, as I could never get the RPM down BEFORE the loco started to slow down.
I did notice something I hadn't noticed before, what with all this time with the tsunami units-
I originally thought they were superior with respect to "white noise" style static that I can hear as a LokSound unit "comes on-line". Turns out the Soundtraxx units have the same static, it just is confined to the individual sample, and not the sound system (for lack or a proper technical term) as a whole, for the decoder. To put it another way, when a Loksound unit is powered up, you can hear static from the point I'm assuming the amp circuit turns on, until the volume of the prime mover sample is loud enough to overcome it. With the tsunami, I could hear what sounded like the same static (at the same frequency) as soon an an indivivdual sound (bell, horn, etc) was triggered, until it was drowned out by the sample. To quote Mr. Spock- "Interesting". This actuall makes me feel a bit better about not fawning all over the "outstanding" tsunami sound quality.
Diesel engines aren't direct drive but electric drive. You don't necessarily have to have the motor wind down before the loco slows. It's possible that it would lag. Correct me if I'm wrong but doesn't the motor respond to load? If so the motor would naturally lag behind the speed change when slowing.
This is what Wikipedia says (http://en.wikipedia.org/wiki/Diesel_locomotive#Diesel-electric_control):
"To set the locomotive in motion, the reverser control handle is placed into the correct position (forward or reverse), the brake is released and the throttle is moved to the run 1 position (the first power notch). An experienced engineer (driver) can accomplish these steps in a coordinated fashion that will result in a nearly imperceptible start. The positioning of the reverser and movement of the throttle together is conceptually like shifting an automobile's automatic transmission into gear while the engine is idling
Placing the throttle into the first power position will cause the traction motors to be connected to the main generator and the latter's field coils to be excited. With excitation applied, the main generator will deliver electricity to the traction motors, resulting in motion. If the locomotive is running "light" (that is, not coupled to a train) and is not on an ascending grade it will easily accelerate. On the other hand, if a long train is being started, the locomotive may stall as soon as some of the slack has been taken up, as the drag imposed by the train will exceed the tractive force being developed. An experienced engineer (driver) will be able to recognize an incipient stall and will gradually advance the throttle as required to maintain the pace of acceleration.
As the throttle is moved to higher power notches, the fuel rate to the prime mover will increase, resulting in a corresponding increase in RPM and horsepower output. At the same time, main generator field excitation will be proportionally increased to absorb the higher power. This will translate into increased electrical output to the traction motors, with a corresponding increase in tractive force."
I was given one of those engineer for an hour treats for one of my old person birthdays. It was an RS. As I recall, the handle on the control stand was advanced to make the engine go faster, and pulled back to get the engine to slow. Obviously, the brake got used if the grade the engine was on a downgrade.
That sounds right but it has nothing to do with the motor. For instance, an emergency generator used in a building will run at full speed once it's called for. After ther isn't a load it will still run to cool down. it isn't like a direct drive where it responds directly to the load. Usually the motor will lag behind the load and advance in front of the load.
There's a small CSX yard about a mile from my house. It's at the juction of two main lines. There's usually a GP39-2 stationed there, and several through trains pass and stop to swap cuts of cars. I think there is also a 20 MPH speed restriction. Amtrak also uses this route for trains from Miami to New York.
I've seen and heard this dozens of times, usually from about 20-100 feet away.
In real life, generally, an increase in throttle (and RPM) leads an increase in speed, and a decrease in throttle (and RPM) leads a reduction in speed. More often than not the prime mover is at idle well before the locomotive begins to slow.
What happens with the tsunami, is that on a decrease of the throttle, the actual motor decreases speed, but the sound of the (pretend) RPM lags and stays high before coming down to where you have set the throttle.
No matter what I try I can't get this worked out.
Momentum did not help. In fact, it got worse.
Same problem with my BLI NW2, however, I now have a QSI upgrade chip for the NW2.
Hopefully that will make it function like the H10-44, which behaves quite nicely out of the box.
Real life loco's are obviously different than models. In real life the throttle can be lowered and you wouldn't see the effect for an extended period due to momentum. They don't respond to throttle controls like models, with the exception of momentum turned on in the model. I think the throttle on a loco is to the traction motor and not the diesel. The engine should respond to the demand and usually lags. If you increase throttle slowly you should also see speed increase over the motor.
On slowdown though the prime mover should slow long before the train, due exactly to the momentum of the train. Plugging momentum into the decoder SHOULD make it work properly - prime mover rev slightly before speed picks up, prime mover slows before loco does. Seems Tsunami doesn't do this. Not good.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Hamltnblue I think the throttle on a loco is to the traction motor and not the diesel.
I don't believe so. The diesel drives the generator, which is electrically connected to the traction motor.
What you were describing above where an increase in load causes the motor to (apparently) speed up is due to a governor on the motor. What happens is that the motor and generator are happily coasting along at, say, no load and you put a load on the motor The governor sees this and says giddy up motor it's time to do some work. In most cases the motor speed will not increase, because the governor is set to maintain a set speed, but the output of the generator will increase because it is trying to satisfy the load demand. If you dump too much load on the generator it will try to keep up, but eventually the demand will exceed the capability of the motor-generator. When this happens either some protective circuit will open to disconnect the load, or the motor-generator will turn into a smoking mess.