Q1a Early EMD Notching and Transitions
By Fred Severson, QSI
Our early EMD Quantum Sound Systems use a prototype model 567 non-turbo charged prime-mover as a sound source. The motor recording for our Quantum system has a noisy lifter, which is a common occurrence on these units particularly after many years of service. Early EMD sound is used in all F units, Geeps, and E units.
Early EMD locomotives had a very distinctive generator whine that could easily be heard whenever the motor was revved down. This along with the noisy lifter adds distinctive sounds that clearly distinguish the early EMD Quantum locomotives from our second-generation EMD Quantum locomotives.
In addition, early EMD locomotives had a unique transition effect that is noticeably different from second-generation EMD transitions. Transitions occur in the prototypes at different speeds depending on gear ratio. Our Quantum model will go through an automatic transition at 22 scale miles per hour.
Transitions have a similar purpose to manual transmission gear shifts in a car except there are no gears to shift. Diesel locomotives start out with their traction motors electrically connected in series, which allows full current available from the diesel-motor/generator to pass through the traction motors for maximum torque. As the motors gain speed, the current starts to drop off until even at notch 8, little additional current can be delivered and the locomotive reaches the maximum speed available in this configuration. Switching the motors from series to parallel connection allows additional current to be delivered to the motors, increasing traction and locomotive speed. This switching is called a transition.
Operation in Disconnect:
To understand the improved notching and transition software in this Quantum locomotive, start by evaluating its performance in Disconnect. Disconnect allows the operator to rev the motor/generator in Neutral without the locomotive moving, simulating the traction motors being disconnected from the motor/generator.
In DCC mode, double-press the F9 key while the locomotive is in Neutral. In
Analog mode, press the Quantum Engineer Disconnect button while the
locomotive is in Neutral. Now, when the throttle is increased or decreased,
the motor will rev up or down in RPM without the locomotive moving. You
will notice that when revving up, the Quantum system will only increase one
notch at a time. This is standard prototype practice to prevent motor
damage. If you increase the throttle to max, you will hear each distinctive
notch increase one by one automatically. However, when you decrease the
throttle to any lower notch, there is no need to stop at each notch setting.
You can reduce the throttle one notch at a time or you can decrease the
notch to any lower level, including idle. In either case, the motor RPM
will decrease quickly to whatever notch you have selected.
When you notch up, you will hear the prime-mover increase with increased
Sound-Of-Power (SOP) during the acceleration period and then level off as
it reaches a steady state RPM. When you rev down in notch, you will hear
the motor drop quickly in RPM and SOP. When this happens, the generator
whine can be distinctly heard. After the motor reaches the final
steady-state RPM, its volume level will increase in SOP to maintain that
notch position. As an exercise, increase the RPM to notch 8 and then drop
back one notch at a time for a few notches and wait for the motor to rev
down to a new steady-state value and then decrease to idle quickly to hear
the generator and motor responses.
Operation in Forward or Reverse:
If you are in DCC mode, we recommend that you set the Acceleration Rate, CV3, to about 175 to 250 and set Deceleration Rate, CV4, to about 150.
In Analog mode, we recommend that you set the Load level to about 13 in
Programming Option #2 (POP #2). This is very easy to do if you have a
Quantum Engineer. If you are using a modern MRC power pack, we also
recommend that you set V-Max to about 80% of full throttle. This will allow
better control over notching since all eight notches will be spread over a
wider voltage range. V-Max default setting is 12 volts but most MRC power
packs produce from 17 to 20 volts max voltage.
Leave Disconnect and start the locomotive in Forward or Reverse. In DCC, you exit Disconnect by double pressing the Start Up key, F6. In Analog, press the Quantum Engineer Start Up key.
While starting out in Forward, increase the throttle to max and wait while the locomotive gradually accelerates from stop to full speed. You will hear the Prime Mover automatically increase RPM one notch at a time. If you have set the Acceleration Rate or Analog Load to the above-recommended values, the locomotive will notch up all the way to notch 8, before it starts the transition sequence at 22 mph.
During transition, you will hear the motor-generator rev down with the
distinctive generator whine dominating during the RPM decrease. After about
six seconds, the RPM will again increase automatically to a higher notch,
but this time at a much higher SOP. Note that the earliest F-Units had
air-operated switching mechanisms, so you would hear a short air let-off
during the transition. Later models used an electro-mechanical switching
mechanism, so there would be no corresponding air let-off for those locos
during transition. If the notch setting prior to transition was higher than
notch 5, the prime mover will drop to notch 5 and then notch up to the
higher notches, one at a time. This is standard prototype practice to
prevent excessive current in the traction motors that could cause damage.
Now, try increasing notches one at a time using the throttle. In DCC mode, a notch will increase every 10 speed-steps. In Analog mode, increasing the track voltage above V-Start gradually increases notches one at a time. Each intermediate voltage is associated with a notch value.
Notice that you can set your notch and it will stay there until you increase it to the next one. However, if you try to increase the notches more than one at a time, you will notice that the locomotive will stair-step up one notch at a time to achieve the final notch setting. This is prototype practice.
When decreasing notches, the SOP will cease immediately and the motor and generator will coast down in RPM to the lower selected notch without stopping at each intermediate notch, just like in Disconnect. Once the RPM reaches the selected lower Notch, the motor will power up to maintain the prime mover at that Notch setting, but it will do so at a lower SOP corresponding to an unloaded diesel motor. If you have set the Deceleration Rate or Analog Load to the above-recommended values, the locomotive will decelerate slowly until it reaches a speed where the motor/generator will re-engage with an increased SOP to maintain locomotive power at that notch setting.
Now try lower DCC Acceleration (CV3) and Deceleration (CV4) or lower Analog Load settings. This reduces SOP effects during acceleration and reduces the time it takes to increase from one notch to the next when increasing the throttle. If you increase the throttle to max, the Quantum system will go up one notch at a time as before but will reach the 22 smph more quickly where the transition effect will occur. At these lower Inertia or Load settings, there may be only three or four notch increases before a transition occurs. When decreasing notches under lower Inertia or Load, it will take less time before the motor/generator re-engages with the increased SOP to maintain the lower speed.
Heavy Load
Heavy Load is a Quantum feature that allows the user to increase the loading to a very large value while the locomotive is moving. This minimizes speed changes from throttle or layout variations to a very small amount. While under Heavy Load, throttle increases will produce high Notch settings at very high SOP values without noticeable speed change. This is a useful feature when entering a grade and you want to Notch Up at maximum power without the locomotive increasing its speed. It is also useful when coasting down grade where you want the locomotive at a reduced Notch with no SOP and no speed change.
In DCC, enter Heavy Load by activating the F9 key (F9=1) while the locomotive is moving. In Analog, press the Load button on Quantum Engineer while the locomotive is moving. In either case, you will hear a single Horn Hoot to indicate that the locomotive has entered Heavy Load. You will immediately notice a dramatic increase in SOP. You will notice that you can increase to higher or decrease to lower settings with little delay between Notches. Heavy Load allows you to tailor the Sound-Of-Power and Notch setting on a moving locomotive to match the power demands on your train and the terrain conditions on your layout.
Leave Heady load by again pressing the F9 key (F9=0) in DCC or double press the Load button on the Quantum Engineer in Analog. In either case, you will hear a double hoot to indicate you have left Heavy Load. Heavy Load will also deactivate if you stop in Neutral or the power is turned off and back on.
