On 2 of my F units, they have 5 prime mover sounds.
EMD 567 Non-Transition Switcher
EMD 567 Non-Transition 12 Cylinder
EMD 567 1st Generation Version 1
EMD 567 1st Generation Version 2
EMD 567D Turbo
What does non transition mean?
If I remember correctly it has to do with the power to the traction motors. In start up it is single phase power and at a certain speed it goes to three phase or vice versa. Manual transition was used on original early diesels and there is a story about an engineer on t he NYC that wouldspill every glass in the dining car by the way he did it. Auto traction control switches each traction motor in sequence making the transition much smoother.
sequence
Wow,
I worked around diesel engines my entire life as a profession.
With the hood closed, I cannot tell the sound of a Caterpillar 3406i from a Cummins N14-450E+.
You guys are much pickier than I would ever be, especially considering the size of the speakers we are using.
-Kevin
Living the dream.
SeeYou190 Wow, I worked around diesel engines my entire life as a profession. With the hood closed, I cannot tell the sound of a Caterpillar 3406i from a Cummins N14-450E+. You guys are much pickier than I would ever be, especially considering the size of the speakers we are using. -Kevin
Regardless of the engine, the transition is a very noticeable audio effect.
The "transition" is kind of like changing gears in a car (sort of). The engine revs up to a certain point, then drops as the locomotive goes through the "transition" and revs up again.
It's not a feature of the diesel engine, it's a feature of the electric part of the diesel-electric locomotive power plant and traction motor drive, changing the wiring and power output to the motors.
And the turbo vs. non-turbo is a very different sound. The EMD turbo at least has a very distinctive "whine" to it.
Chris van der Heide
My Algoma Central Railway Modeling Blog
For an F-unit, you want to use either of these sounds.
Ringo58EMD 567 1st Generation Version 1 EMD 567 1st Generation Version 2
Transition is not 'phase'; it is series/parallel connection of the traction motors. As noted the effect will be marked by the engine responding to the changed load.
As I recall, in early engines you were supposed to drop the engine power briefly while the contactors worked, in both up and down transition. Later systems would cut the generator field to accomplish the same thing, with the engine governor responding to the decreased load by reducing fuel to keep the engine turning at commanded speed rather than revving up -- a different sound.
Ed will have specifics quicker than I can get them, but for a while EMD had automatic 'up' transition but not the reverse. (Dave Klepper, who posts in other Kalmbach forums, as I recall worked on this when fresh out of MIT in the very early '50s). Apparently when PRR had the bright idea of using E units 'no longer needed' for dwindling passenger service on high-speed TOFC trains, freight engineers expecting automatic back transition at high speed wouldn't always make the manual transition 'in time' when braking -- leading to main-generator flashover, which is never a good thing (it might be amusing to simulate the results in a sound set of 'project'; MTH as I recall marketed a 'failing' F unit in O scale at one time... but cab chatter would NOT be family-friendly...)
More modern DC-motored EMDs don't have transition at all: they are permanently in parallel and use multiple stages of field weakening to control back-EMF concerns and the like. (I think this came about mostly in the 645 era, though.)
Some discussion here:
http://cs.trains.com/trn/f/741/p/249329/2783262.aspx
— and here:
http://cs.trains.com/mrr/f/13/t/269844.aspx
(The "hot-link" gremlins are active today )
EMD_Transition_F7-crop by Edmund, on Flickr
Regards, Ed
Ringo58EMD 567 Non-Transition Switcher EMD 567 Non-Transition 12 Cylinder What does non transition mean?
To add to what's been said above: I read somewhere (but have not verified) that old EMD switchers do not make transition. They don't reach high speeds, plus, as I understand it, it's not a problem to be in too low a transition position (i.e. 1 when you should be in 4) but it is a problm to be too high (4 when you should be in 1), so it would make sense that switchers, which need to pull heavy loads, could do without transition. I think we have some switcher operator manuals at the club and I'll look -- I used to have one floating around here (SW1/NW2) and I don't believe it referred to transition.
That said, if that's right, I can't guess what EMD locos other than switchers would have 12-cyl engines and not make transition.
If it hasn't been covered (I'm tired and forgot what I read), on manual-transition locos, transition was made by looking at the ammeter, which had sections labeled 1, 2, 3, 4 corresponding to postions of the transition lever. When you were pulling hard at low speeds, power draw (amps) would be high, and you'd require a lower transition setting. As speed rose, amperage draw lowered and you would "shift" into higher transition position.
I believe EMD introduced automatic transition with the F3 (or perhaps during its run) where the lever stayed in one position, but locos retained their four-position transition levers because you still needed to "shift" if you had manual-transition locos in the consist.
Also IIRC you only had to reduce throttle (down to run 6) for certain transition steps. Reducing power was a problem because lower speed meant higher power draw and you could slip below the locomotive's minimum continuous speed rating.
Actually there are more positions because the transition lever (technically called the selector, I believe) also controlled the dynamic brake.
HTH
Aaron
Autonerdon manual-transition locos, transition was made by looking at the ammeter, which had sections labeled 1, 2, 3, 4 corresponding to postions of the transition lever.
F3_Ammeter by Edmund, on Flickr
Well, I can't speak to the prototype, but on my Tsunami2 equipped Athearn Genesis GP7s, advancing to the next notch creates a near shut down of the prime mover...to idle or just above....and coasts for about a second, before it then revs up and settles down to a higher rpm than before.
Maybe this simulates Transition? And apparently not all 567 equipped locos did this.
- Douglas
Doughlesson my Tsunami2 equipped Athearn Genesis GP7s, advancing to the next notch creates a near shut down of the prime mover...to idle or just above....and coasts for about a second, before it then revs up and settles down to a higher rpm than before.
Note that the eight notches represent an implementation of digital logic with solenoids: each notch is a commanded position of fuel delivery acting to run the engine at an (adjusted) governed speed independent of load. So when you moved 'up a notch' the command from the throttle sets the governor to reach and then hold a rotational speed; even if the load decreases the governor will adjust fuel to keep the engine turning at the commanded speed.
Meanwhile, the load regulator is acting on the traction generator field, modulating it up and down to vary the power going to the motors. Now something Ed's reference didn't say in so many words is that these locomotives started in full series, with the first of the four 'steps' of transition being series-parallel (the motors in each truck in series with each other; the trucks in parallel). To go from series to series-parallel for the 'first stage' of transition, the load regulator would ease off the field for the brief time "programmed in" for all the contactors to open or close and settle for the new high-ampere connections. During that time the engine would of course be overfueled, but the Woodward governor would act to relieve this to keep the engine running at the throttle notch.
False frugality (or a misunderstanding of things like long-term maintenance expenses on locomotive diesels) might have the engineman 'help the load regulator' or 'conserve fuel' by throttling the engine down during the period the main generator field is weakened. One problem with this is that the engine would presumably then have to come back up to speed with the load regulator reapplying field -- Diesel engines don't like accelerating into a load and will take longer and emit more smoke and pollutants if doing so.
Note that transition is related to electrical load and not engine speed. So only a governor problem would cause the engine to drop to commanded idle when taking a notch, then come up to the higher speed. Likewise only a control problem would cause the load regulator to lug the engine down to lower speed before acting to advance the fuel rack.
Now there is a note in the F3 manual that says you take the throttle to idle when about to go across a grade crossing or other known rough track spot at speed, the idea being to reduce motor current through the brushes if mechanical shock bounces them away from the commutator or if the shock briefly 'levitates' conductive brush dust into a conductive flashover-inducing cloud. This could have been done by reducing the generator field instead of the throttle, but this might upset the load regulator, whereas the reduction will be automatic if the engine power is commanded down.
My F2/F3 Operating Manual indicates that automatic transision is more-or-less dependent on speed -- the forward transition relay (FTR) and backward transition relay (BTR) are triggered by voltage, which equates to speed.
For the F3, forward transition from 1 to 2 occurs at about 19 mph, 2-3 at 25 mph, 3-4 at 52 mph. Backwards transition: 4 to 3 at 45 mph, 3-2 at 23 mph, 2-1 at 18 mph.
It also says "Automatic transition was put onto the F3 locomotive for the purpose of making a smoother transition and also insure transition being made at the proper time with the throttle in the Run 8 position." The section on manual transition talks about making transition as the load meter needle crosses the black lines in Run 8.
It says the locomotive must be started with the transition lever in #1 position,but does not indicate what to do if the load meter doesn't reach the far-right side. If you're at half throttle and only drawing 400 amps, can you "shift" directly to 3? Don't know and would love to know.
I don't see anything in the manual about reducing throttle position while making fowards or backwards transition, either manual or automatic.
The SD24 manual says "Additional train acceleration is provided by forward transition taking place automatically during throttle changes or after reaching full throttle."
The E9 manual says backwards (automatic) transition from 2 to 1 only occurs when the throttle is reduced to idle.
While involving 645s rather than 567s, there is an interesting technical discussion of transition in SD-40s in the Garrett/Conrail 'dual-mode-lite' study in 1979-80. (This is in the 'part 2 technical reference' section, and is available online but you may have to look carefully for it; Part 1 is more readily available).
A few of the things they say there were NOT apparently how I understood GM managed transition; this might involve the switch from main generators to traction alternators in the '60s.
Soooooooooooo, I dug up a manual for the SW8/SW9 (which, duh, I just found online here: http://www.chartertoconductor.com/wp-content/uploads/2019/06/sw8-om.pdf).
It says that these switchers do make transition -- however most of the manual only indicates two modes, Series and Series-Parallel. Later in the manual, though, it mentions "automatic shunting in the series-parallel position" and backward transition from series-parallel-shut to series-parallel. With barely a layperson's understanding of electricity, I have no idea how to interpret this. :)
Instead of a transition lever, it has a two-position button, a "transition forestalling switch", that prevents the shift from series to series-parallel. This is replaced by a lever in the TR-5/6 cow-calf unit, though it still has two positions.
Interestingly, the throttle in the single switcher has no notches and is an air throttle, while the TR units have a traditional eight-notch throttle (which I assume is electric). The manual mentions a pneumatic-hydraulic governor for the switches, rather than (IIRC) electo-hydraulic in F3 and later locos and electro-pneumatic in F2 and earlier.