I don't have anything official -- ie printed by maker or railroad -- that actually GIVES a minimum continuous speed for the DL-109.
HOWEVER, I do have an original NYNH&H General Notice that covers operation of all the 0700 class, which was printed by the railroad in October 1946. It does have some figures you (we) might like to note, and compare.
Operation of the units included automatic forward transition, but not automatic back transition. When current in parallel reached 850 Amps with speed decreasing, the throttle was closed and then re-opened which allowed the back transition to series to occur. After that happened, the following limits applied:
0-700 Amps: continuous
700-800 Amps: 1 1/2 Hours
800-900 Amps 20 min
900-1100 Amps 10 min
1100-1500 Amps 4 min
A note at the end of the section on currents: "Always be on the alert to watch traction motor currents when speed is less than 25 MPH."
So, then, we can probably make an educated guess from this information that the minimum continuous speed is REALLY close to 25 MPH. I'm willing to make that jump, anyway.
Later- "Do not operate locomotive faster than 70 MPH with or without power on the traction motors." That is interesting; I had thought the NYNH&H units were geared higher. It's likely a railroad-related, and not locomotive-related restriction (tracking, overturning rail on curves, etc.)
Oh - a digression, Allen - I do not know where the first reference to 726 motors in 244-engined passenger locomotives appeared. I believe, though, it might have been in a book specifically printed on these units a few years ago. I myself am of the mind that none were used in regular production units by way of that table in TP-400.
Now, I do also have several textbooks produced for use in the railroad industry, which are clearly provided with information direct from the builders for the purpose of educating those entering the field in some way or another. One of these, "Diesel Locomotives - Mechanical Equipment" has information on the twin-engine ALCO-GE units. Photos are included of both Southern A&B and NYNH&H units. It was printed the third time in 1947; this copy has a name signed in the cover (the recipient) and a date of 1/31/48.
Information by a speed-TE curve in the book indicates, for units equipped matching the curve that is, two GT-557 generators, 4 GE-730 motors, 58 to 25 gears and 40" wheels. The curve goes up to 120 MPH, and ends there. (So does the whole graph, actually.)
Later: "Find out the maximum speed limit on your particular locomotive and do not exceed it at any time under any condition. There is also a minimum speed limit which is 1/4 of the maximum speed limit. Do not go below this minimum speed with full throttle except for short periods of time, otherwise the traction motors will overheat."
The description of the (dual ammeters and) load limits are slightly different in this account.
White scale / 0 to 700 / Continuous rating
Yellow scale / 700 to 800 / 1 1/2 hours
Red scale / 800 to 1500 / 4 minutes
"Operation in the red scale is prohibited except for starting the train or for very short and intermittent periods of not more than four minutes each."
NOW, a few comments added to the facts. Many many books have been written which include phraseology about the ALCO-GE DL-109, or others, such as "with their larger freight-sized traction motors" or some such. The 730 in the DL series wasn't THAT much more powerful compared to EMD E-units (and that's really what all those authors are comparing, isn't it?) but it was enough to make a difference at the low end.
Here are some common units, geared as close to 98 or 100 MPH as possible (ie as was offered) and their minimum continuous speeds.
DL-109: 25 MPH
ALCO-GE 2000 HP Passenger: 23 MPH
ALCO-GE 2250 HP Passenger: 21.8 MPH
EMD E-7: 35 MPH
EMD E-8: 29.5 MPH
It is on such relationships that such statements originally were based "way back when," when the original authors (David P. Morgan, Don Ball, et al) wrote them. Of course, we did mention the AT&SF and its few ALCO-GE twin-engined A1A-A1A units - and they found out the following fact:
EMD F-3: 22.5 MPH
Yes, the F-3 geared for 100 MPH had a continuous speed right about the same as the post-war ALCO-GE 2000 HP 244-engined units, but also had the advantage of all weight on drivers. Although they did buy a decent number of the ALCO-GE units, we all know very well that they opted for a huge number of passenger F-3 and F-7 units. (The Great Northern, and Northern Pacific, are another two good examples of such experience and thinking.) This relationship may also be another original source of such phraseology as "freight sized traction motors" applied to ALCO-GE road units, either twin or single-engined.
How do I sum this all up?
-Only listing anywhere here for traction motors in ALCO-GE twin engine units is model 730
-Minimum speed of ALCO-GE twin engine units is 1/4 the maximum
-Current limit of ALCO-GE twin engine units both in book stating 730 motors AND in New Haven operating instructions is 700 Amps
-Minimum speed of ALCO-GE twin engine units is much closer to that of later ALCO-GE units with 752 motors than it is to contemporary EMD units
-No unit of any kind for any railroad at any time I have information for here includes ANY 726 motor. None.
Hope that isn't TOO much info for one post, but as regards the whole question of the MCS of the twin-engined ALCO-GE units, well, there you go.
-Will Davis
HOWEVER, I do have an original NYNH&H General Notice that covers operation of all the 0700 class, which was printed by the railroad in October 1946. It does have some figures you (we) might like to note, and compare.
Operation of the units included automatic forward transition, but not automatic back transition. When current in parallel reached 850 Amps with speed decreasing, the throttle was closed and then re-opened which allowed the back transition to series to occur. After that happened, the following limits applied:
0-700 Amps: continuous
700-800 Amps: 1 1/2 Hours
800-900 Amps 20 min
900-1100 Amps 10 min
1100-1500 Amps 4 min
A note at the end of the section on currents: "Always be on the alert to watch traction motor currents when speed is less than 25 MPH."
So, then, we can probably make an educated guess from this information that the minimum continuous speed is REALLY close to 25 MPH. I'm willing to make that jump, anyway.
Later- "Do not operate locomotive faster than 70 MPH with or without power on the traction motors." That is interesting; I had thought the NYNH&H units were geared higher. It's likely a railroad-related, and not locomotive-related restriction (tracking, overturning rail on curves, etc.)
Oh - a digression, Allen - I do not know where the first reference to 726 motors in 244-engined passenger locomotives appeared. I believe, though, it might have been in a book specifically printed on these units a few years ago. I myself am of the mind that none were used in regular production units by way of that table in TP-400.
Now, I do also have several textbooks produced for use in the railroad industry, which are clearly provided with information direct from the builders for the purpose of educating those entering the field in some way or another. One of these, "Diesel Locomotives - Mechanical Equipment" has information on the twin-engine ALCO-GE units. Photos are included of both Southern A&B and NYNH&H units. It was printed the third time in 1947; this copy has a name signed in the cover (the recipient) and a date of 1/31/48.
Information by a speed-TE curve in the book indicates, for units equipped matching the curve that is, two GT-557 generators, 4 GE-730 motors, 58 to 25 gears and 40" wheels. The curve goes up to 120 MPH, and ends there. (So does the whole graph, actually.)
Later: "Find out the maximum speed limit on your particular locomotive and do not exceed it at any time under any condition. There is also a minimum speed limit which is 1/4 of the maximum speed limit. Do not go below this minimum speed with full throttle except for short periods of time, otherwise the traction motors will overheat."
The description of the (dual ammeters and) load limits are slightly different in this account.
White scale / 0 to 700 / Continuous rating
Yellow scale / 700 to 800 / 1 1/2 hours
Red scale / 800 to 1500 / 4 minutes
"Operation in the red scale is prohibited except for starting the train or for very short and intermittent periods of not more than four minutes each."
NOW, a few comments added to the facts. Many many books have been written which include phraseology about the ALCO-GE DL-109, or others, such as "with their larger freight-sized traction motors" or some such. The 730 in the DL series wasn't THAT much more powerful compared to EMD E-units (and that's really what all those authors are comparing, isn't it?) but it was enough to make a difference at the low end.
Here are some common units, geared as close to 98 or 100 MPH as possible (ie as was offered) and their minimum continuous speeds.
DL-109: 25 MPH
ALCO-GE 2000 HP Passenger: 23 MPH
ALCO-GE 2250 HP Passenger: 21.8 MPH
EMD E-7: 35 MPH
EMD E-8: 29.5 MPH
It is on such relationships that such statements originally were based "way back when," when the original authors (David P. Morgan, Don Ball, et al) wrote them. Of course, we did mention the AT&SF and its few ALCO-GE twin-engined A1A-A1A units - and they found out the following fact:
EMD F-3: 22.5 MPH
Yes, the F-3 geared for 100 MPH had a continuous speed right about the same as the post-war ALCO-GE 2000 HP 244-engined units, but also had the advantage of all weight on drivers. Although they did buy a decent number of the ALCO-GE units, we all know very well that they opted for a huge number of passenger F-3 and F-7 units. (The Great Northern, and Northern Pacific, are another two good examples of such experience and thinking.) This relationship may also be another original source of such phraseology as "freight sized traction motors" applied to ALCO-GE road units, either twin or single-engined.
How do I sum this all up?
-Only listing anywhere here for traction motors in ALCO-GE twin engine units is model 730
-Minimum speed of ALCO-GE twin engine units is 1/4 the maximum
-Current limit of ALCO-GE twin engine units both in book stating 730 motors AND in New Haven operating instructions is 700 Amps
-Minimum speed of ALCO-GE twin engine units is much closer to that of later ALCO-GE units with 752 motors than it is to contemporary EMD units
-No unit of any kind for any railroad at any time I have information for here includes ANY 726 motor. None.
Hope that isn't TOO much info for one post, but as regards the whole question of the MCS of the twin-engined ALCO-GE units, well, there you go.
-Will Davis