• Fairbanks-Morse Control Systems

  • Discussion of Fairbanks-Morse locomotive products. Official web site can be found here: www.fairbanksmorse.com.
Discussion of Fairbanks-Morse locomotive products. Official web site can be found here: www.fairbanksmorse.com.

Moderator: pablo

  by Pneudyne
Transferred from the EMD “Field loop Dynamic Brake Control: thread, https://www.railroad.net/emd-field-loop ... 52156.html, specifically from this posting: https://www.railroad.net/post1617096.html#p1617096.
Typewriters wrote: Wed Mar 01, 2023 10:25 am
Off topic for an EMD thread here but F-M also adapted GE control equipment to use an air throttle. That's actually pretty straight forward except in the case of amplidyne excitation they had to add an air operated step controller to set current (excitation) limits progressively as the throttle pipe pressure increased since they couldn't get that signal another way.
That is one that I had not previously known about!

GE itself did use air throttles here and there, examples being the Queensland Railways 1150 and 1170 classes, and the US Gypsum (USG) 54-ton model. But these were with the simple split-pole excitation system. Also, notched throttles (7 or 8 notches) were used, which did allow for some electrical switching at notch changes, and I think this was done for the USG model.

I guess that with the change from Westinghouse to GE electrical equipment, F-M wanted to retain air throttles on those models that had previously used them. And at say the 1600 hp and above level, the split-pole system was probably seen as inadequate, hence the need to adapt the GE Amplidyne system.

Nonetheless, the “translation” from air pressure to electrical control signals does seem to have been viewed as being a more difficult proposition than the other way around, and perhaps something to be avoided if possible. For example, in the British Rail case, it developed an electric-to-air conversion technique, but it addressed the air-to-electric requirement by sidestepping it, and equipping locomotives with dual-function master controllers that could deliver both air and electric signals.

Another case of avoidance was with the early Locotrol system. Rather than “translate” from air pressure to electrical signals, braking control was done electrically by push buttons on the Locotrol control panel, and then translated into the air pressure domain.

Thus, necessity meant that F-M made quite a bold step in using air pressure to electrical translation.

That said, I understand that the original Westinghouse proposal (not implemented) for acceleration control on the PCC streetcar was to use an air manifold with multiple diaphragm operated switches, set to close at progressively higher air pressures, with manifold air pressure progressively increasing under the control of the acceleration relay. So the air-to-electric idea was not new. And techniques were developed in the 1960s when the need arose for blended dynamic braking.

Returning to the F-M case, it did appear to have used a variety of control systems, a partial list being:

Its own air throttle system with Westinghouse equipment on some of the earlier H-series models.

GE Amplidyne with potential wire dynamic braking control on the “Erie-built” models.

Wemco with field loop dynamic braking control on the “Consolidation” line and early TrainMasters.

GE Amplidyne and then Static with its own Universal dynamic brake control on later TrainMasters.

GE Amplidyne with its own air throttle and interface on some later H-series models.

I am not sure if dynamic braking was ever used with any of the F-M air throttle variations.

  by Typewriters
Air throttle: I believe there were no Fairbanks-Morse locomotives built with air throttle and dynamic brake. I do know that over time there were two different pressure ranges employed.

Universal Dynamic Brake: I've just acquired an operators manual for NYNH&H 1600-1614, which were model H16-44 and whose contract information sheet carries approval dates of 3/26/56 and 3/27/56. In the information boxes at the top of this sheet you find a line labeled "MU DATA" and on this one we find "ALCO DL701 EMD GP9 MTR & BRK" (motoring and braking) and sure enough in the list of "electrical specialties" below that we find Universal Dynamic Brake. So far, I can guarantee that the last batch of B&O H16-44 units, these H16-44 units, and Reading 806-807 had the universal dynamic brake; there must have been more but I have no information to tell me which had and didn't have it.
  by Pneudyne
F-M Manual #1204B of 1951 February, covering the H16 and H20 models (1), gave two pressure ranges for the pneumatic throttle, as shown in this page:

F-M H-Series 195102 Sec 132A p.17.png

One may then ask, why two ranges, and did one precede the other.

The H16 and H20 were shown as having the pneumatic-hydraulic version of the Woodward PG governor, thus with internal speed control.

Previously, though, F-M had used the Wabco external diaphragm-type pneumatic governor actuator, as shown in this diagram from McGowan (2):

McGowan p.272,273.png

There is some evidence that this kind of actuator was typically operated with a 60 lbf/in² full throttle pressure. The same or a very similar unit was offered by Westinghouse UK, and used for example by Rolls Royce on DMU powerplants. The 60 lbf/in² number was mentioned in Doherty:

Doherty p.219,220.png

Baldwin also used the same actuator a 60 lbf/in² maximum nominal pressure, but that is something for the Baldwin forum.

Possibly then F-M started with the 60 lbf/in² Wabco number, then when it started using the Woodward PG governor, found that it would work well or perhaps better with a 30 lbf/in² maximum, and chose to standardize on thus number. Although why 30lbf/in² would be better is a matter for speculation. But it still needed to offer the 60 lbf/in² maximum for customers who required backward compatibility with earlier F-M units.

Manual #1204B shows the H16 and H20 as having had what might be called “conventional load control, with the pilot valve internal to the PG governor, this controlling external rotary rheostats. (Unusual though was that these were operated by governor oil, whereas the norm for external rheostats was to use engine oil.) Anyway, with the standard PG governor arrangement, load increased monotonically with engine speed (although there were variations on this for some builders).

How load control was done for the earlier F-M units with Wabco actuators is unknown, other than that it was probably external to the governor. There one finds some variations, e.g. EMD with an external floating lever and pilot valve used with the Woodward (old) SI governor, and Baldwin with a maximum-only load control switch with the Woodward UG8 governor.

(1) F-M Manual #1204B is available at: https://www.rr-fallenflags.org/manual/fm-index.html

(2) George F. McGowan; Diesel-Electric Locomotive Handbook – Electrical Equipment; Simmons-Boardman, 1951.

(3) J.M. Doherty; Diesel Locomotive Practice; Odhams, 1962.

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  by Pneudyne
I should also mention that F-M Manual #1204B had scant mention of dynamic braking. It was referred to only in connection with the selector lever function with the Wemco electric throttle control, and not at all in connection with pneumatic throttle control:

F-M H-Series 195102 Sec 101A p.09.png

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  by Typewriters
Pneudyne wrote: Mon Mar 13, 2023 7:50 pm I should also mention that F-M Manual #1204B had scant mention of dynamic braking. It was referred to only in connection with the selector lever function with the Wemco electric throttle control, and not at all in connection with pneumatic throttle control:

F-M H-Series 195102 Sec 101A p.09.png

No dynamic brake was available at this time on FM road switchers; that copy is lifted from what you see in Baldwin manuals and Lima-Hamilton manuals where there is a selector fitted.

Westinghouse XM-781 controllers with selector levers to control transition in other units that didn't have Westinghouse gear were available in 1950 and were fitted to Erie Railroad BLW DR-4-4-1500 units in the 1100 class.
Last edited by Typewriters on Fri May 05, 2023 12:11 pm, edited 1 time in total.
  by Typewriters
Just a quick note here for some clarification.

Fairbanks-Morse began its locomotive production with Westinghouse Air Brake Co. air throttles, and these were used on all H10-44, H15-44 and H20-44 units through the end of 1949 or roughly thereabouts. The exception here was the Erie-built road locomotives that used entirely GE equipment.

From early 1950 onward, electric throttles were offered on the switchers and road switchers as an option. (More on this to come shortly.) The important thing here is that there were already a significant number of locomotives sold with air throttles and multiple unit control, and this was of course still offered.

The decision by Westinghouse to exit the locomotive traction and control equipment fields was not a death blow to Fairbanks-Morse, but FM did still have a number of good customers out there whose fleets had air throttles. This is the reason that FM developed the combination of air throttle and GE control gear - to allow continued sales to existing customers whose units were air throttle equipped.

In the case of Akron, Canton & Youngstown 207 which was a single unit order and whose operating manual I have here, a significant change was the provision of multiple unit connections on both ends of the locomotive. Prior units were rear end MU only (which was seen often on earlier FM road switchers) and this change allowed three unit sets without doubleheading. Of course, 207 also had to have the FM 12 point MU cables that were not compatible with EMD, ALCO or anything else i.e. not AAR standardized. This unit had amplidyne excitation which requires a current limit control; this was accomplished by an air motor driven current limit control device with 12 steps of resistance that cut out as the throttle progressed over its power range from 15 to 55 psi. This unit had the 3A2EU throttle.

Pittsburg & West Virginia 90 to 93 (I have the manual for these) also had 3A2EU throttles and MU both ends but being later, had static excitation and did not need a signal for current limit derived from throttle position and thus completely omitted the air operated current limit device. These units also had the 12 point MU cable connectors. Both of these locomotive orders used the Woodward PG governor with direct air throttle line connection to the governor and internal diaphragm.

I will have much more to say about FM and its control system options soon.
  by Typewriters
FM Controllers 1

Here begins a brief dissertation on the controllers used in Fairbanks-Morse switchers and road switchers. Keep in mind that a "controller" is that combination of levers, switches, and valves assembled together to control the power functions of a locomotive (direction of travel and applied power).

The very first Fairbanks-Morse switch engine had a fairly unique throttle setup. I believe it was not duplicated or if it was, very few were made.

This locomotive introduced a fixture to come for years in FM locomotives, namely the throttle-reverser. This controller combines the functions of throttle and reverser in a single lever, and is a pneumatic throttle. It appears that this throttle-reverser, whose model is not known, has a forward slot hidden by the handle and a reverse slot. This would require the reducing valve portion of the controller to operate in two directions of rotation with a two-sloped cam.

Above is an image from a small format New York Central System combined operating manual showing the setup in one of that railroad's H2044 units without multiple unit control. We see the familiar two-slot throttle-reverser here; the lower slot is for power in the forward direction, and the upper for reverse. Centered between the slots would be neutral, and I believe this throttle-reverser's handle was rotated to lock it in neutral when required.

Above from the same manual is a closeup of the control stand. Note the HI and LO POWER buttons are to the left of the throttle-reverser. The LO POWER button held the load regulator in the minimum field position until the throttle was advanced to around 2/3 open at which point LO POWER operation was cancelled and the locomotive operated normally at all throttle settings.

It's my belief that the throttle-reverser seen in the above NYC illustrations is the WABCO E-2 model. This throttle-reverser incorporated an air reducer to feed the throttle line, and electrical contacts to translate the signal for forward, reverse or neutral. This throttle did not include any throttle switch; it required an external K-3 throttle switch, located in the electrical cabinet, which picked up two pounds below first notch pressure and applied power to the traction motors. This is just like the D-1 Controlair throttle found in Baldwins in this respect.

Next post, further and newer pneumatic throttle-reversers.

WILL DAVIS 5/7/2023
  by Typewriters
FM Controllers 2

We'll continue a look at controllers used in FM locomotives.

Above we see a slightly different style throttle-reverser, from my copy of Bulletin 1204B, published 1951. We see that the HI and LO POWER buttons have moved to the right of the controller and that the controller's front shape has changed. We'll see it closer in a moment.

Above is the left side stand on a dual-control unit. Note that the brake stand has moved in front of the engineer (on both sides) to allow enough room in the cab. Let's take a closer look at the throttle-reverser.

Examining this throttle-reverser, we can see that the handle inside is hinged and that the handle end just moves up and down depending upon which slot it's traveling in; the air reducer is vertical in the housing, and its cam control shaft is vertical and rotated by the throttle-reverser handle. FOR, N and REV are marked on the face of the unit and an arrow cast into the top marks the First Notch position.

This is the WABCO 3-A2E-U controller, so far as I can deduce. This controller has pneumatic output for throttle and includes electrical contacts for both FOR/N/REV signals as well as "power on" or said another way to close the main contactors and apply power to the traction motors. As such, it is not MU compatible with the previous style that required a K-3 throttle switch. There appear to be two cams available and the manual seems to hint that either the 30 lb max cam or the 60 lb max cam could be fitted to either throttle.

This throttle was used from probably 1951 until the end of production of FM locomotives. By sometime in 1952, the standard throttle on FM road switchers became the electric throttle (more on that later) and the pneumatic throttle-reverser became an option; it was ordered by roads whose fleets built earlier already used pneumatic throttles.

More to come!

WILL DAVIS 5/7/2023
  by Typewriters
FM Controllers 3

Before the end of 1949 it had become apparent that railroads wanted to be able to operate different brands of locomotives in multiple, in order to improve versatility. While many railroads of very large size assigned groups of similar locomotives to given engine terminals and areas, others did not and wished to stop adding units to their rosters that became effectively isolated. To this end, Westinghouse Electric and Manufacturing Company (WEMCO) developed a standardized master controller with an eight notch electric throttle and a selector lever that could be used to control transition on any trailing units that required manual transition control. This controller appeared in mid-late 1949 and was used on all Lima-Hamilton diesel locomotives of all models, on all Fairbanks-Morse Consolidation Line units built in the US, and on a number of Baldwin and Fairbanks-Morse road switchers.


Above from FM manual 1204B again, we see the standard WEMCO XM-781 master controller in an H16-44. The selector on this controller has no effect on field shunt in the locomotive carrying it; it only serves to signal trailing units to make transition (or in the case of some Baldwins that had supervisory control of field shunt, it controlled this as well). This throttle of course had a separate reverser lever. This could be set up to run in multiple with EMD, ALCO-GE, Baldwin and Lima-Hamilton units with the proper MU cable connections.

What is not generally known in the railfan world at all is the fact that Westinghouse AIr Brake Company (WABCO) developed its own eight notch electric throttle, and that this was a combination throttle-reverser like its pneumatically operated throttles had been. It is shown below.


Above, WABCO electric throttle-reverser as installed in New York, New Haven & Hartford FM H16-44 units 560-569. These units, built in November and December of 1950, were the only locomotives this writer can find evidence of that used this device. New Haven historians have written that these units could not run in multiple with any other New Haven diesels, but the actual reason is not clear. These units had 6DS brakes, and what appears to be a single circular MU electrical jumper plug. Exact mechanical and electrical details on the WABCO electric throttle are not known. Continued searching for details on this controller have as yet proven fruitless. One might suspect that hiding inside is the control drum of an XM-781 from WEMCO, but that is a very speculative guess with no evidence to support it. The fact that it was apparently never duplicated tells us something!

Next, a last look at FM locomotive controllers in the GE era.

WILL DAVIS 5/7/2023
  by Typewriters
FM Controllers 4

When Westinghouse Electric & Manufacturing Company announced it would drop out of the railroad traction equipment and control equipment fields, Fairbanks-Morse made arrangements with General Electric to supply equipment for its future construction.


Above, we see the revised cab and control equipment layout found in very late FM road switchers with GE equipment. This illustration is from the operators' manual for B&O 6705-6709 and depicts the GE 17KC92B1 master controller. The throttle handle controls only power while the selector controls both transition on trailing units and dynamic braking if fitted.

Of course, this setup (as with ALCO RS-3 and RS-11 units) could operate in multiple with EMD, ALCO-GE, Fairbanks-Morse, Baldwin / BLH and Lima-Hamilton units with electric throttles and multiple unit control provided the units had the correct MU cable / socket arrangement.

It was at this time that Fairbanks-Morse's engineers developed a Universal Dynamic Brake Control that would allow units to operate either with units using EMD field loop dynamic brake control or else with units using potential dynamic brake control, but not both at once. A number of locomotives were purchased with this option but nothing we see here gives away its inclusion or exclusion.

Even after the change in the product line to use GE equipment, it was necessary to offer a pneumatic throttle as an option since Fairbanks-Morse had a significant number of such locomotives already operating in the fleets of good customers. The WABCO 3-A2E-U throttle was mated with a Woodward PG pneumatic-hydraulic governor and, only in the case of units with amplidyne excitation, a pneumatic current limiter (not needed on later static excitation). We see the cab arrangement for this adaptation below. As always with such units there is no selector lever at all.


Units with GE traction and control equipment but with adaptation for pneumatic throttle are known to include H16-44 units for Pittsburg & West Virginia and for Akron, Canton & Youngstown.

This completes our look at FM controllers in switchers and road switchers. I hope it provides some clarity in an otherwise foggy subject and makes clearer some of the operations and segregations of FM locomotives on the various railroads that owned them.

WILL DAVIS 5/7/2023
  by Pneudyne
Thanks much Will – excellent material and commentary!

Fairbanks-Morse certainly used a diversity of control systems in its relatively short period of locomotive building.

The pneumatic-to-electric (variable pressure to stepped variable voltage) unit used with the pneumatic throttle/Ampliydne combination would have been an interesting device for its time. I guess that it was a form of transducer, but railroad-robust packaged transducers (strain gauge or otherwise) did not seem to become available until the 1960s, initially used for blended braking applications. I can’t trace that F-M patented its device, although it wouldn’t surprise me if it had done so.

There was also quite a range of engine governors in the mix, including the GE 17MG3 or 17MG6 in the Erie-built units. The Woodward PG dated from around 1948-49, and inherited the internal speed control mechanisms (both electric and pneumatic) from the “new” SI of 1945. The UG8 went back further, and was used with external speed control mechanisms, both electric and pneumatic.

The GE KC92 master controller had a long life and a wide range of applications. It was still being used in some GE (and I think MLW) export applications in the 1970s.

The Hi-Power/Lo-Power throttle system was patented. (US2434413 of 1948 Jan 13, filed 1945 Oct 04). The hump controllers later introduced by EMD and Alco could be used to similar effect, but F-M also added that at some stage, and patented an MU version (US2908852 of 1959 Oct 13, filed 1956 Sep 10.)

Add in the Universal Dynamic Brake control, then overall, F-M does seem to have been quite inventive in this field.

  by Pneudyne

“The very first Fairbanks-Morse switch engine had a fairly unique throttle setup. I believe it was not duplicated or if it was, very few were made.”

That controller might be related to the one described in Wabco patent US2608281, perhaps without the combined air brake control.

See: https://patents.google.com/patent/US260 ... =US2608281

And re:

“What is not generally known in the railfan world at all is the fact that Westinghouse AIr Brake Company (WABCO) developed its own eight notch electric throttle, and that this was a combination throttle-reverser like its pneumatically operated throttles had been.”

This might be the non-dynamic brake version of the controller described in Wabco patent US2667247.

There was another version of this controller that could provide both pneumatic and electric control outputs for both power and dynamic braking control, described in Wabco patent US2682784.


https://patents.google.com/patent/US266 ... =US2667247

https://patents.google.com/patent/US268 ... =US2682784

  by Pneudyne
Notwithstanding what I said in this post https://www.railroad.net/post1618559.html#p1618559 in the “EMD Field Loop Dynamic Brake Control Thread” (https://www.railroad.net/emd-field-loop ... 52156.html), and given how inventive F-M was, and that it devised a pneumatic-to-electric translation device to provide an appropriate control voltage input to the GE Amplidyne excitation system, I should not be too surprised if it had also devised a way to derive a dynamic brake control voltage (for the Amplidyne and Static systems) from the field loop control outward current wire. Possibly it was done by using a current measuring reactor (CMR) in the field loop wire. CMRs were anyway part of the GE equipment complement as a means for deriving current-related control voltages, and so were standard items.

If so, it would have made the F-M Universal Dynamic Brake apparently somewhat different to the other dual DB systems that came later. In those, the lead locomotive provided both field loop and potential wire signals, although only using one of them itself. Trailing units then responded to whichever type of signal they were set up for.

If the F-M system was as suggested above, then a GE-equipped unit could both lead and trail in a set of filed loop units, as well as in a set of potential wire units. I think that Will’s comment that the F-M Universal DB system was of the either/or type tends to support this proposition