Lima-Hamilton Diesel Locomotives

Preface:  There seems to be decent amount of writing on the net about Lima-Hamilton diesel locomotives, and my belief is that if all one does is repeat what is on the net, one is adding nothing to the net.  Therefore, instead of trying to retell the story of Lima-Hamilton I'm instead going to tell you about the company's products as seen through some specific sets of original documents and materials.  ALL materials you will see on this page are in my collection as well as others I'm referencing but not showing.

1000 HP Switcher - Trade Papers

The trade magazine MODERN RAILROADS introduced the Lima-Hamilton 1000 HP diesel switcher in its August 1949 issue, showing the original demonstrator unit (seen above, Lima-Hamilton No. 1000) and mentioning the fact that by that time four railroads had ordered a total of 31 units from Lima-Hamilton; 10 were for the Erie, 6 were for New York Central, and 4 for the Nickel Plate being called out specifically.

The locomotive at the time was called out both in this trade paper and others for several specific and peculiar features.

•Pressure charged and intercooled engine.   This was the first diesel engine to be built for use in U.S. locomotives to incorporate intercooling.  The feature was thought both novel and very modern at the time, and much was made of the fact that it materially lowered operating temperatures.  As a matter of fact, the Hamilton T89SA diesel engine had been announced to the railroad world as far back as October 1948 (in Railway Age) as a "1200 HP at sea level" engine.  Even in Lima-Hamilton materials, at the time the locomotives were being marketed as 1000 HP units, the capability of the engine to develop higher power was noted frequently - and as we know, the engine was soon uprated.

•Throttle operation.  While all Lima-Hamilton diesels used the Westinghouse XM-781 electric eight notch throttle, they had interposed in the control circuit a peculiar device which apparently controlled the rate at which the engine's speed could increase.  To quote the material in Modern Railroads:  "Control for this diesel switcher is somewhat different from that used in other locomotives.  A remote, electro-pneumatic, single station control used with a Woodward PG governor and governor operator affects both engine speed and the field of the exciter for the main generator.  A face plate type resistor, having 162 points, is actuated by a vane motor controlled by the governor.  This gives load control and load limit with each of the eight notches of the controller.  The governor is set to give low horsepower in the low notches to facilitate switching passenger equipment, and to give a rapid increase in horsepower in the high notches for heavy freight switching.  When starting a heavy freight load, for example, the controller can be pulled around to the eighth notch, with engine coming up to full speed and full power in 20 seconds."   This all vaguely implies minimum field starting; we'll learn more about this arrangement later.

The propulsion equipment (main generator, traction motors) were conventional Westinghouse equipment, with motors permanently in series-parallel and two steps of field shunt -- just like that found on contemporary Baldwin and Fairbanks-Morse switchers in operation.

Lima-Hamilton 1000 HP Diesel-Electric Locomotive Sales Brochure

 

A sales brochure produced by Lima-Hamilton very early (it has no date; is probably late 1949) shows the locomotive layout, and gives some details on the construction of the diesel engine itself.  The diesel engine's actual construction is rarely discussed these days.  Click any photo to enlarge.

 



 

An interesting feature of this engine is the fact that it uses a dry sump lubricating system - not rocket science, but unusual in U.S. diesel locomotives.

 

1000 HP Switcher Ads - Trade Magazine

 

Two advertisements from Railway Mechanical and Electrical Engineer.  The first is from August 1950 and shows TP&W 300, which is actually the former Lima-Hamilton demonstrator seen earlier.  The second ad is from October 1950 and shows a 1000 HP unit built for NYC&St.L.  Note that the rear cab windows on TP&W 300 appear to have been lowered, entirely; probably to reduce sun glare.  This is the same reason many roads plated over or painted over the small windows over the engine hoods on EMD switchers, and ALCO-GE 660/1000 HP switchers and 1500/1600 HP road switchers.

 

 

 

 

Lima-Hamilton Specification Cards

 

Specification cards are something that some collectors just pile up; I don't, but I have over the years acquired three of them from Lima-Hamilton, all covering switch engines.  I'll show front (picture view) and back (specifications) below; keep in mind that the three cards are stacked up in each scan, oldest on top. 

 

The first card shows the original 1000 HP Lima-Hamilton demonstrator.  The second card shows a 1000 HP unit built for the Erie; this unit is equipped with multiple unit controls on both ends, and the M.U. plug sockets can clearly be seen on the end rails.  The third card shows the first 1200 HP demonstrator unit - and it's labeled on the rear "built for Lima-Hamilton Corporation" just as the card for the first demonstrator was.

 



 



 

Of course, the similarity of the 1000 HP and 1200 HP locomotives is obvious (modelers will note however the unique window arrangements on Lima-Hamilton 1000, as well as the different radiator intake louver design) and we know that some units were uprated in power output, from 1000 HP to 1200 HP.   The 1200 HP unit first appeared about one year after the first 1000 HP unit was built.  We'll see a bit more about the uprating hinted at later.

 

 

Lima-Hamilton Operating Manuals

 

Not a lot has been done to catechize these manuals; they're not exceedingly rare, but they're unusual enough that most folks don't have a pile of them.  I have four, and I can tell you the details for identifying and categorizing them for your future research.  Let's look at the front covers of two manuals first.

 



First of all, Lima-Hamilton manuals don't have part numbers or training series numbers or any such.  On the front, they'll tell you what they're for generally -- both of these say, near the top, "1200 HP Diesel Electric Switching Locomotive."  The key here is on the bottom left corner.  If you look closely, the left hand manual says "Form 1200 STD" while the right manual says "Form 1200 B&O T.R.R.A. -ST. L."   The STD on the left hand manual means "standard," and this is the manual issued for locomotives in basic condition with no options.  The manual on the right is railroad specific for units provided to both Baltimore & Ohio, and Terminal Rail Road Association of St. Louis.  Let's look at the front page photos from each.

What jumps out right away is the fact that the unit pictured in the second manual appears to be a B&O unit painted but not yet lettered, and that the locomotive has multiple unit connector plugs flanking an M.U. access gangway on the end platform; the standard unit just has a straight hand rail and no M.U. plugs.

Sure enough, when we leaf through the manuals we find that while the B&O / TRRA manual is of a slightly later style (these include fold out diagrams instead of one page diagrams) the content is essentially identical until we get to the back, and find that the B&O / TRRA manual has a single page added at the back to cover multiple unit operation that isn't found in the "STD" manual.

So the key to identifying a manual you're looking at is first, the title, and then second the code in the lower left hand corner.  I've also seen these labeled "Form 1200 N.Y. N.H. & H." - obviously for the New Haven, as just one other example.  Now let's look at two other manual covers.

 



The manual on the left covers the New York Central's 1200 HP road switchers.  The manual on the right is the standard manual for Lima-Hamilton transfer locomotives, without dynamic brake or multiple unit control; dual controls were standard on these.  These manuals are less common than those seen earlier; the one on the left is actually pretty hard to find.   These manuals also offer us a couple of very interesting details.

1200 HP Road Switchers

 

Present day historians might assume that the Lima-Hamilton 1200 HP road switcher was very much the 1200 HP switcher machinery on a lengthened frame, with road trucks and steam generator equipment.  That's right - and in that way, these are a lot like contemporary Baldwin 1000 and 1200 HP road switchers - but these Limas have one very important difference.  Unusually for Westinghouse equipped locomotives, these NYC 1200 HP road switchers have a full transition control for power distribution to the traction motors, even though they have Model 362 switcher traction motors.

 

Westinghouse locomotives normally don't change their connections to the traction motors to allow higher and higher speed - typically they just shunt their traction motor fields, early on in two steps and later on in four.  The traction motors are wired permanently in series-parallel.  On these Lima-Hamilton road switcher units however a full transition control is used, with the locomotives starting in series-parallel and then shifting to parallel for high speeds; field shunting is also employed.  This requires the addition of a significant amount of heavy switchgear and smaller control and timing relays never normally found in Westinghouse equipped units -- and that equipment is clearly obvious and clearly labeled in the electrical cabinet diagrams, and of course operation of the units making automatic transition is covered in the operating instructions.  These units do not have selector levers, and the engineman cannot forestall or control transition.  The units were also built with MU connections on the rear end only, as can be seen in the picture.

 

(There's little doubt that the transition control on these units was put in because they were originally intended to operate as passenger units on the Boston & Albany, in pairs.  This would have required good acceleration and high speed capability.  We all know how that worked out - it didn't, and the units ended up on freight in Ohio.)

 

Other than this feature the locomotives have no really surprising features.  Below is a photo of the overall diagram; I didn't wish to flatten and scan the manual due to its condition, so this photo will suffice.  Note that there's a large water cooler on the rear cab wall along with the cab heater, and two cab seats on the left side.



The 2500 HP transfer units' manual reveals nothing particularly surprising except that I might mention, in comparison to the transition of the 1200 HP road switcher that the 2500 HP transfer unit has all of three traction motors per power unit wired permanently in parallel, and incorporates two steps of field shunt.

Lima-Hamilton Modifications

I have in my collection a very tattered three page copied document, whose exact origin is unknown, that covers modifications to Lima-Hamilton diesel locomotives.  I'll give the title of each section and try to tell you what each seems to be describing.

A.  Elimination or Modification of Sequence Converter.

In the electrical cabinet photos of Lima-Hamiltons you see labeled a device called a "sequence converter," described as "a relay panel used to provide the proper synchronization between the throttle lever and the engine governor."  No Baldwins have this - I have to assume that this is specific to the specialized control system on Lima-Hamiltons mentioned much earlier in this post.  Apparently it could be removed or modified, as covered in this brief instruction.  Unfortunately the wiring diagrams that should have accompanied this bulletin aren't with it, or we might know exactly how this worked.  It does appear though that the removal of the Sequence Converter just left you with a conventional eight notch throttle and Woodward PG governor, perhaps operated by internal solenoids as on zillions of EMD locomotives.

Some mention of "dual engine" units is included; obviously, transfer units.

B. Change in Engine Speed Setting with Sequence Converter Removed from Speed Control.

Further evidence that the Sequence Converter was used to take throttle signal, and somehow produce a modified response from the PG governor as compared to what you'd get with just the throttle acting on the solenoids inside (that manipulate the speed control shaft.) 

This instruction does make it clear that the locomotives' governors are set up as Minimum Field Start - the load regulator at minimum field with the throttle in Idle. 

C. Changes Required in Voltage Regulator Circuit of Locomotives equipped with YG-42-A or YG-42-B auxiliary generator when changing idling speed from 350 to 425 RPM.

This detail covers a resetting of electrical components, no doubt to compensate for the higher idling speed.  Why there's a change to a higher idling speed is puzzling, unless the engines were not staying running... or else if they had their camshafts changed during uprating.  That may well be, because the last page does cover what appears to be uprating.

Instructions for setting engine speeds on Lima-Hamilton switch locomotives that have been modified at the Baldwin-Lima-Hamilton Plant, Hamilton, Ohio.

This instruction is a bit vague, but it's perfectly clear in one sense - the engines have been reset so that their maximum (notch 8) RPM is no longer 950 RPM, but 1000 RPM.  It's basically the brief part of the typical governor setting instruction but modified with the new, higher RPM's at each notch.  This then must cover those 1000 HP switchers that were sent back to Lima-Hamilton for uprating to 1200 HP, as the title surely seems to imply.  Being sent back to the factory implies more than just a simple modification to settings was done to whatever units this covers. 

The only idenfication on this increasingly tattered three page affair is at the bottom of the third page, and is as follows:

Office of
Supt. of Equipment,
September 11, 1952  W-4
File 416.05

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I hope you've enjoyed this look at Lima-Hamilton diesels from some unusual sources, and I'll check back occasionally for comments and questions. 

-Will Davis

General Electric's 1977 Series Locomotives

 

What railfans today commonly describe as the "Dash 7" or "-7" line of General Electric diesel locomotives was announced late in 1976 and was described at that time by GE variously as the "1977 Series Locomotives" or else as the "New Series Locomotives."  This new line of domestic diesel-electric road locomotives was advertised in GE sales brochure GEA-10016, published 11/76 (1000 copies); the illustration above is from this brochure, and its cover is reproduced below.

 

 

The line originally included eleven models, which can be seen on the cover of the sales brochure above; this is not uncommon knowledge.  What is uncommon knowledge is what the New Series actually introduced to the GE line, and what it did not; further unstated anywhere is the origin of the design evolution.

 

"A New Industry Standard."

 

General Electric states in the introduction to this brochure that the New Series Locomotive was "the result of an intensive three year design and manufacturing program to further improve the quality of General Electric Locomotives."  This process was of course continuous with GE locomotives already; over the years GE had included product improvements and refinements (as well as power uprates) into locomotives actually built in series production for railroad service, but at the same price as conventional units in the order (for example, GE included two 3300 HP U33B locomotives in the midst of a New York Central production run of 3000 HP U30B units as "pre-production field test units") for the purpose of field testing improvements.  This process had begun with the U25B and continued through the early 1970's; for example, the steel crown piston was introduced first in 1970 on high horsepower models and eventually was applied to all models at all ratings.  (In fact, the original cast iron piston was allowed to go out of production so that, by the time of a 1983 GE publication in the collection, the iron piston had been unavailable brand new "for several years.")  What was different, apparently, with this New Series Locomotive line was the concentration of overall effort from the front of the locomotive to the back in a short period of time.

 

The brochure tells us of two new periods of improvement. Phase One saw GE perform what is described as "an in-depth study" with its customers which resulted in the development of "over 60 product improvements" that were incorporated into the locomotives in 1975 "on a scheduled basis," which simply implies that improvements were phased in as they were ready.  Phase Two consisted of all of the alterations found in the New Series Locomotive lineup; it was considered also to be complete as of the 11/76 publication date of the sales brochure.

 

"Phase One"

 

General Electric issued Specification 3860 in 1975, entitled "1975 Product Improvements."  Brief details of this specification are included in GEA-10016 as is an illustration of the specification itself, seen below.

 





The list of improvements is wide ranging.  58 are listed in GEA-10016 from Specification 3860; these are listed below.  These are not explained but rather are simply listed; most are obvious, but for those which are not I will include a brief description from other official GE publications.

1.  New Platform Sump-Drain System
2.  Newly Designed Braking Switch
3.  Easy Fuel Pump Motor Brush Access
4.  New Self-Cleaning Primary Dirty Air Outlets
5.  High Reliability Governor Plug
6.  Longer Life Cab Gauges
7,  Blue Control Card Labeled When Adjustment Required at Time of Installation
8.  Built-in Engine Barring Over Device
9.  Adequate Drains for Exterior Lights
10.  New Engine Cab Door Latches Provide "Positive" Locking
11.  New Hatch Latch Eliminates Damage to Fuel Lines
12.  Lower Lube-Oil Fill Mark
13.  Cylinder Hold-down Bolt Inserts  (WD note:  This means that inserts were shrunk fit into the engine frame, into which the cylinder hold down bolts threaded; previously, the hold downs were studs threaded directly into the frame itself.)
14.  Dynamic Braking Grid Slag Catcher (WD note:  This catches melted dynamic brake grid material, should this occur due to fault.)
15.  Engine Overspeed Link Redesigned
16.  Cleaner Air Supply to Increase Air Compressor Filter Life
17.  Improved Oil Filtration
18.  New Turbocharger External Air Seal Arrangement
19.  New Fuel Filter Drain Valve
20.  Improved Gardner-Denver Compressors
21.  "B" Platforms Strengthened
22.  Engine Systems Monitor (ESM)
23.  Improved Accessibility to Engine Governor
24.  Settings Now Included on Electrical Schematics to Assist Maintenance Personnel
25.  New Voltage Regulator
26.  Improved Power Rectifier Panel
27.  New Control Compartment Drains
28.  Improved Fasteners for Engine Air Filter Doors
29.  Improved Accessibility to Electric Heat Blower Motor
30.  Test Points Built-In and Data Provided for Maintenance
31.  Removable Cab Heater Headers to Facilitate Core Cleaning
32.  Alternator/Generator Improvements
33.  High Reliability, "Static" Time Delay Relay
34.  Improved Power Cable Labels for Quick Identification
35.  New Governor Cables
36.  New AAR Controller Slide Out Feature
37.  New Labels to Facilitate Reverser and Braking Switch Maintenance
38.  Addition of Cooling System Test Points
39.  Toilet Water Tank Assembly Simplified
40.  Re-Orient Air Valves for Operation Safety
41.  Instruction Plate Added to Facilitate Engine Air Filter Maintenance
42.  Teflon Tape Used at Pipe Connections
43.  Small Resistors Labeled to Aid Troubleshooting
44.  Bolting Ears Added to Engine Air Discharge Elbows for Maximum Performance
45.  New Fluid Amplifier Gasket Material Reduces Leaks (WD note: the fluid amplifier assembly directs water to and from the radiator cores.)
46.  Inspection of Engine Bonded Rubber Drive Simplified
47.  New Fuel Booster Pump Seal for Ease of Assembly
48.  New Water Pump Seal for Longer Life
49.  Two Seals on Lube-Oil Filter for Longer Engine Life
50.  Engine Master Rod Cap Assembly Simplified
51.  Captive, Fast-Action Fasteners Added to Control Stand Access Doors
52.  Fuel Filter Tank Threaded Center Tube Eliminates Rough Weld
53.  Longer Life Cylinder Head Cross Head Guide O-Rings
54.  New Engine Governor Water Diaphragm Material for Longer Life
55.  Lubrication of Engine Cross Rocker Bushings Improved
56.  New Valve Spring Seat Design Extends Cylinder Head Life (WD note: This was referred to in engine manuals as the 'spectacle style' seat.)
57.  15 degree Intake Valves for Reduced Valve Recession (WD note: Started mid-1974.)
58.  New Gasket Material for Longer Life Water Jumper

It should be noted that these improvements are not the XR-series changes, nor are they associated only with New Series Locomotives.  These were applied during the two years prior to the announcement of the New Series and were incorporated in U-series locomotives.

"Phase Two" or the New Series Locomotive / 1977 Series Locomotive

The second round of improvements included five major areas of alteration to design and fifteen further changes to the locomotives.  Some of the 15 further changes had previously been either field tested or offered as extra-cost options (for example, electric cab heat) but now these 15 were incorporated in all locomotives "at no extra charge."

The five major areas of improvement were the following:

1.  The air compressor was moved off of the pedestal supporting the radiator fan gear box, and into a new small compartment of its own separate from the radiator cab.

2.  The arrangement and orientation of the lube oil filter, lube oil cooler and engine water tank was altered and improved.

3.  Only on 4-axle units, the equipment blower was moved into the radiator compartment.  (All U-series locomotives of models U25B and U25C, as well as U28B and U28C locomotives built through about 1/66 had their equipment blowers in the radiator compartment although these older units had a very different arrangement.)

4.  High and low voltage components were separated into two different control compartments - one above the frame, behind the cab and one below.

5.  GE included its interpretation of the AAR Clean Locomotive Cab layout which itself incorporated 18 "significant modifications" to the locomotive cab

I will show a couple of illustrations that point up some of these alterations physically in the New Series Locomotives.

Above, we see the rear or "No. 2 end" of the New Series Locomotive.  A B-B or four axle unit is depicted at top, while a C-C or six axle unit is depicted below.  Immediately obvious is the fact that the air compressor is now in its own compartment, which "isolates the unit from road dust, eliminates oil and oil vapor from the radiator compartment, lessens the chance of winter freeze-up" and also ensures the air compressor a supply of "warm, clean air."  In addition to this change the water tank is redesigned, and no longer supports the oil cooler; the oil filter is reoriented to ensure drainage; the oil filters now have ten instead of eight to stretch changeout time, as well as other changes and improvements.  Note that the equipment blower is behind the radiator fan gear box on the B-B units; this was necessary to allow room for the entirely new layout behind the operators' cab, which we'll see next.  The six axle units had more than enough room to allow the changes without moving the blower.

Above is the New Series Locomotive cab arrangement, incorporating AAR Clean Cab concepts.  The AAR locomotive controller (GE model KC-108) had been in use on GE U-series locomotives since 1972 and of course was incorporated in this design, but access to it and maintenance of it were improved.  The number keys on the illustration are for the following features:

1.  Protective covers over windshield wiper motors
2.  Soft rubber grips on windshield wiper motor handles
3.  Outside access to road number lights and headlights
4.  Flexible hinge guards on locomotive cab doors
5.  Main cab door closure bars
6.  Padding on the upper inside frame of cab doors
7.  Padded engineer's sun visors
8.  Rounded sliding cab window latches
9.  Soft-resilient rubber covered horn handles
10.  Side cab windows of Lexan
11.  Exposed main cab edges have been rounded
12.  Toilet compartment doorways of minimum dimension
13.  Floor drains, one way ventilators and waist-high washable walls have been installed in the toilet compartment
14.  Standard dimensions for water cooler alcoves
15.  Standard location of conductor's emergency brake valve
16.  Radio control head has been recessed in the control console
17.  Benelex Scuffcote floor covering
18.  Wiper valves and light switches have been recessed in the main cab ceiling

In addition to the totally new arrangement (which moves the toilet to a new compartment behind the cab, and incidentally also incorporates electric cab heat as standard equipment on all locomotives - although side strip heaters were not standard) described here, low voltage and low heat electrical components were moved to a compartment above the running board and behind the cab.   This compartment was cooled by locomotive equipment air, but had its own secondary air filters as well.  This move offered greatly improved access and longer component life since all components in both lower and upper compartments were less crowded, as well as "adequate space for customer options."

Earlier I mentioned that there were five major changes to the New Series Locomotive and fifteen additional equipment modifications.  The additional 15 changes were as follows:

1.  Copper power cables, replacing aluminum
2.  Alternator idler gear bearing redesigned with ball bearings instead of needle bearings due to previous design not providing the expected service life
3.  Grooveless lower main crankshaft bearings in all engines
4.  Water header of 12 cylinder engines raised up to height of that of the 16 cylinder engines to improve access to exhaust manifold
5.  Steel alternator slip rings for GTA-11 alternator (on extended field test since 1970)
6.  Electric Cab heat
7.  Babbitted crankshaft thrust bearing surfaces (similar to main bearings) for longer life
8.  New engine compression release valve design
9.  Improved overspeed governor
10.  Radiator clean-out panels (these are the small rectangular bolted panels under the radiator "wings" and above the radiator intakes on New Series units)
11.  Power Diode Retention Hardware - ensures diodes remain firmly attached to heat sink, ensuring heat transfer and extending life.  Previous design "had tendency to relax in service."
12.  Lexan side windows in cab - impact resistant windows for crew protection.
13.  Improved lube oil relief valve seat - now stainless steel to improve life, due to resisting wear
14.  Winter-Summer Engine Air.  This design feature incorporates a damper, manually positioned, that allows warm engine compartment air to mix into the engine intake air in winter "to provide more reliable winter operation."  This door would be repositioned in summer.  Interestingly, this device is mentioned nowhere in a slightly later Operating Manual for New Series Locomotives, GEJ-5729C, dated 5/79.  It may have been deleted.
15.  Oil and Water Piping Thermometer Wells to allow quick verification of temperatures.

External features and final comments.

Most railfan websites have concerned themselves primarily with external features visible on this line of locomotives which distinguish them from earlier U-series locomotives - namely, the widening of the engine cab (or hood) toward the rear and the provision of identical radiator compartments on all units regardless of horsepower rating.

Above is the side view of the B23-7 locomotive from GE Specification 3530D, dated 2/77.  (The hood lines, and ground, should be level, but I'm unable to use a scanner on this somewhat delicate document and was forced to simply photograph it - thus, it wasn't perfectly flat.)  Notable are the wide radiator compartment at the top, or "wings," which on the U-series had appeared only on U33, U34 and U36 models.  Also apparent are the new arrangement of radiator compartment intakes as compared with late U-series units and the small rectangular radiator clean out access covers.  This specification for the B23-7 and GE Specification 3390G for the C30-7, dated 2/77 (and thus both very early for this line) both clearly indicate that dynamic braking was included as standard equipment on the units, with extended range dynamic braking being an option.  This is not listed as a change to the product line per se in any of the New Series Locomotive sales material, but seems significant to note from a sales standpoint.

Above is a side view of the B23-7 from GE Specification 3530E, which interestingly has no publication date anywhere but is the next after that depicted above.  (Again, same disclaimer about lines should be straight!)  This locomotive has been modified to incorporate an exhaust silencer stack and to remove the oval side cab windows - changes across the entire New Series in 1980.  Dynamic braking is still standard.  A number of other features have changed, particularly the traction motor gear ratios, but the locomotive is largely the same product.

-Finis-

•Railfans should be aware that massive changes to very complicated manufactured products such as diesel-electric locomotives are not undertaken lightly, and that in many cases what has been printed in railfan press over the years is not completely indicative of the actual progression of developmental advances in these machines.  Until now, most railfans would have been led to believe that the major changes in the "Dash 7" GE locomotives (a name that you will notice GE did not, and does not use referring to its own products in these publications) centered on the oil filter / oil cooler and some miscellaneous reliability / maintenance improvements.  My purpose in writing this article (and in reviving the long-dormant blog on which it's posted) is both to correct the written "history" of this line, and to try to get railfans to think more mechanically and be more curious about reality and history as it really did occur.

Sources: 

"1977 Series Locomotive - A New Industry Standard."  GEA-10016, 11/76

B23 Locomotive Specification 3530D  2/77

B23 Locomotive Specification 3530E  no date

C30 Locomotive Specification 3390G  2/77

Operating Manual - New Series Diesel-Electric Locomotive GEJ-5729C 5/79

GE Locomotive Training Manual, undated.

Krauss-Maffei Diesel-Hydraulic locomotives on the D&RGW 2

In our last installment, we looked at the history of diesel-hydraulic road locomotive development in Germany. We noted the early development of twin-engined diesel-hydraulic road locomotives as early as 1953 by a consortium of German locomotive and engine builders and the DB itself; one of these early V200 locomotives is shown below from the Henschel Locomotive Engineer's Manual (pub. 1960.)

Design work progressed in high speed, light weight locomotive engines in Germany such that by 1959-1960 instead of 800 to 1100 HP V-12 engines, there were now V-16 engines capable of anywhere from 1600 to 2000 HP and transmissions which were capable of taking at least 1800 HP input by 1959. We will now move on to the ML4000C'C' as built for the US railroads - in this case, our data will be specific to the three units produced for the D&RGW railway.

Two further volumes will be consulted, whose covers are shown below.


These manuals are the Parts Manual for the ML4000C'C' locomotive, and the Diesel Engine Maintenance Manual for the ML4000C'C'.

Below is an overall external view of the locomotive as delivered from the factory. Remember to click any photos on this site to enlarge them.

Of course, one unit is shown, but it should be remembered that the original operation on the D&RGW for these units involved always using all three units in multiple, frequently with a dynamometer car. The intention was that three K-M units could replace the regular sets of EMD units D&RGW was using to haul trains, which normally amounted to six or seven units each rated 1500 or 1750 HP for traction.

Below we see an illustration from the parts manual showing the layout of equipment in the locomotive. Note that the engine compartments are leading, or are toward No. 1 end, from the radiator compartments but that the forward diesel engine's orientation is opposite that of the after engine because the Voith hydraulic transmissions are toward the ends of the locomotive.



Notable features in this illustration are the high mounted cab floor, raised over the high speed drive shaft for No. 1 powerplant; the compact diesel engines, each with two turbochargers mounted directly on top of the engine; the large Voith transmissions; and the cardan shafts (shafts with splines and universal joints) used to make the connections to drive the axles. Below, a diagram showing just the drive line components from the same manual.

The Dynastarter is both generator and starter motor; it starts the diesel engine through the high speed shaft (4) and thereafter functions as a generator for on board power and battery charging. The shafting is very obvious in this view, from engine to transmission, then to an intermediate gearbox, and finally to the axle drives.

The trucks and suspension on these locomotives are peculiar, largely because the mechanical equipment just described makes conventional center-pivot U.S. style trucks impossible. For this reason, K-M had developed a fairly complicated truck and suspension design for the V200, then for the six axle ML2200 / ML3000 and finally further for the ML4000 locomotive. Below, views of the truck construction and suspension arrangements.



Our final view is a cut showing the rear cab wall and the side cab view to give a complete idea of what the cab arrangement internally was like.


In our next and final installment on these locomotives, we will cover design details of the diesel engines, and discuss authoritatively the actual power ratings of these locomotives.

Krauss-Maffei Diesel-Hydraulic locomotives on the D&RGW 1

After a very long time on the RIP track, I've decided to haul our blog RAILROAD LOCOMOTIVES out of the weeds and place it back into service. Here's the first new run.

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Krauss-Maffei Diesel-Hydraulic locomotives on the D&RGW 1

I have been very fortunate recently to acquire some new material which describes the type ML4000C'C' diesel-hydraulic locomotives built by Krauss-Maffei of Munich, Germany and which were delivered to two U.S. railroads (Denver & Rio Grande Western, three units, and Southern Pacific, three units) in August 1961. While very much has been written and repeated about locomotive design in the United States up until the time that the arrangements were made to construct these units and the effect this had on the desire to increase unit horsepower, very little has been presented in the English language in a brief form to explain the background behind their development in Germany. Using the newly found materials, and a number of documents and magazine scans sent to me over six years ago by Steve Palmano, I'll try to fill in both some of the background information and some design details of these units.

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Development in Germany prior to 1960

The earliest developments in hydraulic transmissions for use in diesel locomotives in Germany, prior to the war, did not result in anything which we would consider full capacity road locomotives here in the United States. After the war, the nationalized West German railway system, known as the Deutsche Bundesbahn or most often simply DB decided that it would eventually have to embark on either electrification (which was highly desired) or else dieselization and developed a series of specified design parameters for locomotives which were grouped into a designation system with "V" designators. For example, in this overall plan, there was to be a switching locomotive for very low speed service known as the V60 which would be rated roughly 600 horsepower - that is to say, the diesel engine installed would have a brake horsepower rating of 600. Below, a diagram of a V60 from our copy of the 1960 Henschel Locomotive Engineer's Manual showing external view and internal details.

In this view, the diesel engine is easily made out under the larger of the two hoods, with high speed drive shaft to the hydraulic transmission. The transmission then drives the jackshaft which is connected to the driving wheels by side rods just like steam locomotives or some electric locomotives.

Moving more toward our story, now, the DB made the move in 1951 to apply this kind of technology to a true road locomotive. Clearly, side rods were not permissible and so trucks would have to be used; also, a steam generator to heat passenger cars was desirable to give the locomotive dual service capability. The DB had also provided a specification for a new range of diesel engines to be used in diesel-hydraulic locomotives that spurred competition between engine makers because it clearly implied that large contracts for production engines might be in the offing. The specification did however push the envelope of existing engine technology because of the requirements for very high power to weight ratio and the statement of a required top running speed of 1500 RPM.

The result in 1951-1952 was the construction of ten V80 class prototype locomotives. Three different makes of diesel engine were used experimentally - these being Daimler-Benz's Mb820Ab, the M-A-N L12V 17.5/22B, and the Maybach MD650. All were high speed V-12 four stroke diesel engines with what in European circles is referred to as pressure charging by exhaust-driven turbosupercharger. We simply use the term "turbocharged." Although the engines were of similar size envelope, there were many construction detail differences and the fact was that the M-A-N engine was fairly bad in service while the other two were good. Below, a V80 locomotive photo from the Henschel manual.

In these locomotives, two different makes of hydraulic transmission were used; the Voith Turbo and the Maybach Mekhydro. The Voith was a complicated unit that used three different torque convertors which were emptied and filled automatically, giving a starting high-torque range and two running speed ranges. The Maybach unit used one torque convertor and four power shifted gears, like a large automobile transmission. On both, shifting was totally automatic; inputs to shift control were throttle position and track speed.

A number of detail problems were made quickly apparent by these units, most notably the tendency of the long intermediate drive shafts from the transmission (centrally mounted) to the two truck assemblies to twist under heavy load. In later units of this size and power range, the transmission was much lower and very short shafts used to the trucks in order to avoid this torque twisting.

The "type" program now evolved into two important types for road service - a V100 of about 1000 HP based on the V80, with improvements, and a large road locomotive of twice the power to be called V200. The V200 was the first large diesel-hydraulic road locomotive type in the world; these were built beginning in 1953 with several prototypes. Below, the V200.

The well publicized tour of one of the original units of this type over a large portion of Europe, sponsored by its builder, Krauss-Maffei, spurred the order for three locomotives of modified design for Yugoslavia. These units were slightly longer, had six axles instead of four, and had two 1100 HP engines. These were classed by Krauss-Maffei as its ML2200 type.

One further six-axle unit of this type was built in 1957 for testing in Germany. As the decade was moving to an end, there was a massive rush of locomotive development in Germany. At once, much higher powered engines and hydraulic transmissions capable of taking their output began to be developed, in part in response to the specification for a single-engine locomotive between the V100 and V200 in output. This would become the V160, first actually built in 1960. Below, a view of one of the first prototype V160 locomotives.


For this range of locomotive, both Maybach and Daimler-Benz had developed 16 cylinder high speed engines of 1600-2000 HP output range; Voith and Maybach were hard at work to produce transmissions which could handle the output.

The most important step in the development between the ML2200 and the ML4000 was the conversion of the single German ML2200 into the prototype ML3000 in 1959. This involved replacing the original MD650 engines with MD655 engines; these Maybach 12-cylinder engines were very much the same except that "charge air cooling" or intercooling was employed, with a higher boost pressure. The new engines were rated 1500 brake horsepower; new Maybach Mekhydro transmissions of type K184 were installed that could handle the increased output. The locomotive immediately proved very powerful and capable.

This locomotive (when completed in new form in the first quarter of 1958) was rated a total of 3000 brake horsepower, had a weight in working order, fully loaded of almost 114 short tons (a very high power to weight ratio,) a starting tractive effort at 30% adhesion of 65,800 lbs when 2/3 loaded, a continuous drawbar rating of 59,500 lbs at 12.3 MPH and a top speed of 87 MPH. This was probably the first diesel-hydraulic road locomotive that approached characteristics that could get the attention of U.S. railroads in a serious way. Krauss-Maffei continued its efforts to construct locomotives for export in addition to continuing to build "V" classification locomotives for the DB, and the stage was set for immediate development of the ML4000 by simple extrapolation.

NEXT TIME: THE ML4000C'C' IN DETAIL

Ingersoll-Rand 10" x 12" 300 HP Diesel Engine

Most historians and railfans are aware that the first commercially successful diesel-electric locomotives to be produced in the United States incorporated a diesel engine manufactured by Ingersoll-Rand, but have never seen that engine. Let's take a brief look at this design and how it was built.

For this article, we're using an Ingersoll-Rand maintenance manual for the photos and data, courtesy the David A. Davis collection. We think it may have been printed about 1935. At left is an overall view of the engine, which had the following characteristics: 10 inch bore and 12 inch stroke; idle speed 250-275 RPM depending upon auxiliary load; full speed 550 RPM at full load, and with light load full speed was 570-575 RPM. The engine was rated at 300 brake horsepower.

This diesel engine was developed by Ingersoll-Rand for use in locomotives - but in fact this diesel engine really bears no resemblance in any way to common diesel engines for locomotive service that appeared later. For example, the use of exposed push rods was common at the time (even in submarine diesels) and so it was carried over here; no doubt, the problems of dirt and dust in locomotive service weren't yet well appreciated. Note also the use of totally exposed cylinder units; these were a common thing in early, large gasoline, distillate and oil (otherwise known as Diesel) engines at the time as well but later engines of all builders enclosed the cylinders fully in the engine frame. (Item: The first to get back away from this was the Cooper-Bessemer FWL and later FDL series.)

The manual covers two models of engine, known as the 360C and 420C models. These differ mechanically in compression ratio; the model numbers used are actually references to the peak compression pressures for each model. Valve timing and injection timing also differ between the two models. The modest power output of these engines, given their displacement and speed, is more understandable when one reads tha the peak firing pressure of these engines was on the order of 500 to 550 pounds - so that for the 420C the firing pressure at the maximum limit was only 130 pounds higher than the compression pressure. One other change between models was minor- the location of the fuel transfer pump.

Let's take a look at a section drawing of the engine to begin to see some construction features.

This drawing was originally intended to show oil flow - which with the red lines we can see flows through the drilled crankshaft to the connecting rods and then to the pistons, finally draining from their undersides into the sump - but really shows other details quite well. Note at the right the large flange used to mount the main generator, and the flexible coupling inside of that. These engine-generator sets used spring loaded bolts to hold the sets to the I-beams in the center of the locomotives, helping ensure that road shock and frame flex were not transmitted to the set (and thus the crankshaft.) Note also the pent-roof pistons, commonly seen with the Price fuel injection system concept which we'll examine in a moment. Some cylinder head details are visible here; note the long studs going from the top of the heads all the way down into the cylinders. Note also that the heads make positive full contact between each other; the heads not only contain (enclose) passages that connect to one another forming intake and exhaust manifolds (with appropriate pipe connections at the ends of the engine) but also form an upper longitudinal strength member for the engine.

Here's a closer look at the cylinder head - and if we look closely we see that the head is actually mounted on top of a piece that is interposed between it and the cylinder unit. This piece is called the combustion chamber; thus, the head itself contains only the valves, rockers, injection nozzles and so forth and is mounted on top of a separate cylindrical but short piece that forms the combustion volume when the piston is at TDC. The two fuel injector nozzles pointing into the combustion chamber at 180 degrees from each other are typical of the Price injection system design. The small valve is for air starting the engine.

Here is the engine base, turned upside down. This is the main strength member of the engine; it mounts the main bearings and thus the crankshaft as well as the camshaft. The cam deck is visible on the bottom (remember that this view is upside down as in the manual) with holes for the push rods to pass through. The housing mounts on top of a base, which serves only to collect lube oil acting as a sump, and of course as a support.



At left, one of the cylinder units. Six studs are visible which are used to attach the cylinder head (with interposed combustion chamber.) Note the flange around the base of this unit, used to bolt it to the engine housing we just saw. The four identical openings on the cylinder itself are actually normally blanked clean-out openings; the small flanged connection visible here in the center near the lower end is the cooling water inlet. Since no cooling water comes in contact with the main engine frame, we can classify this engine as a "dry block" engine.





The manual only shows a few locomotives, and all of them shown were built after ALCO left the group and went off on its own. Here we see two locomotives; at the top, Illinois Central 9000, a 100 ton 600 horsepower twin-engine box cab locomotive, and below is Bush Terminal 2, a 60 ton 300 horsepower switcher style locomotive. It is interesting to note that while the box cab design went away in favor of locomotives with narrow hoods, the characteristics of the locomotives built to the upper twin-engine design - namely, weight in working order of 100 tons and horsepower of about 600 - were established by this design and remained in production and competitive until several years after the end of the Second World War, at which time the competitive situation drove the horsepower ratings of 100 ton switching locomotives above the 600/660 HP level to 750, 800 and even higher. In other words, the original rating of the 100 ton unit conceived by ALCO-GE-IR in the mid 1920's remained useful and competitive for about 20 more years.

Ingersoll-Rand attempted to remain in the locomotive field only briefly after its original engine became non-competitive. It built its Model S, with the same bore and stroke but overall new construction and much higher rating which failed to meet any wide industry acceptance, and apparently exited the market after 1936. We hope you've enjoyed this brief look at this truly pioneering diesel engine.

{First in a series on the design and construction of diesel engines for use in locomotives.}

General Electric Wheel Slip U25-U36

{I originally wrote and disseminated this document in mid-2005. At that time, I placed it on file in a number of locomotive forums. I have updated the information in this document and it appears here in this form only; consider this version to supersede others extant.}

Wheel slip control in the General Electric Universal Series.

When General Electric began demonstration of the U25B, it was already aware that the railroads would have concerns about adhesion, considering the high power per driving axle. In order to mitigate these concerns, and give the locomotive true drag capability, GE chose to employ a piece of equipment which had already independently been under test in the US for several years (both by Westinghouse Air Brake and by New York Air Brake) as standard equipment.

This device was known as the Slip Suppression Brake Valve, or SSBV. The principle of the SSBV was that wheel slip could be corrected not by reduction of power and application of sand, but by an extremely quick application and release of the independent brake on the locomotive wheels. This device had already been installed experimentally on EMD units on the Western Maryland and had shown an ability to allow increased tonnage ratings in drag service, due to its ability to arrest slip with the locomotive still producing full power. The idea was that any brief track perturbation or weight transfer between axles which caused the slip would be passed fairly quickly, and so simply identifying the slip condition and arresting it without reducing power would not allow speed to drop further, as it would if excitation were reduced, albeit temporarily.

GE also chose to employ a new speed sensing system on the U25B which could provide better monitoring of axle speeds, through individual direct measurement. Normally, wheel slip relays in locomotives were picked up by voltage imbalance between traction motor leads. The new Axle Alternator system used a journal-box-mounted alternator on each axle, whose output was then conditioned into a usable signal for detection of slip, and for transition control as well. This system, with theoretically more rapid detection of slip / incipient spin, coupled with the SSBV to stop it, was supposed to allow unusually high factors of adhesion. Tests with the U25B prototypes actually did show much better adhesion (over the normal 18-20%) in drag service.

With this system, there was a backup; if the slip continued for longer than three seconds, then sand would be applied, excitation reduced (through action of relay and energizing of the ORS solenoid on the governor, which moved the load regulator toward minimum field position,) and the warning light and buzzer sounded. Incidentally, this was not the original design; General Electric 751 and 752, when operating in 1960 as the experimental, prototype U25B locomotives had the slip suppression brake equipment but did NOT reduce main generator excitation upon detection of wheel slip {ref. GEJ-3807, Operating Instructions General Electric Model U25B 2500 HP Diesel-Electric Locomotive - for road no’s. 751-752, page 44.} These units only gave a light and buzzer indication of slip coupled with SSBV operation, without sanding or generator excitation reduction. This design didn’t make it to production units.

Early on, each railroad buying the U25B also bought it with the Slip Suppression equipment since it was standard. However, some roads began to complain of pinion slippage and worn wheels. In brief, the operation of the U25B in mountainous terrain did actually lead to still-unfavorable wheel slip conditions, even with Slip Suppression. In the cases where Automatic Power Matching was employed, this condition was made less severe, but as this system derated the locomotive when excessive traction motor field temperature was reached, the advantage of the high horsepower was lost. The problem continued, and worsened with the U28B, especially on the Pittsburgh & Lake Erie, where U28B units were often used in drag service. General Electric was already aware that refinement was necessary. (It also developed an optional Pinion Slip Alarm at the request of the Louisville & Nashville, although GE’s stated opinion on the subject was that properly applied traction motor pinions did not slip -- a statement condemning the maintenance performed by the railroads.)

In 1964, GE began using new control equipment in the U25B. A new Type FL7 Adhesion Loss Detection Panel replaced the original 17FM190 panel; a new Type FL10 Speed Sensing Panel replaced the original 17FM191 Automatic Transition Control Panel. It appears that the purpose of the new equipment was performance related, although details are not given; these changes are found only by comparison of a number of manuals. One alteration is the addition of circuitry in the FL7 panel that attempts to detect synchronous slip, not addressed with the earlier model, and which only operates upon a simultaneous high speed signal from all axles. This particular protective feature would be improved upon in later locomotives.

During late U25 production, GE had made available an optional All-Electric Wheel Slip System. This was basically the same as the original system without the SSBV, and included instant triggering of the slip relay. One GE representative noted, a few years later, that the actual air valve in the SSBV system was “like any other air component -- you have to maintain it properly or it isn’t going to work.” It seems clear that GE felt that the original idea was still good enough to retain, but also noted that some railroads had continued to buy the system on later units (U28, U30) and that some did not, and might have credited improper maintenance of the equipment with its operational shortcomings.

In the U30, GE kept the options of either Slip Suppression Wheel Slip Control, or else All-Electric Wheel Slip Control, but augmented both with new circuitry designed to detect and correct conditions not detected or corrected by the early U25/U28 systems. The new system could detect synchronous slip of all driving axles simultaneously at low locomotive speeds, and could detect simultaneous high-speed wheel spin of all axles as well. Two different circuits were used, one for each condition, while retaining the Axle Alternator detection system to monitor axle speeds.

With the new system, normally fitted without the SSBV, the ORS solenoid on the governor was not used in conjunction with the wheel slip detection to reduce excitation and thus power. Instead, the completely new excitation system (developed for use with alternator-rectifier transmission) employed inputs from the wheel slip circuit cards to immediately reduce excitation by action of reducing the output of the pulse-width modulator used to supply field to the exciter. This system was both more sensitive and much faster. (With the SSBV, only a slip condition longer than three seconds duration would trigger excitation reduction, sanding and operator warning; without, either in U25/U28 or the new U30 units, these latter actions were immediate.) In later U23 units with GT-581 (U23B) or GT-586 (U23C) generators, the new system was altered to, in fact, return to use of the ORS solenoid.

One of the features of the Universal Series locomotives from nearly the beginning was a system called Automatic Power Matching which reduced locomotive output under adverse operating conditions, which theoretically also had the advantage of reducing wheel slip. In the U25 and U28, this system was not triggered until an over temperature condition was detected in the traction motor shunt field windings (indirectly, by voltage drop.) This system pulsed the ORS solenoid on the governor to force the load regulator wiper arm to assume, on average, a lower field strength position; the pulses or cycles occurred at about 15 times per minute. The Power Matching Panel for the U25B was part number 17FM211C1, and our shop manual for the NYC’s U25B units instructs the setting of the resistor on this panel to correspond to a generator load of 700V / 2000A or about 1876 horsepower. The system remained operative until a timer circuit cleared, which ran seven minutes. Engine speed remained responsive to throttle setting allowing full ventilating air to the traction motors.

Statements by GE engineers at the time indicated that this Power Matching was as much to protect their warranty-covered traction motors on the U25B as it was to match the units to those with which GE units would operate. Regardless, this was the first system of its kind in the USA. This system was standard equipment on U25 and U28 units.

In the early U30 units for what appears to be several months of production, this system may have been retained. Mid-way through 1968, the locomotive manuals begin to describe the addition of a further static control panel in the electrical equipment cabinets: the 17FL24 Power Matching Panel. This panel was used to condition the reference signal for the aforementioned pulse-width modulator to effect a (constant, non-pulsed, non-timed) reduction in power at lower speeds when the locomotive was operating in series-parallel only. It appears by mention in the manuals, and in various statements by GE officials, that on the U30 the system was optional; on later U33B units it was standard, and optional on the U33C. U36B and U36C units followed the same pattern.

This card caused a limit of reference current with decreasing speed down to about 8 MPH in the U33B, below which the full normal range of current limit was available for starting. Above this speed, the reference current was limited essentially until the locomotive made transition to parallel. (Field shunting was not used on these locomotives, but transition was employed.) GE felt that no limit was necessary at speeds above that required for transition, and in fact, the temperature-triggered system on early units was also nullified at the time the locomotive made the transition from series-parallel to series-parallel shunted field (which for the U25B typically occurred at about 19 MPH with standard gears.) In the early system, if the time limit for power reduction (7 minutes) was not expired and the locomotive made forward transition to series-parallel with shunted field, and then back, the limit was still present; if the time had expired, and speed increased and then dropped, it would be necessary to have another over temperature condition to trigger the Power Matching again. In the later units, the system always operated (if fitted) in series-parallel. Both old and new systems could be adjusted, by rheostat, to finely tune the desired amount of power reduction and thus the actual minimum continuous speed.

One further feature included in the U33 (and added to the U30 after this) was the introduction of a rate of change limit on excitation. With this circuitry, there was a limit on how fast the excitation signal could increase, and was in effect at all times, and for any action (throttle manipulation, slip recovery, load regulator action.) One GE representative referred to this as “rounding off the notches,” meaning that no abrupt increase in excitation, and thus alternator output, was possible. This further improved (theoretically) the ability of the locomotives to hold the rail, especially the four-axle units.

As we can see, the systems fitted to the GE U-series evolved over time, and the changes did not necessarily exactly coincide with model changes either. At the time that the above improvements were introduced, one further addition was in the works as regards the wheel slip system, which first appears in manual GEJ-3868, an electrical equipment manual which is the first to cover models U23, U30 and U33. This addition is sometimes referred to as the Rate of Change system, and is also sometimes referred to (especially by GE engineers and representatives) as the Power Tie Circuit. These terms are proven synonymous by this manual.

Around the time that EMD introduced its new 645 line of locomotives, there had still been outside research going on not directly connected with the locomotive manufacturers. One such concept was the use of direct measuring coils, mounted on the traction motor leads, which could detect small but instantaneous changes in actual traction motor current. This system was developed and tested by outside companies and various railroads, but EMD essentially adopted it about one year after the new 645-powered locomotives were introduced, as its IDAC Wheel Slip Control System.

General Electric was still employing the same axle alternator units as primary detection as had been used since the U25. However, the challenges of maintaining adhesion with the U33B were proving daunting, and GE added a similar system in concept sometime around the middle of 1968 in its ROC or Power Tie system. This required the addition of yet another static panel, the FM262 ROC panel, and ROC slip sensing transformers. The power tie was connected between the midpoints of pairs of motors when in series-parallel; because of this location, with all axles rotating at the same speed, there should be either a tiny amount of current flowing through this cable, or else (usually) none. If one axle begins to slip, the amount of current drawn by the sets of motors will change relative to each other, and this would then cause current to flow in this power tie. The detection of slip by this indirect method was more sensitive than the axle-alternator detection. The normal wheel-slip system as previously described was still retained, but special circuitry was included to reduce the effect of the relay normally operated by the old wheel slip system when the ROC system relay was picked up. The new system also included the design consideration that rapid and frequent small slips would cause a proportional slight lowering of excitation (and an even more tapered power recovery) which would allow the unit to maintain the highest possible power in the given rail condition. In parallel transition, the ROC system was completely cut out.

This new system did not in any way require the use of axle alternators. Within several years, GE had developed it to the point that the old axle alternator system was deleted, along with its supporting circuitry, and all wheel slip detection performed by coils; this was the Current Measuring Reactor system, or CMR system, and while this system is normally associated with the later “Dash 7” units, one will note that a number of orders of late Universal Series locomotives completely lack axle alternators (except one for speed indicator/recorder drive.) This indicates application of this CMR system. Reportedly, this system could react in one thirtieth of one second.

This concludes our investigation of wheel slip control as applied to the General Electric Universal Series. GE entered the market with the advantage of high horsepower per axle, and in a sense bet its fortune on the concept of high haulage capacity combined with high power and nominally similar weight. The one Achilles heel of this concept was the ability of design engineers to cope rapidly enough with adhesion difficulties as the horsepower race accelerated between the builders, and we have seen that GE was more than mildly active concerning modifications to the U-series over time to address this problem. While many have faulted GE for locomotive quality issues in this early period, it is clear that GE was making every effort to correct the problems and still move ahead in power, allowing it to retain a competitive position -- which in the end helped to drive ALCO out of the business.

Source material for this document includes not only a number of GE locomotive maintenance manuals, but a series of lectures delivered to conventions of the Railway Fuel & Operating Officers' Association by GE engineers over a span of years covering models U25 through U33.