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Conrail Technical Society - Conrail Cadillacs, The SD80MAC

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Conrail Technical Society

Conrail Cadillacs

SD80 #4117


...the purchase is compared to the transition from steam to diesel...

by Kevin Burkholder

(Note: You will need a table aware browser to see the tabled information.)

Conrail is taking major strides in becoming the industry leader through the purchase of 28 SD80MAC's, numbered 4100- 4127. To some in the railroad industry, the purchase is compared to the transition from steam to diesel powered locomotives. The new units will not only provide Conrail with the highest available freight horsepower in North America, but will also introduce a new look for Big Blue. The most remarkable spotting feature of the new units will be the "White Smile" paint scheme. The idea behind the new scheme was not to liven the old blue scheme, but to serve a purpose! The "White Smile" was designed to make recognition of the new AC fleet quite easy for shop and maintenance personnel. The 'AC~Radial' logo below the cab number probably doesn't hurt either. The SD80MAC utilizes some of the most advanced technological breakthroughs in the railroad industry to put Conrail in a better position to make a run at the 21st Century. The 5000 horsepower 2 stroke 20 cylinder engine is the largest prime mover available in the railroad industry. Coupled with an airconditioned Whisper Cab , Integrated Cab Electronics, desk top controls, and the HTCR radial trucks, these units are the Cadillacs of the fleet.


The most important advance of the SD80 is the AC traction motors. AC or alternating current motors have been around for many years, but were never able to match the starting torque of the DC or direct current traction motors. DC motors not only provided high starting torque, but brought many limitations. DC traction motors are equipped with commutators and carbon brushes which are subjected to very high current loads or Amps. A DC motor that would have high current loads while not in motion or while moving slowly, would receive major damage or burn-out if a high current would be applied for too long a period of time. At low speeds, the high amperage damage would occur within minutes. AC traction is favorable in that the motors are not equipped with the commutators and brushes, eliminating the limitations of the low speed-high throttle position. The SD80MAC utilizes alternating current (AC) power that is derived from direct current (DC) power and the engine. The diesel engine drives the alternator and creates direct current power. The DC output or DC Link travels to inverters on the unit which convert the power back to AC, which is utilized to power the traction motors. The DC and AC sides of the circuit are decoupled by the inverter, meaning that both DC and AC components receive power supplied from opposite sides of the inverter. AC motors allow the SD80MAC's to have more pulling power, eliminates stall burns in the traction motors, and have very low maintenance requirements. DC traction motors require high current levels or amps, to produce high power. Heavy conductors and traction motor leads must be used to carry this high current and the high current levels produce a great deal of heat, further limiting the DC traction motor. The SD80MAC's traction motor relies on voltage and frequency to produce power more than current. This feature also eliminates the ammeter from the cab, replaced by a Tractive Effort Display. The AC motor will not allow dramatic wheel slip. The motor speed is controlled by the design of the motor and the frequency of the input voltage. Since the frequency is closely controlled by onboard computer systems, motors cannot run away as they would on a DC locomotive. All of the rest of Conrail's locomotives utilize DC power derived by the diesel engine, to power DC traction motors. The AC traction system, coupled with a very aggressive computer controlled wheel creep system, allow the 80MAC to achieve much higher adhesion levels than any other Conrail locomotive. The SD80MAC is now capable of 45% adhesion, versus the 27% achieved by the SD60 series. The SD80MAC is then capable of providing 185,000 pounds of starting tractive effort and because of the AC traction system design, longer periods of high throttle. Initial loading on the MAC's is slower than that of the DC counterparts, and locomotive roll back is possible. With DC units, the normal starting procedure would be to release the independent brake, then throttle up to move. The 80MAC's require the throttle to be advanced before releasing the independent brake. Starts on heavy grades require the throttle to be turned up and additional 1 or 2 notches from the DC counterparts. Sound and feel of the SD80MAC is very different from DC units. The aggressiveness of the wheel creep system may feel like the locomotive is experiencing run away wheel slip. Under normal DC conditions, the throttle would be increased, however on the MAC's, the throttle remains untouched unless a special 'wheel slip' light illuminates to the engineer. This will allow the unit to provide a very high adhesion and tractive effort at very low speeds.



Conrail was the industry leader with the first production SD60I unit in 1994, numbered 5544 and delivered as the last unit in the 5500-5544 order. The unit, as well as the SD80MAC's utilize the Whisper Cab to enhance crew safety and comfort. The SD60M and GE C40-8W classes made the first strides toward crew safety and comfort with more comfortable seating, desktop controls and reduced noise. Even with the regular wide cab units, the engine and the cab are mounted on the locomotive underframe, causing continued vibrations and moderate noise in the cab. Through the cooperative effort of EMD and Conrail, the Whisper Cab was born. The design of regular wide cabs, has the cab bolted to the underframe. With the Whisper Cab , the entire passenger compartment and about one foot of the hood ride on rubber pads or isolators. The rubber pads are mounted on shock absorbers, which allow the cab some freedom from the underframe and highly reduce both rough ride and noise in the isolated or "I" cabs. Rubber insulated slip joints are utilized at the front and rear of the cab to allow the movement on the shock absorbers. The cab noise speaks for itself as the 80MAC under load in throttle position 8 will provide the same noise and vibration level as a non-isolated cab at idle speed!


Demand in locomotive and train control devices have increased in the cab of the locomotives, necessitating the need to integrate systems. EMD and Rockwell teamed up to produce the Integrated Cab Electronics or ICE. ICE is a computer system that consolidates the functions of the speedometer, crew alerter system, end-of-train telemetry, and a multitude of other systems. Many of the SD60M's, and SD60I's already are equipped with ICE. The current ICE equipped units are sport Conrail Specific screens, meaning that the displays were designed to accommodate Conrail specifically. The SD80MAC uses the standard or universal MR screen format. This differs from the Conrail screen, providing a less cluttered appearance. The AAR screen differs from the Conrail screen in the following:

The ICE system also incorporates Distributed Power, similar to the Locotrol system, allowing SD80MAC's to be placed in unmanned mid- train or rear-end helper service. The distributed power would allow the units to be placed within a train and controlled remotely via radio transmission from the lead unit. The operation and performance of all units on-line would be displayed on the ICE screen of the lead unit. The electronic air brake equipment or EPIC is also now integrated into the ICE system.

Major Dimension Comparisons

Locomotives-> SD80MAC SD60/M&I SD50
Length over coupler pulling faces 80'2" 71'2" 71'2"
Width over hand rail supportsfaces 10'3 1/8" 10'3 1/8" 10'3 1/8"
Heigth, rail to top of cooling fan guards 16'1" 15'1 1/8" 15'1 1/8"
Curve Negotiation (F-Type Coupler)
Single Unit 27.4 Degree 29 Degree 29 Degree
Two Identical Units 21.2 Degree 24 Degree 24 Degree
Unit coupled to a 50' Box Car 15 Degree" 16 Degree 16 Degree
GearRatio 83:16 70:17 70:17
Fuel 5800 Gallons 4400 Gallons 4400 Gallons
Lube Oil 510 Gallons 436 Gallons 395 Gallons
Cooling Water 342 Gallons 276 Gallons 276 Gallons
Sand 40 Cubic Feet 56 Cubic Feet 56 Cubic Feet
Air Compressor Water Cooled
4 Cylinder
Motor Driven
Water Cooled
3 Cylinder
Shaft Driven
Water Cooled
3 Cylinder
Shaft Driven
Pulling Power
Horsepower 5000 3800 3500
Kilowatt Output 3500 2862 2611
Tractive Effort
185,000 lbs 100,000 lbs
Tractive Effort
147,000 lbs


Some will remember Conrail's test stint with the SD70M's and the EMD radial trucks on the Ellsworth Branch. The tests and data from the MR Test Center must have impressed Conrail enough to order all of the 80MAC's with the 6 axle radial trucks. The former HTC trucks on other 6 axle EMD units are rigid and cannot conform to rail curves. The flanges of the HTC bite into the gauge face of the rail, and wear metal from both the rail and wheel surfaces. The HTCR truck reduces the angle of attack, and literally steers through curves, keeping wheels parallel to the curvature of the rails. Tests by the Association of American Railroads show that curve performance of the HTCR truck is far superior to even two-axle trucks. Locomotive related rail wear in curves may be reduced by up to 66% with the HTCR vs. HTC truck. Conrail has also ordered the largest wheels available, in 45 inches! Former wheel sets were 40 inches, including the radial truck equipped Burlington Northern SD70MAC's. The larger wheels and the overall truck design improves weight distribution to the axles and allow better steering in curves, thus maximizing adhesion. Additionally, a flange lubricant system is housed within the trucks and is designed to reduce curve resistance, wheel flange wear, and rail wear. This series of truck, combined with the AC traction motors will create at least a 35% adhesion, a 10% jump from the DC HTC truck units. Cost savings will also become evident, as the current HTC trucks require overhaul at 500,000 miles, but the HTCR is designed to go 1 million miles between overhaul. The new HTCR trucks should:


Don't look for an external brake wheel anywhere on the Conrail SD80MAC's. The industry standard to date has been to place a brake wheel either on the firemen side short hood (non-wide cab units) or on the engineer side rear of the long hood. The SD80MAC is the introduction of EMD's new electrically applied/released parking brake. The device replaces the traditional hand brake mechanism in its entirety. The new device is activated from the cab's Engine Control Panel. A push-button activates a motor that drives a screw jack brake rigging on the conductor's side of the locomotive for the second and third axle. A meter on the panel indicates whether the brake is applied, released, or inactive. A back-up exists in the case of electronic failure, and requires hand cranking the screw jack from the conductor's side of the unit.


The Harmon Ultra Cab II is similar to the Ultra Cab 1, in that it is a highly advanced microprocessor based Cab Signal and Train Control system. That is about where the similarities between UC I and UC II end. Under the ICE system, the LSL and Cab Signal test are integrated into one display. The Ultra Cab performs a combined LSL and Cab Signal self- test if the unit is in the "Non-Cab or Cab modes". A Cab Signal self-test will be initiated if me UC is in the "CS only mode". Harmon has integrated an internal speed generator into the UC II system, making testing for overspeed and overspeed penalty possible. This will speed shop testing this system, as no external speed source is necessary to verify the operation of the Ultra Cab. The new system is a modular system designed for high reliability and quick replacement, as well as the possibility for upgrade requirements. The system would allow the addition of multi-territory capabilities and advanced train control (ATC).


The electronic fuel injection or EFI is what makes these 20 cylinder monsters feasible for service into the 21st Century. The throttle commands are sent via the ICE to the EM2000 (the EMD computer system that controls the entire unit), where the signal is read and then sent to the interface board in the AC electronic cabinet. The electronic control module or ECM gets involved here and inputs the request from throttle to the engine sensors. The engine sensors measure multiple functions, such as fuel temperature, air pressure, and other features detrimental to providing the best fuel efficiency. The ECM takes those readings and energizes the EFI at the most appropriate time to receive the most efficient and cleanest burn possible. The mechanical energy needed to atomize the fuel is still generated by the cam shaft, however the timing and duration of the fuel injection are now electronically controlled.


Conrail's SD80MAC's are the most powerful engines currently in revenue freight service in North America. The 80MAC's utilize a prime mover size that will be a "blast from the past" for some, 20 cylinders! Many will remember that the SD45 and SD45-2 series utilized a 20 cylinder power plant to generate 3600 horsepower. The SD45 and 45-2 had one disadvantage with the 20 cylinders which was their fuel efficiency. For that very reason, the SD45 fell into disfavor on Conrail and all were retired or sold and removed from the roster by 1989. The SD45-2 fleet remains in service on Conrail, but shy of the 3600 horsepower that was once generated by 20 cylinders. The SD45-2's have been receiving upgrades through the Juniata back shop, dropping the 20 cylinder power plant, replaced with 16 cylinders that are capable of generating 3000 horsepower. The SD45-2 was well liked by Conrail, as the Erie Lackawanna had ordered the units with 5000 gallon fuel tanks, making the units ideal for helper service over the Allegheny Mountains. The SD80MAC's utilize 20 cylinders, however are equipped with earlier mentioned electronic fuel injection (EFI) making them ideal for all types of service. The SD80MAC has a newly designed power plant, the 20- 710-G3B-ES. A break-down on the prime mover type: '20' is for the number of cylinders; '710' is the displacement of each cylinder measured in cubic inches; 'G' is the design of the crankcase; '3' is the designation for a turbocharged locomotive application; 'B' denotes improved fuel economy; 'E' for EFI; 'S' for split cooling. The new EMD 20 cylinder also utilizes a larger turbocharger, as the engine's oxygen requirements are higher than previous models. For comparison sake, Conrail's other 3rd generation EMD's, the SD50, SD60, SD60M, and SD60I, all use EMD's 16 cylinder prime movers. The SD50 uses a 16-645-F3B, which produces 3500 horsepower. The SD60 series utilize a 16-710-G3 series, which generate 3800 horsepower.


Similar to recent General Electric locomotives, the SD80MAC uses a split cooling system with the engine coolant moved by two separate pumps. This differs from previous EMD's in that the coolant pumps are different sizes from each other. The two cooling circuits are normally independent of each other and supply cooling for (1) the power assembly and lube oil cooling; and (2) the air compressor and tubocharger intercoolers. These independent circuits usually use their own segment of the main radiators. Engine cooling takes precedence over combustion air cooling on the SD80MAC. The linking valve connects the two systems in the event of an imminent engine overheat condition. Due to the increased size of the radiators, the radiator hatch was designed in a "V-shape". The increased radiator size and split cooling give the SD80MAC the GE like flared radiator sections near the end of the long hood. The temperature control is regulated by the EM2000 computer, by governing air flow through the radiators with the use of shutters and fans. The temperature sensor communicates with the EM2000 and maintains engine coolant temperature at 160 to 170 degrees Fahrenheit in Throttle position 1 and idle and 175 to 185 degrees Fahrenheit in Throttle position 2 through 8. Engine performance is increased due to the new air system. The temperature of the incoming combustion air has a big effect on engine performance. On the SD80MAC the inlet air temperature is reduced, increasing engine performance through combustion or the charge air cooling system and four pass aftercoolers that recycle the water through the cooler before it's discharged to provide higher cooling capacity.


Not that important in the EMD guide but a noise reduction feature was the relocation of the dynamic brakes to the rear of the unit. The 52" dynamic brake fan resides behind the split cooling radiators (flared section) and the trio of 48" cooling fans. The nose features the engineer side entry door, similar to the SD60I's but opposite the SD60M's. Above the cab mounted headlights and number boards are also Conrail specified options. The FRA mandated ditch lights are applied below the front anti- climber and on the front only. Horns are standard Leslie RSL-3L-R, placed just ahead of the flared radiators, centered on the long hood. The rear sand box is placed exteriorly on the rear-end porch. The cab roof is cluttered with 4 antennae, one large Sinclair antenna, and three small Sinclair antennae that provide radio communication, telemetry transmission and reception, as well as the distributed power transmission/reception.


Conrail generated an actual test plan, assigning multiple pairs of units to various aspects of service to find out which the units are best suited. The assignment summary is as follows; the Intermodal network receives 6 units, for service on TV9/TV14, TV1/Mail 8M, and TV3/Mail 44; the CORE Network receives 7 pairs for ELSE/SEEL, ELPI B/PIEL, ELIN/INEL, INSE/SEIN, COPI/PICO, PICC/CCPI, and PICA/CAPI; the Unit Train Operations receive 4 pairs, to be operated on UWZ, UNS, ULK A, and ULK C pools. These assignments are obviously variable and the units could, have, and will stray from these assignments at the request of Philadelphia.

Conrail has sent the 4100 and 4101 to Conway for the training of road foremen and other important Conrail employees. The 4102 and 4104 kicked off service, breaking-in on PIAT/ATPI for three round trips. Upon completion of the mandated break-in, 4102 and 4104 were placed in unit train/mineral service, hauling coal loads from West Brownsville to Enola. The second trip even saw the pair operating all the way through to the York Haven PP&L power plant. Initial plans called for the West Brownsville-Enola pair to operate on ULK-A & C unit trains, however the pair had settled in on hauling coal for PP&L on the UFM/UFY series. On the fourth trip over the Alleghenies, 4102 and 4104 were given the honors of powering UFY-950, and 12,600 tons without the use of helpers. This was to be a test not looked highly upon by those involved. On the West Slope, approaching Lilly, PA, the pair gave it their best shot but were outdone by the 1 +% grade. HLP-21G was summoned from Altoona, and with a pair of SD40-2's, helped the UFY over the hill. Upon arrival at Enola that evening, both units were shopped and then placed in school and instruction service at Enola, PA. 4100 and 4101 were operated to Conway for training on a light engine move. Their first 'real' assignment was to haul PIAT-7 from Conway to Altoona on February 17. A quick return to Conway on ATPI-7, turned the power for PIMO-8 out of Conway, another train not shown on the initial test plan. After the 4100 and 4101 arrived Morrisville, PA in the wee hours of February 19, they were operated on a light engine move, ENS-101-19 to Oak Island. At Oak Island, the units were looked over by personnel and foremen, before being broken up and placed in TV-11/12 service (ed. -another pair of trains not listed in the test distribution plan). To date, the 4100 and 4101 have been handling the TV-1 1 and TV-12 trains as single units, occasionally passing in the night. 4105 and 4108 were released on Friday February 16 and operated in test helper service out of Cresson, PA. The pair began their ATPI/PIAT break-in runs on the ATPI-8X on Sunday February 18. The pair had continued in break-in service, with a glitch causing both units to be returned to Altoona for further work. After being released again from Altoona, both units returned to ATPI/PIAT service until March 1, when the worked east to Harrisburg on train PIBA-1X. The power was quickly turned and shipped further east on train HBAL-1B. After arriving at Allentown, the set made another quick turn, for train ALSE-3X. This move was to get the 4105 and 4108 to Selkirk for training and instruction. The 4106 was also released, and almost immediately placed into TV-11/TV-12 service, as the 4100 and 4101 began experiencing fuel injector problems. 4100 was pulled from service briefly, at Elkhart, where the injector problems were remedied. 4107 and 4103 also have been released and have been performing their obligatory PIAT/ATPI break-in runs. 4109,4110,4111, and 4112 have all been delivered to Altoona in their undecorated states, where Juniata will apply the "White Smiley" paint. 4103 and 4107 had been in test helper service between Altoona and Cresson, and were expected to be returned to the PIAT/ATPI service shortly. By late-March, the remainder of the units on-hand at Altoona should be in service. The remainder of this batch of 28 units should also be delivered before Spring.

Proposed Test Distribution Plan

Trains Assigned

Between (Cities)

TV14 / TV9 Chicago, IL Boston, MA
Mail 8M / TV1 Chicago, IL Morrisville, PA
Mail 44 / TV3 E. St. Louis, IL Kearny, NJ
UWZ Fola, WV Ashtabula, OH
UNS West Bronsville Somerset, NY
ULK-A / ULK-C West Brownsville Baltimore, MD
ELSE / SEEL Elkhart, IN Selkirk, NY
ELPI-B / PIEL Elkhart, IN Pittsburgh, PA
ELIN / INEL Elkhart, IN Indianpolis, IN
INSE / SEIN Indianpolis, IN Selkirk, NY
COPI / PICO Columbus, OH Pittsburgh, PA
PICA / CAPI Pittsburgh, PA Camden, NJ
PICC / CCPI Pittsburgh, PA Oak Island, NJ


Conrail is looking ahead and trying to increase utilization with the purchase of the SD80MAC's. These 28 units could be the precursor of something much larger, but will be analyzed in many aspects to see if large quantity purchases are feasible. Conrail hopes that fuel efficiency will be increased, and the horsepower per tonnage ratio can be decreased. Time Out of Service (TOS) and Time Available (TA) or not utilized percentages will be recorded and acted upon. The 80MAC was designed on a 122-day maintenance cycle, meeting Conrail's goal to provide a low-cost, high quality locomotive. The SD80MAC will allow Conrail to begin fleet size reductions, and eventually reduce or eliminate the need of helper sets for the fight over the Allegheny Mountains. Conrail has ordered a total of 108 SD80MAC's, but with the introduction of the SD90MAC, could be changed. Union Pacific has already taken the next stride in the horsepower race, with purchase of upgradable SD90MAC's. The SD9OMAC's being delivered to UP are rated at 4300 horsepower but eventually will have the engine replaced with a 6000 horsepower prime mover. Will Conrail go with the SD9OMAC in the future? Will Conrail scrap the whole AC program? Only time and testing will tell, but remember, Conrail was also a "Guinea Pig" for the Dash-8 line in 1984 with the acquisition of 10 C32-8's...Conrail's Dash-8 fleet now numbers over 350 units!

SD80MAC Update January 3, 1997

edited by J. Alex Lang

As more and more of the Big Macs arrived, Conrail strayed from their original plan. Certain trains, such as TV-11/12 and PICC were powered by SD80's quite often, while others like PICA were not. As the summer of 1996 began, most of the 4100's found their way to assignments on the Boston Line, replacing the venerable Dash 7's. A handful of SD80's remained on the Pittsburgh and Philadelphia divisions to handle coal and ore trains. On September 15, 1996, train ZWW-848 departed Philadelphia-Greenwich with three Locotrol-equipped C40-8W's on the point, and three more mid-train. This monsterous loaded ore train had 160 cars! This was the first of several Greenwich ore trains to have mid-train helpers, at least two of which were powered by four SD80MAC's pulling 200 cars! Throughout the summer, the 80MAC's could have been found in the Conway-Elkhart-Avon-Conway triangle, running on trains like PIEL and INPI. The MAC's have since found their way back to the central part of the system, and usually run on priority general freights or heavy coal drags.

Conrail seems to be happy with its new "Cadillacs", as it purchased EMD demonstrators 8000 and 8001 as Conrail 4128-4129 in the third quarter of 1996. Conrail has also placed a 1997 order for 30 more SD80MAC's (numbered 4130-4159).

Photos ©1997, Jeffrey A. Lubchansky