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y ,:"'1. AN AMTRAK TRAIN PULLED by a high-speed electric locomotive of Swedish design at Stamford, Connecticut, USA. Note the complex triangular structure of the high voltage catenary wire, necessary to hold it very rigid for high speed operation. The simpler catenaries are for lower speed freight trains. < THE EVOLUTION OF ELECTRIC RAILWAYS Amtrak is the American government-sponsored rail passenger system which provides service between many large cities. It does not own lots of track but it runs America's largest fleet of passenger rolling stock. By BRYAN MAHER With the advent of the jet airliner and the creation of America's large expressway network after World War II, US rail passenger services fell into rapid decline. Many small and large railroad companies went bankrupt and ceased operations or were absorbed by larger companies. This eventually culminated in severe financial difficulties for two of the biggest railroad companies, the Pennsylvania Railroad and the New York Central. Ultimately, the US Government recognised that unless they took immediate action there would soon be no viable passenger services in the whole country. Furthermore, national security was a consideration, in the event of any further large scale wartime emergency. So it seemed essential to actively maintain passenger services, even though such an enterprise would be hard put to avoid massive financial losses in plant and running expenses. Therefore, in 1970 the US Con- PT.18: THE STORY OF AMfRAK PASSENGER SERVICES 82 SILICON CHIP ALTHOUGH IT ONLY HAS FOUR AXLES, this Amtrak loco delivers 5700 horsepower to the rails. Of Swedish design, it is designed to run at speeds up to 200km/h but is much smaller than typical American locomotives. Note the bank of resistors on top of the roof for dynamic braking. gress passed an Act creating the National Rail Passenger Corporation, to be called "Amtrak". This Act relieved US railroad companies of the obligation to run their moneylosing passenger services and in return Amtrak acquired all passenger rolling stock and equipment. Most railroads accepted the Government's offer although a few declined. The service would have to provide fast and efficient trains, with little of the opulence that was expected in the heyday of steam. From those unsteady beginnings in the early 1970s, Amtrak's services have greatly increased so that the future of passenger services in America now seems much more certain. High speeds Amtrak's express and passenger trains in America today clock up some fast speeds though they still have yet to match the high speed running of the Chicago to Los Angeles Sante Fe "Chief" crack express, or the "Hiawatha" on the Milwaukee Railroad in the 1930s. Whereas the "Hiawatha" did the 680km run between Chicago and Minneapolis in 6 hours 30 minutes, Amtrak's time is now 8 hours 45 minutes. Amtrak achieves its best speeds on the North East Corridor, that heavily used right-of-way between Washington, New York and Boston. This busy track section was purchased by Amtrak from Conrail (which had previously absorbed the Pennsy Railroad) in 1975. Amtrak now rent back to Conrail the right to run its trains on the North East Corridor for $53 million per annum. Much of the North East Corridor is electrified by llkV 25Hz single phase AC. This electrification is a legacy of past days when the now failed Pennsy Railroad ran the GGl high speed 12-motor electric locomotives. Initially Amtrak owned no locomotives, so it leased locos from the private railroad companies to haul their second-hand carriages. Gradually this carriage situation was improved by either completely refurbishing rolling stock or by the purchase of brand new "Amfleet" cars as shown in our photographs. The locomotive situation was harder to solve. The cost of leasing locomotives is high but the cost of wholesale purchase of new locos for Amtrak was astronomical. However, the brave decision to authorise such expenditure was taken and by 1980 370 brand new locomotives were hauling Amtrak trains. As well as new locomotives for the electrified section of the North East Corridor, advanced diesel electric locomotives were purchased for Amtrak trains in other areas in the country, served by 20 long distance "name" trains. The South West Limited, replacing the Super APRIL 1989 83 AMTRAK'S DOUBLE-DECK SUPERLINER coaches set a new standard for luxurious rail travel. Of all stainless steel construction, the coaches are 25.9 metres long, 4.9 metres high, 3.1 metres wide and weigh 71.2 tonnes. ' controlled with six traction motors. An on-board 1 lkVAC transformer stepped the voltage down for the thyristor controller and traction motors. These AEM6 class locomotives, numbered in the 950 series, were long and impressive in appearance but were disappointing in service. Their American designed suspension systems were unsatisfactory at the high speeds sought, prompting Amtrak to look overseas for alternatives. The success of the Swedish railway· (SJ) in running high speed Rc4-class Ho-Bo electric locomotives on their 15kV 16.6Hz single phase AC lines inspired Amtrak to lease one for trial. Thev also tried one CC21000-class French electric locomotive. The French locomotive proved to have unsuitable suspension for American conditions but the Swedish Rc4 showed the Americans how it should be done. Accordingly a deal was made with the Swedish company Allmanna Svenska Aktiebogalat (ASEA) whereby 67 electric locomotives were built in America to the Swedish ASEA design. General Motors Electro Motive Division (EMD) secured the contract and they sublet the assembly of the locomotives to the Budd company. ASEA supplied most of the electrical equipment, traction motors and thyristor controls. The AEM-7 class AMTRAK'S SUPERLINER LOUNGE/CAFE car has windows which run right up into the roof for dramatic views when passing through the Rockies. Chier of past days, does one of the longest runs, from Chicago to Los Angeles. vices exclusively, freight being relegated to adjacent parallel tracks. Shared tracks The AEM6 class This practice of one railroad running locomotives and rolling stock over another railroad's tracks is well known in the USA (and is also practised to some extent in Australia). By this means,· Amtrak operates over 41,600 kilometres of track. In addition, on the North East Corridor, Amtrak has some tracks dedicated to fast passenger ser- To fully utilise the available high speed tracks on the electrified section, Amtrak pur,chased a consignment of 176-tonne 3.BMW electric locos during 1974. These were designated as class AEM6 and rated at 137km/hour. The new locos were wired for the 1lkV AC 25Hz single phase overhead conductor and were thyristor 84 SILICON CHIP These American built locomotives were named the AEM-7 class and were numbered from 901 upwards. The AEM-7 locos are an exceptional design. Though they weigh only 91.3 tonnes, their four traction motors develop a total of 4.25MW (5700 hp). Amtrak employees have given them the nickname ''Mighty Mouse" because they are so powerful. The springing and bogie suspension design performs admirably at high speed on the electric sections of the dedicated high speed passenger tracks on the North East Corridor. Triple coil compression springs provide the primary suspension, maintaining excellent balance of wheel power and f ffl , I ~ HAIL, RAIN, SLEET AND SNOW: Amtrak trains have to cope with very cold weather as this winter shot shows. Note how the snow is pulled up into the turbulence of the train's slipstream. loading weight, and preventing load transfer from axle to axle when running over track irregularities at high speeds. If not prevented such weight-transfer could be a cause of driving wheel slip with consequent loss of driving power. Electrically the AEM-7 is quite sophisticated, running on the existing overhead conductor supply of 1 lkV AC at 25Hz. 25 or 60Hz? However, looking to the planned extension of electrification into the future, should the low-frequency system be perpetuated or should future locos run directly from a higher voltage 60Hz supply? Originally, in the 1930s, rotary converters were used to generate the 1 lkV 25Hz supply from 60Hz mains or 25Hz AC was produced directly by lower speed steam-turbine alternators. Modern trackside substations simply use transformers and banks of thyristors to convert from the 3-phase 60Hz national power grid supply to 25Hz single phase output. Either a complex version of the thyristor cycloconverter configuration is used or silicon rectifiers convert the 3-phase incoming supply to DC which then drives pulsed thyristor bridges to generate the single phase 25Hz AC output for the overhead contact wire. The second method is less efficient than the first and care must be taken with the design of either method to minimise harmonic content in the 25Hz output and also the feedback of harmonics into the national grid system. Such harmonic currents can cause havoc to radio and telephone communications, and to railway signalling systems. With these questions in mind, Amtrak have had the AEM-7 dieselelectric locomotive designed so that its on-board transformer will accept either 1 lkV AC at 25Hz, 12.5kVAC 25Hz, 12.5kVAC 60Hz or 25kV AC 60Hz. The thyristor bridges and controlling pulse generators are also designed to accept either frequency. In this way, the AEM-7 locomotive could run on the 25kV 60Hz AC single phase overhead contact wire systems that are expected to one day radiate over the whole of the USA. When the world's oil supplies do finally give up the ghost, or oil prices itself out of the fuel market, railway electrification driven by hydroelectric and coal burning 60Hz power stations must surely prevail in the USA and elsewhere. Traction motors At high speeds and/or on any track irregularities, a problem in all electrically driven or diesel electric vehicles is the torque-shock transferred from the running wheel gear to the motor armature. Such rotary shock loading on the motor pinion causes excessive wear on the gear teeth, as the motor pinion is directly coupled to the heavy armature. These transmitted shocks also shorten the life of the armature winding slot insulation. Over the years, various locomotive designers have considered this problem and one effective method was used by the famous APRIL 1989 85 AN AMTRAK "SHORTIE" PULLED BY a diesel electric loco skirts the Windsor Locks in Connecticut. Raymond Loewy and others on the Pennsylvania Railroad with the GG-1 back in 1934: hollow shafts. Accordingly, the AEM-7's traction motor armatures have hollow shafts. Within this hollow shaft lies a second shaft on which is mounted the driving gear pinion. The inner shaft is fixed to the outer shaft (which carries the armature) only at the other end (ie, the commutator end), thus allowing torsion twisting spring action to occur while effectively isolating the armature itself from rotary shock loading. Motor control The four traction motors of the AEM-7 are each rated at 1.063MW. This power rating of greater than lMW (1340 horsepower) per axle is very high. Indeed, it does not seem long since the world marvelled at the Swiss Federal Railways when they introduced a locomotive which boasted 1000 horsepower per axle! The reason why so much power can be delivered reliably to the four axles is the complex thyristor control system. The AC supply from the on-board transformer is rectified and varied as required by phase 86 SILICON CHIP controlled thyristor bridges to provide DC to the traction motors. Additional thyristor bridges and associated gating pulse generators separately control the power to armature and field coils. In this way the motors can be made to exhibit variable characteristics, from a series characteristic producing exceptionally high starting torque (hence high tractive effort) at starting, to the weak field condition more like a shunt DC motor, for high speed running. Dynamic braking is by the conventional method whereby the traction motors are connected as generators, with their field current still supplied from the thyristor control system. The high currents generated under braking are dissipated in large fan-cooled resistor banks. Automatically blended loco air brakes and train air brakes take over at very low speeds. Full air brakes are always available for emergency stops. High speed contact wire For high speed electric running, the overhead conductor and supportive catenary suspension wiring must be well designed and installed, and properly tensioned. Ideally, the overhead contact wire should always be at a constant height above the track but as this is not attainable, the variation (ie, sag) in height between supports should be minimised. This is to enable the pantograph mounted atop the locomotive to maintain contact with the overhead wire at all speeds. For very high speeds (up to 193 km/h), the next design step is to install a lightweight pantograph assembly so that its upward spring system can quickly respond to changes in contact wire height. A lightweight pantograph design is allowed because the contact wire current is relatively small (385 amps maximum) compared with over 3000 amps which would be demanded by any 1500V DC locomotive. The Amtrak AEM-7 locomotive is equipped with two pantographs, though it is usual to run with only one raised. One of the photos in this article shows an Amtrak AEM-7 locomotive running through Stamford, Connecticut. You will notice that causes travel sickness in passengers. Modern methods of laser controlled survey and alignment produce excellent smooth track. Signalling systems also must be upgraded for such fast running. Today's Amtrak system gives drivers three kilometres or more warning of any stop signal ahead. Amfleet THREE OF AMTRAK'S FP40H DIESEL electric locos await their next task. Amtrak purchased 370 of these locos to pull its passenger trains all over the non-electrified routes of America. As with most American locos, it is fitted with an integral plough to enable it to cope with snow on the tracks. AMTRAK'S SINGLE DECK CARS are used on shorter routes where sleeping accommodation is not necessary. the overhead catenary suspension system is complex, consisting of four longitudinal cables, including the lower contact wire. As well as providing additional current carrying capacity (and less line voltage drop), the overhead construction aims to minimise vertical and sideways bounce of the contact wire as a train runs beneath it. The problem of bounce is put into perspective when you consider that, at 200km/h, a train runs at 56 metres per second or one metre every 18 milliseconds. So any sag in the overhead contact wire is lifted by the pantograph in about 25 milliseconds, an action which may give rise to excessive bounce unless closely controlled. Naturally for such high speeds the track alignment must be exceptionally good, both vertically and hoizontally. Excessive sideways misalignment, as well as giving passengers rough riding conditions, causes rail and flange wear. Too much vertical misalignment also Amtrak is progressively introducing new express passenger cars to provide their patrons with increased comfort and enjoyable riding on long distance trains. Running over great distances, trains on such runs as Chicago-Los Angeles provide luxury service with their "superliners". Built by Pullman Standard at their Hammond plant in Indiana, the day coaches are of stainless steel, double deck, 26 metres long, 3.13m wide and 4.92m high. These large and impressive eight wheel vehicles weigh 71.2 tonnes empty. The lounge-cafe car shown in one of the photos has similar dimensions. It allows passengers to eat on the lower or upper deck, or to enjoy the magnificent scenery when passing through the Rocky Mountains. The longitudinal lounge seats on the upper deck combine with broad side and roof windows to give an unimpeded view. Amtrak also provides a double deck restaurant car with 72 seat saloon and waiter service on the upper deck. The air-conditioned all electric kitchen is on the lower deck. Sleeping accommodation is available in three classes of berth: an economy unit, a family bedroom suite and a deluxe bedroom suite with swivel chair, two beds, private toilet and washroom facilities. Diesel electric Diesel electric locomotives are used outside the North East Corridor electrified regions . The backbone of the fleet is the General Motors EMD F40PH, as shown in our photos. This locomotive is 17.28 metres long, 4.75 metres high and 3.29 metres wide. It weighs 118 tonnes and carries 7600 litres of diesel fuel and 3.24 tonnes of cooling APRIL 1989 87 AN AMFLEET-EQUIPPED TRAIN, pulled by an AEM-7 locomotive, leaves Washington DC for its high-speed dash to New York City. The AEM-7 locomotives, based on an ASEA design, were built by the Electro-Motive division of General Motors at LaGrange, Illinois. water, lubricating oil and sand .. As well as pulling the train. these 2.24MW (3000 hp) Bo-Bo locomotives are required to provide as much as 800kW of electrical power loading for train heating, air conditioning, lighting and the kitchens. Suen enormous electrical train loading is unknown in Australia as our trains do not have to climb through snow drifts and ice in mountainous regions. These locos are capable of negotiating curves as sharp as 43-metre radius for 42° turning [engine alone) or 97-metre radius for 18° turning when hauling trains. Multiple units The F40PH locos may be operated multiple-unit by hooking up eight electrical control cables. Additional air hoses join all loco main air reservoirs together when in multiple-unit. This facility, never provided in steam locomotives, gives extra air flow rate for hard braking. Wheel slip detection and control 88 SILICON CHIP is provided under acceleration and wheel slide under braking is prevented by using separate dynamic braking resistors for each traction motor, allowing separate control. Alternator The diesel engine direct drives the 16-pole main alternator to generate 3-phase 200VAC which is rectified to give 600V DC for the four traction motors. The alternator fields are supplied through separate silicon rectifiers. Standby electrical power is provided by a 32-cell 64V DC 420Ah battery mounted under the frame, each battery cell having 25 plates. The battery is charged by an auxiliary 24kW generator driven by the diesel engine. The 64V DC supply powers all motor, engine and dynamic brake control circuits, the cab and headlights. Also the battery is used to drive two 32V starter motors connected in series to start the diesel engine. The driver alertness . control is the "Train Sentry 11 Alertor", manufactured by Pulse Electronics Inc. This is activated by remote radio signal and if the driver .does not respond, it will shut down the diesel engine to idle, apply brakes, blow the air horn and wait for manual reset. An event recorder, also made by Pulse Electronics Inc, records nine principal functions: time, distance, speed, motor current, throttle position, brake condition, horn operation, cab signal acknowledgment by the driver and action of multiple units. So in the last ten years or so, Amtrak has gone a long way to upgrade and expand passenger services in the USA. Though it has its critics, Amtrak carries over 20 million passengers per year and operates 500 rail stations. However, the system still loses money. Only time will tell whether the faith Congress has in its future will be justified. ic Acknowledgement: our thanks to Amtrak , USA for their assistance in preparing this article and for all the photographs .