Adiesel locomotiveis a type ofrailwaylocomotivein which theprime
moveris adiesel engine. Several types of diesel locomotive have
been developed, differing mainly in the means by which mechanical
power is conveyed to the driving wheels (drivers).
TheInterCity 125, the current confirmed record holder as
thefastest diesel-powered trainat 148mph (238km/h); is made up of
twopower cars, one at each end of a fixed formation of carriages;
capable of 125mph (201km/h) in regular service.
Twin-section diesel locomotive2M62M-1198(rebuilt
withCATengines), near Kyviks,Lithuania.Contents[hide] 1Overview
2History 2.1Adaptation of the diesel engine for rail use 2.2Advance
of diesel traction in USA 2.3Early diesel locomotives and railcars
in Europe 2.4Early diesel locomotives and railcars in Asia 2.5Early
diesel locomotives and railcars in Australia 3Diesels advantages
over steam 4Transmission types 4.1Diesel-mechanical
4.2Diesel-electric 4.3Diesel-hydraulic 4.4Diesel-steam
4.5Diesel-pneumatic 5Multiple-unit operation 5.1Cab arrangements
5.2Cow-calf 6Flameproof diesel locomotive 7Lights 8Environmental
impact 8.1Mitigation 9See also 10References 10.1Sources 11External
linksOverview[edit]This sectiondoes notciteanyreferences or
sources.Please help improve this section byadding citations to
reliable sources. Unsourced material may be challenged
andremoved.(April 2013)
Earlyinternal combustion engine-powered locomotives and
railmotors usedgasolineas their fuel. Soon after Dr.Rudolf
Dieselpatented his firstcompression ignition engine[1]in 1892, it
was considered for railway propulsion. Progress was slow, however,
as several problems had to be overcome.
Petrol-electricWeitzer railmotor, first 1903, series 1906Power
transmission was a primary concern. As opposed to steam and
electric engines, internal combustion engines work efficiently only
within a limited range of turning frequencies. In light vehicles,
this could be overcome by aclutch. In heavy railway vehicles,
mechanical transmission never worked well or else wore out too
soon. Experience with early gasoline powered locomotives and
railcars was valuable for the development of diesel traction. One
step towardsdiesel-electrictransmission was petrol-electric
vehicle, such as theWeitzer railmotor(1903 ff.)[2]Steady
improvements in diesel design (many developed bySulzer
Ltd.ofSwitzerland, with whom Dr. Diesel was associated for a time)
gradually reduced its physical size and improved its
power-to-weight ratio to a point where one could be mounted in a
locomotive. Once the concept of diesel-electric drive was accepted,
the pace of development quickened, and by 1925 a small number of
diesel locomotives of 600 horsepower were in service in the United
States. In 1930, Armstrong Whitworth of the United Kingdom
delivered two 1,200hp locomotives using engines of Sulzer design
toBuenos Aires Great Southern Railwayof Argentina.By the mid-1950s,
with economic recovery from the Second World War, production of
diesel locomotives had begun in many countries and the diesel
locomotive was on its way to becoming the dominant type of
locomotive. It offered greater flexibility and performance than
thesteam locomotive, as well as substantially lower operating and
maintenance costs, other than where electric traction was in use
due to policy decisions. Currently, almost all diesel locomotives
are diesel-electric, although the diesel-hydraulic type was widely
used between the 1950s and 1970s.The Soviet diesel
locomotiveTEP80-0002lays claim to the world speed record for a
diesel railed vehicle, having reached 271km/h (168mph) on 5 October
1993.History[edit]Adaptation of the diesel engine for rail
use[edit]
A WDM-3A diesel locomotive of Indian Railways, used to haul both
passenger and freight.
A string of four diesel locomotives haul a long freight train in
the U.S. state ofWashington.Earliest recorded examples of an
internal combustion engine for railway use included a prototype
designed byWilliam Dent Priestman, which was examined bySir William
Thomsonin 1888 who described it as a"[Priestman oil engine] mounted
upon a truck which is worked on a temporary line of rails to show
the adaptation of a petroleum engine for locomotive
purposes.".[3][4]In 1894, a 20 h.p. two axle machine built
byPriestman Brotherswas used on theHull Docks.[5][6]In 1896 an
oil-engined railway locomotive was built for theRoyal
Arsenal,Woolwich,England, in 1896, using an engine designed
byHerbert Akroyd Stuart.[7][unreliable source?]It was not,
strictly, a diesel because it used ahot bulb engine(also known as a
semi-diesel) but it was the precursor of the diesel.Following the
expiration of Dr.Rudolf Diesels patent in 1912, his engine design
was successfully applied to marine propulsion and stationary
applications. However, the massiveness and poor power-to-weight
ratio of these early engines made them unsuitable for propelling
land-based vehicles. Therefore, the engine's potential as a
railroad prime mover was not initially recognized.[8]This changed
as development reduced the size and weight of the engine.The worlds
first diesel-powered locomotive was operated in the summer of 1912
on theWinterthur-Romanshorn Railroadin Switzerland, but was not a
commercial success.[9]In 1906,Rudolf Diesel,Adolf Kloseand the
steam and Diesel engine manufacturer Gebrder Sulzer founded
Diesel-Sulzer-Klose GmbH to manufacture Diesel-powered locomotives.
Sulzer had been manufacturing Diesel engines since 1898. The
Prussian State Railways ordered a Diesel locomotive from the
company in 1909, and after test runs between Winterthur and
Romanshorn the Diesel-mechanical locomotive was delivered in Berlin
in September 1912. During further test runs in 1913 several
problems were found. After the First World War broke out in 1914,
all further trials were stopped. The locomotive weight was 95
tonnes and the power was 883kW with a maximum speed of
100km/h.[10]Small numbers of prototype diesel locomotives were
produced in a number of countries through the mid-1920s.Advance of
diesel traction in USA[edit]Early American
developments[edit]Adolphus Buschpurchased the American
manufacturing rights for the Diesel engine in 1898 but never
applied this new form of power to transportation. Only limited
success was achieved in the early twentieth century with
direct-driven gasoline and Diesel powered railcars.[11]General
Electric(GE) entered therailcarmarket in the early twentieth
century, asThomas Edisonpossessed a patent on the electric
locomotive, his design actually being a type of electrically
propelled railcar.[12]GE built its first electric locomotive
prototype in 1895. However, high electrification costs caused GE to
turn its attention to Diesel power to provide electricity for
electric railcars. Problems related to co-coordinating the Diesel
engine andelectric motorwere immediately encountered, primarily due
to limitations of theWard Leonardelectric elevator drive system
that had been chosen.A significant breakthrough occurred in 1914,
whenHermann Lemp, aGEelectrical engineer, developed and patented a
reliabledirect currentelectrical control system (subsequent
improvements were also patented by Lemp).[13]Lemp's design used a
single lever to control both engine and generator in a coordinated
fashion, and was theprototypefor all diesel-electric locomotive
control systems.In 191718, GE produced three experimental
diesel-electric locomotives using Lemp's control design, the first
known to be built in the United States.[14]Following this
development, the 1923Kaufman Actbanned steam locomotives fromNew
York Citybecause of severe pollution problems. The response to this
law was to electrify high-traffic rail lines. However,
electrification was uneconomical to apply to lower-traffic
areas.The first regular use of diesel-electric locomotives was in
switching (shunter) applications. General Electric produced several
small switching locomotives in the 1930s (the famous "44-tonner"
switcher was introduced in 1940) Westinghouse Electric and Baldwin
collaborated to build switching locomotives starting in 1929.
However, theGreat Depressioncurtailed demand for Westinghouses
electrical equipment, and they stopped building locomotives
internally, opting to supply electrical parts instead.[15]First
American series production locomotives[edit]General Electric
continued to be interested in developing a practical diesel railway
locomotive, and approachedIngersoll-Randin 1924. The resulting 300
horsepower locomotive was fitted with anelectrical
generatorandtraction motorssupplied byGE, as well as a form of
Lemp's control system, and was delivered in July 1925. This
locomotive demonstrated that the diesel-electric power unit could
provide many of the benefits of anelectric locomotivewithout the
railroad having to bear the sizeable expense of
electrification.[16]The unit successfully demonstratedin switching,
road freight and passenger serviceon a bakers dozen of railroads,
and became the prototype for 33 units of 600 horsepowerAGEIR
boxcabswitching locomotivesbuilt by a consortium of GE, I-R and
theAmerican Locomotive Companyfor several New York City
railroads.[17]In June 1925,Baldwin Locomotive Worksoutshopped a
prototype diesel-electric locomotive for "special uses" (such as
for runs where water for steam locomotives was scarce) using
electrical equipment fromWestinghouse Electric Company.[18]Its
twin-engine design was not successful, and the unit was scrapped
after a short testing and demonstration period.[19]Industry sources
were beginning to suggest the outstanding advantages of this new
form of motive power.[20]In 1929, theCanadian National
Railwaysbecame the first North American railway to use diesels in
mainline service with two units, 9000 and 9001, from
Westinghouse.[21]Diesel-electric railroad locomotion entered the
American mainstream when theBurlington RailroadandUnion Pacificused
Diesel "streamliners" to haul passengers, both since
1934.[11][22]Following the successful 1939 tour of General
Motors'EMD'sFTdemonstrator freight locomotive set, the transition
from steam to Diesel power began, the pace substantially quickening
in the years following the close ofWorld War
II.Fairbanks-Morsedeveloped a uniqueopposed-piston enginethat was
used in their locomotives, as well as in submarines.[23]Early
diesel-electric locomotives in the United States used direct
current (DC) traction motors, but alternating current (AC) motors
came into widespread use in the 1990s, starting with
theElectro-Motive SD70MACin 1993 and followed by theGeneral
Electric's AC4400CWin 1994 andAC6000CWin 1995.[24]Early diesel
locomotives and railcars in Europe[edit]
Swiss&Germanco-production: world's first functional
diesel-electric railcar 1914First functional diesel
vehicles[edit]In 1914, world's first functional diesel-electric
railcars were produced for theKniglich-Schsische
Staatseisenbahnen(Royal Saxon State Railways) byWaggonfabrik
Rastattwith electric equipment fromBrown, Boveri & Cieand
diesel engines fromSwissSulzer AG. They were classified asDET 1 and
DET 2(de.wiki). Due to shortage of petrol products duringWorld War
I, they remained unused for regular service in Germany. In 1922,
they were sold to SwissCompagnie du Chemin de fer Rgional du
Val-de-Travers(fr.wiki), where they were used in regular service up
to theelectrificationof the line in 1944. Afterwards, the company
kept them in service as boosters till 1965.Fiatclaims a first
Italian diesel-electric locomotive built in 1922, but little detail
is available. A Fiat-TIBB diesel-locomotive "A", of 440CV, is
reported to have entered service on the Ferrovie Calabro Lucane in
southern Italy in 1926, following trials in 1924-5.[25]
World's first useful diesel locomotive for long distancesSD
Eel2, 1924 inKievIn 1924, two diesel-electric locomotives were
taken in service by theSoviet railways, almost at one time: The
engine 2 (Eel2original number 001/Yu-e 001) started on October 22.
It had been designed by a team led byYuri Lomonosovand built
19231924 byMaschinenfabrik Esslingenin Germany. It had 5 driving
axles (1'E1'). After several test rides, it hauled trains for
almost three decades from 1925 to 1954.[26]Though proved to be
world's first functional diesel locomotive, it didn't become a
series. But it became a model for several classes of Soviet diesel
locomotives. (see alsoCategory:Diesel locomotives of Russia) The
engine 1 (Shch-el 1, original number2/Yu-e 2), started on November
9. It had been developed byYakov Modestovich Gakkel(ru.wiki) and
built byBaltic ShipyardinSaint Petersburg. It had ten driving axles
in threebogies(1' Co' Do' Co' 1'). From 1925 to 1927, it hauled
trains betweenMoscowandKurskand inCaucasusregion. Due to technical
problems, afterwards it was out of service. Since 1934, it was used
as a stationary electric generator.In
1935,Krauss-Maffei,MANandVoithbuilt the first diesel-hydraulic
locomotive, calledV 140, in Germany. The German railways (DRG)
being very pleased with the performance of that engine,
diesel-hydraulics became the mainstream in diesel locomotives in
Germany. Serial production of diesel locomotives in Germany began
after World War II.Switchers[edit]
Shunter ofNederlandse Spoorwegenfrom 1934, in modern liveryIn
many railway stations and industrial compounds, steam shunters had
to be kept hot during lots of lazy breaks between scattered short
tasks. Therefore, diesel traction became economic for shunting,
before it became economic for hauling trains. The construction of
diesel shunters began in 1920 in France, in 1925 in Denmark, in
1926 in the Netherlands, and in 1927 in Germany. After few years of
testing, hundreds of units were produced within a decade.Diesel
railcars for regional traffic[edit]
Renault VH,France, 1933/34Diesel-powered or "oil-engined"
railcars, generally diesel-mechanical, were developed by various
European manufacturers in the 1930s, e.g. byWilliam Beardmore and
Companyfor theCanadian National Railways(theBeardmore Tornadoengine
was subsequently used in theR101airship). Some of those series for
regional traffic were begun with gasoline motors and then continued
with diesel motors, such as Hungarian BCmot(The class code doesn't
tell anything but "railmotor with 2nd and 3rd class seats".), 128
cars built 1926 1937, or GermanWismar railbuses(57 cars 1932 1941).
In France, the first diesel railcar wasRenault VH, 115 units
produced 1933/34. In Italy, after 6 Gasoline cars since 1931, Fiat
andBredabuilt a lot of diesel railmotors, more than 110 from 1933
to 1938 and 390 from 1940 to 1953,Class 772known asLittorina, and
Class ALn 900.High speed railcars[edit]In the 1930es, streamlined
highspeed diesel railcars were developed in several countries: In
Germany, theFlying Hamburgerwas built in 1932. After a test ride in
December 1932, this two coach diesel railcar (in English
terminology a DMU2) started service atDeutsche Reichsbahn(DRG) in
February 1933. It became the prototype ofDRG Class SVT 137with 33
more highspeed DMUs, built for DRG till 1938, 13 DMU 2 ("Hamburg"
series), 18 DMU 3 ("Leipzig" and "Kln" series), and 2 DMU 4
("Berlin" series). FrenchSNCFclasses XF 1000 and XF 1100 comprised
11 high speed DMUs, also called TAR, built 19341939. In
Hungary,Ganz WorksbuiltArpd railmotor(see hu.wikiandde.wiki), a
kind of a luxurious railbus in a series of 7 items since 1934, and
started to buildHargitaDMU amazingly in 1944 (see hu.wiki)Diesel
overcomes steam[edit]
British Rail Class D16/1, since 1948In 1945, a batch of 30
Baldwin diesel-electric locomotives,Baldwin 0-6-6-0 1000, was
delivered from the United States to the railways of the Soviet
Union.In 1948, the London Midland & Scottish Railway introduced
the first of a pair of 1,600hp Co-Co diesel-electric locomotives
(laterBritish Rail Class D16/1) for regular use in the United
Kingdom, although British manufacturers such as Armstrong Whitworth
had been exporting diesel locomotives since 1930. Fleet deliveries
to British Railways, of other designs such as Class 20 and Class
31, began in 1957.Series production of diesel locomotives
inItalybegan in the mid-1950s. Generally, diesel traction in Italy
was of less importance than in other countries, as it was amongst
the most advanced countries in electrification of the main lines
and, as a result of Italian geography, even on many domestic
connections freight transport over sea is cheaper than rail
transport.Early diesel locomotives and railcars in
Asia[edit]Japan[edit]In Japan, since the 1920s, some
petrol-electric railcars were produced. The first diesel-electric
traction and the first air-streamed vehicles on Japanese rails were
the two DMU3s of class Kiha 43000 (43000)[27]Japan's first series
of diesel locomotives was class DD50 (DD50), twin locomotives,
developed since 1950 and in service since 1953.[28]China[edit]One
of the first home developed diesel vehicles of China was the
DMUDongfeng(), produced in 1958 byCSR Sifang. Series production of
China's first diesel locomotive class, the DFH 1, began in 1964
following construction of a prototype in 1959.Early diesel
locomotives and railcars in Australia[edit]TheTrans-Australian
Railwaybuilt 1912 to 1917 by Commonwealth Railways (CR) passes
through 2000km of waterless (or salt watered) desert terrain
unsuitable for steam locomotives. The original engineerHenry
Deaneenvisageddiesel operationto overcome such problems.[29]Some
have suggested that the CR worked with the South Australian
Railways to trial diesel traction.[30]However, the technology was
not developed enough to be reliable.As in Europe, the usage of
internal combustion engines advanced more readily in self-propelled
railcars than in locomotives. Some Australian railway companies
boughtMcKeen railcars. In the 1920s and 1930s, more reliable
Gasoline railmotors were built by Australian industries.
Australia's first diesel railcars wereNSWGR 400 & 500 Classin
1938. High speed vehicles for those days' possibilities
on3ft6in(1,067mm) were the 10Vulcan railcarsof 1940 for New
Zealand.Diesels advantages over steam[edit]Diesel engines slowly
eclipsed those powered by steam as the manufacturing and
operational efficiencies of the former made them cheaper to own and
operate. While initial costs of diesel engines were high,steam
locomotiveswere custom-made for specific railway routes and lines
and, as such, economies of scale were difficult to
achieve.[31]Though more complex to produce with exacting
manufacturing tolerances (110000-inch (0.0025mm) for diesel,
compared with1100-inch (0.25mm) for steam), diesel locomotive parts
were more conducive to mass production. While the steam engine
manufacturerBaldwinoffered almost five hundred steam models in its
heyday,EMDoffered fewer than ten diesel varieties.[32]Diesel
locomotives offer significant operating advantages over steam
locomotives.[33]They can safely be operated by one person, making
them ideal for switching/shunting duties in yards (although for
safety reasons many main-line diesel locomotives continue to have
2-man crews: an engineer and a conductor/switchman) and the
operating environment is much more attractive, being much quieter,
fully weatherproof and without the dirt and heat that is an
inevitable part of operating a steam locomotive. Diesel locomotives
can be workedin multiplewith a single crew controlling multiple
locomotives throughout a single trainsomething not practical with
steam locomotives. This brought greater efficiencies to the
operator, as individual locomotives could be relatively low-powered
for use as a single unit on light duties but marshaled together to
provide the power needed on a heavy train still under the control
of a single crew. With steam traction a single very powerful and
expensive locomotive was required for the heaviest trains or the
operator resorted todouble headingwith multiple locomotives and
crews, a method which was also expensive and brought with it its
own operating difficulties.Diesel engines can be started and
stopped almost instantly, meaning that a diesel locomotive has the
potential to incur no costs when not being used. However, it is
still the practice of large North American railroads to use
straight water as a coolant in diesel engines instead of coolants
that incorporate anti-freezing properties; this results in diesel
locomotives being left idling when parked in cold climates instead
of being completely shut down. Still, a diesel engine can be left
idling unattended for hours or even days, especially since
practically every diesel engine used in locomotives has systems
that automatically shut the engine down if problems such as a loss
of oil pressure or coolant loss occur. In recent years, automatic
start/stop systems such as SmartStart have been adopted, which
monitor coolant and engine temperatures. When these temperatures
show that the unit is close to having its coolant freeze, the
system restarts the diesel engine to warm the coolant and other
systems.[34]Steam locomotives, by comparison, require intensive
maintenance, lubrication, and cleaning before, during, and after
use. Preparing and firing a steam locomotive for use from cold can
take many hours, although it may be kept in readiness between uses
with a smallfireto maintain a slight heat in theboiler, but this
requires regularstokingand frequent attention to maintain the level
of water in the boiler. This may be necessary to prevent the water
in the boiler freezing in cold climates, so long as the water
supply itself is not frozen.Moreover, maintenance and operational
costs of steam locomotives were much higher than diesel
counterparts even though it took diesel locomotives almost 50 years
to reach the same power output that steam locomotives could achieve
at their technological height.[citation needed]Annual maintenance
costs for steam locomotives accounted for 25% of the initial
purchase price. Spare parts were cast from wooden masters for
specific locomotives. The sheer number of unique steam locomotives
meant that there was no feasible way for spare-part inventories to
be maintained.[35]With diesel locomotives spare parts could be
mass-produced and held in stock ready for use and many parts and
sub-assemblies could be standardised across an operator's fleet
using different models of locomotive from the same builder. Parts
could be interchanged between diesel locomotives of the same or
similar design, reducing down-time; for example, a locomotive's
faulty prime mover may be removed and quickly replaced with another
spare unit, allowing the locomotive to return to service whilst the
original prime mover is repaired (and which can in turn be held in
reserve to be fitted to another locomotive). Repair or overhaul of
the main workings of a steam locomotive required the locomotive to
be out of service for as long as it took for the work to be carried
out in full.Steam engines also required large quantities of coal
and water, which were expensive variable operating
costs.[36]Further, thethermal efficiencyof steam was considerably
less than that of diesel engines. Diesels theoretical studies
demonstrated potential thermal efficiencies for a compression
ignition engine of 36% (compared with 610% for steam), and an 1897
one-cylinder prototype operated at a remarkable 26%
efficiency.[37]However, one study published in 1959 suggested that
many of the comparisons between diesel and steam locomotives were
made unfairly mostly because diesels were newer. After painstaking
analysis of financial records and technological progress, the
author found that if research had continued on steam technology
instead of diesel, there would be negligible financial benefit in
converting to diesel locomotion.[38]By the mid-1960s, diesel
locomotives had effectively replacedsteam locomotiveswhere electric
traction was not in use.[36]Attempts to developAdvanced steam
technologycontinue in the 21st century but have not made a
significant impact.Transmission types[edit]Unlike steam engines,
internal combustion engines require a transmission to power the
wheels. The engine must be allowed to continue to run when the
locomotive is stopped.Diesel-mechanical[edit]
ABritish Rail Class 03diesel-mechanicalshunter(switcher) with
ajackshaftunder the cab.A diesel-mechanical locomotive uses
amechanical transmissionin a fashion similar to that employed in
most road vehicles. This type of transmission is generally limited
to low-powered, low speedshunting (switching)locomotives,
lightweightmultiple unitsand self-propelledrailcars.
Schematic illustration of a diesel mechanical locomotiveThe
mechanical transmissions used for railroad propulsion are generally
more complex and much more robust than standard-road versions.
There is usually afluid couplinginterposed between the engine and
gearbox, and the gearbox is often of theepicyclic (planetary)type
to permit shifting while under load. Various systems have been
devised to minimise the break in transmission during gear changing;
e.g., the S.S.S. (synchro-self-shifting) gearbox used byHudswell
Clarke.Diesel-mechanical propulsion is limited by the difficulty of
building a reasonably sized transmission capable of coping with the
power andtorquerequired to move a heavy train. A number of attempts
to use diesel-mechanical propulsion in high power applications have
been made (e.g., the 1,500kW (2000 horsepower)British Rail
10100locomotive), although none have proved successful in the
end.Diesel-electric[edit]For locomotives powered by both external
electricity and diesel fuel, seeelectro-dieselbelow. For
locomotives powered by a combination of diesel or fuel cells and
batteries orultracapacitors, seehybrid locomotive.
Schematic diagram of diesel electric locomotiveIn
adiesel-electriclocomotive, the diesel engine drives either an
electricalDC generator(generally, less than 3,000 horsepower
(2,200kW) net for traction), or an electricalAC
alternator-rectifier(generally 3,000 horsepower (2,200kW) net or
more for traction), the output of which provides power to
thetraction motorswhich drive the locomotive. There is no
mechanical connection between the diesel engine and the wheels.The
important components of diesel-electric propulsion are the diesel
engine (also known as theprime mover), the main
generator/alternator-rectifier,traction motors(usually with four or
six axles), and a control system consisting of the
enginegovernorand electrical and/or electronic components,
includingswitchgear,rectifiersand other components, which control
or modify the electrical supply to the traction motors. In the most
elementary case, the generator may be directly connected to the
motors with only very simple switchgear.
TheEMD F40PH(left) andMPI MPXpress-series MP36PH-3S
(right)locomotivescoupledtogether byMetrausediesel-electric
transmission.
Soviet 2TE10U locomotiveOriginally, the traction motors and
generator wereDCmachines. Following the development of
high-capacitysilicon rectifiersin the 1960s, the DC generator was
replaced by analternatorusing adiode bridgeto convert its output to
DC. This advance greatly improved locomotive reliability and
decreased generator maintenance costs by elimination of
thecommutatorandbrushesin the generator. Elimination of the brushes
and commutator, in turn, disposed of the possibility of a
particularly destructive type of event referred to as aflashover,
which could result in immediate generator failure and, in some
cases, start an engine room fire.Current North American practice is
for four axles for high-speed passenger or "time" freight, or for
six axles for lower-speed or "manifest" freight.In the late 1980s,
the development of
high-powervariable-frequency/variable-voltage(VVVF) drives, or
"traction inverters," has allowed the use of polyphase AC traction
motors, thus also eliminating the motor commutator and brushes. The
result is a more efficient and reliable drive that requires
relatively little maintenance and is better able to cope with
overload conditions that often destroyed the older types of
motors.
Engineer's controls in a diesel-electric locomotive cab. The
lever near bottom-centre is the throttle and the lever visible at
bottom left is the automatic brake valve control.Diesel-electric
control[edit]
MLWmodel S-3 produced in 1957 for theCPRadhering to designs
byALCO.A diesel-electric locomotive's power output is independent
of road speed, as long as the units generator current and voltage
limits are not exceeded. Therefore, the unit's ability to
developtractive effort(also referred to asdrawbar pullortractive
force, which is what actually propels the train) will tend to
inversely vary with speed within these limits. (See power curve
below). Maintaining acceptable operating parameters was one of the
principal design considerations that had to be solved in early
diesel-electric locomotive development and, ultimately, led to the
complex control systems in place on modern units.Throttle
operation[edit]
AnEMD 12-567BRoots-blown 12-cylinder diesel engine (square "hand
holes"), stored pending rebuild, and missing some components, most
notably the two Roots blowers, with a 16-567C or D 16-cylinder
engine (round "hand holes") behind it, also missing some
components. EMD 645 and EMD 710 engines appear identically to the
567 C or D engines, and are the same size externally, although the
displacement is quite different.[relevant?discuss]The prime
mover'spoweroutput is primarily determined by its rotational speed
(RPM) and fuel rate, which are regulated by agovernoror similar
mechanism. The governor is designed to react to both the throttle
setting, as determined by the engine driver and the speed at which
the prime mover is running.[39]Locomotive power output, and thus
speed, is typically controlled by the engine driver using a stepped
or "notched"throttlethat producesbinary-like electrical signals
corresponding to throttle position. This basic design lends itself
well tomultiple unit(MU) operation by producing discrete conditions
that assure that all units in aconsistrespond in the same way to
throttle position. Binary encoding also helps to minimize the
number oftrainlines(electrical connections) that are required to
pass signals from unit to unit. For example, only four trainlines
are required to encode all possible throttle positions.North
American locomotives, such as those built byEMDorGeneral Electric,
have nine throttle positions, one idle and eight power (as well as
an emergency stop position that shuts down the prime mover).
ManyUK-built locomotives have a ten-position throttle. The power
positions are often referred to by locomotive crews as "run 3" or
"notch 3", depending upon the throttle setting.In older
locomotives, the throttle mechanism wasratchetedso that it was not
possible to advance more than one power position at a time. The
engine driver could not, for example, pull the throttle from notch
2 to notch 4 without stopping at notch 3. This feature was intended
to prevent rough train handling due to abrupt power increases
caused by rapid throttle motion ("throttle stripping," an operating
rules violation on many railroads). Modern locomotives no longer
have this restriction, as their control systems are able to
smoothly modulate power and avoid sudden changes intrainloading
regardless of how the engine driver operates the controls.When the
throttle is in the idle position, the prime mover will be receiving
minimal fuel, causing it to idle at low RPM. In addition, the
traction motors will not be connected to the main generator and the
generator's field windings will not be excited (energized) the
generator will not produce electricity with no excitation.
Therefore, the locomotive will be in "neutral". Conceptually, this
is the same as placing an automobile's transmission into neutral
while the engine is running.To set the locomotive in motion,
thereverser control handleis placed into the correct position
(forward or reverse), thebrakeis released and the throttle is moved
to the run 1 position (the first power notch). An experienced
engine driver can accomplish these steps in a coordinated fashion
that will result in a nearly imperceptible start. The positioning
of the reverser and movement of the throttle together is
conceptually like shifting an automobile's automatic transmission
into gear while the engine is idlingPlacing the throttle into the
first power position will cause the traction motors to be connected
to the main generator and the latter's field coils to be excited.
With excitation applied, the main generator will deliver
electricity to the traction motors, resulting in motion. If the
locomotive is running "light" (that is, not coupled to the rest of
a train) and is not on an ascending grade, it will easily
accelerate. On the other hand, if a long train is being started,
the locomotive may stall as soon as some of the slack has been
taken up, as the drag imposed by the train will exceed the tractive
force being developed. An experienced engine driver will be able to
recognize an incipient stall and will gradually advance the
throttle as required to maintain the pace of acceleration.As the
throttle is moved to higher power notches, the fuel rate to the
prime mover will increase, resulting in a corresponding increase in
RPM and horsepower output. At the same time, main generator field
excitation will be proportionally increased to absorb the higher
power. This will translate into increased electrical output to the
traction motors, with a corresponding increase in tractive force.
Eventually, depending on the requirements of the train's schedule,
the engine driver will have moved the throttle to the position of
maximum power and will maintain it there until the train has
accelerated to the desired speed.As will be seen in the following
discussion, the propulsion system is designed to produce maximum
traction motor torque at start-up, which explains why modern
locomotives are capable of starting trains weighing in excess of
15,000 tons, even on ascending grades. Current technology allows a
locomotive to develop as much as 30 percent of its loaded driver
weight intractive force, amounting to some 120,000 pounds-force
(530kN) ofdrawbar pullfor a large, six-axle freight (goods) unit.
In fact, aconsistof such units can produce more than enough drawbar
pull at start-up to damage or derail cars (if on a curve) or break
couplers (the latter being referred to in North American railroad
slang as "jerking a lung"). Therefore, it is incumbent upon the
engine driver to carefully monitor the amount of power being
applied at start-up to avoid damage. In particular, "jerking a
lung" could be a calamitous matter if it were to occur on an
ascending grade, except that the safety inherent in the correct
operation ofautomatic train brakesinstalled in wagons today,
prevents runaway trains by automatically applying the wagon brakes
when train line air pressure drops.Propulsion system
operation[edit]As previously explained, the locomotive's control
system is designed so that the main generatorelectrical poweroutput
is matched to any given engine speed. Given the innate
characteristics of traction motors, as well as the way in which the
motors are connected to the main generator, the generator will
produce high current and low voltage at low locomotive speeds,
gradually changing to low current and high voltage as the
locomotive accelerates. Therefore, the net power produced by the
locomotive will remain constant for any given throttle setting (see
power curve graph for notch 8).
Typical main generator constant power curve at "notch 8".In
older designs, the prime mover's governor and a companion device,
the load regulator, play a central role in the control system. The
governor has two external inputs: requested engine speed,
determined by the engine driver's throttle setting, and actual
engine speed (feedback). The governor has two external control
outputs:fuel injectorsetting, which determines the engine fuel
rate, and load regulator position, which affects main generator
excitation. The governor also incorporates a separate overspeed
protective mechanism that will immediately cut off the fuel supply
to theinjectorsand sound an alarm in thecabin the event the prime
mover exceeds a defined RPM. Not all of these inputs and outputs
are necessarily electrical.The load regulator is essentially a
largepotentiometerthat controls the main generator power output by
varying its field excitation and hence the degree of loading
applied to the engine. The load regulator's job is relatively
complex, because although the prime mover's power output is
proportional to RPM and fuel rate, the main generator's output is
not (which characteristic was not correctly handled by theWard
Leonardelevator- and hoist-type drive system that was initially
tried in early locomotives). Instead, a quite complex
electro-hydraulicWoodwardgovernor was employed. Today, this
important function would be performed by the Engine control unit,
itself being a part of the Locomotive control unit.As the load on
the engine changes, its rotational speed will also change. This is
detected by the governor through a change in the engine speed
feedback signal. The net effect is to adjust both the fuel rate and
the load regulator position so that engine RPM andtorque(and thus
power output) will remain constant for any given throttle setting,
regardless of actual road speed.In newer designs controlled by a
traction computer, each engine speed step is allotted an
appropriate power output, or kW reference, in software. The
computer compares this value with actual main generator power
output, or kW feedback, calculated from traction motor current and
main generator voltage feedback values. The computer adjusts the
feedback value to match the reference value by controlling the
excitation of the main generator, as described above. The governor
still has control of engine speed, but the load regulator no longer
plays a central role in this type of control system. However, the
load regulator is retained as a back-up in case of engine overload.
Modern locomotives fitted withelectronic fuel injection(EFI) may
have no mechanical governor; however a virtual load regulator and
governor are retained with computer modules.Traction motor
performance is controlled either by varying the DC voltage output
of the main generator, for DC motors, or by varying the frequency
and voltage output of theVVVFfor AC motors. With DC motors, various
connection combinations are utilized to adapt the drive to varying
operating conditions.At standstill, main generator output is
initially low voltage/high current, often in excess of
1000amperesper motor at full power. When the locomotive is at or
near standstill, current flow will be limited only by the DC
resistance of the motor windings and interconnecting circuitry, as
well as the capacity of the main generator itself. Torque in
aseries-wound motoris approximately proportional to the square of
the current. Hence, the traction motors will produce their highest
torque, causing the locomotive to develop maximumtractive effort,
enabling it to overcome the inertia of the train. This effect is
analogous to what happens in an automobileautomatic transmissionat
start-up, where it is in first gear and thus producing maximum
torque multiplication.As the locomotive accelerates, the
now-rotating motor armatures will start to generate
acounter-electromotive force(back EMF, meaning the motors are also
trying to act as generators), which will oppose the output of the
main generator and cause traction motor current to decrease. Main
generator voltage will correspondingly increase in an attempt to
maintain motor power, but will eventually reach a plateau. At this
point, the locomotive will essentially cease to accelerate, unless
on a downgrade. Since this plateau will usually be reached at a
speed substantially less than the maximum that may be desired,
something must be done to change the drive characteristics to allow
continued acceleration. This change is referred to as "transition,"
a process that is analogous to shifting gears in an
automobile.Transition methods include: Series / Parallel or "motor
transition". Initially, pairs of motors are connected in series
across the main generator. At higher speed, motors are reconnected
in parallel across the main generator. "Field shunting", "field
diverting", or "weak fielding". Resistance is connected in parallel
with the motor field. This has the effect of increasing
thearmaturecurrent, producing a corresponding increase in motor
torque and speed.Both methods may also be combined, to increase the
operating speed range. Generator transition Reconnecting the two
separate internal main generatorstator windingsfrom parallel to
series to increase the output voltage.In older locomotives, it was
necessary for the engine driver to manually execute transition by
use of a separate control. As an aid to performing transition at
the right time, theload meter(an indicator that informs the engine
driver on how much current is being drawn by the traction motors)
was calibrated to indicate at which points forward or backward
transition should take place. Automatic transition was subsequently
developed to produce better operating efficiency, and to protect
the main generator and traction motors from overloading from
improper transition.Modern locomotives incorporate
tractionalternators, AC to DC, with the capability to deliver 1,200
volts (earlier tractiongenerators, DC to DC, had the capability to
deliver only 600 volts). This improvement was accomplished largely
through improvements in silicon diode technology. With the
capability to deliver 1,200 volts to the traction motors, the
necessity for "transition" was eliminated.Dynamic braking[edit]Main
article:Dynamic brakeA common option on diesel-electric locomotives
isdynamic (rheostatic) braking.Dynamic braking takes advantage of
the fact that thetraction motorarmatures are always rotating when
the locomotive is in motion and that a motor can be made to act as
ageneratorby separately exciting the field winding. When dynamic
braking is utilized, the traction control circuits are configured
as follows: The field winding of each traction motor is connected
across the main generator. The armature of each traction motor is
connected across a forced-air-cooledresistance grid(the dynamic
braking grid) in the roof of the locomotive's hood. The prime mover
RPM is increased and the main generator field is excited, causing a
corresponding excitation of the traction motor fields.The aggregate
effect of the above is to cause each traction motor to generate
electric power and dissipate it as heat in the dynamic braking
grid. A fan connected across the grid provides forced-air cooling.
Consequently, the fan is powered by the output of the traction
motors and will tend to run faster and produce more airflow as more
energy is applied to the grid.Ultimately, the source of the energy
dissipated in the dynamic braking grid is the motion of the
locomotive as imparted to the traction motor armatures. Therefore,
the traction motors impose drag and the locomotive acts as a brake.
As speed decreases, the braking effect decays and usually becomes
ineffective below approximately 16km/h (10mph), depending on the
gear ratio between the traction motors andaxles.Dynamic braking is
particularly beneficial when operating in mountainous regions;
where there is always the danger of a runaway due to overheated
friction brakes during descent (see also comments in theair
brakearticle regarding loss of braking due to improper train
handling). In such cases, dynamic brakes are usually applied in
conjunction with theair brakes, the combined effect being referred
to asblended braking. The use of blended braking can also assist in
keeping the slack in a long train stretched as it crests a grade,
helping to prevent a "run-in", an abrupt bunching of train slack
that can cause a derailment. Blended braking is also commonly used
withcommuter trainsto reduce wear and tear on the mechanical brakes
that is a natural result of the numerous stops such trains
typically make during a run.Electro-diesel[edit]
Metro-North's GE GenesisP32AC-DMelectro-diesel locomotive can
also operate off ofthird-railelectrification.Main
article:Electro-diesel locomotiveThese special locomotives can
operate as anelectric locomotiveor as a diesel locomotive. TheLong
Island Rail Road,Metro-North RailroadandNew Jersey Transit Rail
Operationsoperate dual-mode diesel-electric/third-rail (catenary on
NJTransit) locomotives between non-electrified territory andNew
York Citybecause of a local law banning diesel-powered locomotives
inManhattantunnels. For the same reason,Amtrakoperates a fleet of
dual-mode locomotives in the New York area.British Railoperated
dual diesel-electric/electric locomotives designed to run primarily
as electric locomotives with reduced power available when running
on diesel power. This allowed railway yards to remain
un-electrified, as the third rail power system is extremely
hazardous in a yard area.Diesel-hydraulic[edit]Diesel-hydraulic
locomotives use one or moretorque converters, in combination with
gears, with a mechanical final drive to convey the power from the
diesel engine to the wheels.Hydrostatic transmission systems are
also used in some rail applications, primarily low speed
shunting[citation needed]and rail-maintenance vehicles.Hydrokinetic
transmission[edit]See also:Torque converterandFluid coupling
DBclassV 200diesel-hydraulic
A Henschel (Germany) diesel-hydraulic locomotive inMedan,North
SumatraHydrokinetic transmission (also called hydrodynamic
transmission) uses atorque converter. A torque converter consists
of three main parts, two of which rotate, and one (thestator) that
has a lock preventing backwards rotation and adding output torque
by redirecting the oil flow at low output RPM. All three main parts
are sealed in an oil-filled housing. To match engine speed to load
speed over the entire speed range of a locomotive some additional
method is required to give sufficient range. One method is to
follow the torque converter with a mechanical gearbox which
switches ratios automatically, similar to an automatic transmission
on a car. Another method is to provide several torque converters
each with a range of variability covering part of the total
required; all the torque converters are mechanically connected all
the time, and the appropriate one for the speed range required is
selected by filling it with oil and draining the others. The
filling and draining is carried out with the transmission under
load, and results in very smooth range changes with no break in the
transmitted power.Passenger Multiple units[edit]Diesel-hydraulic
drive is common in multiple units, with various transmission
designs used includingVoithtorque converters, andfluid couplingsin
combination with mechanical gearing.The majority ofBritish Rail's
second generation passenger DMU stock used hydraulic
transmission.In the 21st century designs using hydraulic
transmission
includeBombardier'sTurbostar,Talent,RegioSwingerfamilies; diesel
engined versions ofSiemens'sDesiroplatform, and theStadler
Regio-Shuttle.Locomotives[edit]
British Rail diesel-hydraulic locomotives:Class 52
"Western",Class 42 "Warship"andClass 35 "Hymek"Diesel-hydraulic
locomotives are less efficient than diesel-electrics. The
first-generation BR diesel hydraulics were significantly less
efficient (c. 65%) than diesel electrics (c. 80%)[citation needed]
moreover initial versions were found in many countries to be
mechanically more complicated and more likely to break
down.[citation needed]Hydraulic transmission for locomotives was
developed in Germany.[citation needed]There is still debate over
the relative merits of hydraulic vs. electrical transmission
systems: advantages claimed for hydraulic systems include lower
weight, high reliability, and lower capital cost.[citation
needed]By the 21st century, for diesel locomotive traction
worldwide the majority of countries used diesel-electric designs,
with diesel hydraulic designs not found in use outside Germany and
Japan, and some neighbouring states, where it is used in designs
for freight work.In Germany and Finland, diesel-hydraulic systems
have achieved high reliability in operation.[citation needed]In the
UK the diesel-hydraulic principle gained a poor reputation due to
the poor durability and reliability of the MaybachMekydrohydraulic
transmission.[citation needed]Argument continues over the relative
reliability of hydraulic systems, with questions over whether data
has been manipulated favour local suppliers over non-German
ones.[citation needed]Examples[edit]See
also:Category:Diesel-hydraulic locomotives
AVRClass Dv12diesel-hydraulic locomotive
AGMDGMDH-1diesel-hydraulic locomotiveDiesel-hydraulic
locomotives have a smaller market share than those with diesel
electric transmission - the main worldwide user of main-line
hydraulic transmissions was theFederal Republic of Germany, with
designs including the 1950sDB class V 200, and the 1960/70'sDB
Class V 160 family.British Railintroduced a number of diesel
hydraulic designs during it1955 Modernisation Plan, initially
license built versions of German designs
(seeCategory:Diesel-hydraulic locomotives of Great Britain). In
SpainRENFEused high power to weight ratio twin engined German
designs to haul high speed trains from the 1960s to 1990s.
(seeRENFE Classes 340,350,352,353,354)Other main-line locomotives
of the post war period included the 1950sGMD GMDH-1experimental
locomotives; theHenschel & SonbuiltSouth African Class 61-000;
in the 1960sSouthern Pacificbought 18 Krauss-MaffeiKM
ML-4000diesel-hydraulic locomotives. TheDenver & Rio Grande
Westernalso bought three, all of which were later sold to SP.[40]In
Finland, over 200 Finnish-built VR classDv12and Dr14
diesel-hydraulics withVoithtransmissions have been continuously
used since the early 1960s. All units of Dr14 class and most units
of Dv12 class are still in service. VR has abandoned some
weak-conditioned units of 2700 series Dv12s.[41]In the 21st century
series production standard gauge diesel-hydraulic designs include
theVoith Gravita, ordered byDeutsche Bahn, and theVossloh
G2000,G1206andG1700designs, all manufactured in Germany for freight
use.Hydrostatic transmission[edit]Hydraulic drive systems using a
hydrostatichydraulic drive systemhave been applied to rail use.
Modern examples included 350 to 750hp (260 to 560kW) shunting
locomotives byCMI Group(Belgium),[42]4 to 12 tonne 35 to 58kW (47
to 78hp) narrow gauge industrial locomoitves byAtlas
Copcosubsidiary GIA.[43]Hydrostatic drives are also utilised in
railway maintenance machines (tampers, rail
grinders).[44]Application of hydrostatic transmissions are
generally limited to small shunting locomotives and rail
maintenance equipment, as well as being used for non-tractive
applications in diesel engines such as drives for traction motor
fans.[citation needed]Diesel-steam[edit]Main article:Steam diesel
hybrid locomotiveSteam-diesel hybrid locomotives can use steam
generated from a boiler or diesel to power a piston engine.
TheCristiani Compressed Steam Systemused a diesel engine to power a
compressor to drive and recirculate steam produced by a boiler;
effectively using steam as the power transmission medium, with the
diesel engine being theprime mover[45]Diesel-pneumatic[edit]The
diesel-pneumatic locomotive was of interest in the 1930s because it
offered the possibility of converting existing steam locomotives to
diesel operation. The frame and cylinders of the steam locomotive
would be retained and the boiler would be replaced by a diesel
engine driving anair compressor. The problem was lowthermal
efficiencybecause of the large amount of energy wasted as heat in
the air compressor. Attempts were made to compensate for this by
using the diesel exhaust to re-heat the compressed air but these
had limited success. A German proposal of 1929 did result in a
prototype[46]but a similar British proposal of 1932, to use anLNER
Class R1locomotive, never got beyond the design stage.Multiple-unit
operation[edit]
Diesel-electric locomotive built by EMD for service in the UK
and continental Europe.Most Diesel locomotives are capable
ofmultiple unit operation (MU)as a means of
increasinghorsepowerandtractive effortwhen hauling heavy trains.
AllNorth Americanlocomotives, including export models, use a
standardizedAARelectrical control system interconnected by a
27-pinjumper cablebetween the units. For UK-built locomotives, a
number of incompatible control systems are used, but the most
common is the Blue Star system, which is electro-pneumatic and
fitted to most early diesel classes. A small number of types,
typically higher-powered locomotives intended for passenger only
work, do not have multiple control systems. In all cases, the
electrical control connections made common to all units in
aconsistare referred to astrainlines. The result is that all
locomotives in aconsistbehave as one in response to the engine
driver's control movements.The ability to couple Diesel-electric
locomotives in an MU fashion was first introduced in theEMD
FTfour-unit demonstrator that toured theUSAin 1939. At the time,
American railroad work rules required that each operating
locomotive in a train had to have on board a full
crew.EMDcircumvented that requirement by coupling the individual
units of the demonstrator withdrawbarsinstead of
conventionalknuckle couplersand declaring the combination to be a
single locomotive. Electrical interconnections were made so one
engine driver could operate the entire consist from the head-end
unit. Later on, work rules were amended and the semi-permanent
coupling of units with drawbars was eliminated in favour of
couplers, as servicing had proved to be somewhat cumbersome owing
to the total length of the consist (about 200 feet or nearly 61
meters).In mountainous regions, it is common to interposehelper
locomotivesin the middle of the train, both to provide the extra
power needed to ascend a grade and to limit the amount
ofstressapplied to thedraft gearof the car coupled to the head-end
power. The helper units in suchdistributed powerconfigurations are
controlled from the lead unit's cab through coded radio signals.
Although this is technically not an MU configuration, the behaviour
is the same as with physically interconnected units.Cab
arrangements[edit]Cab arrangements vary by builder and operator.
Practice in the U.S. has traditionally been for a cab at one end of
the locomotive with limited visibility if the locomotive is not
operated cab forward. This is not usually a problem as U.S.
locomotives are usually operated in pairs, or threes, and arranged
so that a cab is at each end of each set. European practice is
usually for a cab at each end of the locomotive as trains are
usually light enough to operate with one locomotive. Early U.S.
practice was to add power units without cabs (booster orB units)
and the arrangement was often A-B, A-B-A, or A-B-B-A where A was a
unit with a cab. Center cabs were sometimes used for switch
locomotives.Cow-calf[edit]Main article:Cow-calfIn North American
railroading, acow-calfset is a pair of switcher-type locomotives:
one (the cow) equipped with a driving cab, the other (the calf)
without a cab, and controlled from the cow through cables. Cow-calf
sets are used in heavy switching andhump yardservice. Some are
radio controlled without an operating engineer present in the cab.
This arrangement is also known asmaster-slave. Where two connected
units were present,EMDcalled these TR-2s (approximately 2,000 HP);
where three units, TR-3s (approximately 3,000 HP).Cow-calves have
largely disappeared as these engine combinations exceeded their
economic lifetimes many years ago.Present North American practice
is to pair two 3,000 HPGP40-2orSD40-2road switchers, often nearly
worn-out and very soon ready for rebuilding or scrapping, and to
utilize these for so-called "transfer" uses, for which the TR-2,
TR-3 and TR-4 engines were originally intended, hence the
designation TR, for "transfer".Occasionally, the second unit may
have its prime-mover and traction alternator removed and replaced
by concrete and/or steel ballast and the power for traction
obtained from the master unit. As a 16-cylinder prime-mover
generally weighs in the 36,000 pound range, and a 3,000 HP traction
alternator generally weighs in the 18,000 pound range, this would
mean that 54,000 pounds would be needed for ballast.A pair of fully
capable "Dash 2" units would be rated 6,000 HP. A "Dash 2" pair
where only one had a prime-mover/alternator would be rated 3,000
HP, with all power provided by master, but the combination benefits
from the tractive effort provided by the slave as engines in
transfer service are seldom called upon to provide 3,000 HP much
less 6,000 HP on a continuous basis.Flameproof diesel
locomotive[edit]A standard diesel locomotive presents a very low
fire risk but flame proofing can reduce the risk even further. This
involves fitting a water-filled box to the exhaust pipe to quench
any red-hot carbon particles that may be emitted. Other precautions
may include a fully insulated electrical system (neither side
earthed to the frame) and all electric wiring enclosed in
conduit.The flameproof diesel locomotive has replaced thefireless
steam locomotivein areas of high fire risk such asoil
refineriesandammunition dumps. Preserved examples of flameproof
diesel locomotives include: Francis Baily of Thatcham(ex-RAF
Welford) atSouthall Railway Centre Naworth(ex-National Coal Board)
at theSouth Tynedale Railway[47]Latest development of the
"Flameproof Diesel Vehicle Applied New Exhaust Gas Dry Type
Treatment System does not need the water
supply.[48]Lights[edit]ACanadian National Railwaytrain showing the
placement of the headlight and ditch lights on the locomotive.The
lights fitted to diesel locomotives vary from country to country.
North American locomotives are fitted with two headlights for
redundancy and a pair of ditch lights. The latter are fitted low
down at the front and are designed to make the locomotive easily
visible as it approaches agrade crossing. Older locomotives may be
fitted with a Gyralite orMars Lightinstead of the ditch
lights.Environmental impact[edit]See also:Diesel exhaustAlthough
diesel locomotives generally emit less sulphur dioxide, a
majorpollutantto the environment, and greenhouse gases than steam
locomotives, they are not completely clean in that
respect.[49]Furthermore, like other diesel powered vehicles, they
emitnitrogen oxidesandfine particles, which are a risk to public
health. In fact, in this last respect diesel locomotives may
perform worse than steam locomotives.For years, it was thought by
American government scientists who measureair pollutionthat diesel
locomotive engines were relatively clean and emitted far less
health-threatening emissions than those of diesel trucks or other
vehicles; however, the scientists discovered that because they used
faulty estimates of the amount of fuel consumed by diesel
locomotives, they grossly understated the amount of pollution
generated annually (In Europe, where most major railways have been
electrified, there is less concern). After revising their
calculations, they concluded that the annual emissions of nitrogen
oxide, a major ingredient insmogandacid rain, and soot would be by
2030 nearly twice what they originally assumed.[50][51]This would
mean that diesel locomotives would be releasing more than 800,000
tons of nitrogen oxide and 25,000 tons of soot every year within a
quarter of a century, in contrast to the EPA's previous projections
of 480,000 tons ofnitrogen dioxideand 12,000 tons of soot. Since
this was discovered, to reduce the effects of the diesel locomotive
onhumans(who are breathing the noxious emissions) and
onplantsandanimals, it is considered practical to install traps in
the diesel engines to reduce pollution levels[52]and other forms
(e.g., use ofbiodiesel).Diesel locomotive pollution has been of
particular concern in the city ofChicago. TheChicago
Tribunereported levels of diesel soot inside locomotives leaving
Chicago at levels hundreds of times above what is normally found on
streets outside.[53]Residents of several neighborhoods are most
likely exposed to diesel emissions at levels several times higher
than the national average for urban areas.[54]Mitigation[edit]In
2008, theUnited States Environmental Protection Agency(EPA)
mandated regulations requiring all new or refurbished diesel
locomotives to meetTier IIpollution standards that slash the amount
of allowable soot by 90% and require an 80% reduction innitrogen
oxideemissions.SeeList of low emissions locomotives.Other
technologies that are being deployed to reduce locomotive emissions
and fuel consumption include "Genset" switching locomotives and
hybridGreen Goatdesigns. Genset locomotives use multiple high-speed
diesel engines and generators (generator sets), rather than a
single medium-speed diesel engine and a single generator.[55]Green
Goats are a type ofhybridswitching locomotive utilizing a small
diesel engine and a large bank of rechargeable
batteries.[56][57]Switching locomotives are of particular concern
as they typically operate in a limited area, often in or near urban
centers, and spend much of their time idling. Both designs reduce
pollution below EPA Tier II standards and cut or eliminate
emissions during idle.See also[edit] Diesel multiple unit
Diesel-electric transmission Diesel engine Electric locomotive
Electrification Electro-diesel locomotive Hybrid electric vehicle
Hybrid locomotive Non-road engineReferences[edit]1. Jump up^Diesel,
Rudolf. U.S. Patent No. 608,845, filed July 15, 1895, and issued
August 9, 1898Accessed via Google Patent Search at:US Patent
#608,845on February 8, 2007.2. Jump up^References for Weitzer
railmotor: Arnold Heller:Der Automobilmotor im Eisenbahnbetriebe,
Leipzig 1906, reprinted by Salzwasserverlag 2011,ISBN
978-3-86444-240-7 Rll:Enzyklopdie des EisenbahnwesensElektrische
Eisenbahnen, there go toVII. Automobile Triebwagenzu b) Benzin-,
Benzol- oder Gasolin-elektrischen Triebwagen
http://www.us.archive.org/about/terms.phpSearch:Self-Contained
Railway Motor Cars and Locomotives GO! Raymond S Zeitler, American
School (Chicago, Ill.):Self-Contained Railway Motor Cars and
Locomotives, sectionSELF-CONTAINED RAILWAY CARS 5759 Rll:Arader und
Csander Eisenbahnen Vereinigte Aktien-Gesellschaft Museal railcars
of BHV and their history3. Jump up^"Motive power for British
Railways"(PDF),The Engineer202, 24 April 1956: 2544. Jump up^The
Electrical Review22, 4 May 1888: 474,A small double cylinder engine
has been mounted upon a truck, which is worked on a temporary line
of rails, in order to show the adaptation of a petroleum engine for
locomotive purposes, on tramwaysMissing or empty|title=(help)5.
Jump up^Diesel Railway Traction(Railway Gazette)17, 1963: 25,In one
sense a dock authority was the earliest user of an oil-engined
locomotive, for it was at the Hull docks of the North Eastern
Railway that the Priestman locomotive put in its short period of
service in 1894Missing or empty|title=(help)6. Jump up^Day, John
R.; Cooper, Basil Knowlman (1960),railway Locomotives, Frederick
Muller, p.42,The diesel has quite a long history, and the first one
ran as far back as 1894. This was a tiny 30-h.p. two-axle
standard-gauge locomotive with a two- cylinder engine designed by
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Locomotive". Douglas-self.com. Retrieved2011-08-20.47. Jump
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Jerry A. (1973).The Second Diesel Spotters Guide. Milwaukee WI:
Kalmbach Books.ISBN0-89024-026-4.External links[edit]Wikimedia
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