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A hood unit, in
North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...
n
railroad terminology Rail terminology is a form of technical terminology. The difference between the American term ''railroad'' and the international term ''railway'' (used by the International Union of Railways and English-speaking countries outside the United Sta ...
, is a body style for diesel and electric
locomotive A locomotive or engine is a rail transport vehicle that provides the Power (physics), motive power for a train. If a locomotive is capable of carrying a payload, it is usually rather referred to as a multiple unit, Motor coach (rail), motor ...
s where the body is less than full-width for most of its length and walkways are on the outside. In contrast, a
cab unit In North American railroad terminology, a cab unit is a railroad "locomotive" with its own cab and controls. "Carbody unit" is a related term, which may be either a cabless booster unit controlled from a linked cab unit, or a cab unit that cont ...
has a full-width carbody for the length of the locomotive and walkways inside. A hood unit has sufficient visibility to be operated in both directions from a single cab. Also, the
locomotive frame A locomotive frame is the structure that forms the backbone of the railway locomotive, giving it strength and supporting the superstructure elements such as a cab, boiler or bodywork. The vast majority of locomotives have had a frame structure o ...
is the main load-bearing member, allowing the hood to be non-structural and easily opened or even removed for maintenance.


History

The hood unit evolved from the
switcher A switcher, shunter, yard pilot, switch engine, yard goat, or shifter is a small railroad locomotive used for manoeuvring railroad cars inside a rail yard in a process known as ''switching'' (US) or ''shunting'' (UK). Switchers are not inten ...
locomotive. A switcher's long hood is normally low enough that the crew can see over it, and there typically is no short hood.
Alco The American Locomotive Company (often shortened to ALCO, ALCo or Alco) was an American manufacturer of locomotives, diesel generators, steel, and tanks that operated from 1901 to 1969. The company was formed by the merger of seven smaller locomo ...
introduced the
road switcher A road switcher is a type of railroad locomotive designed to both haul railcars in mainline service and shunt them in railroad yards. Both type and term are North American in origin, although similar types have been used elsewhere. A road ...
concept with the RS-1, which was an enlarged switcher with a short hood ahead of the cab. This was added to provide protection for the crew in case of a collision. The low long hood was retained, though its increased length made visibility over it useless. Later, EMD introduced the GP7, which had a similar layout, though both hoods were as high as the cab roof. The high long hood became standard for virtually all hood unit locomotives thereafter. The long hood of a locomotive is usually about as tall as the cab roof in order to fit the large
prime mover Prime mover may refer to: Philosophy *Unmoved mover, a concept in Aristotle's writings Engineering * Prime mover (engine), motor, a machine that converts various other forms of energy (chemical, electrical, fluid pressure/flow, etc) into energy ...
and its related subsystems. Originally the short hood of the locomotive was the same height, which is referred to as a ''high-nose'' or, confusingly, ''high short hood.'' Starting in the mid to late 1950s, the height of the short hood was reduced to increase visibility, creating a ''low-nose'' or ''low short hood'' locomotive. Some locomotives that were originally built with a high nose were later modified to have a low nose. Lately it has become common to make the short hood not only lower but also full-width, creating a wider nose which is usually referred to as a ''North American Safety Cab'' or Canadian comfort cab. The visibility and access advantages mean that the hood unit is overwhelmingly the most popular style of locomotive in
North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...
, as well as many other regions.


Operation

Although the crew cabin is centered on some hood units (particularly in the case of dual, relatively small prime-movers), in most cases the cab is closer to one end of the locomotive than the other (in the case of a single, relatively large prime-mover), breaking the locomotive up into ''
long hood The long hood of a hood unit-style diesel locomotive is, as the name implies, the longer of the two hoods (narrower sections of the locomotive body in front and behind of the cab) on a locomotive, particularly American-type freight locomotives. ...
'' and '' short hood'' sections. It is generally preferred to run a hood unit ''short hood forward'' so that the cab is closer to the front, but there is enough visibility in the other direction that they can run ''long hood forward'' at regular speeds. Some railroad companies (notably, the
Norfolk & Western The Norfolk and Western Railway , commonly called the N&W, was a US class I railroad, formed by more than 200 railroad mergers between 1838 and 1982. It was headquartered in Roanoke, Virginia, for most of its existence. Its motto was "Precisi ...
and the Southern) ordered locomotives with cabs facing long hood forward so that the short hood is actually the rear of the locomotives, but that practice has become increasingly rare. This was usually done to offer greater protection to the crew in the event of a collision. Other locomotives were set up with
dual control stand Rail terminology is a form of technical terminology. The difference between the American term ''railroad'' and the international term ''railway'' (used by the International Union of Railways and English-speaking countries outside the United St ...
s so that they could operate in both directions, making it unnecessary to turn the locomotive around at the end of a run. Some cabless hood units were also built. The long hood ran the whole length of those locomotives. In North America, all locomotives are required to have the letter F printed on the side sill at the end which is normally operated as its front.


Freight-oriented hood units

*
EMD GP7 The EMD GP7 is a four-axle ( B-B) diesel-electric locomotive built by General Motors Electro-Motive Division and General Motors Diesel between October 1949 and May 1954.Pinkepank, Jerry A. (1973) pp. 53 Power was provided by an EMD 567B 1 ...
*
EMD GP9 The EMD GP9 is a four-axle diesel-electric locomotive built by General Motors' Electro-Motive Division between 1954 and 1959. The GP9 succeeded the GP7 as the second model of EMD's General Purpose (GP) line, incorporating a new sixteen-cylind ...
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EMD GP20 An EMD GP20 is a 4-axle diesel-electric locomotive built by General Motors' Electro-Motive Division between November 1959 and April 1962. Power was provided by an EMD 567D2 16-cylinder turbocharged engine which generated . EMD was initially hes ...
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EMD GP28 An EMD GP28 is a 4-axle diesel-electric locomotive built by General Motors Electro-Motive Division between March 1964 and November 1965. Power was provided by an EMD 567D1 16-cylinder engine which generated . This locomotive was basically a no ...
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EMD GP30 The EMD GP30 is a four-axle diesel-electric locomotive built by General Motors Electro-Motive Division of La Grange, Illinois between July 1961 and November 1963. A total of 948 units were built for railroads in the United States and Canad ...
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EMD GP35 The EMD GP35 is a 4-axle diesel-electric locomotive built by General Motors Electro-Motive Division between July 1963 and December 1965 and by General Motors Diesel between May 1964 and January 1966. 1251 examples were built for American railro ...
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EMD GP38-2 The EMD GP38-2 is an American four-axle diesel-electric locomotive built by General Motors, Electro-Motive Division. Part of the EMD Dash 2 line, the GP38-2 was an upgraded version of the earlier GP38. Power is provided by an EMD 645E 16-cyl ...
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EMD GP40-2 The EMD GP40-2 is a 4-axle diesel locomotive built by General Motors Electro-Motive Division as part of its Dash 2 line between April 1972 and December 1986. The locomotive's power is provided by an EMD 645E3 16-cylinder engine which generates ...
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EMD GP50 An EMD GP50 is a 4-axle diesel-electric locomotive built by General Motors Electro-Motive Division (EMD). It is powered by a 16-cylinder EMD 645F3B diesel engine, which can produce between . 278 examples of this locomotive were built by EMD b ...
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EMD GP60 An EMD GP60 is a 4-axle (AAR wheel arrangement#B-B, B-B) diesel locomotive, diesel-electric locomotive built by Electro-Motive Diesel, General Motors Electro-Motive Division between 1985 and 1994. The GP60 was EMD's first engine that was classif ...
*
EMD SD7 An SD7 is a 6-axle diesel locomotive built by General Motors Electro-Motive Division between May 1951 and November 1953. It had an EMD 567B 16-cylinder engine producing for its six traction motors. 188 were built for United States railroads. ...
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EMD SD9 An SD9 is a 6-axle diesel locomotive built by General Motors Electro-Motive Division between January 1954 and June 1959. An EMD 567C 16-cylinder engine generated . Externally similar to its predecessor, the SD7, the SD9 was built with the improv ...
* EMD SD24 * EMD SD38-2 *
EMD SD39 An SD39 is a 6-axle diesel-electric locomotive built by Electro-Motive Diesel, General Motors Electro-Motive Division between August 1968 and May 1970. 54 were built for American railroads. In 1966 Electro-Motive Diesel, EMD replaced all their ...
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EMD SD39-2 An SD39 is a 6-axle diesel-electric locomotive built by Electro-Motive Diesel, General Motors Electro-Motive Division between August 1968 and May 1970. 54 were built for American railroads. In 1966 Electro-Motive Diesel, EMD replaced all their ...
*
EMD SD40 The EMD SD40 is an American 6-axle diesel-electric locomotive built by General Motors Electro-Motive Division between January 1966 and August 1972. 1,268 locomotives were built between 1966 and 1972. In 1972, an improved version with new electroni ...
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EMD SD40-2 The EMD SD40-2 is a C-C diesel-electric locomotive built by EMD from 1972 to 1989. The SD40-2 was introduced in January 1972 as part of EMD's '' Dash 2'' series, competing against the GE U30C and the ALCO Century 630. Although higher-horsepowe ...
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EMD SD45 The SD45 is a six-axle diesel-electric locomotive built by General Motors Electro-Motive Division between 1965 and 1971. It has an EMD 645E3 twenty-cylinder engine generating on the same frame as the SD38, SD39, SD40, and SDP40. As of 2022, mos ...
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EMD SD45-2 The EMD SD45-2 is a 6-axle diesel-electric locomotive built by General Motors Electro-Motive Division (EMD). EMD built 136 locomotives between 1972–1974, primarily for the Atchison, Topeka and Santa Fe Railway (ATSF). The SD45-2 was an improved ...
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EMD SD50 The EMD SD50 is a diesel-electric locomotive built by General Motors Electro-Motive Division. It was introduced in May 1981 as part of EMD's "50 Series"; production ceased in January 1986. The SD50 was a transitional model between EMD's Dash ...
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EMD SD60 The EMD SD60 is a , six-axle diesel-electric locomotive built by General Motors Electro-Motive Division, intended for heavy-duty drag freight or medium-speed freight service. It was introduced in 1984, and production ran until 1995. History and d ...
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EMD SD70 series The EMD SD70 is a series of diesel-electric locomotives produced by the US company Electro-Motive Diesel in response to the GE Dash 9-44CW. Production commenced in late 1992 and since then over 5,700 units have been produced; most of these are t ...
*
EMD SD75I EMD may refer to: Finance and commerce * Emerging market debt * Earnest money deposit, in the United States, a security deposit, especially for real estate Medicine * Electromagnetic diaphragm * Electromechanical dissociation * Emergency m ...
* EMD SD75M *
EMD SD80MAC The SD80MAC was a C-C diesel-electric locomotive. It was powered by a 20-cylinder version of EMD's 710G prime mover, and was the second diesel locomotive by GM-EMD to use a v20 engine, since EMD's SD45 and SD45-2. It introduced a wide radia ...
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EMD SD90MAC The EMD SD90MAC is a model of C-C diesel-electric locomotive produced by General Motors Electro-Motive Division. It is, with the SD80MAC, one of the largest single-engined locomotives produced by EMD, surpassed only by the dual-engined DDA ...
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EMD DD35 The EMD DD35 was a diesel-electric locomotive of D-D wheel arrangement built by General Motors Electro-Motive Division for the Union Pacific Railroad and Southern Pacific Railroad. History In the early 1960s, Union Pacific started asking for ...
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EMD DD35A The EMD DD35A, also known as the EMD DDA35, was a diesel-electric locomotive of D-D wheel arrangement built by General Motors Electro-Motive Division exclusively for the Union Pacific Railroad. They were a cab-equipped variant of the previou ...
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EMD DDA40X The EMD DDA40X is a 6,600 hp (4,943 kW) D-D locomotive, built by EMD from 1969 to 1971 exclusively for the Union Pacific Railroad. It is the most powerful diesel-electric locomotive model ever built on a single frame, having two 16 ...
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GE U23B The GE U23B was a 2,250 horsepower diesel-electric locomotive built by GE Transportation from 1968 to 1977. It was one of the most successful models of the Universal Series, with 481 units built, including 16 exported to Peru. The U23B was replace ...
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GE U23C The 2300 horsepower GE U23C diesel-electric locomotive model was first offered by GE in 1968, and featured a V-type 12 cylinder version of the standard GE FDL diesel motor. Designed as a competitor to EMD's SD38 and SD39 series, it was intended ...
* GE U25B * GE U25C * GE U28C * GE U30B *
GE U30C The GE U30C is a six-axle locomotive built by General Electric from 1966 to 1976. With 600 units sold, the U30C proved to be a viable alternative for customers who were unable to purchase SD40s from Electro-Motive Diesel (EMD) due to production bac ...
* GE U33B *
GE U33C The GE U33C is a 6-axle diesel-electric locomotive built by GE Transportation Systems between January 1968 and January 1975. 375 examples of this locomotive were built for 11 North American railroads and one construction contractor. Original ow ...
*
GE U36B The GE U36B was a four-axle B-B diesel-electric locomotive produced by General Electric from 1969 to 1974. It was primarily used by the Seaboard Coast Line Railroad and its successors, although thirteen provided the power for the original ''Auto ...
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GE U36C The GE U36C was a 3600  hp diesel-electric locomotive model built by GE Transportation Systems GE Transportation is a division of Wabtec. It was known as GE Rail and owned by General Electric until sold to Wabtec on February 25, 2019. T ...
* GE U50 *
GE U50C The GE U50C was a diesel-electric locomotive built by GE Transportation Systems. Each was powered by two diesel engines. History Forty were built between November 1969 and November 1971 solely for Union Pacific, which numbered them 5000 to 50 ...
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GE Dash 7 Series The Dash 7 Series is a line of diesel-electric freight locomotives built by GE Transportation Systems. It replaced the Universal Series in the mid-1970s, and was superseded by the Dash 8 Series in the mid-1980s. Specifications All models of ...
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GE Dash 8 Series The Dash 8 Series is a line of diesel-electric freight locomotives built by GE Transportation Systems. It replaced the Dash 7 Series in the mid-1980s, and was superseded by the Dash 9 Series for freight usage and the Genesis Series for passen ...
* GE Dash 9 Series *
GE AC4400CW The GE AC4400CW, sometimes referred as "AC44CW" is a diesel-electric locomotive that was built by GE Transportation Systems between 1993 and 2004. It is like the Dash 9-44CW, but features AC traction motors instead of DC, with a separate invert ...
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GE AC6000CW The AC6000CW is a diesel electric locomotive built between 1995 and 2001 by GE Transportation. It is among the world's most powerful single-engined diesel locomotives. The locomotive was designed for extremely high horsepower needs, such as pull ...
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GE Evolution Series The Evolution Series is a line of diesel locomotives built by GE Transportation Systems (now owned by Wabtec), initially designed to meet the U.S. EPA's Tier 2 locomotive emissions standards that took effect in 2005. The first pre-production ...


Passenger-oriented hood units

* Brookville BL20GH *
GP40TC The passenger locomotives derivatives of the General Motors EMD GP40 diesel-electric locomotive have been, and continue to be, used by multiple passenger railroads in North America. For passenger service, the locomotives required extra compone ...
* EMD GP40P * EMD GP40P-2 * EMD GP40PH-2 * EMD GP39H-2 * EMD GP40WH-2 * EMD GP40-3H *EMD GP40MC * EMD SDP35 *
EMD SDP40 An SDP40 is a 6-axle passenger diesel-electric locomotive built by General Motors Electro-Motive Division (EMD) between June 1966 and May 1970. Design Like its predecessor in EMD's catalog, the SDP35, the SDP40 is a high-horsepower freight locom ...
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EMD SDP45 The SDP45 is a six-axle, C-C, diesel-electric locomotive built by General Motors' Electro-Motive Division of La Grange, Illinois. It was a passenger-hauling version of the SD45 on a stretched locomotive frame with an extended, squared-off long ...
* EMD SD70MACH *
GE U28CG The GE U28CG was a dual-service diesel-electric locomotive produced in 1966 by GE Transportation Systems and derived from their freight-hauling U28C design. The sole customer was the Atchison, Topeka and Santa Fe Railway, which ordered ten ea ...
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GE U34CH The U34CH was a passenger diesel locomotive built by General Electric between 1970 and 1973. In total, 33 U34CH units were built; 32 were built for the New Jersey Department of Transportation and operated by the Erie Lackawanna Railway and, lat ...
* GE Dash 8-32BWH *
MPI MP32PH-Q MPXpress is a series of diesel-electric passenger train locomotives designed for commuter rail service. The locomotives are built by MotivePower, a subsidiary of Wabtec. To date, MPI has offered five main variants: MP36PH-3S, MP36PH-3C, MP40PH- ...


United Kingdom

The term "hood unit" is not used in the UK but a few locomotives of the hood unit type are in service. Some of these locomotives may also be classified as cab forwards when running in reverse. * British Rail Class 70 (introduced 2009) * British Rail Class 08 (introduced 1952) * British Rail Class 09 (introduced 1959) *
British Rail Class 20 The British Rail Class 20, otherwise known as an English Electric Type 1, is a class of diesel-electric locomotive. In total, 228 locomotives in the class were built by English Electric between 1957 and 1968, the large number being in part b ...
(introduced 1957) Withdrawn hood unit types include: * British Rail 10800 *
British Rail Class 15 The British Rail Class 15 diesel locomotives, also known as the BTH Type 1, were designed by British Thomson-Houston, and built by the Yorkshire Engine Company and the Clayton Equipment Company, between 1957 and 1961. They were numbered D8200-D ...
*
British Rail Class 16 The British Rail Class 16 also known as the North British Type 1 was a type of diesel locomotive designed and manufactured by the North British Locomotive Company. A total of ten were produced, these being numbered D8400-D8409. The type was or ...
* British Rail Class 58


France

The term "hood unit" is not used in France but a few locomotives of the hood unit type are or were in service: * BB 63000 *
BB 66000 BB, Bb, or similar, may refer to: In arts and entertainment *BB, abbreviation for a catalogue of works by Béla Bartók#Catalogues and opus numbers, Béla Bartók * BB (album), ''BB'' (album), by Mod Sun (2017) *"BB Talk", 2015 song by Miley ...
*
BB 66400 BB, Bb, or similar, may refer to: In arts and entertainment *BB, abbreviation for a catalogue of works by Béla Bartók * ''BB'' (album), by Mod Sun (2017) *"BB Talk", 2015 song by Miley Cyrus * BB (Transformers), a character in the franch ...
* Y 8000


Turkey

Almost all Turkish locomotives have this design. Cab units recently imported and produced under licence.


Czechoslovakia

Locomotives of the hood unit type in Czech are: *
ChME3 The ČKD ČME3 is a six-axle diesel-electric locomotive built by ČKD. The class was used primarily for shunting and mainline duties. With over 8,000 produced during a production run of 31 years, it is one of the most produced locomotives in the ...


China

Locomotives of the hood unit type in China are: * China Railways DF2 * China Railways DF4DD *
China Railways DF5 The Dongfeng 5, or DF5 for short, () is a diesel-electric locomotive used by China Railway in the People's Republic of China. It has been in production since 1976 and is still produced as of 2006 by several local companies. It is the most comm ...
*
China Railways DF7 China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's List of countries and dependencies by population, most populous country, with a Population of China, population exceeding 1.4 billion, slig ...
* China Railways DF7B * China Railways DF7C * China Railways DF7E * China Railways DF7G * China Railways DF10DD * China Railways DF12 *
China Railways HXN3B China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's List of countries and dependencies by population, most populous country, with a Population of China, population exceeding 1.4 billion, slig ...