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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.
The long hood normally contains the diesel engine (prime mover), the main generator or alternator, the locomotive's cooling radiators, the dynamic brake resistor grids if fitted, and most of the locomotive's auxiliary equipment. Head-end power equipment, if fitted, is normally in the long hood; steam generators for heating older passenger cars may be either in the long or short hoods.
Normally, the long hood is the rear of the locomotive. For early hood unit models, this was not the case; railroads preferred to run with the long hood at the front and the cab at the rear (referred to as operating long hood forward or LHF). This is a holdover from the steam era of railroads where almost all locomotives were built with the cab placed at the rear of the locomotive. It is a common misconception that locomotives were run LHF to provide greater protection, although it may have been a secondary benefit. Southern Railway and Norfolk and Western Railway operated their locomotives bidirectionally to make coal shifting more efficient. By putting the engineer on the right side with the Long Hood Forward, the engineer could see signals down the long hood and around the short hood for operations in both directions. [1] Later, preferences changed to having the short hood at the front and the long hood at the rear for better visibility and with the advent of Wide, or Comfort, cabs. Visibility became a deciding factor when more powerful engines required larger, visibility-obscuring radiator units.
The railroads that held out the longest for long-hood leading were the Norfolk and Western Railway and the Southern Railway (later merged into the Norfolk Southern Railway). When Southern Railway received their first EMD GP7s, they were delivered with a high short hood, and Southern Railway pointed the locomotive LHF for crew safety. After the first GP7s hit the Southern Railway System, subsequent locomotives were ordered with the high short hood and the long hood designated (starting after the SD45 order) as the front. Here is a list of each locomotive Southern ordered with a high short hood, and operated LHF.
(note: the SD50 and the GP59 are the first units ordered with the low, short hood, and pointed LHF)
The Norfolk and Western Railway (NW) operated as Southern Railway did, with the long hood toward the front; the only difference between NW locomotives and Southern locomotives was the position of the bell. NW had the bell on the short hood while Southern had the bell on the long hood.
Many early diesel locomotive builders designated the long hood end of their road switchers as the front. Examples include models manufactured by the American Locomotive Company and Baldwin Locomotive Works.
Long hood forward is a fading practice. Most modern locomotives produced in the USA feature wide-nose Canadian comfort cabs with desktop style controls, which bar the ability to operate the unit long hood forward because the desktop style prevents the engineer from turning in his or her chair to face the other end of the locomotive.
The term 'long hood forward' is not used in Britain, as the hood would be described as a "bonnet" or "engine compartment". Most British diesel locomotives have a cab at each end, so the term does not apply. Where a single-cab design was used, it was designed to be operated long hood forward, but, in practice, it might operate in either direction, like a steam tank locomotive. Apart from shunters, the only single-cab class still in service in Britain is the class 20. These are now usually operated cab forward (often in pairs) to give the driver a better view of the track ahead, while some have been fitted with nose-mounted video cameras for use when working long hood forward. [ citation needed ]
Philippine National Railways is operating long hood forward on their locomotives on passenger operations depending on what direction the locomotive is facing.
PT Kereta Api Indonesia formerly operated locomotives long hood forward for both passenger & freight operations. It now operates most trains short hood forward for safety reasons, but at least one train still runs long hood forward. [ citation needed ]
The SD80MAC was a 5,000 horsepower (3.7 MW) 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 series. It introduced a wide radiator housing similar to GE Transportation locomotives and the placement of dynamic brakes at the rear of the locomotive, which is a quieter location, features that were incorporated into the SD90MAC and SD70ACe models. Key spotting differences between the SD80MAC and SD90MAC include no external rear sandbox on the SD90MAC, no rear lighted number boards on the SD90MAC, and the placement of the front numberboards. The SD80MAC also had recessed red marker lights in the nose, an identifying feature unique to Conrail (CR) locomotives, although Norfolk Southern (NS) had removed the lights on most of their former Conrail engines.
A cowl unit is a diesel locomotive with full-width, enclosing bodywork, similar in appearance to the cab unit-style of earlier locomotives, such as the EMD F-units of the 1940s and 1950s. The term cowl unit is of North American origin, although similarly-styled locomotives exist elsewhere.
The EMD GP30 is a 2,250 hp (1,680 kW) 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 Canada, including 40 cabless B units for the Union Pacific Railroad.
A hood unit, in North American railroad terminology, is a body style for diesel and electric locomotives where the body is less than full-width for most of its length and walkways are on the outside. In contrast, a cab unit 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 is the main load-bearing member, allowing the hood to be non-structural and easily opened or even removed for maintenance.
In North American railroad terminology, a cab unit is a railroad locomotive with its own cab and controls.
A road switcher locomotive 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.
The EMD SD40-2 is a 3,000-horsepower (2,200 kW) C-C diesel-electric locomotive built by EMD from 1972 to 1989.
The EMD NW5 was a 1,000 hp (750 kW) road switcher diesel-electric locomotive built by General Motors Electro-Motive Division of La Grange, Illinois between December 1946 and February 1947.
The EMD Dash 2 is a line of diesel-electric locomotives introduced by General Motors' Electro-Motive Division (EMD) on January 1, 1972. Designations of these models were those of the former models with "-2" added. They retained the basic specifications of the earlier models in terms of power output and most other features, but introduced a number of improvements to the locomotives' internal systems, specifically the electrical systems and the trucks of the locomotives. These were intended to improve availability, efficiency, and ease of maintenance.
The EMD SD50 is a 3,500-horsepower (2,610 kW) 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 2 series which was produced throughout the 1970s and the microprocessor-equipped SD60 and SD70 locomotives. A total of 431 were built.
The EMD SD60 is a 3,800 horsepower (2,800 kW), 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.
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.
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-cylinder engine, which generates 2,000 horsepower.
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 electronics was developed and marketed as a new locomotive, the SD40-2.
An SDP40 is a 6-axle passenger diesel-electric locomotive built by General Motors Electro-Motive Division (EMD) between June 1966 and May 1970.
The SD45 is a six-axle diesel-electric locomotive class built by General Motors Electro-Motive Division between 1965 and 1971. It has an EMD 645E3 twenty-cylinder engine generating 3,600 hp (2,680 kW) on the same frame as the SD38, SD39, SD40, and SDP40. As of 2023, most SD45s have been retired, scrapped or rebuilt to SD40-2 standards.
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 and 1974, primarily for the Atchison, Topeka and Santa Fe Railway (ATSF). The SD45-2 was an improved version of the EMD SD45; the primary visual difference is the absence of flared radiators on the SD45-2.
The SD45T-2 is a model of diesel-electric locomotive built by EMD for the Southern Pacific Railroad. Like the later SD40T-2 it is colloquially nicknamed a tunnel motor. 247 total units were produced from February 1972 to June 1975, including 84 for SP's subsidiary Cotton Belt. From April 1986 to December 1989, 126 were rebuilt and re-designated as SD45T-2R, including 24 for Cotton Belt.
The Krauss-Maffei ML 4000 is a road switcher diesel-hydraulic locomotive, built between 1961 and 1969 by German manufacturer Krauss-Maffei in Munich, Germany. It generated 3,540 horsepower (2,640 kW) from two Maybach V16 engines. 37 examples were built for two North American railroads and one South American railroad.
A B unit, in railroad terminology, is a locomotive unit which does not have a control cab or crew compartment, and must therefore be operated in tandem with another coupled locomotive with a cab. The terms booster unit and cabless are also used. The concept is largely confined to North America and post-Soviet countries. Elsewhere, locomotives without driving cabs are rare.