B unit
Encyclopedia
A "B" unit, in railroad terminology
Rail terminology
Rail terminology is a form of technical terminology. The difference between the American term railroad and the international term railway is the most obvious difference in rail terminology...
, is a locomotive
Locomotive
A locomotive is a railway vehicle that provides the motive power for a train. The word originates from the Latin loco – "from a place", ablative of locus, "place" + Medieval Latin motivus, "causing motion", and is a shortened form of the term locomotive engine, first used in the early 19th...
unit (generally a diesel locomotive
Diesel locomotive
A diesel locomotive is a type of railroad locomotive in which the prime mover is a diesel engine, a reciprocating engine operating on the Diesel cycle as invented by Dr. Rudolf Diesel...
) which does not have a driving cab
Cab (locomotive)
The cab, crew compartment or driver's compartment of a locomotive is the part of the locomotive housing the train driver or engineer, the fireman or driver's assistant , and the controls necessary for the locomotive's operation....
, or crew compartment, and must therefore be controlled from another, coupled
Coupling (railway)
A coupling is a mechanism for connecting rolling stock in a train. The design of the coupler is standard, and is almost as important as the railway gauge, since flexibility and convenience are maximised if all rolling stock can be coupled together.The equipment that connects the couplings to the...
locomotive with a driving cab (an A unit
A unit
An A unit, in railroad terminology, is a locomotive equipped with a driving cab, or crew compartment, and the control system to control other locomotives in a multiple unit, and therefore able to be the lead unit in a consist of several locomotives controlled from a single position...
). The term booster unit is also used. The concept was largely confined to North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
. Elsewhere, locomotives without driving cabs were rare.
Controls
Some "B" units cannot be moved without a controlling unit attached, but most have some simple controls inside, and often a side window at that control station. For example, B unit versions of the EMD FTEMD FT
The EMD FT was a diesel-electric locomotive produced between November 1939, and November 1945, by General Motors' Electro-Motive Division . All told 555 cab-equipped A units were built, along with 541 cabless booster B units, for a grand total of 1,096 units. The locomotives were all sold to...
with conventional couplers had a fifth porthole-style window added on the right side only for the control station. Other models used existing windows. These controls enable a hostler to move the B-unit locomotive by itself in a yard or shops. A hostler is an employee permitted to move locomotives within the confines of a yard or shops complex, but not on the main railroad. B units without controls are generally semi-permanently coupled to controlling units. Sometimes, there is a terminology distinction between the types: a booster is a B unit with hostler controls, and a slave is a B unit without hostler controls.
Reasons for use
The reasons railroads ordered B units included the fact that a B unit was slightly cheaper. With no driving cab, B units lack windshields, crew seats, radios, heating, and air conditioning. There would also be no toilets, which were usually found in the short hood of an A unit. In the early days of dieselization, there was also no argument from the railroad unions that a B unit deserved a second crew; this was a major point of contention for a while. Additionally, at first, railroads bought multiple-unit diesel locomotives as one for one replacements for steam locomotives; the flexibility of interchangeable units which could be assembled into any power output the railroad desired was not well realised. When a three or four unit locomotive was considered an indivisible unit, there was no point in the intermediate units having cabs. Finally, B units gave a smoother line to the train for passenger service.The B unit era
B units were commonly built in the cab unitCab unit
A cab unit and a carbody unit are body styles of locomotives in railroad terminology. While closely related, they are not exactly the same....
days in the 1930s, 1940s and 1950s. When hood unit
Hood unit
A hood unit, in railroad terminology, is a body style for diesel and electric locomotives. On a hood unit, the body of the locomotive is less than full-width for most of the locomotive's length, with walkways on the outside of the locomotive. In contrast, a cab unit has a full-width carbody for...
road switcher
Road switcher
A road switcher is a type of railroad locomotive used for delivering or picking up cars outside of a railroad yard. Since the road switcher must work some distance away from a yard, it needs to be able to operate at road speeds, it must also have high-visibility while it is switching, and it must...
s became the common kind of diesel locomotive, some B units were built, but many railroads soon came to the opinion that the lower cost of a B unit did not offset the lack of operational flexibility. Few B units have been built in the last 40 years. Railroads that kept ordering B units longer than most were largely Western roads, including the Union Pacific
Union Pacific Railroad
The Union Pacific Railroad , headquartered in Omaha, Nebraska, is the largest railroad network in the United States. James R. Young is president, CEO and Chairman....
, Burlington Northern
Burlington Northern Railroad
The Burlington Northern Railroad was a United States-based railroad company formed from a merger of four major U.S. railroads. Burlington Northern operated between 1970 and 1996....
, and the Santa Fe
Atchison, Topeka and Santa Fe Railway
The Atchison, Topeka and Santa Fe Railway , often abbreviated as Santa Fe, was one of the larger railroads in the United States. The company was first chartered in February 1859...
. Santa Fe ordered the GP60B model in 1991, which were the final B units built for road service in North America as of 2005. However they're experiencing a comeback of sorts recently for radio controlled yard switching units, which don't require a traditional cab.
Conversions
In some cases, a B unit is converted from an already existing A unit. The cab is either removed or has its windows blanked out (such as on CSX GE BQ23-7GE BQ23-7
The GE BQ23-7 was a model of diesel locomotive manufactured by General Electric, a variant of the B23-7 built between 1978 and 1979 . Identical to a regular B23-7, but equipped with an enlarged operating cab for accommodating the train crew, thus making a case for eliminating the caboose from the...
units), and all non-essential equipment is removed. The degree to which this equipment is removed depends on the railroad, but may (and usually) include the removal of the speedometer, event recorder, horn, headlights, toilet, and cab heaters. This conversion was sometimes performed when the A unit had been in a collision and rebuilding the cab was not cost-effective. And in some rare instances, B units were converted to incorporate a cab, such as on the Chicago & North Western Railway in the 1970s with some EMD E8
EMD E8
The EMD E8 was a , A1A-A1A passenger train locomotive manufactured by General Motors' Electro-Motive Division of La Grange, Illinois. The cab version, or E8A, was manufactured from August, 1949 to December, 1953, and 449 were produced – 446 for U.S., and 3 for Canada...
B units bought from the Union Pacific. The homebuilt cabs were referred to as "Crandall Cabs." Also, the Santa Fe rebuilt four of its five GP7Bs
EMD GP7
The EMD GP7 is a four-axle diesel-electric locomotive built by General Motors Electro-Motive Division and General Motors Diesel between October, 1949 and May, 1954. Power was provided by an EMD 567B 16-cylinder engine which generated . The GP7 was offered both with and without control cabs, and...
to GP9us with cabs. In the Illinois Central Gulf's GP11 rebuild program, some of the engines used were ex-UP GP9Bs, and in their SD20 program, some ex-UP SD24Bs were also used.
Unusual consists
In rare instances, a B unit will run at the front of a train. This is avoided because it limits visibility from the locomotive cab, but locomotive orientation and operational requirements may dictate the B-unit running first. See this photo of a SD40-2/SD45-2B, a GP30/GP30B and GP35/GP9B for examples.List of B unit locomotive models
Slug (railroad)
A railroad slug is an accessory to a diesel-electric locomotive. It has trucks with traction motors but is unable to move about under its own power, as it does not contain a prime mover to produce electricity...
s and snail
Rotary snowplow
A rotary snowplow is a piece of railroad snowfighting equipment. It is characterized by the large circular set of blades on its front end that rotate as a unit to cut through the snow on the track ahead of it.-History:...
s are not listed. Cow-calf
Cow-calf
In North American railroading, a cow-calf locomotive is a set of switcher-type diesel locomotives. The set usually is a pair; some 3-unit sets were built, but this was rare. A cow is equipped with a driving cab; a calf is not...
units are also not listed, since these were considered a single locomotive. The New York City Revenue cars 66 and 67 were R8A units which were B units also.
United States
Factory-built:- ALCO/MLWMontreal Locomotive WorksMontreal Locomotive Works was a Canadian railway locomotive manufacturer which existed under several names from 1883–1985, producing both steam and diesel locomotives. For a number of years it was a subsidiary of the American Locomotive Company...
- Black Maria Booster, DL-108, DL-110, FB-1, FB-2, FPB-2, FPB-4, PB-1, PB-2, C855B, M420B - BaldwinBaldwin Locomotive WorksThe Baldwin Locomotive Works was an American builder of railroad locomotives. It was located in Philadelphia, Pennsylvania, originally, and later in nearby Eddystone, Pennsylvania. Although the company was very successful as a producer of steam locomotives, its transition to the production of...
- AS-616BBaldwin AS-616The Baldwin AS-616 was a diesel-electric locomotive of the road switcher type rated at , that rode on three-axle trucks, having a C-C wheel arrangement.Nineteen railroads bought 214 locomotives, and two railroads bought seven cabless B units....
, DRS-6-6-1500B, DR-4-4-15BBaldwin DR-4-4-15The Baldwin DR-4-4-15 was a cab unit-type diesel locomotive built for freight service by the Baldwin Locomotive Works between November 1947 and June 1950. It was produced in two different body types, nicknamed the "Babyface" and "Sharknose" styles by railfans, though Baldwin used the same model...
, RF-16BBaldwin RF-16The Baldwin RF-16 is a cab unit-type diesel locomotive built for freight service by the Baldwin Locomotive Works between 1950 and 1953. All RF-16s were configured with a B-B wheel arrangement and ran on two AAR Type B two-axle road trucks, with all axles powered. A total of 109 cab-equipped A...
, DR-6-4-15B, DR-6-4-20B - EMD E units - EB, E1B, E2B, E3B, E4B, E5BEMD E5The EMD E5 was a , A1A-A1A passenger train-hauling diesel locomotive manufactured by Electro-Motive Corporation, and its corporate successor, General Motors' Electro-Motive Division of La Grange, Illinois, and produced exclusively for the Chicago, Burlington and Quincy Railroad , and its...
, E6BEMD E6The EMD E6 was a , A1A-A1A, passenger train locomotive manufactured by Electro-Motive Corporation, and its corporate successor, General Motors Electro-Motive Division, of La Grange, Illinois. The cab version, or E6A, was manufactured from November, 1939 to September, 1942, and 91 were produced...
, E7BEMD E7The EMD E7 was a , A1A-A1A passenger train locomotive manufactured by General Motors' Electro-Motive Division of La Grange, Illinois. The cab version, or E7A, was manufactured from February, 1945 to April, 1949, and 428 were produced. The booster version, or E7B, was manufactured from March, 1945...
, E8BEMD E8The EMD E8 was a , A1A-A1A passenger train locomotive manufactured by General Motors' Electro-Motive Division of La Grange, Illinois. The cab version, or E8A, was manufactured from August, 1949 to December, 1953, and 449 were produced – 446 for U.S., and 3 for Canada...
, E9BEMD E9The EMD E9 was a , A1A-A1A passenger train-hauling diesel locomotive built by General Motors' Electro-Motive Division of La Grange, Illinois between April 1954 and January 1964. 100 cab-equipped lead A units were produced, along with 44 cabless booster B units. All were for service within the... - EMD F-unitEMD F-unitEMD F-units were a line of Diesel-electric locomotives produced between November 1939 and November 1960 by General Motors Electro-Motive Division and General Motors-Diesel Division. Final assembly for all F-units was at the GM-EMD plant at La Grange, Illinois and the GMDD plant in London, Ontario...
s - FTBEMD FTThe EMD FT was a diesel-electric locomotive produced between November 1939, and November 1945, by General Motors' Electro-Motive Division . All told 555 cab-equipped A units were built, along with 541 cabless booster B units, for a grand total of 1,096 units. The locomotives were all sold to...
, F2BEMD F2The EMD F2 was a freight-hauling diesel locomotive built by General Motors Electro-Motive Division between July 1946 and November 1946. It succeeded the FT model in GM-EMD's F-unit sequence, and was replaced in turn by the F3...
, F3BEMD F3The EMD F3 was a , B-B freight- and passenger-hauling diesel locomotive produced between July 1945 and February 1949 by General Motors’ Electro-Motive Division. Final assembly was at GM-EMD's La Grange, Illinois plant...
, F7BEMD F7The EMD F7 was a Diesel-electric locomotive produced between February 1949 and December 1953 by the Electro-Motive Division of General Motors and General Motors Diesel . It succeeded the F3 model in GM-EMD's F-unit sequence, and was replaced in turn by the F9. Final assembly was at GM-EMD's La...
, F9BEMD F9The EMD F9 was a Diesel-electric locomotive produced between February 1953 and May 1960 by the Electro-Motive Division of General Motors and General Motors Diesel . It succeeded the F7 model in GM-EMD's F-unit sequence. Final assembly was at GM-EMD's La Grange, Illinois plant. The F9 was also... - EMD Hood unitHood unitA hood unit, in railroad terminology, is a body style for diesel and electric locomotives. On a hood unit, the body of the locomotive is less than full-width for most of the locomotive's length, with walkways on the outside of the locomotive. In contrast, a cab unit has a full-width carbody for...
s – DD35EMD DD35The 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. In the early 1960s Union Pacific started asking for a 15,000 hp 3-unit locomotive set to replace the turbines...
, GP7B, GP9B, GP30B, GP60B, SD24B - Fairbanks-MorseFairbanks-MorseFairbanks Morse and Company was a manufacturing company in the late 19th and early 20th century. Originally a weighing scale manufacturer, it later diversified into pumps, engines, windmills, locomotives and industrial supplies until it was merged in 1958...
- B ErieFM Erie-builtThe Erie-built was the first streamlined, cab-equipped dual service diesel locomotive built by Fairbanks-Morse, introduced as direct competition to such models as the ALCO PA and EMD E-unit...
, CFB-16-4, CFB-20-4, CPB-16-4, CPB-16-5 - GE Transportation SystemsGE Transportation SystemsGE Transportation, formerly known as GE Rail, is a division of General Electric. The organization manufactures equipment for the railroad, marine, mining, drilling and energy generation industries. It is based in Erie, Pennsylvania. Locomotives are assembled at the Erie plant, while engine...
- UM20B booster, B30-7A
Rebuilds:
- EMD Hood unitHood unitA hood unit, in railroad terminology, is a body style for diesel and electric locomotives. On a hood unit, the body of the locomotive is less than full-width for most of the locomotive's length, with walkways on the outside of the locomotive. In contrast, a cab unit has a full-width carbody for...
s - GP38-2BEMD GP38-2An EMD GP38-2 is a four-axle diesel-electric locomotive of the road switcher type 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...
(by BN), SD40BEMD SD40The EMD SD40 is a 6-axle diesel locomotive built by General Motors Electro-Motive Division between January 1966 and August 1972.-Design:Like its predecessor in EMD's catalog, the SD35, the SD40 is a high-horsepower, six-motor freight locomotive....
(by BN), SD40-2B (by BN), SD45BEMD SD45The EMD SD45 is a six-axle diesel locomotive built by General Motors Electro-Motive Division between December, 1965, and December, 1971. Power was provided by an EMD 645E3 twenty-cylinder engine which generated 3,600 HP. This locomotive shared the same common frame with the EMD SD38, EMD SD39, EMD...
(by ATSF), SD45-2B (by ATSF)
- GE Transportation SystemsGE Transportation SystemsGE Transportation, formerly known as GE Rail, is a division of General Electric. The organization manufactures equipment for the railroad, marine, mining, drilling and energy generation industries. It is based in Erie, Pennsylvania. Locomotives are assembled at the Erie plant, while engine...
- U30CBGE U30CThe GE U30C was one of the earliest successes from General Electric in the diesel locomotive market. With 600 units sold, the U30C proved to be a choice for customers who weren't able to purchase SD40's or SD40-2's from EMD due to mass orders...
(by BN; MP also operated a cabless U30C but did not give it this designation), B36-7 (B)GE B36-7The GE B36-7 is a 4-axle diesel locomotive built by GE Transportation Systems between 1980 and 1985. 222 examples of this locomotive were built for North American railroads and eight units were built for a Columbian coal mining operation. The units were designed as successors to GE's U36B's...
(by SSW)
Australia
- Pacific National XRB classPacific National XRB classThe XRB class diesel electric locomotives were introduced by Pacific National in 2005. Built at the South Dynon workshops in Victoria, the XRB class are mechanically similar to the XR class, but are B units without driving cabs. The class are primarily used as middle units on standard gauge...
- CM40-8ML - cabless version of C40-8 built on C636 frames for BHP. See http://www.pilbararailways.com.au/bhp/loco/dash8/dash8.htm and http://www.pilbararailways.com.au/bhp/loco/bhpb-roster.html
- Australian National BU class - built from the existing 600 class. All currently in storage.