EMD SD24
Encyclopedia
The EMD SD24 was a 2,400 hp (1,800 kW) C-C diesel locomotive
built by General Motors' Electro-Motive Division of La Grange, Illinois
between July, 1958 and March, 1963. A total of 224 units were built for customers in the United States
, comprising 179 regular, cab-equipped locomotives and 45 cabless B unit
s. The latter were built solely for the Union Pacific Railroad
.
The SD24 was the first EMD locomotive to be built with an EMD turbocharged
diesel engine, sixteen months before the four-axle (B-B) model GP20
. Power output was substantially higher than the 1,800 hp (1,350 kW) of the concurrent Roots blower-equipped SD18s
with the same engine displacement
.
In terms of sales, the SD24 was only a moderate success, and few had long service lives in SD24 configuration (though a few rebuilds are still in operation), but the SD24 was a milestone in EMD locomotive development and the forerunner to today's high-powered six-axle locomotives.
controls, a steam generator
, dynamic brakes, winterization equipment, an air signal line, and hump control, but actually almost all delivered SD24s were very similar in configuration.
The standard fuel tank offered a 1,200 US gallon capacity, while 2,400 or 3,000 US gallon tanks were optional. In practice, all SD24s ordered had the 3,000 gallon tank except for the last built, Kennecott Copper's single locomotive. In order to provide room for a larger fuel tank, the air reservoirs were relocated on the roof just behind the locomotive's cab
. The tanks were known as "torpedo tubes" due to their long, thin design.
Winterization included a winterization hatch over one of the radiator fans, to direct warm air back into the engine compartment.
Either a low or high short hood
could be ordered; in either case, the short hood was front by default. The Burlington, Southern and first EMD demonstrator had high short hoods; all others were low. Low short hoods from the factory had a pronounced downward slope of the top towards the nose, as did those of the contemporary GP20. Many of the high short hood units had their noses chopped later on, often as a consequence of rebuilding; these as a rule have flat-topped short hoods.
rebuilt its fleet of eighty SD24 locomotives, naming the resulting type the SD26
. The rebuild boosted the power output of the locomotives by upgrading the 16-567D3
engines with EMD 645 power assemblies. Other work improved the reliability by replacing the entire electrical systems, and replacing the multiple body-side vents with a central air filtration system. The large box fitted high on the body behind the cab for the air filters required relocating the "torpedo tube" air reservoirs further back on the long hood, and gave the SD26 a noticeable "hump-backed" appearance. One unit was wrecked, 44 were traded to EMD in 1985 and 35 were sold to Guilford Rail System
in 1986. All have since been scrapped.
modified three SD24 locomotives experimentally to see if it would be worthwhile to upgrade their fleet of 30 such locomotives.
Unit 410 received the most minor modification: upgraded air filters.
UP 423, however, was substantially rebuilt to UP 3100 in August 1968 with a constant-speed 16-645
3,000 hp (2,240 kW) prime mover, a new alternator and new traction motors. With the constant-speed engine, speed control was via changing the level of excitation
of the alternator; the traction motors were permanently wired in parallel. New, variable dynamic brakes were also fitted, as was a self load feature enabling testing under load without an external electrical load apparatus. This latter feature became standard on later locomotive models. The constant-speed prime mover, on the other hand, was not successful enough to duplicate. The locomotive was from 1975 used as a heavy switcher
at UP's North Platte, Nebraska
hump yards, a fate common to UP's other surviving SD24s.
UP 414 did not receive as major a modification as #423, but it was refitted with a 16-645 engine, AR10 alternator and Dash Two electrical cabinet in May 1974, making it effectively a EMD SD40-2
. This was a testbed for a proposed upgrade of all UP's SD24s, but UP decided not to go ahead with the work. Both UP 3100 and UP 414 were classified as "SD24m" by the UP, but some UP internal documents class UP 414 as a "SD24-4".
SD24s were rebuilt by the Milwaukee Road
and Morrison Knudsen for Precision National's lease fleet in 1979. The turbochargers and dynamic brakes were removed, and Precision gave them class SD10. In 1980 more followed, though they were low-nose units of Union Pacific
origin. In 1982 the Chicago & North Western
bought 22 of the high-nose and four of the low-nose units. Producing 1800 horsepower (without the turbocharger,) they were designated model SD18R - not to be confused with actual SD18
locomotives as manufactured by General Motors Electro-Motive Division.
504, formerly Burlington Northern
6244 (which can be seen in the movie Groundhog Day
), has been restored at the Illinois Railway Museum
. Wisconsin Central
2402, ex-Fox River Valley
2402, ex-Burlington Northern
6255, originally Burlington
510 is at the National Railroad Museum
in Green Bay, WI, mechanically complete except for traction motors.
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...
built by General Motors' Electro-Motive Division of La Grange, Illinois
La Grange, Illinois
La Grange, a suburb of Chicago, is a village in Cook County, in the U.S. state of Illinois. The population was 15,608 at the 2000 census.-History:...
between July, 1958 and March, 1963. A total of 224 units were built for customers in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
, comprising 179 regular, cab-equipped locomotives and 45 cabless B unit
B unit
A "B" unit, in railroad terminology, is a locomotive unit which does not have a driving cab, or crew compartment, and must therefore be controlled from another, coupled locomotive with a driving cab . The term booster unit is also used. The concept was largely confined to North America...
s. The latter were built solely for the Union Pacific Railroad
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....
.
The SD24 was the first EMD locomotive to be built with an EMD turbocharged
Turbocharger
A turbocharger, or turbo , from the Greek "τύρβη" is a centrifugal compressor powered by a turbine that is driven by an engine's exhaust gases. Its benefit lies with the compressor increasing the mass of air entering the engine , thereby resulting in greater performance...
diesel engine, sixteen months before the four-axle (B-B) model GP20
EMD GP20
An EMD GP20 is a 4-axle diesel 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 2000 horsepower...
. Power output was substantially higher than the 1,800 hp (1,350 kW) of the concurrent Roots blower-equipped SD18s
EMD SD18
An EMD SD18 is a 6-axle diesel locomotive built by General Motors Electro-Motive Division between April 1960 and March 1963. Power was provided by an EMD 567D1 16-cylinder engine which generated 1800 horsepower ....
with the same engine displacement
Engine displacement
Engine displacement is the volume swept by all the pistons inside the cylinders of an internal combustion engine in a single movement from top dead centre to bottom dead centre . It is commonly specified in cubic centimeters , litres , or cubic inches...
.
In terms of sales, the SD24 was only a moderate success, and few had long service lives in SD24 configuration (though a few rebuilds are still in operation), but the SD24 was a milestone in EMD locomotive development and the forerunner to today's high-powered six-axle locomotives.
Options
Optional equipment that could be specified by ordering railroads included multiple unitMultiple unit
The term multiple unit or MU is used to describe a self-propelled carriages capable of coupling with other units of the same or similar type and still being controlled from one driving cab. The term is commonly used to denote passenger trainsets consisting of more than one carriage...
controls, a steam generator
Steam generator (railroad)
Steam generator is the term used to describe a type of boiler used to produce steam for climate control and potable water heating in railroad passenger cars...
, dynamic brakes, winterization equipment, an air signal line, and hump control, but actually almost all delivered SD24s were very similar in configuration.
The standard fuel tank offered a 1,200 US gallon capacity, while 2,400 or 3,000 US gallon tanks were optional. In practice, all SD24s ordered had the 3,000 gallon tank except for the last built, Kennecott Copper's single locomotive. In order to provide room for a larger fuel tank, the air reservoirs were relocated on the roof just behind the locomotive's 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....
. The tanks were known as "torpedo tubes" due to their long, thin design.
Winterization included a winterization hatch over one of the radiator fans, to direct warm air back into the engine compartment.
Either a low or high short hood
Short hood
The short hood of a hood unit-style diesel locomotive is, as the name implies, the shorter of the two hoods on a locomotive...
could be ordered; in either case, the short hood was front by default. The Burlington, Southern and first EMD demonstrator had high short hoods; all others were low. Low short hoods from the factory had a pronounced downward slope of the top towards the nose, as did those of the contemporary GP20. Many of the high short hood units had their noses chopped later on, often as a consequence of rebuilding; these as a rule have flat-topped short hoods.
Original purchasers
| Railroad | Qty | Road numbers | Notes |
|---|---|---|---|
| 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... |
80 | 900–979 | Guilford Rail System Pan Am Railways Pan Am Railways, Inc. , known as Guilford Rail System before March 2006, is a holding company that owns and operates Class II regional railroads covering northern New England from Mattawamkeag, Maine to Rotterdam Junction, New York... purchased 35 in 1986; all have since been scrapped. |
| Burlington Route Chicago, Burlington and Quincy Railroad The Chicago, Burlington and Quincy Railroad was a railroad that operated in the Midwestern United States. Commonly referred to as the Burlington or as the Q, the Burlington Route served a large area, including extensive trackage in the states of Colorado, Illinois, Iowa, Kentucky, Missouri,... |
16 | 500–515 | High short hood, to 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.... 6240–6255. |
| General Motors-EMD (demonstrators) | 4 | 5579 and 7200–7202 | 5579 first SD24 build, high hood; 7200–7202 next to last built, low hood. All sold to UP 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.... as numbers 448 (EMD 5579) and 445 – 447 (EMD 7200 – 7202). |
| Kennecott Copper | 1 | 904 | Last SD24 ordered, turbocharging required due to high altitude operation. Small fuel tank fitted, only SD24 not to have "torpedo tube" air reservoirs. No MU fitted. |
| Southern Southern Railway (US) The Southern Railway is a former United States railroad. It was the product of nearly 150 predecessor lines that were combined, reorganized and recombined beginning in the 1830s, formally becoming the Southern Railway in 1894... |
48 | SOU 2502–2524, CNTP 6305 – 6325, NO&NE 6950–6953 |
High short hood |
| 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.... |
75 | 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... s 400–429, B unit B unit A "B" unit, in railroad terminology, is a locomotive unit which does not have a driving cab, or crew compartment, and must therefore be controlled from another, coupled locomotive with a driving cab . The term booster unit is also used. The concept was largely confined to North America... s 400B–444B |
Rebuilds
As the SD24 locomotives aged, they began to develop reliability problems, especially electrical ones. In addition, the extra maintenance requirements of the turbocharged engine were acceptable when they were some of the most powerful locomotives available, but in secondary service, they were an expensive way to get 2,400 hp. Thus, a large number of SD24s were rebuilt by various owners to extend their lives.Santa Fe SD26
From January, 1973 through January, 1978 the Atchison, Topeka and Santa Fe RailwayAtchison, 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...
rebuilt its fleet of eighty SD24 locomotives, naming the resulting type the SD26
SD26
The SD26 is an EMD SD24 diesel locomotive that was rebuilt by the Atchison, Topeka and Santa Fe Railway between January 1973 and January 1978. In an effort to spare the cost of purchasing new motive power, the Santa Fe elected to expand on the success of its CF7 and other capital rebuild programs...
. The rebuild boosted the power output of the locomotives by upgrading the 16-567D3
EMD 567
The EMD 567 is a line of diesel engines built by General Motors' Electro-Motive Division. This engine, which succeeded Winton's 201-A, was used in EMD's locomotives from 1938 until its replacement in 1966 by the EMD 645. It has a bore of , a stroke of and a displacement of 567 in³ per cylinder...
engines with EMD 645 power assemblies. Other work improved the reliability by replacing the entire electrical systems, and replacing the multiple body-side vents with a central air filtration system. The large box fitted high on the body behind the cab for the air filters required relocating the "torpedo tube" air reservoirs further back on the long hood, and gave the SD26 a noticeable "hump-backed" appearance. One unit was wrecked, 44 were traded to EMD in 1985 and 35 were sold to Guilford Rail System
Pan Am Railways
Pan Am Railways, Inc. , known as Guilford Rail System before March 2006, is a holding company that owns and operates Class II regional railroads covering northern New England from Mattawamkeag, Maine to Rotterdam Junction, New York...
in 1986. All have since been scrapped.
Union Pacific SD24m
The Union Pacific RailroadUnion 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....
modified three SD24 locomotives experimentally to see if it would be worthwhile to upgrade their fleet of 30 such locomotives.
Unit 410 received the most minor modification: upgraded air filters.
UP 423, however, was substantially rebuilt to UP 3100 in August 1968 with a constant-speed 16-645
EMD 645
The EMD 645 family of diesel engines was designed and manufactured by the Electro-Motive Division of General Motors. Intended primarily for locomotive, marine and stationary engine use, one 16-cylinder version powered the 33-19 "Titan" prototype haul truck designed by GM's Terex...
3,000 hp (2,240 kW) prime mover, a new alternator and new traction motors. With the constant-speed engine, speed control was via changing the level of excitation
Excitation (magnetic)
An electric generator or electric motor consists of a rotor spinning in a magnetic field. The magnetic field may be produced by permanent magnets or by field coils. In the case of a machine with field coils, a current must flow in the coils to generate the field, otherwise no power is transferred...
of the alternator; the traction motors were permanently wired in parallel. New, variable dynamic brakes were also fitted, as was a self load feature enabling testing under load without an external electrical load apparatus. This latter feature became standard on later locomotive models. The constant-speed prime mover, on the other hand, was not successful enough to duplicate. The locomotive was from 1975 used as a heavy switcher
Switcher
A switcher or shunter is a small railroad locomotive intended not for moving trains over long distances but rather for assembling trains ready for a road locomotive to take over, disassembling a train that has been...
at UP's North Platte, Nebraska
North Platte, Nebraska
North Platte is a city in and the county seat of Lincoln County, Nebraska, United States. It is located in the southwestern part of the state, along Interstate 80, at the confluence of the North and South Platte Rivers forming the Platte River...
hump yards, a fate common to UP's other surviving SD24s.
UP 414 did not receive as major a modification as #423, but it was refitted with a 16-645 engine, AR10 alternator and Dash Two electrical cabinet in May 1974, making it effectively a EMD SD40-2
EMD SD40-2
The EMD SD40-2 is a C-C locomotive produced by EMD from 1972 to 1989.The SD40-2 was first introduced in January 1972 as the mid-range offering in EMD's six-axle "Dash-2" series, competing against the GE U30C and the MLW M630...
. This was a testbed for a proposed upgrade of all UP's SD24s, but UP decided not to go ahead with the work. Both UP 3100 and UP 414 were classified as "SD24m" by the UP, but some UP internal documents class UP 414 as a "SD24-4".
CNW SD18R
Several high-nose SouthernSouthern Railway (US)
The Southern Railway is a former United States railroad. It was the product of nearly 150 predecessor lines that were combined, reorganized and recombined beginning in the 1830s, formally becoming the Southern Railway in 1894...
SD24s were rebuilt by the Milwaukee Road
Chicago, Milwaukee, St. Paul and Pacific Railroad
The Milwaukee Road, officially the Chicago, Milwaukee, St. Paul and Pacific Railroad , was a Class I railroad that operated in the Midwest and Northwest of the United States from 1847 until its merger into the Soo Line Railroad on January 1, 1986. The company went through several official names...
and Morrison Knudsen for Precision National's lease fleet in 1979. The turbochargers and dynamic brakes were removed, and Precision gave them class SD10. In 1980 more followed, though they were low-nose units of 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....
origin. In 1982 the Chicago & North Western
Chicago and North Western Railway
The Chicago and North Western Transportation Company was a Class I railroad in the Midwest United States. It was also known as the North Western. The railroad operated more than of track as of the turn of the 20th century, and over of track in seven states before retrenchment in the late 1970s...
bought 22 of the high-nose and four of the low-nose units. Producing 1800 horsepower (without the turbocharger,) they were designated model SD18R - not to be confused with actual SD18
EMD SD18
An EMD SD18 is a 6-axle diesel locomotive built by General Motors Electro-Motive Division between April 1960 and March 1963. Power was provided by an EMD 567D1 16-cylinder engine which generated 1800 horsepower ....
locomotives as manufactured by General Motors Electro-Motive Division.
Preservation
At least two SD24s survive in museums. Chicago Burlington & QuincyChicago, Burlington and Quincy Railroad
The Chicago, Burlington and Quincy Railroad was a railroad that operated in the Midwestern United States. Commonly referred to as the Burlington or as the Q, the Burlington Route served a large area, including extensive trackage in the states of Colorado, Illinois, Iowa, Kentucky, Missouri,...
504, formerly 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....
6244 (which can be seen in the movie Groundhog Day
Groundhog Day (film)
Groundhog Day is a 1993 American comedy film directed by Harold Ramis, starring Bill Murray and Andie MacDowell. It was written by Ramis and Danny Rubin, based on a story by Rubin....
), has been restored at the Illinois Railway Museum
Illinois Railway Museum
The Illinois Railway Museum is the largest railroad museum in the United States and is located in Union, Illinois, northwest of Chicago...
. Wisconsin Central
Wisconsin Central Railway
The original Wisconsin Central Railroad Company was established by an act of the Wisconsin State Legislature and incorporated in February 1871. It built track throughout Wisconsin, connecting to neighboring states, before being leased to Northern Pacific Railway between 1889–1893...
2402, ex-Fox River Valley
Fox River Valley Railroad
The Fox River Valley Railroad was a short-lived railroad in eastern Wisconsin from 1988 to 1993 with about 214 miles of track, all of which was former Chicago and North Western Railway trackage. The line ran from Green Bay, Wisconsin to the north side of Milwaukee. Owned by the Itel Rail...
2402, ex-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....
6255, originally Burlington
Chicago, Burlington and Quincy Railroad
The Chicago, Burlington and Quincy Railroad was a railroad that operated in the Midwestern United States. Commonly referred to as the Burlington or as the Q, the Burlington Route served a large area, including extensive trackage in the states of Colorado, Illinois, Iowa, Kentucky, Missouri,...
510 is at the National Railroad Museum
National Railroad Museum
The National Railroad Museum is a railroad museum located in Ashwaubenon, Wisconsin, in suburban Green Bay.The museum is one of the oldest institutions in the United States dedicated to preserving and interpreting the nation's railroad history. It was founded in 1956 by community volunteers in...
in Green Bay, WI, mechanically complete except for traction motors.
External links
- EMD SD24 Diagram at the Illinois Railway Museum official website.
