PRR S1
Encyclopedia
The PRR
S1 class steam locomotive
(nicknamed "The Big Engine") was an experimental locomotive that was the largest rigid frame passenger locomotive ever built. The streamlined
Art Deco
styled shell of the locomotive was designed by Raymond Loewy
.
The S1 was the only locomotive ever built to use a 6-4-4-6
wheel arrangement
. Also, the S1 class was a duplex locomotive
, meaning that it had two pairs of cylinder
s, each driving two pairs of driving wheel
s. Unlike similar-looking articulated locomotive
designs, the driven wheelbase of the S1 was rigid. The S1 was completed January 31, 1939 and was assigned locomotive number 6100.
At 140 foot over engine and tender the S1 was the longest reciprocating steam locomotive ever built; it could not negotiate curves on much of the PRR system. This problem, along with wheel slippage, limited the S1's usefulness. No further S1 models were built as focus shifted to the T1
class. The last run for the S1 was in December 1945 and the engine was scrapped in 1949.
officials decided to build a new passenger locomotive to replace its aging K4s locomotive. The PRR officials also hoped that the new S1 steam locomotive would have performance equal to their GG1 electric locomotive.
In a collaborative effort, the Pennsylvania Railroad, Baldwin Locomotive Works
, the Lima Locomotive Works
and the American Locomotive Company
contributed to the experimental S1 design.
The S1 was the largest express passenger locomotive ever constructed, with an overall length was 140 foot. At 77 feet (23.5 m) long and a weight of 97600 pounds (44.3 t), the cast steel locomotive bed
plate made by General Steel Castings
was the largest single-piece casting ever made for a locomotive application.
The boiler unit for the S1 was the largest built by the Pennsylvania Railroad. The six-wheel leading and trailing trucks were added, as the locomotive's design became too heavy for four-wheel units. However, the locomotive was still overweight by a significant margin. The streamlined
Art Deco
styled shell of the locomotive was designed by Raymond Loewy
, for which he received U.S. Patent No. 2,128,490
The final construction cost for the S1 was $669,780.00.
The S1 was displayed at the New York World's Fair
of 1939 with the lettering "American Railroads" rather than "Pennsylvania Railroad", as 27 eastern railroads had one combined 17 acres (6.9 ha) exhibit, which also included the Baltimore & Ohio's duplex locomotive
. To reach the New York World's Fair, the S1 took a circuitous route over the Long Island Rail Road
. Many obstacles had to be temporarily removed and other obstacles were passed at a slow crawl to reach the fairgrounds. At the World's Fair the S1 was a dynamic display; the drive wheels operated under the locomotive's own steam power. This was done by placing the S1 on a platform that had rollers under the drive wheels. By using this type of display, visitors could see the duplex drive in use. After the World's Fair, the S1 was relettered and numbered for use in the Pennsylvania Railroad fleet. The S1 was used by the PRR for publicity purposes as well and its image was featured in calendars and brochures.
The S1 class locomotive was so large that it could not negotiate the track clearances on most of the lines of the PRR system. In its brief service life it was restricted to the main line between Chicago, Illinois and Crestline, Ohio
. It was assigned to the Fort Wayne Division and based at the Crestline enginehouse. The S1 hauled passenger trains such as The General and The Trailblazer on this route. Crews liked the S1, partly because of its very smooth ride. The great mass and inertia of the locomotive soaked up the bumps and the surging often experienced with duplex locomotives.
Starting tractive effort calculated in the usual way (85% mean effective pressure) comes out 76,400 lb, but the engine used 70% limited cutoff (presumably to increase port openings at short cutoff) so the railroad claimed a correspondingly lower tractive effort.
When the powered wheels of a steam locomotive lose their adhesion to the rails and freely spin, the instantaneous result is over speed damage. If the locomotive's engineer does not detect and rectify this situation at once two things will occur, first, the metal tires that surround the driving wheels will be seriously damaged; second, the piston rods, their bearings and the other equipment associated with the reciprocating motion of the engine will be overstressed and destroyed; the engine will literally tear itself apart, by its operation at speeds well beyond the design limitations.
Normally, in a standard locomotive when starting under load from standing start, the engineer would observe his rearmost driving wheels and compare their movement to the relative forward movement of his locomotive over the ground. As locomotives grew larger, the engineer would have to listen to the rhythmic sound of the engine’s exhaust (the characteristic “chug-chug”) and compare the rhythm of this sound with the observed movement of his locomotive over the ground.
If, as he opened his engine’s throttle, the rate of increase of the “chug chug” sound was out of sync with the forward progress of his locomotive, he knew his wheels were slipping. A passenger locomotive with 72 inches (1,828.8 mm) drivers would travel twelve (12) feet or four (4) yards per “chug-chug”. It was therefore easy to correlate the rhythmic sound of the exhaust of a starting locomotive with the locomotive’s progress from a standing start. An engineer could thereby avoiding applying too much power to a starting locomotive (by opening the steam throttle valve too much, and too quickly) and causing the wheels to slip.
The S1’s duplex engine design meant that two separate engines were concurrently and in sequence exhausting into the single smoke stack. This made it nearly impossible for a locomotive engineer to distinguish the behavior of an individual engine set, based upon the sound of its exhaust. Unless both sets of engines experienced wheel slip simultaneously, the sound of the normal set would mask the sound of the set that was slipping and over speeding. If the wheels began to slip he would have no knowledge of this fact until he had already damaged the tires of the duplex engine’s wheels; or he heard the crashing sounds of a duplex engine tearing itself apart, in over speed.
The S1 had a further handicap in the area of slippage. Unlike virtually all other steam locomotives that faced wheel slippage when starting; the S1 (because of the very light weight on the driving wheels) would experience engine wheel slip over the road at operating speed. The adhesion of the wheels to the rails was so light, that even minor variations in the roadbed would cause either the forward or rearward duplex engines to slip. This hazard more than any other doomed the operating life of this engine. The loss of adhesion at speed (30 – 50+ mph) always did serious mechanical damage to the engine, which lost adhesion, and to the locomotive as well.
Its high speed capability was such that some have claimed the S1 may have even exceeded the 126 mi/h record steam locomotive speed set in 1938 by the LNER locomotive Mallard
. The locomotive was also rumoured to have operated at speeds exceeding 156 mph on the Fort Wayne-Chicago Railroad, as it was rumoured that the PRR received a fine posted by an interlocking tower on the division, proving the claim. However, it appears that no verifiable records are available to authenticate the claims.
continued developing the T1
class of 4-4-4-4
duplex locomotives but this locomotive model also met with limited success.
Pennsylvania Railroad
The Pennsylvania Railroad was an American Class I railroad, founded in 1846. Commonly referred to as the "Pennsy", the PRR was headquartered in Philadelphia, Pennsylvania....
S1 class steam locomotive
Steam locomotive
A steam locomotive is a railway locomotive that produces its power through a steam engine. These locomotives are fueled by burning some combustible material, usually coal, wood or oil, to produce steam in a boiler, which drives the steam engine...
(nicknamed "The Big Engine") was an experimental locomotive that was the largest rigid frame passenger locomotive ever built. The streamlined
Streamliner
A streamliner is a vehicle incorporating streamlining in a shape providing reduced air resistance. The term is applied to high-speed railway trainsets of the 1930s to 1950s, and to their successor "bullet trains". Less commonly, the term is applied to fully faired recumbent bicycles...
Art Deco
Art Deco
Art deco , or deco, is an eclectic artistic and design style that began in Paris in the 1920s and flourished internationally throughout the 1930s, into the World War II era. The style influenced all areas of design, including architecture and interior design, industrial design, fashion and...
styled shell of the locomotive was designed by Raymond Loewy
Raymond Loewy
Raymond Loewy was an industrial designer, and the first to be featured on the cover of Time Magazine, on October 31, 1949. Born in France, he spent most of his professional career in the United States...
.
The S1 was the only locomotive ever built to use a 6-4-4-6
6-4-4-6
A 6-4-4-6 steam locomotive, in the Whyte notation for describing locomotive wheel arrangements, is one with six leading wheels, two sets of four driving wheels, and six trailing wheels.Other equivalent classifications are:...
wheel arrangement
Wheel arrangement
In rail transport, a wheel arrangement is a system of classifying the way in which wheels are distributed beneath a locomotive.. Several notations exist to describe the wheel assemblies of a locomotive by type, position, and connections, with the adopted notations varying by country...
. Also, the S1 class was a duplex locomotive
Duplex locomotive
A duplex locomotive is a steam locomotive that divides the driving force on its wheels by using two pairs of cylinders rigidly mounted to a single locomotive frame; it is not an articulated locomotive...
, meaning that it had two pairs of cylinder
Cylinder (engine)
A cylinder is the central working part of a reciprocating engine or pump, the space in which a piston travels. Multiple cylinders are commonly arranged side by side in a bank, or engine block, which is typically cast from aluminum or cast iron before receiving precision machine work...
s, each driving two pairs of driving wheel
Driving wheel
On a steam locomotive, a driving wheel is a powered wheel which is driven by the locomotive's pistons...
s. Unlike similar-looking articulated locomotive
Articulated locomotive
Articulated locomotive usually means a steam locomotive with one or more engine units which can move independent of the main frame. This is done to allow a longer locomotive to negotiate tighter curves...
designs, the driven wheelbase of the S1 was rigid. The S1 was completed January 31, 1939 and was assigned locomotive number 6100.
At 140 foot over engine and tender the S1 was the longest reciprocating steam locomotive ever built; it could not negotiate curves on much of the PRR system. This problem, along with wheel slippage, limited the S1's usefulness. No further S1 models were built as focus shifted to the T1
PRR T1
The Pennsylvania Railroad's 52 T1 class duplex-drive 4-4-4-4 steam locomotives, introduced in 1942 and 1946 , were their last-built steam locomotives and their most controversial. They were ambitious, technologically sophisticated, powerful, fast, and uniquely streamlined by Raymond Loewy...
class. The last run for the S1 was in December 1945 and the engine was scrapped in 1949.
Construction history
In 1937, Pennsylvania RailroadPennsylvania Railroad
The Pennsylvania Railroad was an American Class I railroad, founded in 1846. Commonly referred to as the "Pennsy", the PRR was headquartered in Philadelphia, Pennsylvania....
officials decided to build a new passenger locomotive to replace its aging K4s locomotive. The PRR officials also hoped that the new S1 steam locomotive would have performance equal to their GG1 electric locomotive.
In a collaborative effort, the Pennsylvania Railroad, Baldwin Locomotive Works
Baldwin Locomotive Works
The 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...
, the Lima Locomotive Works
Lima Locomotive Works
Lima Locomotive Works was an American firm that manufactured railroad locomotives from the 1870s through the 1950s. The company took the most distinctive part of its name from its main shops location in Lima, Ohio. The shops were located between the Baltimore & Ohio's Cincinnati-Toledo main line...
and the American Locomotive Company
American Locomotive Company
The American Locomotive Company, often shortened to ALCO or Alco , was a builder of railroad locomotives in the United States.-Early history:...
contributed to the experimental S1 design.
The S1 was the largest express passenger locomotive ever constructed, with an overall length was 140 foot. At 77 feet (23.5 m) long and a weight of 97600 pounds (44.3 t), the cast steel locomotive bed
Locomotive bed
A locomotive bed is a one-piece steel casting for a steam locomotive that consists of the locomotive frame, the cylinders and valve chests, steam pipes, and smokebox saddle, all as a single component. It was a development of the final years of steam locomotive design in the United States. Most...
plate made by General Steel Castings
General Steel Castings
The General Steel Castings Corporation was a steel casting corporation in the United States established in 1928by the Baldwin Locomotive Works, American Locomotive Company, and American Steel Foundries....
was the largest single-piece casting ever made for a locomotive application.
The boiler unit for the S1 was the largest built by the Pennsylvania Railroad. The six-wheel leading and trailing trucks were added, as the locomotive's design became too heavy for four-wheel units. However, the locomotive was still overweight by a significant margin. The streamlined
Streamliner
A streamliner is a vehicle incorporating streamlining in a shape providing reduced air resistance. The term is applied to high-speed railway trainsets of the 1930s to 1950s, and to their successor "bullet trains". Less commonly, the term is applied to fully faired recumbent bicycles...
Art Deco
Art Deco
Art deco , or deco, is an eclectic artistic and design style that began in Paris in the 1920s and flourished internationally throughout the 1930s, into the World War II era. The style influenced all areas of design, including architecture and interior design, industrial design, fashion and...
styled shell of the locomotive was designed by Raymond Loewy
Raymond Loewy
Raymond Loewy was an industrial designer, and the first to be featured on the cover of Time Magazine, on October 31, 1949. Born in France, he spent most of his professional career in the United States...
, for which he received U.S. Patent No. 2,128,490
The final construction cost for the S1 was $669,780.00.
World's fair display
1939 New York World's Fair
The 1939–40 New York World's Fair, which covered the of Flushing Meadows-Corona Park , was the second largest American world's fair of all time, exceeded only by St. Louis's Louisiana Purchase Exposition of 1904. Many countries around the world participated in it, and over 44 million people...
of 1939 with the lettering "American Railroads" rather than "Pennsylvania Railroad", as 27 eastern railroads had one combined 17 acres (6.9 ha) exhibit, which also included the Baltimore & Ohio's duplex locomotive
Baltimore and Ohio Class N-1
The Baltimore and Ohio Railroad's sole Class N-1 steam locomotive, #5600 George H. Emerson, was the first duplex locomotive and the first 4-4-4-4 locomotive ever built. It was designed and built by the railroad's own shops in 1937. The rear set of cylinders were placed beside the firebox. This...
. To reach the New York World's Fair, the S1 took a circuitous route over the Long Island Rail Road
Long Island Rail Road
The Long Island Rail Road or LIRR is a commuter rail system serving the length of Long Island, New York. It is the busiest commuter railroad in North America, serving about 81.5 million passengers each year. Established in 1834 and having operated continuously since then, it is the oldest US...
. Many obstacles had to be temporarily removed and other obstacles were passed at a slow crawl to reach the fairgrounds. At the World's Fair the S1 was a dynamic display; the drive wheels operated under the locomotive's own steam power. This was done by placing the S1 on a platform that had rollers under the drive wheels. By using this type of display, visitors could see the duplex drive in use. After the World's Fair, the S1 was relettered and numbered for use in the Pennsylvania Railroad fleet. The S1 was used by the PRR for publicity purposes as well and its image was featured in calendars and brochures.
Service history
Crestline, Ohio
While the Census Bureau recognizes Crestline as a village, its 2000 population of 5,088 makes it a city under Ohio law.Crestline operates under a mayor-council system, with a council of eight members...
. It was assigned to the Fort Wayne Division and based at the Crestline enginehouse. The S1 hauled passenger trains such as The General and The Trailblazer on this route. Crews liked the S1, partly because of its very smooth ride. The great mass and inertia of the locomotive soaked up the bumps and the surging often experienced with duplex locomotives.
Starting tractive effort calculated in the usual way (85% mean effective pressure) comes out 76,400 lb, but the engine used 70% limited cutoff (presumably to increase port openings at short cutoff) so the railroad claimed a correspondingly lower tractive effort.
Design flaws
The S1 had a serious design flaw; the locomotive had too small a fraction of its total weight on the driving wheels. “The Big Engine” put less than forty percent of her total weight on the eight driving wheels. The rest of her weight was carried by the massive six-wheel pilot (leading) and trailing truck. This left the two sets of four duplex driving wheels susceptible to wheel slippage, a dangerous condition for any steam locomotive.When the powered wheels of a steam locomotive lose their adhesion to the rails and freely spin, the instantaneous result is over speed damage. If the locomotive's engineer does not detect and rectify this situation at once two things will occur, first, the metal tires that surround the driving wheels will be seriously damaged; second, the piston rods, their bearings and the other equipment associated with the reciprocating motion of the engine will be overstressed and destroyed; the engine will literally tear itself apart, by its operation at speeds well beyond the design limitations.
Normally, in a standard locomotive when starting under load from standing start, the engineer would observe his rearmost driving wheels and compare their movement to the relative forward movement of his locomotive over the ground. As locomotives grew larger, the engineer would have to listen to the rhythmic sound of the engine’s exhaust (the characteristic “chug-chug”) and compare the rhythm of this sound with the observed movement of his locomotive over the ground.
If, as he opened his engine’s throttle, the rate of increase of the “chug chug” sound was out of sync with the forward progress of his locomotive, he knew his wheels were slipping. A passenger locomotive with 72 inches (1,828.8 mm) drivers would travel twelve (12) feet or four (4) yards per “chug-chug”. It was therefore easy to correlate the rhythmic sound of the exhaust of a starting locomotive with the locomotive’s progress from a standing start. An engineer could thereby avoiding applying too much power to a starting locomotive (by opening the steam throttle valve too much, and too quickly) and causing the wheels to slip.
The S1’s duplex engine design meant that two separate engines were concurrently and in sequence exhausting into the single smoke stack. This made it nearly impossible for a locomotive engineer to distinguish the behavior of an individual engine set, based upon the sound of its exhaust. Unless both sets of engines experienced wheel slip simultaneously, the sound of the normal set would mask the sound of the set that was slipping and over speeding. If the wheels began to slip he would have no knowledge of this fact until he had already damaged the tires of the duplex engine’s wheels; or he heard the crashing sounds of a duplex engine tearing itself apart, in over speed.
The S1 had a further handicap in the area of slippage. Unlike virtually all other steam locomotives that faced wheel slippage when starting; the S1 (because of the very light weight on the driving wheels) would experience engine wheel slip over the road at operating speed. The adhesion of the wheels to the rails was so light, that even minor variations in the roadbed would cause either the forward or rearward duplex engines to slip. This hazard more than any other doomed the operating life of this engine. The loss of adhesion at speed (30 – 50+ mph) always did serious mechanical damage to the engine, which lost adhesion, and to the locomotive as well.
Alleged speed records
It was hoped that the locomotive could haul 1,000 tons at 100 miles per hour, but this goal was not reached. While an article "Riding the Gargantua of the Rails" in the Dec. 1941 Popular Mechanics Magazine cites a speed of 133.4 miles an hour, there are apocryphal stories of the S1 reaching or exceeding 140 miles per hour, but there is no documentation of these and it is considered unlikely by experts.Its high speed capability was such that some have claimed the S1 may have even exceeded the 126 mi/h record steam locomotive speed set in 1938 by the LNER locomotive Mallard
LNER Class A4 4468 Mallard
Number 4468 Mallard is a London and North Eastern Railway Class A4 4-6-2 Pacific steam locomotive built at Doncaster, England in 1938. While in other respects a relatively typical member of its class, it is historically significant for being the holder of the official world speed record for steam...
. The locomotive was also rumoured to have operated at speeds exceeding 156 mph on the Fort Wayne-Chicago Railroad, as it was rumoured that the PRR received a fine posted by an interlocking tower on the division, proving the claim. However, it appears that no verifiable records are available to authenticate the claims.
Removal from service
No further S1 models were built and the last run for the S1 was in December 1945 and was scrapped in 1949. The PRRPennsylvania Railroad
The Pennsylvania Railroad was an American Class I railroad, founded in 1846. Commonly referred to as the "Pennsy", the PRR was headquartered in Philadelphia, Pennsylvania....
continued developing the T1
PRR T1
The Pennsylvania Railroad's 52 T1 class duplex-drive 4-4-4-4 steam locomotives, introduced in 1942 and 1946 , were their last-built steam locomotives and their most controversial. They were ambitious, technologically sophisticated, powerful, fast, and uniquely streamlined by Raymond Loewy...
class of 4-4-4-4
4-4-4-4
A 4-4-4-4 steam locomotive, in the Whyte notation for describing locomotive wheel arrangements, has a four-wheel leading truck, two sets of four driving wheels, and a four-wheel trailing truck.Other equivalent classifications are:...
duplex locomotives but this locomotive model also met with limited success.
Modern culture
The design of the S1 has proved to be very popular:- The S1 appears in the Sandman comic series, book IX.
- The S1 is was also represented in a (c)1939 painting by railroad artist Grif Teller that appeared in the Pennsylvania Railroad's picture calendar.
- A limited HO Scale brass model version of the PRR S1 was produced by Gem Models during the 1960s to the 1970s. These models are now very rare, although they could be found on eBay from time to time. Not much information exists about them.
- In the PC game Gadget: Invention, Travel, & AdventureGadget: Invention, Travel, & AdventureGadget: Invention, Travel, & Adventure is a videogame or interactive movie, first released by Synergy Interactive in 1993. Gadget resembles a point-and-click adventure game similar to Myst, but with a strictly linear storyline culminating in a fixed finale. Thus it tends to be classified more as...
, one of the trains the player travels on is pulled by an S1 modeled locomotive. - In the animeAnimeis the Japanese abbreviated pronunciation of "animation". The definition sometimes changes depending on the context. In English-speaking countries, the term most commonly refers to Japanese animated cartoons....
series, the Galaxy Railways, the engine for Vega Platoon, Iron Burger, is loosely based on the S1