Big John and Other Big Cars
R E V I S E D   4   A U G U S T   2 0 1 3

At the beginning of the Railway Age in the United States, most railroad cars rode on two axles; but by the middle of the Nineteenth Century, most new cars rode on two 4-wheel trucks.  This has remained the standard freight car configuration for over 150 years; however, there have been some notable exceptions.
B E F O R E   1 9 6 0

For over a hundred years, heavy-duty flat cars have ridden on more than four axles; but these cars have typically been built in very small numbers and have not been very common.  The most widespread use of 6-wheel trucks under freight cars took place between 1912 and 1922 when the three major Pocahontas Region coal roads – Norfolk & Western, Virginian and Chesapeake & Ohio – purchased over 5,000 of their so-called Battleship Gons with a nominal capacity of 100 tons, although the actual capacity varied from 90 to 115 tons.  While a few of these cars survived into the 1960's, the construction of 6-axle freight cars has never been repeated on such a large scale.

At about the same time as the N&W was building its first production (i.e. not a prototype) 6-axle gondolas, the U.S. steel industry began buying 6-axle hot metal cars.  This design, sometimes referred to as a bottle or torpedo car, was patented by John D. Pugh in 1915 and the first examples were built by the M.H Treadwell Co. of Easton, PA the next year.  The first cars had a capacity of 80 tons, but the typical capacity of a 6-axle car is 125-150 tons.  Standard hot metal cars have also built with four 4-axle trucks (200-250 tons) and four 6-axle trucks (300 tons).  A few 150-ton cars were built with 10 axles instead of eight, having two 4-wheel and two 6-wheel trucks, to provide a lower axle load.  About 500 cars have been built, most notably by Treadwell and by the William B. Pollock Co. of Youngstown, OH.  They are still available from Reichard Industries of Columbus, OH; although 12-axle cars now use six 4-axle trucks instead of four 6-wheel trucks, just like some modern heavy-duty flat cars.

After the Battleship Gon Era, the next large purchase of 6-axle freight cars occured in 1952 and 1953 when the U.S. Army bought 755 flat cars with a nominal capacity of 100 tons, and most of these remained in service into the early 1990's.  Between 1981 and 1992, the Department of Defense supplemented its heavy-duty flat car fleet with almost 600 new 6-axle 150-ton cars.  DOD also has a small fleet of special-duty flat cars with six, eight, or twelve axles.

B I G   J O H N
The Southern Railway's Big John 100-ton covered hoppers only had four axles, but they – and the court battle that followed their introduction – set the groundwork for almost all of the high-capacity cars that followed.  Competition from other modes of transportation had been a growing threat to railroads for much of the 20th Century, but the competiton really heated up after World War II.  On the freight side of the business, truck and vessel technology was improving, and governments were spending generously on highways and waterways. 

Shortly after the passage of the law authorizing the Interstate Highway System in 1956, the Southern Railway began collaborating with the Magor Car Corp. and Reynolds Aluminum on the design of the first mass-produced aluminum freight cars.  These cars would ride on 100-ton trucks, giving them a gross rail load of 263,000 pounds; and this, combined with the weight advantage of aluminum construction, would give the cars very generous load limits.  Southern's first order was for 455 covered hoppers in three sizes, which were delivered between December 1959 and May 1960:

  • 200 2-bay cars (4000-4199), 2605 cubic feet, weight 21 tons, capacity 110 tons
  • 180 3-bay cars (6000-6179), 3318 cubic feet, weight 25 tons, capacity 106 tons
  • 075 4-bay cars (8000-8074), 4713 cubic feet, weight 28 tons, capacity 103 tons

    The first two groups of cars did not generate any controversy, but the last group certainly did!  The Southern knew that these cars, which it eventually nicknamed Big Johns, would provide a much more efficient way to ship grain than 40-foot, 40-ton boxcars; and this would enable the railroad to drastically reduce rates on large shipments, allowing it to better compete with trucks and barges... and other railroads!

    The Southern attempted to implement a 60% rate reduction in August 1961; but the Interstate Commerce Commission blocked these tarriffs on the grounds that they could drive truckers and other railroads out of business.  To qualify for the new rate, a shipment had be at least five cars and had to be shipped on one bill of lading, to one consignee, at one destination.  The railroad offered even lower 10-car and 20-car rates.  While the ICC postponed the implementation of the new rates, they were used on intrastate shipments. 

    ICC hearings began on 8 January 1962, and the issue went all the way to the Supreme Court twice!.  The Southern won both times.  By the time the new rates finally went into effect on 11 May 1963, the railroad was receiving the first of 500 bigger (4,948 CF) Big Johns, but less than two months later the ICC told the railroad it could only have a 53.5% reduction.  The Southern challanged the ICC again and the matter went back to the Supreme Court, which ruled in the railroad's favor in January 1965.  The next month the railroad received 500 even bigger (5,325 CF) cars, for a total of 1,075 Big Johns.

  • A F T E R   B I G   J O H N

    What followed Big John was a significant increase in the size of many freight cars.  Some cars didn't look much different, although they had a higher load limit; but many car types got bigger, and in some cases, a LOT bigger!  Box cars which had been 40 or 50 feet long became 60, 70 and even 86 feet long. Other cars got bigger too, but in most cases their nominal capacity seldom exceeded 100 tons.  During this time, the 125-ton 4-axle truck (7x12-inch journal bearings) was introduced; but relatively few 125-ton cars were built.

    Almost all of these big cars rode on 4-wheel trucks.  The 819 RailWhales were the most notable exception; but after the first 8-axle tank car was completed in 1963, a few other 6- and 8-axle cars were built, mostly gondolas and open hoppers; but all of these were developmental dead-ends. 

    In September 1963, six months after the first RailWhale, a 146-ton, 6-axle hopper rolled out of the Norfolk & Western's Roanoke Shops.  N&W 76950 rode on a pair of 6-wheel Buckeye trucks and was almost 70 feet long.  It had a light weight of 101,300 pounds, a load limit of 293,200 pounds, and a volume of 5460 cubic feet.  Unfortunately, the car had two drawbacks: its size was incompatible with the railroad's rotary car dumpers at Norfolk; and its size only enabled it to haul 133 tons of coal, 13 tons less than its capacity.  It was retired and scrapped after five years.

    In June 1964 Pullman-Standard constructed a 135-ton, 6-axle covered hopper for the Atlantic Coast Line.  ACL 500000 made extensive use of stainless steel and rode on a pair of 6-wheel American Steel Foundries trucks.  The car had a light weight of 93,500 pounds and a volume of 5,006 cubic feet.  While its trucks gave it a theoretical load limit of 301,000 pounds, its official capacity was 271,500 pounds.  Like N&W 76950, ACL 500000 was also a one-of-a-kind car; but it has fared much better than the N&W hopper and remained in service through the end of the 20th century.  After being sold for scrap, the car was purchased by the North Carolina Department of Transportation and is on display at Rocky Mount.

    In August 1965, aircraft builder Aeronca Manufacturing Co. of Middletown, Ohio built a 260-ton, 8-axle aluminum hopper car for the Southern Railway.  Unlike typical 8-axle cars, this 103-foot car consisted of four permanently-connected 25-foot units, each riding on two axles.  Southern 100 was loaded with inovations, including disk brakes, 7x12 bearings, and 38-inch wheels.  The latter features gave the car a gross rail load of 630,000 pounds.  It had a light weight of 96,000 pounds and load limit of 534,000 pounds, giving it a very impressive net-to-tare ratio with a volume of 9,000 cubic feet.

    The Chesapeake & Ohio and Bethlehem Steel jointly developed a 120-ton, 6-axle hopper car.  C&O 300011 consisted of two articulated parts and rode on three conventional 4-wheel trucks.  Built in November 1968, the 56-foot car had a light weight of 65,200 pounds, a load limit of 243,300 pounds, and a volume of 4186 cubic feet.

    The cars already mentioned in this section were one-off prototypes, but in 1970 Thrall built seventy-five 150-ton bathtub gondolas for the Kansas City Southern.  These 404000-series cars were built to form a unit train for service between a coal mine near Howe, Oklahoma and an export terminal at Port Arthur, Texas; but they spent most of their lives hauling wood chips in Louisiana.  The 70 remaining cars were sold to General American in 2005, right around their 35th birthday, and were renumbered GACX 914-983.  All of the GACX cars had 4-wheel trucks and were retired by 2011.


    Four-wheel freight cars have been common in much of the world, and a couple of prototypes were built in the U.S. in the 1950's.  Southern hopper 100 consisted of four 4-wheel sections; and after 1970, car designers briefly moved back in this direction.

    Greenville developed its fully-enclosed 129-foot Auto Guard, a tri-level automobile carrier which could hold 18 full-size autos.  Each Auto Guard consisted of three permanently-connected 40-foot units, each riding on two axles; but only two were built – Southern Railway 599000 and 599001 – in September 1973.  The cars had a light weight of 84,600 pounds and an indicated load limit of 100,000 pounds.  They utilized truck components from hopper car 100, although these were refitted with 6x12 bearings and 33-inch wheels.  The 599001 was retired after an accident when it was only a couple of years old, but the other remained in service for 20 years.  Norfolk Southern retired the 599000 in October 1993 and donated it to the Virginia Transportation Museum in Roanoke.

    A decade after the Auto Guard was introduced, Trailer Train had a brief fling with 2-axle cars for intermodal service.  First came 101 TTFX 4-Runners in 1981, which consisted of four permanently-coupled 4-wheel platforms.  These were followed two years later by the first TTOX (later TTUX) Front Runner stand-alone cars, and about 3,240 were built before production ended in 1989.  By that time TTX, the carbuilders and the railroads had decided that articulated cars using conventional 4-wheel trucks could achieve almost the same weght savings as the 4-wheel cars, while offering better tracking and simpler maintenence.


    How much weight a freight car can carry is detemined by several factors, such as the structural design of the car and the design of the trucks, including wheel and bearing size, springs and the number of axles.  Of course, the quality and condition of the track can affect how much a car can carry too.  Factors such as rail size, cross tie spacing, and bridge design strength figure into this; but even heavy rail can't support much weight if it hasn't been properly maintained.

    Most track can accomodate almost any load, if the weight is spread out over enough axles; but this principle doesn't apply to bridges. A bridge is designed to accomodate a specific maximun weight, referred to as its Cooper's Rating.  The number of axles required to support a specific load on a rail line are determined by the track's maximum axle loading.

    The maximum axle loading permitted for unrestricted interchange in the United States is currently 65,750 pounds, although there is a move on to raise this to 71,000 pounds, and some cars are built for a maximum axle loading of 78,750 pounds.  The heaviest 6-axle locomotives have an axle loading of around 72,000 pounds, but some 4-axle units have a higher loading.

    In 1920 the railroad industry adopted a standard system for identifying standard journal bearing sizes, and it is still used today.  The nominal capacity is the gross weight for a 4-axle car minus the weight of a typical car, typically 50,000-65,000 pounds.  Below is a list of standard bearing sizes up through 1970.

    4 AXLES
    6 AXLES
    8 AXLES
    20 TONS
    16,500 66,000 99,000 132,000
    30 TONS
    25,750 103,000 154,500 206,000
    40 TONS
    35,500 142,000 213,000 284,000
    50 TONS
    44,250 177,000 265,500 354,000
    70 TONS
    55,000 220,000 330,000 440,000
    100 TONS*
    65,750 263,000 394,500 526,000
    71,500 286,000 429,000 572,000
    125 TONS
    7 x 12
    78,750 315,000 472,500 630,000

    * Most 4-axle cars built on or after 1 January 1995 with Type F bearings have a maximum gross weight of 286,000 pounds, and some older cars have had their maximum gross weight increased from 263,000 to 286,000 pounds through the installation of new truck springs.  The owners of these older cars also had to submit engineering documentation to the Association of American Railroads which showed that these cars are structurally capable of handling the extra load.  In 2002 the AAR adopted the Type K 6x9 bearing for 286,000 pound cars.

    © 2003-2013 Michael M. Palmieri