A Brief History of Coal Hoppers
by David Thompson
Pressed Steel (PSC) developed a version of their car without separate side sills in 1900 and moved into the general freight car business. Cambria Steel Car (CSC) started out as a gondola builder in 1901, but soon moved into building Vanderbilt-design hoppers. The Vandy was a bizarre creature, with a hopper body supported by a maze of steel trusswork. American Car & Foundry's (AC&F's) early steel cars were built at their Detroit plant, with one group of diagonal-truss hoppers going to the LS&MS in 1902. Standard Steel Car (SSC) got its start in 1902 utilizing ex-PSC personnel to build their own hoppers made from standard channels and angles instead of the stampings characteristic of PSC's cars.
Up until 1905, each of the main builders had their own proprietary design (except for AC&F which apparently abandoned its LS&MS design in favor of building PSC and SSC clones), but changes were on the way. In 1904, Cambria and AC&F built an 8-panel design with a combination of pressed and standard shapes (this eventually became the PRR Gv). A year later, B&O adopted a similar 8-panel car (class N-10), and PRR Lines West took delivery of a 6-panel version of the Gv (known as the GLa) from the "Big Four" builders. Also in 1905, another 6-panel design was adopted by the builders and built in massive numbers for the next two decades. This "early standard" design proved to be extremely popular. The old PSC designs and the Vandy hoppers were largely abandoned at this point, but variants of the Standard Steel car were adopted by a few roads (Reading and DL&W, for example) and built in fair numbers into the Teens. There was a blizzard of other designs, but most of these were one-offs or peculiar to one or two roads.
Most steel hoppers followed what quickly became the standard layout of two sawtooth hoppers and outside bracing for the sides. The C&O, however, stayed with the old horizontal-door arrangement on their first steel cars in 1901 and 1902, and the N&W stuck by that old standby straight into 1921. Some cars were built with "clamshell" hoppers similar to the old-style doors on the PRR H21; more common was a side-dump hopper setup. Some roads weren't ready for an all-steel car yet and either stuck with old wood designs or adopted cars patterned after the "Seley" hopper, named for the N&W's Mechanical Engineer of the time. The Seley car was a steel-frame, wood-bodied hopper with steel truss framing on the sides along with the old horizontal doors. N&W was the largest buyer, but SAL, ACL, Virginian, B&O, C&O, and perhaps Rock Island had similar cars.
The Teens saw the beginnings of the gradual move
toward larger cars than the de facto standard of 50 tons. PRR converted their 50-ton H21
coke hoppers into 70-ton coal cars beginning in 1909, C&O received its first 70-ton
hoppers in 1914, the N&W jumped straight to 90-ton "battleship" coal gons
(NOT hoppers) in 1914, and Virginian's first 120-ton battleship gons came in 1917. World
War I spawned a brief flurry of wood-and-steel composite hoppers (and the N&W's
famously unsuccessful wood-frame hoppers) and possibly spurred Southern's conversion of
their "early standard" hoppers into Seley-style composite cars in the 1920s. The
C&O and the NYC adopted the USRA 70-ton design after the war, and the USRA 50-ton car
came to be seen as the new "standard" hopper. The N&W finally converted to
sawtooth hoppers with their 70-ton class HU of 1922.
The late 1920s saw the introduction of the AAR
standard "offset-side" 50- and 70-ton hoppers. The design went through several
variations in the late 1920s and early 1930s before settling on two versions of the 50-ton
car and one 3-bay, 70-ton car in 1935. Most roads went for the AAR standard designs, but
the N&W, VGN, and Pennsy were notable holdouts. World War II brought the famous
"war emergency" hoppers (only the N&W and MP bought the 70-ton version) and
several composite versions of existing designs. After the war, AC&F found some brief
success with a welded outside-stake hopper design, but the weld joints broke under the
stress of loading and unloading rather than flexing like riveted joints. The offset-side
design also had problems: the inside stakes were more prone to corrosion, and they
suffered worse from loading and unloading stress than outside-staked hoppers. The design
waned in the 1950s and was all but abandoned for new cars by 1960. Some roads (notably the
C&O, the B&O, and the L&N) made the best of a bad situation by rebuilding
their offset-side cars with all new outside-staked sides in the late 1950s and early
1960s.
The "small market" for coal had largely dried up after the war, and the
existing 50-ton fleets were more sufficient for the remaining single-car-loading traffic.
The focus shifted to larger cars: first to 70-ton cars in the 1950s, then to 85 and 90-ton
cars in the early 1960s, and finally to 100-ton cars after the AAR revised the axle
ratings in 1963. The increased use of cars for unit trains and other dedicated services
saw a brief revival of interest in gondola-type cars in the early 1960s, but this was soon
swamped by a tidal wave of 100-ton triple and 
quad hoppers in the late 1960s and
1970s. This period also saw many new innovations, like the rapid discharge hopper, to
facilitate unit train operations. The 1980s brought a near-crash in the freight car
market, and it wasn't until the 1990s that more new cars were needed. By then, most
industrial customers had facilities for rotary dumping, so new cars were built as
trough-bottomed gondolas (not really hoppers anymore, but they're built along hopper lines
otherwise), and older cars are slowly being rebuilt into gondolas with troughs replacing
their hoppers. While the heyday for coal hoppers has probably come and gone, their
place in history is assured. 