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INTRODUCTION OF
THE LOCOMOTIVE
SAFETY TRUCK
_by John H. White_
Paper 24 pages 117-131, from
CONTRIBUTIONS FROM THE MUSEUM
OF HISTORY AND TECHNOLOGY
UNITED STATES NATIONAL MUSEUM
Bulletin 228
Smithsonian Institution
Washington, D.C., 1961
Contributions from
The Museum of History and Technology:
Paper 24
Introduction of
The Locomotive Safety Truck
_John H. White_
INTRODUCTION OF
THE LOCOMOTIVE SAFETY TRUCK
_John H. White_
_Pioneer railroading was dangerous. With increased speed and density
of traffic came an increase in catastrophic wrecks that forced
operators to take heed for the safety of their passengers and
freight. This safety was painfully achieved through the slow process
of improving equipment part by part._
_Antedating such spectacular post-Civil War advances as the steel
rail, automatic coupler, and airbrake, was the invention of the
safety truck for locomotives. Intended to lead the bobbing, weaving
locomotive around curves on the rough track of the early roads, it
did much to reduce the all too numerous derailments that were a
major cause of accidents._
The Author: _John H. White, is associate curator, in charge of land
transportation, in the Smithsonian Institution's Museum of History
and Technology, United States National Museum._
American railroads of the early 19th century were cheaply and hastily
built. They were characterized by inferior roadbeds, steep grades, sharp
curves, and rough track. In spring, poor drainage and lack of ballast
might cause the track to sink into the soggy roadbed and produced an
unstable path. In winter this same roadbed could freeze into a hard and
unyielding pavement on which the rolling stock was pounded to pieces.
In those pioneering times the demand for new roads left little capital
to improve or expand existing lines; therefore equipment was needed that
could accommodate itself to the existing operating conditions.
The first locomotives used in this country had been imported from
England. Designed for well-ballasted track with large-radius curves and
gentle gradients, they all too frequently left the rails, and the
unsuitability of the essentially rigid British design soon became
apparent.
The challenge posed by the American roadbed was met by American
mechanics. By the mid-1830's a distinctive American locomotive had
evolved that might best be described by the word "flexible." The basic
features of its running gear were a bar frame and equalizing levers to
provide vertical relief and a leading truck to provide lateral relief.
Of these devices the truck was probably the most important, and more
readily than any one component distinguished the American running gear
from that used by the British before 1860.
[Illustration: FIGURE 1.--Design drawing showing the 4-wheel leading
truck, developed in 1831 by John B. Jervis, applied to the _Brother
Jonathan_. This locomotive, one of the earliest to use a leading truck,
was built in June 1832 by the West Point Foundry Association for the
Mohawk and Hudson Rail Road. The truck is attached to the locomotive
frame by a center pin, but the forward weight of the locomotive is
carried by a roller which bears on the frame of the truck.
(_Smithsonian photo 36716-a_)]
It was John B. Jervis who is generally credited with first applying the
truck to the locomotive. His design, shown in figure 1, was developed in
1831-32. Its merits quickly became apparent, and by 1835 it had been
universally recognized in this country. The truck successfully led the
locomotive around sharp curves, the resultant 3-point suspension enabled
the machine to traverse even the roughest of tracks, and, altogether,
the design did far less damage to the lightly built U.S. lines than did
the rigid, imported engines.[1]
The truck frame, fabricated from iron straps and castings, was attached
to the locomotive by a pin around which it might rotate. At first the
weight was received by rollers or chafing pads mounted on the side beams
of the truck. However, the friction of these bearing surfaces and their
location at a considerable distance from the center pin combined to
restrict the free movement of the truck. By the early 1850's the point
of bearing was transferred to the center plate, producing a truck that
turned more freely.[2]
[Illustration: FIGURE 2.--The 4-wheel Bissell truck as shown in the
drawing for British patent 1273, issued May 5, 1857.]
[Illustration:
A--Truck frame
B--Equalizing lever
C--Locomotive frame
D--Double incline plane
(_Centering device_)
E--Truck bolster
F--Swivel pin
(_Pivot point_)
_Drawn by J. H. White. June, 1960_
FIGURE 3.--Typical 4-wheel Bissell Safety truck of 1860. This drawing is
based on plate 69 of Alexander L. Holley's, _American and European
Railway Practice in the Economical Generation of Steam_, New York, 1861.
(_Smithsonian photo 46946_)]
For single axle engines this simple form of truck was entirely
satisfactory, but it proved less satisfactory for 4- and 6-coupled
machines. Also, as train speeds increased, so did the number of
derailments. Many of these could be traced to the inability of the
engine to negotiate curves at speed. Levi Bissell, a New York inventor
who investigated this problem in the 1850's, correctly analyzed the
difficulty. He observed that when the engine was proceeding on straight
tracks the leading truck tended to oscillate and chatter about the
center pin, and he noted that it was this action that imparted a fearful
pitching motion to the locomotive at speed. The derailments were traced
to the action of the truck as the engine entered a curve.
This action can be more easily understood from reference to Bissell's
patent drawing in figure 2. For example, let us say that an 8-wheel
engine, fitted with a center-swing truck, enters a right-hand curve. The
left truck wheels bear hard against the left rail. The drivers jam
obliquely across the track, with the right front and left rear wheels
grinding into the rails. As a result, the locomotive tends to leave the
track in the direction of the arrow shown on the figure (bottom
drawing). It will be noted that the truck center pintle is in fact the
fulcrum for this leverage. Under such strain the truck wheels are
particularly likely to leave the rails when they encounter an
obstruction. Once derailed, the truck would then spin around on the
deadly center pin, throwing the locomotive over.
In effect, then, the center pin of the conventional truck extended the
rigid wheelbase of the engine, and caused the truck to act much as
would a single set of leading wheels fitted rigidly to the engine frame
far ahead of the front driving wheels. Bissell proposed to correct the
faults of the conventional truck by fitting the locomotives with his
invention, the first practical safety truck to be patented. Since the
primary requirements were to keep the leading wheel axles at right
angles to the rails whether on a straight or curved track, and to allow
the driving axles to remain parallel, or nearly so, to the radial line
of the curve, he moved the center pin to a point behind the truck and
just in front of the forward driving axle. This shortened the wheelbase
of the engine and removed the danger of the pintle serving as a fulcrum
between the truck and the driving wheels, thus allowing them to assume a
comfortable position on a curve.
[Illustration: FIGURE 4.--A 4-wheel safety truck fitted with A. F.
Smith's swing-bolster centering device. Built by the Hinkley Locomotive
Works. From Gustavus Weissenborn, _American Locomotive Engineering and
Railway Mechanism_, New York, 1871, pl. 88.]
Since the truck could assume the correct angle when entering curves, it
was claimed in the patent specification that, unless all four wheels
were simultaneously lifted off the track, the truck could pass over
"quite a considerable obstruction."[3] Bissell further claimed:
In running on either a straight or curved track one of the truck
wheels often breaks off, and the truck swivels around on its center
pin in consequence, and throws the engine off the track, but with my
device one wheel, or even the two wheels on the opposite sides
diagonally of the truck might break off and still the truck would
not run off, because its position is set and it has no axis of
motion around which it could swing....
The other problem Bissell wished to correct was the oscillation and
chatter of the leading truck. This was accomplished by a simple
centering device in the form of a pair of V-shaped double incline planes
(D on fig. 3) situated at the center of the truck frame (A). The lower
planes of the pair were fastened to the truck frame and the upper, cast
in the form of a bridge, were attached to the locomotive frame (C) by a
center plate. But while the portion of the locomotive's weight assigned
to the leading wheels was borne at the center of the truck, as in the
conventional design, the center plate was no longer the point of
rotation. On a straight track the V's would be at their bottom position
and thus prevent the truck from vibrating.[4] When the locomotive
entered a curve the planes allowed its forward weight to bear
continuously on all four wheels, and at the same time controlled any
exaggerated swing caused by centrifugal force.
The centering device is thus explained in the patent specification
(figure numbers are omitted):
I therefore obviate this difficulty [the oscillation of the truck]
by providing two inclined planes ... formed double as shown and of
an angle proportioned to the weight of the forward part of the
locomotive and the velocity of the same.... The position of the
inclines is such that the blocks [V's] rest in the lowest part of
the double inclines when the engine is on a straight track, and on
coming onto a curve the inertia of the engine ... is expended in
going up the inclines, as the truck moves laterally toward the inner
part of the curve; and on coming onto a straight line the blocks,
descend to the bottom of the inclines and the engine is prevented
from acquiring a sidewise or oscillating motion.
[Illustration: FIGURE 5.--Detail drawing of the radius-bar truck,
patented by William S. Hudson in 1864, as applied to the New Jersey
Railroad and Transportation Company No. 44. From Gustavus Weissenborn,
_American Locomotive Engineering and Railway Mechanism_, New York, 1871,
pl. 8.]
Bissell applied for a U.S. patent on April 23, 1857. His petition was
initially denied. A weary debate of several months duration followed
between the patent examiner and Bissell's attorneys.
During this time Bissell was busy promoting the application of his truck
even though he had no patent for protection. In May of 1857 he showed a
working model of his improvement to Gilbert M. Milligan, secretary of
the Central Railroad Company of New Jersey.[5] Samuel L. Moore, master
mechanic of that railroad, also inspected the model. Both were so
impressed that it was decided to fit the device to the locomotive
_Lebanon_, which at the time was undergoing repairs at the road's
Elizabeth Port, New Jersey, shops.[6] Although the engine was less than
18 months old, her tires were badly worn and she oscillated at high
speed.
Early in June of that year a series of tests were held with the
_Lebanon_. Moore said of these trials:[7]
After the said invention of Bissell had been applied the engine was
run out onto a curve which she turned apparently with nearly as much
facility as she would travel on a straight line, and the forward
part of the engine rose on the inclines as the truck entered the
curve and remained fixed while running around said curve and then
resumed its former position on entering a straight track, and the
trial was pronounced by all who saw it as most satisfactory, even by
those who before pronounced that it would be a failure.
At a subsequent trial under a full pressure of steam and a velocity
of about thirty miles per hour the entering and leaving the curve
was equally satisfactory, the same being accurately observed by a
man located on the cow catcher.
... The engine was run at its greatest possible velocity at least
forty miles per hour on a straight track and the previous "shaking
of the head" [oscillation] was found to be entirely overcome, and
the engine run as steadily as a car would have done....
At one of the trials a bar of iron 3/4 x 4 inches was spiked down
across one of the _rails diagonally of the track_, ... and the
employees of the company took the precaution to fill in around the
track to facilitate getting the engine back again, supposing she
must jump off; however on passing over slowly she still kept the
track and the speed was increased until she passed over said bar ...
while under a considerable speed.
Messrs. Moore and Milligan heartily endorsed the truck as a complete
success. Milligan predicted that[8] "the time is not far distant when
locomotives will be considered incomplete and comparatively unsafe
without this improvement particularly on roads which have many curves."
[Illustration: FIGURE 6.--The New Jersey Railroad and Transportation
Company _No. 12_, built in 1868, was equipped with the radius bar truck,
a modification by William S. Hudson of the original Bissell truck. The
_General Darcy_ and several other engines built at the Jersey City shops
of the road, under the direction of John Headden, were fitted with the
Hudson truck. Note that the radius bar is connected to the truck frame
just behind the rear leading wheels. (_Smithsonian photo 46806-l_)]
U.S. Patent Commissioner Charles Mason was so impressed by the evidence
of the New Jersey trials, reinforced by the arguments of Bissell's
attorneys, that he agreed to grant a United States patent.[9] It was
issued as no. 17913 on August 4, 1857, and reissued October 18, 1864 as
no. 1794. British patent 1273 had been issued earlier (May 5, 1857), and
patents were also secured in France, Belgium, Austria, and Russia.
The Rogers Locomotive Works in 1858 was one of the earliest builders to
apply the improved truck. By 1860 they had fitted many of their engines
with it and were endorsing the device to prospective customers.
In the same year the _American Railway Review_ noted that the truck was
in extensive use, stating:[10]
... the advantages of the arrangement are so obvious and its results
so well established by practice in this country and Europe that a
treatise on its principles will hardly be needed.
It is no longer an experiment; and the earlier it is applied to all
engines, the better the running and repair accounts will look.
The success of Bissell's invention prompted others to perfect safety
trucks for locomotives. Alba F. Smith came forward in 1862 with the
simple substitution of swing links (fig. 4) for the incline planes.[11]
A swing-bolster truck had been developed 20 years earlier for use on
railroad cars,[12] and while Smith recognized this in his patent, he
based his claim on the specific application of the idea to locomotive
trucks. That the swing links succeeded the incline planes as a centering
device was mainly because they were cheaper and simpler to construct,
and not, as has been claimed, that the V's wore out quickly.[13]
[Illustration: FIGURE 7.--Bissell's 2-wheel truck of 1858 as shown by the
drawing for British patent 2751, issued December 1, 1858.]
Smith's swing-bolster truck, with the heart pendant link, a later
refinement, became the dominating form of centering devices and was used
well into this century. It was to be superseded in more recent years by
the constant resistance and gear roller centering devices which, like
Bissell's invention, depended on the double incline plane principle.
The British-born engineer William S. Hudson, superintendent of the
Rogers Works and an early proponent of the Bissell truck, in 1864
obtained a patent[14] for improving Bissell's safety truck. Hudson
contended that since the Bissell arrangement had a fixed pivot point it
could traverse only one given radius accurately. He proposed to replace
the fixed pivot with a radius bar (see fig. 5) one end of which was
attached to the locomotive under the smoke-box and the other to rear of
the truck frame, at the same point of attachment as in the Bissell plan.
Thus, according to Hudson, the pivot point could move laterally so that
the truck might more easily accommodate itself to a curve of any radius.
He further claimed that a better distribution of weight was effected and
that the use of the radius bar relieved the center bearing casting of
much of the strain of propelling the truck.
[Illustration: FIGURE 8.--A 2-wheel Bissell truck installed on the
Pennsylvania Railroad's _No. 91_. This engine originally an 0-8-0 Winans
Camel built in February 1854, was rebuilt by John P. Laird in 1867, at
which time the Bissell truck was added. Note that Hudson equalizing
lever was not used. (_Smithsonian photo 46806-k_)]
The British journal _Engineering_, in an article otherwise friendly to
the inventor, expressed some skepticism as to the real merit of Hudson's
invention.[15]
If Mr. Hudson's truck, ... be examined, it will be seen that the
radius link serves no other purpose than that of carrying the truck
along with the engine, and this could obviously be equally done by
the pivot or central pin of the truck itself.
It is probable that few builders other than Rogers made use of the
Hudson radial link.[16] One of these was John Headden, whose _General
Darcy_, shown in figure 6, was fitted with the Hudson truck.
Thus, by 1860 there had been perfected and adopted a successful 4-wheel
safety truck for 4-4-0's and 4-6-0's used in general mixed and passenger
service. But as the decade advanced, the need grew for heavy freight
engines that could be safely run at speed. Without a pilot truck, the
leading driving axle of the freight engine was generally overloaded.
While the application of a 4-wheel truck reduced this front-end overload
and permitted faster running it materially reduced the traction of the
drivers by bearing too great a portion of the total weight. This loss of
traction was of course highly undesirable and generally disqualified the
use of 4-wheel trucks for freight engines. What was needed was a truck
which would guide the 0-6-0's and 0-8-0's around curves and yet leave
the greater portion of the weight on the drivers. The 2-wheel, or pony,
truck met these requirements.[17]
[Illustration: FIGURE 9.--Running gear and truck designed by John L.
Whetstone, as shown in the drawing for U.S. patent 27850, issued April
10, 1860.]
Levi Bissell produced the basic patent for such a truck in 1857. Zerah
Colburn in September of that year had suggested to Bissell that he
develop a 2-wheel truck. Such a device, he believed, would be well
received in Britain.[18] He was quite correct, as will shortly be seen.
In nearly every respect Bissell's 2-wheel truck (see fig. 7) followed
the idea of the original patent for the 4-wheel truck, which he claimed
as the basis for the present invention. The pintle was located behind
the truck axle, near the front driving-wheel axle, and the weight was
carried by incline planes that also served as the centering device.
A study of the patent drawing in figure 7 reveals several interesting
points. Note that the V's, and thus the point of bearing, are slightly
in front of the center line of the truck axle. It was suggested in the
patent specification that the V's might be placed to the front, rear, or
directly over the axle, but in most actual applications they were placed
directly over the axle. Note also that the locomotive shown on the
figure is obviously a standard high-wheel American type which has
suffered the rather awkward substitution of a pony truck for its regular
4-wheel arrangement. It is probable that few if any American types were
so rebuilt.
Bissell was granted U.S. patent 21936 on November 2, 1858. British
patent 2751 was issued for the same device on December 1, 1858. A few
months later, in the summer of 1859, service tests of Bissell's new truck
began in England.
First known use of the truck was on the British Eastern Counties Railway
_No. 248_, a rigid-frame 2-4-0 built by Kitson in 1855. The leading
wheels of the engine, as originally constructed, were attached to the
frame in the same manner as the drivers and thus had no lateral
freedom. For the test the front pedestals, which held the journal boxes
of the leading wheels, were cut off and a Bissell pony truck was
substituted. About a year later Alexander L. Holley reported on the
success of the test.[19] The 248 had operated 17,500 miles, at speeds up
to 50 m.p.h., safely and satisfactorily. The engine not only rode more
steadily but showed a remarkable reduction in flange wear. The road was
so pleased that by 1866 they had equipped 21 locomotives with Bissell
trucks.[20] Several other British lines followed the example of the
Eastern Counties Railway.
[Illustration: FIGURE 10.--The Hudson-Bissell truck permitted the
introduction of Mogul and Consolidation type freight locomotives. This
drawing shows a typical installation for a Consolidation of the 1880's.
Item A is the equalizing lever which connects the truck to the springs
of the front driving wheels. From figures 891-3 in J. G. A. Meyer,
_Modern Locomotive Construction_, New York, John Wiley, 1904, p. 543.]
At first Bissell's 2-wheel truck received wider application in Europe
than in this country, because most American roads, despite the interest
in developing heavier freight locomotives, continued to depend upon the
4-4-0 as a dual-purpose machine. It was not until after 1870, when Mogul
and Consolidation types appeared in greater numbers, that the 2-wheel
truck became common in the United States.
The first use, known to the writer, of the Bissell pony in this country
occurred in November or December of 1859 on the Memphis and Charleston
Railroad. D. H. Feger, master mechanic of the railroad reported, eight
months later, that since the locomotive had been fitted with the Bissell
truck "she has never left the rail and previous to her having this truck
she was off the rail almost daily."[21] In the same report Feger stated
that he planned to re-equip another locomotive in the same manner.
[Illustration:
ANTHRACITE COAL BURNING FREIGHT LOCOMOTIVE
ROGERS LOCOMOTIVE & MACHINE WORKS
FIGURE 11.--The New Jersey Railroad and Transportation Company _No. 36_,
built by the Rogers Locomotive and Machine Works in 1863, was one of the
first locomotives to be equipped by this firm with a 2-wheel Bissell
truck. (_Smithsonian photo 46806-m_)]
The Baldwin Locomotive Works in December 1860 built a group of rather
awkward looking 2-6-0's for the Louisville and Nashville Railroad.
Equipped with Bissell trucks, these were undoubtedly among the very
first new locomotives to be so built. The first consolidation type was
built by Baldwin in 1866; it was equipped with a 2-wheel Bissell safety
truck.
The Rogers Locomotive and Machine Works and the New Jersey Locomotive
and Machine Works, both of Paterson, New Jersey, in the early 1860's
began building Moguls; these are known to have had Bissell trucks. Other
builders followed their example, so that by the 1870's 2-wheel trucks
had become relatively common.
It should be noted that the 2-wheel truck was not an absolute success
until it was equalized with the front driving axle. This arrangement was
perfected in 1864 by William S. Hudson, but before describing his
invention it will be helpful to discuss several earlier attempts to
equalize pony trucks with the drivers.
In 1857 John P. Laird, then master mechanic of the Marietta and
Cincinnati Railroad, rebuilt an old Niles 8-wheeler into a curious 2-6-0
on which only the two rear driving wheels were coupled. The front driver
was driven by a chain and sprocket, and the pilot wheels were equalized
with the front driving axle. The success or failure of the arrangement
has not been definitely determined, but whatever the outcome, Laird
continued his experiments when he became superintendent of motive power
for the Pennsylvania Railroad in 1862. He abandoned the chain drive for
a more conventional arrangement of side rods, but the truck and his plan
of equalization were much the same as that tried earlier. Laird used two
equalizing levers, attached at one end to the front spring hangers and
at the other to the truck, but in a way to allow the truck to swing
horizontally. The fulcrum for each lever was mounted on the underside of
the front frame rail. A number of old 8-wheel Baldwin flexible-beam
engines and several Winans' Camels were rebuilt in this way. One of
these is shown in figure 8. Laird, however, eventually became
dissatisfied with his arrangement and re-equipped the engines with
Bissell trucks.
[Illustration:
LOCOMOTIVE ENGINE SAFETY TRUCK CO.
OF NEW YORK.
Proprietors of the following Letters Patent granted to Levi Bissell,
Aug. 4, 1857, Nov. 2, 1858 (extended Nov. 2, 1872); A. W. Smith,
Feb. 11, 1862; D. R. Pratt. Oct. 16, 1860; W. S. Hudson, April 5,
18[digits missing] and May 10, 1864.
DRAWINGS FURNISHED AND LICENSES GRANTED ON APPLICATION.
A. F. SMITH, President. M. F. MOORE, Sec'y and Agent
ALBERT BRIDGES. Treas. No 46 Cortlandt st. N. Y.
FIGURE 12.--Notice of the Locomotive Safety Truck Company listing the
patents held by it. From _Railroad Gazette_, March 3, 1876.]
John L. Whetstone on April 10, 1860, obtained U.S. patent 27850, which
strikingly anticipated the plan Hudson was to develop four years
later.[22] Whetstone did not use a Bissell truck and was in fact more
concerned in relieving the excess weight, often a 50% overload, from the
front axle of 0-6-0 locomotives and in distributing a portion of that
weight to a pony truck. His arrangement may be readily understood from
the patent drawing in figure 9. Probably the best features of the design
was the transverse H-beam that connected the spring hangers to the truck
frame, which in this case also served as the equalizing lever (note that
the ball "C" acts as the fulcrum).
Hudson made use of this same device but in a more practical manner. He
found that while the Bissell pony truck could satisfactorily adjust
itself laterally and could lead the locomotive around curves, it could
not handle the varying loads imposed upon it by the rough trackage
typical of American railroads. At one moment an undue amount of weight
would fall upon the truck because the drivers were over a depression in
the roadbed. This condition overloaded the truck's springs and also
resulted in a momentary loss of adhesion, causing the drivers to slip.
Conversely, when the truck hit a depression too much weight was thrust
upon the driving wheels, and broken springs or other damage might
result.
Hudson's ingenious remedy to this problem was simple and straightforward
(see fig. 10). A heavy equalizing lever that connected the truck to the
springs of the front driving wheels was placed on the longitudinal
centerline of the locomotive, with the fulcrum under the cylinder
saddle. Thus the truck and front driver reacted together to all the
inequalities and shocks offered by the roadbed.
In October of 1863, under Hudson's direction, two 2-6-0's equipped with
Bissell trucks were built at the Rogers Works for the New Jersey
Railroad and Transportation Company. Probably some fault was found with
the suspension of these machines, numbered 35 and 36, for the next
2-6-0, numbered 39, built for the New Jersey road was equipped with
Hudson's equalizer. This engine, completed in January 1865, is believed
to be the first Mogul so equipped.[23]
The Locomotive Engine Safety Truck Company (see fig. 11) was formed in
the 1870's, with A. F. Smith as president, to exploit the patents of
Bissell, Smith, and Hudson. For several years notices appeared in the
columns of the _Railroad Gazette_ reporting suits by the Company against
various railroads and locomotive builders for unauthorized use of their
patents. The _Gazette_ of May 29, 1875, carries a protest of the Company
against the Manchester Locomotive Works for unlicensed use of Smith's
patent of 1862. In the issue of August 28, 1875, is reported the
Company's success in establishing the validity of Smith's patent:
Some important settlements for the use of the patent have lately
been made with the company, one of them being with the Western
Railroad Association, whose headquarters are at Chicago, which
includes the principal western roads. Through this the company
receives its royalty on several hundred locomotives.