Editors of other technical journals are invited to reprint articles
from this journal, provided due credit be given the PROCEEDINGS.

PROCEEDINGS

OF

ASTOR, LENOX TILDIN FOUNDATIONS,

THE ENGINEERS' CLUB

OF PHILADELPHIA.

ORGANIZED DECEMBER 17, 1877.

INCORPORATED JUNE 9, 1892.

NOTE.-The Club, as a body, is not responsible for the statements and opinions advanced in its publications.

Vol. XXI.

JANUARY, 1904.

No. 1

DEVELOPMENT OF THE BRILL SYSTEM OF TRUCKS FOR
ELECTRIC MOTOR CARS.

WM. H. HEULINGS, JR.

Read October 3, 1903.

DURING the Centennial Exposition several types of steam motor cars were put in use on the streets of this city. The Vice-President of the J. G. Brill Company, Mr. Jno. A. Brill, saw that if cars were to be selfpropelled a framework would be required separate from the car body to carry the motors, as it would not do to connect the motors directly with the car body; the framework of the cars must be as light as possible, and therefore the vibrations and straining of the motors would quickly rack the car to pieces.

Street railway men thought Mr. Brill's idea not practicable because the motors would be brought too near the pavement and would therefore become clogged with dirt; they also thought an independent truck would be too cumbersome to use under light cars. It was not until 1885 that the idea was presented in anything like a complete form, and not until two years later was it accepted by any of the street railways or manufacturing companies. In 1887 two cars were built for Scranton with motors upon the trucks; before that, Vanderpoele built two cars with the motor set upon the front platform and con

nected with the axles by chains and sprocket wheels; the strain of driving was thrown upon the body of the car-in fact, upon the front platform timbers; the extra weight thus carried so far from point of support was bad, and the cars could be run in but one direction. The racking and straining quickly shook these cars to pieces. In Sprague's early electric cars the motors were hung from the body and drove the axles through gears, but as in the Vanderpoele experiment, the strains were thrown on the car framing.

The first trucks which we built had each pair of pedestals cast in a single piece and bolted to sub-sills which were connected at either end by straight crossings, each pedestal enclosed a coil spring, and therefore four pairs of coil springs comprised the spring arrangement; the side bars were set very low and secured under the pedestals; the motor was hung on the axle and supported by springs and links from a channel iron crossbar at the center. This is what we now call "nose suspension." The truck was the starting-point of the mechanical success of electric motors and street cars. We built several hundred of these trucks, some of which are running to this day and giving good service. It is an interesting fact that the right method of motor support was adopted with this first truck and is the method which is now in universal use. Thus the independent truck was established in street railway practice.

Among the changes which quickly followed, and which were destined to be permanent features of this type of truck, were the abandonment of the enclosed pedestal springs and the adoption of spring posts. This necessitated the use of post stays, or lower chords, which, before the use of solid side frames, were trussed to the upper chords; the journal boxes were constructed with ears which carried the springs as in the old horse-car method; the base of each box was rigidly connected with the side frames, but this method did not give sufficient stability to the support of the car body, nor was there enough strength in the connection between the frames and the boxes to keep the truck square.

It had appeared necessary to preserve the continuity of these side bars. Experience proved that the boxes must work in jaws which must be an integral part of the side frames. This step was a radical departure which embodied the correct principles of all truck construetion; namely, the independent frame, in addition to carrying the motors, must keep the boxes and axles in parallel relation; in other words, the squareness of the truck must depend upon the truck frames.

The axle-box yokes in the side frames were necessary not only for truck squareness, but also to permit the body of the truck to be lifted off the axles so that the motors might be inspected and repaired in pits.

The early motors were arranged to be carried low, therefore the side frames were also carried low. Soon motors were constructed that could be carried higher, and, what was of supreme importance, were completely encased. The encasing of the motors, protecting them from moisture and dirt, was the real beginning of the general use of electric motor cars, since it removed one of the chief obstacles. The motor supports were wholly depended on to connect one side frame rigidly with the other. The heavy motors that came into use with the use of larger car bodies brought too much stress upon these center crossings; therefore independent motor supports were placed upon the frame and straight crossings were used at the centers between the wheels and also at the ends of the frames outside the wheels.

An important advance on this construction was the introduction of diagonal crossings at the centers of the frames. A serious difficulty which for a long time baffled all attempts to overcome was the bounding motion, or oscillation, of the car body; there was evidently something wrong with the spring system. We were the first to recognize that the difficulty lay in the fact that the rail joints produced a rhythmic motion in the coil springs; we therefore introduced slower acting elliptical springs. This discovery was made about the same time we commenced making solid forged side frames; therefore it was a simple matter to lengthen the extensions and mount the elliptical springs at the ends of the extensions, thus breaking the rhythm set up by the coil springs, and to a large extent preventing oscillation. At the same time the elliptical springs extended the spring base. Later on the full-elliptical springs were superseded by semi-elliptics, which still further extended the spring base and were slower acting.

The correct principle in all truck-building is to have the frames support the car body as nearly as possible over the points where they are themselves supported.

When axle-box yokes were first adopted, rubber cushions were interposed between boxes and yokes, as no way of carrying the frame upon springs had been devised, and the importance of absorbing vibrations and shocks before they reached the frames was not realized. Rubber was a poor makeshift, however, and soon careful attention was given to this part of the spring arrangement. After various experiments, a satisfactory method was adopted of supporting the frames on

large-diameter coil springs set in pairs in ears, cast on both sides of the journal boxes; by this means the truck frame was carried low, and therefore the car body was carried low-a very essential matter, since the single truck is mostly used in city service where it is necessary to have the car steps as low as possible to facilitate ingress and egress. These coils being in pairs, the boxes were held in an upright position enabling them to work freely in the jaws.

While the single truck was being developed, the necessity for longer car bodies arose, requiring pivotal trucks. The height of cars could be little increased, space between the tracks could not be widened, and the radii of curves must remain practically the same as before. How to find room for double trucks to radiate under narrow cars was the

problem. Little was to be learned from steam practice. The limitations of operating on streets made the case entirely different, requiring the evolving of new principles of construction throughout. To give room for the motor and to allow the trucks to be located near the ends of the car body, and yet avoid the steps, were the reasons for placing the bolster out of center in the first pivotal truck which was built. This resulted in loss of traction, as the motor was applied to the wheels carrying the smaller proportion of the load; it was, in fact, a true "minimum traction" truck. The advantage of having ample tractive power was quickly discovered, and the next type was the "Maximum" Traction Truck-the first of its kind, unique in idea and design, the truck consisting of a pair of ordinary sized driving wheels and a pair of pony wheels with the weight eccentrically distributed

so that the large wheels carried nearly all of the load, the pony wheels bearing just enough to enable them to guide on the track. There was no bolster, the load being carried on side bearings over the journals of the drivers; a pivotal plate over the rear axle took none of the load, its office being merely to take the draft of the truck. While this arrangement enabled one end of the truck to swing clear of the sills of the car body in operation, it was found that the springs at the sides of the axle boxes of the pony wheels interfered with the running-board, or step, of open cars; it therefore became necessary to make other disposition of them, as the truck was limited to use under closed cars. This difficulty was overcome by narrowing the upper chord at the forward end

and seating the springs on the front crossing. This, however, was a temporary expedient. Permanent corrections were the doing away with the drawing plate over the rear axle which interfered with the motor and substituting a radial casting by which the truck was drawn, and by the use of guides secured to the car body for the side bearings. The truck was thereby made to radiate from an imaginary point located about six inches inside the driving axle. This was the first truck to have solid forged side frames. The composite frames were so unsatisfactory, bolts and nuts could not be kept tight, and, difficult as the forging of such frames was, we believed that the success of the truck depended upon it. We shall have more to say later of forged frames.