IMPROVEMENTS APPLICABLE TO TRAMWAY CARS AND OTHER LIKE VEHICLES FOR EFFECTING THE PROPULSION OF THE SAME, AND IN APPARATUS OR MEANS CONNECTED THEREWITH
Year: 1879

page_text: PROVISIONAL SPECIFICATION left by John Henry Johnson at the Office
of the Commissioners of Patents on the 28th October 1879. A communi-
cation from abroad by Charles Arson, of Paris, in the Republic of France,
Engineer.
JOHN HENRY JOHNSON, of 47, Lincoln's Inn Fields, in the County of Middlesex,
Gentleman. "IMPROVEMENTS APPLICABLE TO TRAMWAY CARS AND OTHER LIKE
VEHICLES FOR EFFECTING THE PROPULSION OF THE SAME, AND IN APPARATUS OR
MEANS CONNECTED THEREWITH," A communication from abroad by Charles Arson,
of Paris, in the Republic of France.
This Invention relates to a combination of boilers and engines suitable for the
propulsion of such tramway cars as are not of sufficient size to justify the employ-
ment of a separate locomotive, and also for the propulsion of tramway cars
travelling in streets where there is a considerable amount of traffic precluding the
employment of trains of heavy and cumbrous vehicles.
In carrying out this Invention the engine or engines are arranged at one end of
the under frame of the car, and the boiler for generating the required supply of
steam is arranged at the opposite end of the same frame. The engines are situate
underneath the conductor's platform at the hinder part of the car and require no
attention. The boiler is arranged upon the driver's platform at the fore part of
the car, so as to counter balance the weight of the engines at the hinder part; it
requires but little attention, that of the driver or an assistant provided for the
purpose being sufficient.
The arrangement which forms the subject of this Invention is thus distinguished
by three main features, viz; 1st, the application of propelling apparatus to the
same vehicle which carries the passengers, thus avoiding the additional employment
of a special heavy, cumbrous, and expensive propelling carriage; 2nd, the uniting
of all the parts constituting two engines upon a single independent and light
frame, so as to render the whole removable at will when any part of the mechanism
requires repairs, the engines being replaced by another set while the repairs are
being effected; 3rd, the peculiar construction of the boiler, which is specially
designed with a view to the requirements of the case, combining a large area of
heating surface with lightness and economy of space.
The frame upon which the engines are mounted is constructed of angle iron, and
carried underneath the car, to which it is secured by bolts, and supports all the
tubes and other parts of the machinery. This arrangement enables the car to be
constructed in any convenient manner, with a view to cheapness and lightness

page_text: according to the methods adopted in the trade, it being simply necessary to provide
an under frame affording firm points of support for attaching the frame carrying
the engine.
With regard to the third characteristic feature of this Invention, which relates to
the arrangement of the boiler and details of the feed apparatus, the parts are so
constructed as to reduce their weight, in order to enable the whole of the propelling
apparatus to be carried on one vehicle.
This portion of the apparatus is composed of three distinct parts, viz., a fire box,
evaporating tubes, and a steam reservoir. The fire box encloses the furnace and
ash hox, so as to prevent waste of heat by radiation, affording a convenient space
for the deposition of calcareous salts, so as to ensure the preservation of the boiler,
and providing a heating surface which will produce, say, from four to five times as
much steam as that of an ordinary stationary boiler.
The tubes are arranged at the upper part of the fire box above the grate, and
afford a large heating surface combined with great lightness. The tubes are bent
double so as to be attached to one tube plate, and may be slightly inclined so as to
facilitate the escape of the steam; they communicate with a water space at the
fore part of the boiler. The sides of the boiler on a level with the tubes may be
enclosed by chambers constructed of thin sheet iron in which the feed water
circulates without pressure.
The steam reservoir encloses the lower part of the chimney. An outer casing to
the boiler is provided for the purpose of protecting the woodwork of the car from
injury from the heat, and to prevent inconvenience to the attendants from the
same source.
The furnace is formed by two metal plates in the form of a U and enclosing a
space between them for the circulation of water. This arrangement utilises the
caloric to the best advantage and effects a rapid evaporation. The steam reservoir
consists of a cylindrical chamber provided at the upper part of the boiler, and
communicating with the water space in the said boiler, so that the water level
rises and falls within this chamber between the maximum and minimum height,
the said level being regulated by means of a feed apparatus connected to the side
of the boiler by three small tubes arranged one above the other. The lower tube
serves for the supply of water to the boiler, the next tube forms the communication
between the feed apparatus and the water space in the boiler, and the upper tube
forms the communication between the feed apparatus and the steam space.
The feed apparatus consists of a chamber arranged at one end of the steam
reservoir, and containing a float which rises and falls with the level of the water in
the boiler. The float is connected with a piston valve working freely in a small
cylinder arranged at right angles to the lower tube, hereinbefore referred to, for the
supply of water to the boiler. When the level of water in the boiler sinks the
float descends with it, and presses down the piston valve so as to uncover the end
of the tube for the supply of water to the boiler, and the water continuously
injected by the pump is then freely admitted to the interior of the boiler. When
on the other hand the level of the water in the boiler rises the float rises at the
same time, and acts upon the piston valve so as to reduce the orifice for the
admission of the feed water, the surplus of which then escapes through a safety
valve on the pipe conducting the water to the feed apparatus and returns to the
reservoir.
This safety valve should be adjusted to a pressure slightly in excess of the
maximum pressure at which the boiler is to be worked.