IMPROVEMENTS IN HEATED-AIR ENGINES
Year: 1866

page_text: PROVISIONAL SPECIFICATION left by Henry Messer at the Office of the
Commissioners of Patents, with his Petition, on the 11th October
1866.
I, HENRY MESSER, of No. 1, Northumberland Court, Charing Cross, in
the County of Middlesex, Engineer, do hereby declare the nature of the said
Invention for "IMPROVEMENTS IN HEATED-AIR ENGINES," to be as follows:-
£
The said improvements consist, first, in the novel construction of the
furnace, and its casing, whereby a more perfect combustion of the volatile
products of the fuel is effected and the removal of the liuing of the said furnace.
when required is greatly facilitated.
Second in the construction of the supply pipe leading from the furnace to
the valve chest containing the induction and eduction valves, whereby the air
is caused to travel a greater distance in passing from the furnace to the said
valve chest.
Third, in arranging the said valves in such a manner that more ready access
is allowed thereto for repairing or other purposes.
Fourth, in the arrangement of the air passages (leading from the air pump.
to the furnace and cylinder) and dampers for closing the said, passages.
..And, fiftb, in the mode of driving the governor, whereby the speed of the
engine may be regulated by an attendant from any desired part of a house or
other building wherein the engine is placed.
The bed or foundation plate is by preference constructed of cast iron, and is
of suitable form and strength to support firmly the furnace, the air pump and

page_text: other parts of the engine, and to allow of the formation therein of passage
ways leading from the air pump to the furnace and cylinder of the said engine.
The said furnace is firmly secured by bolts or screws to this foundation plate,
and is provided with two doors, one of which communicates with the ash-pit,
and the other with the furnace near the top thereof. These doors and their
frames should be so constructed and fitted together that when the former are
closed and secured by a latch or other suitable fastening they are perfectly
air-tight.
. The furnace is of a circular form and is constructed with an outer casing of
iron having a lining of fire-clay, fire-brick, or other suitable material. Near
the top of the said lining a passage way is formed, extending around about
one-half the circumference thereof, and communicating with the interior of
the furnace by a series of small holes, all of which converge towards the centre
of the furnace. The air is admitted into the said furnace through these holes
in small jets or currents. By this means the air is more uniformly and
effectually heated and expanded, and the combustion of the fuel is more per-
fectly accomplished. The outer cylindrical casing which surrounds the furnace
and lower portion of the cylinder is divided horizontally at or near the top of
the furnace;. the lower portion of this casing is open at both ends, flanges
being formed thereon. The said casing is secured to the bed plate of the
engine, and also united to the upper portion of the said casing by bolts or
screws passing through the said flanges. The upper portion of this casing is
also provided with flanges at each end, the lower flange extending outwardly
to allow of being secured to the lower or furnace portion thereof, while the
upper flange is extended inwardly to allow of the upper end of the cylinder
being secured thereto. The bottom of the upper part of the said casing is
closed, so as to shut off all communication between the furnace and the
cylinder, except through the supply pipe. This upper part is lined with fire-
clay or brick and forms the lower portion of the working cylinder; this method
of constructing the casing allows the furnace lining to be removed and repaired
with great facility.
Air passages are provided leading from the passages formed in the bed plate
and communicating with the ash-pit with a passage way formed in the lining
of the furnace, and with an annular space formed round the lower end of the
upper portion of the cylinder, which annular space communicates by means of
another passage way with the furnace above the fuel. Dampers are provided,
by means of which the said passages are opened or closed as required, and the
air caused to pass from the air pump, either into the ash-pit below the fuel,
into the furnace above the fuel, or upward into the-space around the bottom

page_text: of the upper portion of the cylinder, whence it passes downward. into the
furnace above the fuel, or the air may be caused to pass partly in either
direction. The lower portion of the furnace casing is provided with brackets,
upon which are supported and secured the upright standards or colunms which
carry in suitable bearings the gudgeon's of a strong vibrating or working
beam. The bearings.carrying the main shaft.are also cast or otherwise.firmly_
fixed upon the said standard. One end of the working beam is connected by
suitable rods to the crank on the main shaft, and to the piston of the air.
pump; the other end of this working beam is connected by one or more rod's
to the piston of the working cylinder, the said piston being guided by a rod or
rods fitted to slide through a fixed cross-head attached to the top of the
said cylinder..
:
On one end of the main shaft a disc or plate is secured, the said plate being
provided with an excentric pin. This pin is jointed to one end of a rod, and
thereby communicates motion to a rocking shaft, which works in bearings
supported and secured upon the valve chest or other convénient portion of
the engine. The said shaft carries the tappets for lifting the induction
and eduction valves of the cylinder. The rods or spindles of these valves pass
upward through suitable guides, and are provided with adjustable studs or
fingers for the tappets to act upon. If necessary springs may be provided to
ensure the proper falling of these valves upon their. seats when released 'from
the tappets. These rods pass through suitable stuffing boxes, their ends being
firmly secured to the valves, which consist of circular metal plates properly
fitted to faces. or seats fixed or formed within the valve chest in the same
horizontal plane. The passage ways inside the valve chest are so arranged
that both valves open in their upward movement and close in their downward
movement. This arrangement allows the said valves to be readily adjusted
or removed when required for repairing or other purposes.
In heated air engines where the cylinder is placed over the furnace, as
hitherto constructed, great difficulty is experienced in getting the valves properly
placed with regard to the cylinder, and far enough from the furnace to ensure
a more perfect combustion of the volatile products of the fuel before they
enter the valve chest. This difficulty is entirely obviated by constructing the
pipe which conveys the heated air from the furnace to the cylinder with a
bend in the form of a U or horse-shoe. One end of this pipe is attached to and
communicates with the interior of the valve chest, which is secured to the
casing surrounding the lower portion of the cylinder, the other end of the said
pipe being attached to and opening into the furnace. An aperture is formed.
in this bent pipe near the furnace end thereof, which communicates with

page_text: a pipe or flue leading directly, to the chimney. This, aperture is furnished
with a valve or damper, which is closed, ordinarily when the engine is at
work, but which is opened when the fire is to be lighted. By means of
this direct communication between the furnace, and the chimney a sufficiently
strong draught or current of air is obtained to insur the quick burning
of the fire after the same is lighted, and the smoke is prevented passing
through the valve chest and forming a deposit upon the valves and seats.
The main shaft of the engine is provided with a conical pulley from which a
-belt or band passes over a similarly formed pulley on the governor, the two
pulleys being so arranged that the small end of one is opposite the large end
of the other.. This belt passes through an adjustable guide, by which its
position upon the two pulleys can be changed as required. When the speed
of the engine is to be accelerated, the guide is moved to draw the belt
towards the small end of the pulley on the main shaft, and when the speed
of 'the engine is to be slackened the guide is moved to draw the belt towards
the opposite end of the said pulley. One end of a cord or chain is attached
to the adjustable guide, the said cord being extended to any desired part
of the building wherein the engine is placed. By pulling this cord the speed
of the engine may be varied as required. A weight or spring is provided to
move the guide in the opposite direction, or if preferred a second cord may be
provided for that purpose.