IMPROVEMENTS IN CALORIC OR HOT AIR ENGINES, AND IN CARRIAGES TO BE PROPELLED BY THE SAME
Year: 1881

page_text: PROVISIONAL SPECIFICATION left by Louis Wolff at the Office of the
Commissioners of Patents on the 5th July 1881.
LOUIS WOLFF, of Magdeburg, in the Kingdom of Prussia, German Empire.
"IMPROVEMENTS IN CALORIC OR HOT AIR ENGINES, AND IN CARRIAGES TO BE
PROPELLED BY THE SAME."
This Invention relates to an improved combined hot air engine and carriage for
use upon ordinary streets or roads or upon rails. This vehicle consists of two
divisions forming separate spaces, the rear one of which serves for the passengers
or goods to be conveyed, and the front one for the reception of the hot air motor.
The latter is a double-acting hot air engine having a working cylinder and a closed
fire box.
The power of the apparatus is about three horse, and its weight about 125 kilo-
grammes, this small weight being rendered possible not only by reason of the
arrangement hereinafter described, but also by the use of only one working
cylinder, although the engine is double-acting. As in this case the cylinder is
exposed to a considerably greater action of the heat than in a single acting hot air
cylinder, special provision has to be made for cooling the cylinder, so as to prevent
combustion of the lubricant.
In carrying the said Invention into practice I provide a cylinder having a piston
which is hollow, and is connected to a hollow piston rod passing through the
stuffing box of an air pump arranged above the said cylinder. Inside of this
hollow piston rod and concentrically with the same a tube is firmly fixed, which
is open at both ends. The exterior diameter of this tube is slightly less than the
interior diameter of the piston rod, so that a space is provided between the two.
This space is therefore connected on the one hand with the atmospheric air, and
on the other hand with the interior of the piston. Into the inner tube a piston
is fitted, the rod of which is attached at a fixed point above the air pump. Now
as this small piston during the upstroke of the main piston and piston rod moves
downward with relation to the inner tube, it will force the heated air within the
piston out through the space between the two tubes; during the downstroke this
inner piston draws fresh atmospheric air into the hollow of the main piston through
the same space. By this continuous renewal of the air in the hollow piston, over-
heating of the body of the same and of the piston rod is prevented.

page_text: The engine consists of large parts made of steel, copper, and brass, large iron
castings being altogether excluded. The cylinder, air-pump, and the chamber in
which the air is preliminarily heated are not as is usual made of cast iron, but of
wrought, copper, brass, and shect-iron. The chamber has inside the same an easily
interchangeable wrought iron fire box or vessel, and is without the ordinary
refractory lining, which increases the weight. Exteriorly this chamber consists
of lighter sheet-metal.
The air is heated by coke; the hot gases produced thereby pass through the
cylinder, acting therein in the well-known manner, and then flow through an
exhaust pipe. Above the mouth thereof, on the roof of the vehicle, a cowl of wire
gauze with small meshes is placed. This effects the retention of any sparks that
may pass into the exhaust pipe. Smoke and gas do not visibly escape from the
engine.
Two pulleys are secured at each end of the crank shaft driven from the piston,
the outer pulley on each side being half or about half the diameter of the other
two. There are also four other pulleys opposite those on the crank-shaft, this
second set of pulleys being arranged on two short shafts, two on one shaft and two
on the other. These short shafts extend outside the vehicle, and each one carries
at its outer extremity a chain wheel. The second set of pulleys are all of the same
Bize.
Chains are used for transmitting motion from. these chain wheels to chain wheels
twice as large as the others mounted on the naves or hubs of the rear wheels of
the carriage.
The pulleys mounted on the crank shaft as well as those on the two front or
short shafts are provided with raised edges to prevent the belts when they lie
slack on the pulleys from slipping off. The pulleys on the crank shaft drive
by means of belts the corresponding pulleys on the front or short shafts, and
consequently the rear wheels of the carriage; the tightening of the belts is effected
by special tightening rollers, whose position with relation to the corresponding
belts is determined by a hand lever through a suitable angle lever and connecting
rod. When the said hand lever, which is placed by the side of the driver's seat,
is in a vertical position, all the driving belts between the crank shaft and the short
front shafts are slack, and the carriage stops although the engine continues to
work. This is allowed to take place only during short stoppages.
If the hand lever is so operated that the belts on the four inner pulleys are
tight, the carriage will gradually begin to move. When the hand lever is moved
in the opposite direction, the result is that the other four pulleys work instead of
the four inner ones, and the carriage moves at a reduced speed, and is thus enabled
to overcome steeper inclines.
Each of the rear wheels of the carriage is mounted loose on its arm of the axle
and receives independent motion from the motor by chain gearing, so as to facilitate
travelling in a curved path.
The driver's seat is so mounted on a platform that the adjusting mechanism is
casily accessible to him, and he is enabled quickly to enter the engine room or cab,
which is closed by sliding doors.
The steering of the carriage is effected by moving a front wheel by means of a
hand wheel, on whose shaft is fixed a pinion which actuates an interiorly toothed
turning disc in connection with the steering wheel. The starting and stopping of
the engine and the maintenance of determined speeds, as well as the steering of the
carriage, are effected by a single person, the adjustment of the two hand levers
being alone required for the purpose. The desired speed may be regulated by the
partial opening of a valve provided on a valve chest on the air pump, whereby a
greater or less part of the air which is ordinarily intended for the working is
allowed to escape; this quantity of air does not pass through the fire space, and
therefore the power exerted through the cylinder and consequently the speed of
the carriage are correspondingly diminished. A small hand lever placed in close
proximity to the driver serves for operating this valve.

page_text: The power to be exerted by the engine may be regulated by another arrange-
ment, which affords means for driving the compressed air either over the fire bars
or from below the same through the layer of burning coke. For this purpose a
slide is provided, and the path to be taken by the air is determined by the driver
by adjusting this slide. When the latter is drawn upward the air is admitted
below the fire bars into the space for preliminary heating, and when the slide is
moved down the air passes thereto above the fire-bars. By employing a hot air
engine having slides instead of other valves noiseless working is ensured.
The brake is applied to the carriage by means of a hand crank which causes
brake blocks to bear against the wheels of the carriage. For instantaneously
stopping an excentrically acting falling brake is also provided.
If the carriage is to run on rails, instead of employing one front wheel only two
are employed which are either fixed on one rotating shaft common to both or may
be separately mounted loose, either on a common shaft or on separate ones.