Year: 1897

page_text: I, LEONARD JENNETT TODD, of 25, Brooke Road, Stoke Newington, in the County
of Middlesex, Locomotive Engineer, do hereby declare the nature of this invention
to be as follows:-
Steam engine cylinders from which part of the waste steam is released by means
of an elongated main piston uncovering escape holes at the end of each single
stroke in the center of the length of the cylinder, and from which the remaining
portion of the waste steam is released by an ordinary valve situated at either end
of the cylinder at which the boiler steam enters, are known as dual-exhaust
cylinders.
According to my invention I form the main piston of a dual-exhaust locomotive
cylinder of two truncated cones (or their equivalents) with their apexes together
in the center, and with their bases united by a light shell fitted with one or more
packing rings at each end. The two cones and the shell and the packing rings,
are all held together by a large and substantial screw and nut on the end of the
piston rod.
To each dual-exhaust locomotive cylinder with a dual-coned piston, I fit a dual-
piston steam distribution valve, for admitting the boiler steam to each end of the
cylinder, and emitting part of the waste steam from each end of the cylinder.
To locomotives with one or more cranks between the driving wheels, I fit one or
more dual-exhaust cylinders in the center of the cross-section of the locomotive, so
as to work respectively on to each of such cranks. Then either one or more dual-
piston valves are placed either on the top, or below, or laterally outside of each
cylinder, as most convenient. The passages from the central waste release and from
the ordinary waste release communicate with each other, and the final waste pipe
from these emerges below the bottom of the cylinder, so as to drain it; and passes
if necessary, right down below the locomotive main frame and then turns upwards
outside, and then converges to the center below the funnel, into which it discharges.
To locomotives with cranks outside of the driving wheels, I fit a dual-exhaust
cylinder so that it can work on to each of such cranks. One or more dual-piston
valves are then placed either on the top, or below, or centrally inside of each
cylinder, as most convenient. The passages from the central waste release and
from the ordinary waste release communicate with each other, and the final waste
pipe from these emerges below the bottom of the cylinder so as to drain it, and
passes if necessary right down below the locomotive main frame, and then turns
upwards inside, and converges to the center below the funnel, into which it
discharges.
I supply motive power to each dual-exhaust locomotive cylinder from a suitable
steam generating boiler; and control the motion of each dual-piston valve by a
reversing mechanism; and connect each dual-exhaust cylinder piston motion, to
one or more driving wheels
•

page_text: In certain cases I use steam distribution valves of either the flat, vibrating, or
other types, in place of the dual-piston valves.
Dual-exhaust steam locomotives may either have each dual-exhaust cylinder
working separately on the single expansion system, or may have the steam passing
from one cylinder to another on the compound system.
Dual-exhaust steam locomotives may work either on railways, or on tramways,
or on common roads.
Dual Exhaust Steam Locomotives.
I, LEONARD JENNETT TODD, of 25, Brooke Road, Stoke Newington, in the County
of Middlesex, Locomotive Engineer, do hereby declare the nature of this invention
and in what manner the same is to be performed, to be particularly described and
ascertained in and by the following statement:―
Steam engine cylinders from which part of the waste steam has been released
by means of an elongated main piston uncovering escape holes at the end of each
single stroke in the center of the length of the cylinder, and from which the remain-
ing portion of the waste steam is released by an ordinary valve situated at either
end of the cylinder at which the boiler steam enters, are known as dual-exhaust
cylinders.
According to my invention, I form the main piston of a dual-exhaust locomotive
cylinder of two separate ends united by a light distance piece in the center, all
held together by a large and substantial screw and nut on the end of the piston rod.
To each dual-exhaust locomotive cylinder, I fit a dual-piston steam distribution
valve, for admitting the boiler steam to each end of the cylinder, and emitting part
of the waste steam from each end of the cylinder.
To locomotives with one or more cranks between the driving wheels, I fit one
or more dual-exhaust cylinders in the center of the cross-section of the locomotive,
so as to work respectively on to each of such cranks. Then either one or more
dual-piston valves are placed either on the top, or below, or laterally outside of each
cylinder, as most convenient. The passage from the central waste release and from
the ordinary waste release communicate with each other, and the final waste pipe
from these emerges below the bottom of the cylinder, so as to drain it; and passes
if necessary, right down below the locomotive main frame and then turns upwards
outside, and then converges to the center below the funnel, into which it discharges.
To locomotives with cranks outside of the driving wheels, I fit a dual-exhaust
cylinder so that it can work on to each of such cranks. One or more dual-piston
valves are then placed either on the top, or below, or centrally inside of each
cylinder, as most convenient. The passages from the central waste release and from
the ordinary waste release communicate with each other, and the final waste pipe
from these emerges below the bottom of the cylinder so as to drain it, and passes
if necessary right down below the locomotive main frame, and then turns upwards
inside, and converges to the center below the funnel, into which it discharges.
I supply motive power to each dual-exhaust locomotive cylinder from a suitable
steam generating boiler; and control the motion of each dual-piston valve by a
reversing mechanism; and connect each dual-exhaust cylinder piston motion, to
one or more driving wheels.
In certain cases I use steam distribution valves of either the flat, vibrating, or
other types, in place of the dual-piston valves.
Dual-exhaust steam locomotives may either have each dual-exhaust cylinder

page_text: working separately on the single expansion system, or may have the steam passing
from one cylinder to another on the compound system.
Dual-exhaust steam locomotives may either work on railways, or on tramways,
or on common roads.
In order that my invention may be more easily understood, I have attached to
this description five sheets of explanatory drawings, numbered Sheet 1, 2, 3, 4,
and 5, respectively.
Sheet 1. This shows a section of my improved dual-exhaust cylinder, with its
elongated main piston marked A, A. And it also shows the dual-piston steam
valves marked B, B, for regulating the inlet steam to, and part of the outlet steam
from, each end of the cylinder.
Sheet 2. This shows the construction of the elongated piston with flat ends, when
it is desired to reduce the waste clearance spaces at the ends to a minimum; and
the dual-piston valve which is marked B, B, as before.
Sheet 3. This shows a cross section of a railway locomotive engine, with two of
my improved dual-exhaust cylinders, marked C, C., working on to cranks placed
between the driving wheels. And it also shows the dual-piston valves, marked B, B,
placed on the tops of the main cylinders.
Sheet 4. This shows a cross section of a railway locomotive engine, with two of
my improved dual-exhaust cylinders, marked C, C., working on to cranks placed
between the driving wheels. And it also shows the dual-piston valves,
marked B, B, placed below the main cylinders, and the waste pipes from these to
the funnel, marked E, E., which drain the cylinders of water, and prevent danger
from the rigid piston valves being unable to rise from their seats.
Sheet 5. This shows a cross section of a railway locomotive engine, with two of
my improved dual-exhaust cylinders, marked C, C., working on to cranks placed
outside of the driving wheels. And it also shows the dual-piston valves, marked
B, B., placed inside of the cylinders, and the waste pipes from these to the funnel,
marked E, E., which drain the cylinder of water, and prevent danger from the rigid
piston valves being unable to rise from their seats.
The economic advantages of my invention rest on three principal effects that it
produces, and which are as follows:-
First. The opening for the escape of the waste steam from the cylinder is larger
than can otherwise be arranged, and hence the resistance of this waste steam is
less than in ordinary locomotives, so that the effective power, from this cause alone,
may be increased 5 per cent., or even more, without any extra steam being used.
Second. As the steam inlet passage has not to be enlarged to allow of all the
waste steam escaping through it, as is usually the case, the dual-exhaust loco-
motive has waste clearance spaces at the cylinder ends, which may be made 10
or 15 per cent. less in capacity than these spaces are in ordinary locomotives, and
the economy from this cause alone may exceed 5 per cent.
Third. The annular escape ports in the cylinder, allow a large portion of the
cold expanded waste steam to escape without returning to cool the inlet end of
the stroke in the usual manner, so that the incoming boiler steam is not then con-
densed as much as usual, and I have experimentally determined that the economy
of steam from this cause alone, may exceed 5 per cent.
So that my dual-exhaust locomotive, when properly proportioned, can thus give
5 per cent. more power from 5 per cent. less steam, which, with the advantage
from the reduced clearance, gives a total economy of from 10 to 15 per cent.
beyond ordinary non-compound engines; and this without in any way increasing
the usual number of working parts found in the common locomotive.
Having now particularly described and ascertained the nature of my said
invention, and in what manner the same is to be performed, I declare that what
I claim is:-
1. Combining and arranging a dual-exhaust cylinder in a locomotive engine,
substantially as described or illustrated.

page_text: 2. A locomotive engine, formed by a combination of one or more dual-exhaust
main driving cylinders each with a dual piston valve, a steam boiler, a reversing
mechanism, and driving wheels.
3. A locomotive engine having a dual-exhaust main driving cylinder with the
waste steam from the dual-exhaust conducted away below the cylinder.
Dated this 7th day of January 1898.
LEONARD J. TODD.