IMPROVED ARRANGEMENTS FOR APPLYING COMPRESSED AIR OR OTHER FLUID TO PROPEL OMNIBUSES OR OTHER VEHICLES ON RAILWAYS
Year: 1870

page_text: LETTERS PATENT to David Laidlaw and John Thomson, both of
Glasgow, in the County of Lanark, North Britain, Engineers, for
the Invention of "IMPROVED ARRANGEMENTS FOR APPLYING COMPRESSED
AIR OR OTHER FLUID TO PROPEL OMNIBUSES OR OTHER VEHICLES ON RAILWAYS,
m
"
PROVISIONAL SPECIFICATION left by the said David Laidlaw and John
Thomson at the Office of the Commissioners of Patents, with their
Petition, on the 17th October 1870.
We, DAVID LAIDLAW and JOHN THOMSON, both of Glasgow, in the
County of Lanark, North Britain, Engineers, do hereby declare the nature
of the said Invention for "IMPROVED ARRANGEMENTS FOR APPLYING COMPRESSED
AIR OR OTHER FLUID TO PROPEL OMNIBUSES OR OTHER VEHICLES ON RAILWAYS,
TRAMWAYS, OR COMMON ROADS, AND IN PART APPLICABLE OTHERWISE," to be as
follows, that is to say :-
This Invention, which relates to the propulsion of omnibuses or other
vehicles on railways, tramways, or common roads, comprises improved.,

page_text: arrangements for compressing air or other fluid to be employed as the
propelling agent; an improved safety reservoir or receiver for carrying
the compressed fluid, with a special reducing valve; and improved
arrangements for transmitting the power to the driving wheels; and for
steering the locomotive, traction engine, or vehicle on which the
motive power apparatus is fitted.
For compressing the air or other fluid a pump is employed with two
or more cylinders of graduated sizes connected together in line and with
their several pistons on one rod. Valves are fitted at the ends of the
cylinders and to the pistons, and the fluid first entering the largest is
compressed in succession by each piston so as to finally leave the
smallest cylinder in a highly compressed state.
The receiver or reservoir consists of a series of tubes of malleable
iron, steel, or other metal capable of containing a fluid under enormous
pressure. The ends are closed by cupped or flanged discs, which are
welded or brazed by the flanges to the tube ends, and a number of the
tubes are connected by small pipes and are combined together according
to the capacity or power required, being arranged in any convenient way
on the framing of the vehicle. The motive power may be obtained
from the compressed fluid by means of any suitable form of engine, but
it is preferred to adopt a simple pair of cylinders with trunk pistons
connected to cranks on the first motion shaft, the valves being by
preference of the piston class, and when compressed air is used allowing.
the exhaust to take place from the open ends of the valve tube in which
they work. The reducing valve used to obtain a regular working
pressure from the varying pressure in the receiver, consists of a cylin-
drical barrel having working in it two pistons on a spindle, the space
between them being in communication with the receiver. The outer
side of one piston is exposed to the pressure in the pipe leading to the
engine, and an adjustable spring is applied to the outer side of the other
piston. The spring moves the two pistons so that the further one
uncovers openings leading from the middle space to the engine passage,
but only to such an extent that the fluid passing through by its pressure
on one piston balances that of the spring on the other piston, so that
the pressure of the acting fluid will depend on and never exceed that
of the spring, which can be adjusted at pleasure. Belts are employed
for transmitting the power from the first motion shaft to the driving
axle or axles.
.

page_text: In one modification a pair of driving wheels are used, but arranged
to turn independently of each other, and fast and loose pulleys are
adapted to each, so that for steering purposes motion may be imparted
to either wheel whilst the other is unacted upon.
In another modification cone pulleys are used, and connected forks
for shifting the belts simultaneously, so that when one wheel is driven
faster the other one will be driven more slowly. The appliance for
acting on the belts may be connected with the parts for acting on the
steering wheel in front,, so that when that wheel is turned to either
side the motions of the driving wheels will be correspondingly modified.
The receiver and engine may be combined in one vehicle with
accommodation for passengers or goods, it is however preferred to arrange.
the tractive vehicle to a certain extent separately, but so as to be easily
connected to or combined with existing omnibuses or other vehicles,
the front pair of wheels being in that case removed from the omnibus,
and its front end supported by the back of the tractive vehicle.
The belt gearing and steering. arrangements. are obviously applicable
to steam locomotives and traction engines..
SPECIFICATION in pursuance of the conditions of tlie Letters Patent,
filed by the said David Laidlaw and John Thomson in the Great
Seal Patent Office on the 17th April 1871..
TO ALL TO WHOM THESE PRESENTS SHALL COME, we, DAVID
LAIDLAW and JOHN THOMSON, both of Glasgow, in the County of Lanark,
North Britain, Engineers, send greeting..
WHEREAS Her most Excellent Majesty Queen Victoria, by Her
Letters Patent, bearing, date the Seventeenth day of October, in the
year of our Lord One thousand eight hundred and seventy, in the
thirty-fourth year of Her reign, did, for Herself,, Her heirs and suc-
cessors, give and grant unto us, the said David Laidlaw and John
Thomson, Her special licence that we, the said David Laidlaw and
John Thomson, our executors, administrators, and assigns,. or such
others as we, the said David Laidlaw and John Thomson,, our executors,,
administrators, and assigns, should at any time agree with,, and no
others, from time to time and at all times thereafter during the term.

page_text: therein expressed, should and lawfully might make, use, exercise, and
vend, within the United Kingdom of Great Britain and Ireland, the
Channel Islands, and Isle of Man, an Invention for "IMPROVED ARRANGE-
MENTS FOR APPLYING COMPRESSED AIR OR OTHER FLUID TO PROPEL OMNIBUSES OR
OTHER VEHICLES ON RAILWAYS, TRAMWAYS OR COMMON ROADS, AND IN PART
APPLICABLE OTHERWISE," upon the condition (amongst others) that we, the
said David Laidlaw and John Thomson, our executors or administrators,
by an instrument in writing under our, or their, or one of their hands
and seals, should particularly describe and ascertain the nature of the said
Invention, and in what manner the same was to be performed, and cause
the same to be filed in the Great Seal Patent Office within six calendar
nionths next and immediately after the date of the said Letters Patent.
NOW KNOW YE, that we, the said David Laidlow and John
Thomson, do hereby declare the nature of our said Invention, and in
what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement in writing, reference
being had to the accompanying Drawings, that is to say:-
Our said Invention, which relates to the propulsion of omnibuses or
other vehicles on railways, tramways, or common roads, comprises
improved arrangements for compressing air or other fluid to be employed
as the propelling agent; an improved safety reservoir or receiver for
carrying the compressed fluid, with a special reducing valve; and improved
arrangements for transmitting the power to the driving wheels; and for
stcering the locomotive, traction engine, or vehicle on which the motive
power apparatus is fitted.
And in order that our said Invention and the manner of performing
the same may be properly understood we hercunto append a Sheet of
explanatory Drawings to be herein-after referred to and representing an
example of our improved arrangements. In these Drawings the same
reference numerals are used to mark the same or like parts wherever
they are repeated.
For compressing the air or other fluid we employ a pump, one modifi-
cation of which is shown in sectional elevation in Figure 1. We connect
together two or more cylinders 1, 2, 3, of graduated sizes with their
several pistons on one rod 4, and we fix two or three sets of such
cylinders in an inverted position on a framing 5, and work the pistons
from a crank shaft 6 arranged in the lower part of the framing and
actuated in any convenient way. The air enters the largest cylinder 1

page_text: through openings 7 in its side, just below which the piston 8 passes at
the bottom of its stroke. The piston is packed by means of a thin brass
or steel ring which is distended by rubber or other elastic rings 9 inside
it, and on the uppermost of these rings there rests a disc 10, fitted so
as to be capable of a slight movement on the rod 4. As the piston
approaches the top of its stroke and the resistance of the compressed
air increases, the air causes the disc 10 to press down the rubber rings 9
so as to force out the packing ring more strongly, and this packing ring
is thus made to act with sufficient tightness when the air is much com-
pressed, whilst at the beginning of the stroke it acts with much less
pressure and consequent friction. At the end of the cylinder 1 (and
similarly at the upper end of each of the other cylinders) there is a
valve 11, consisting of a disc covering the entire end of the cylinder 1,
and the piston disc 10 goes up into close contact with it at the top of
the stroke to insure the complete expulsion of the air, the stroke being
by preference arranged so as to carry the piston disc 10 slightly beyond
the end of the cylinder 1. A spring 12 insures the closing of the
valve 11 when the piston below returns down. These valve arrange-
ments are advantageously applicable with a single compressing cylinder.
When two or more connected cylinders are used, the air is more and
more compressed in each in succession, but when the increased number
of parts is considered the advantages of the series of graduated cylinders
are not as great as might at first appear, and in most cases we should
prefer to use the similar arrangement of a single cylinder. A tank 13
may be formed round the cylinder or cylinders to receive cold water for
removing the heat developed by compressing the air.
Our improved receiver or reservoir consists of a series of tubes of
malleable iron, steel, or other metal capable of containing a fluid under
enormous pressure. The ends of each tube are closed in a manner that
will be understood from Figure 2, which is a half-size section. A flanged
or cupped disc 14 is welded or brazed by its flanges in each end of the
tube 15, and a number of such tubes 15 are connected by small pipes 16,
and are combined in the manner, for example, shown in end and side
clevation in Figures 3 and 4, according to the capacity or power required.
being arranged in any convenient way on the framing 17 of the vehicle.
The motive power may be obtained from the compressed air by means
of any suitable form of engine, but we prefer to adopt a simple pair of
cylinders 18, with their pistons connected to cranks on a first motion
shaft 19, and with common slide or other suitable valves. We employ

page_text: belts 20 for transmitting the power from the first motion shaft 19 to
the driving wheels 21.
In the modification shown in Figures 3 and 4, the driving wheels 21
are arranged to turn independently of each other, being fixed on separate
short tubular shafts on a central connecting axle 22. Fast and loose
pulleys 23, 24, are mounted on each tubular shaft, so that the driving
belts 20 can be shifted and either wheel be driven whilst the other is
unacted upon. A transverse bar with forks 25 is provided for shifting
the belts, and this bar is moved by a horizontal bell crank lever connected
by a link 26 to a hand lever 27 at the front of the vehicle.
In another modification cone pulleys are used and connected forks for
shifting the belts simultaneously, so that when one wheel is driven
faster the other one will be driven more slowly. The lever or appli-
ance for acting on the belts may be connected with the lever 28 or other
parts for acting on the steering wheel 29 in front, so that when that
wheel is turned to either side the motions of the driving wheels will be
correspondingly modified.
The improved reducing valve which we use to obtain a regular
working pressure from the continually varying pressure in the receiver
is shown in vertical section in Figure 5, and of a size suitable for
working apparatus of the kind shown in Figures 3 and 4.
The arrange-
ment consists of a barrel 30, with an accurately formed cylindrical bore
in which there work two carefully turned pistons 31, 32, connected by
a spindle 33. The space between the pistons 31, 32, is in communication
with the receiver by the branch pipe 34, and whilst the outer-side of
one piston 32 is exposed to the pressure in the pipe 35 leading to the
engine an adjustable spring 36 is applied to the outer side of the other
piston 31. The spring 36 moves the two pistons, so that the further
one 32 uncovers openings 37 leading from the middle space into the
engine passage 35, but only to such an extent that the air passing
through balances the strain of the spring by its pressure on the bottom
of the lower piston 32, so that the pressure of the air or fluid acting in
the engine will depend on and never exceed that of the spring which
can be adjusted at pleasure.
The receiver and engine may be combined in one vehicle with accommo-
dation for passengers, as shown in Figures 3 and 4, or with provision for
receiving goods, we however prefer to arrange the tractive vehicle to a
certain extent. separately, but so as to be easily connected to or combined

page_text: with existing omnibuses or other vehicles, the front pair of wheels being
in that case removed from the omnibus, and its front end being
supported by the back of the tractive vehicle.
Our improved belt gearing and steering arrangements are obviously
applicable to steam locomotives and traction engines.
Having thus particularly described our said Invention, and the
manner in which the same is to be performed, we have to state that we
do not restrict ourselves to the precise details herein described or
delineated, but that what we believe to be novel and original, and claim
as the Invention secured to us by the herein-before in part recited
Letters Patent is,―
1. The combining together of the parts of compressing pumps and
the fitting of their pistons and valves in the improved manner herein
described and delineated.
2. The constructing of a receiver or reservoir for compressed air or
other fluid by combining together a number of tubes having their ends
closed in the manner herein-before described.
3. The applying of motive power to the driving wheels of a self
moving or tractive vehicle by means of belts and pulleys, and the
arranging of such details so that the wheels may be driven independently
or at different speeds, substantially as herein-before described.
4. The constructing of a pressure reducing valve in the improved
mode herein described and delineated.
In witness whereof, we, the said David Laidlaw and John Thomson,
have hereunto set our hands and seals, this Fourteenth day of
April, in the year of our Lord One thousand eight hundred and
seventy-one.
30 Witness,
EDMUND HUNT,
Patent Agent,
Glasgow.
DAVID LAIDLAW. (L.S.)
JOHN THOMSON.
(L.S.)