IMPROVEMENTS IN LOCOMOTIVE ENGINES
Year: 1882

page_text: PROVISIONAL SPECIFICATION left by John Henry Johnson at the Office
of the Commissioners of Patents on the 3rd May 1882. A cominunication
from abroad by Louis Brière of Paris in the Republic of France
JOHN HENRY JOHNSON of 47 Lincoln's Inn Fields in the County of Middlesex
Gentleman "IMPROVEMENTS IN LOCOMOTIVE ENGINES" a communication from
abroad by Louis Brière of Paris in the Republic of France
This Invention relates to improvements in the construction of locomotive engines
and it consists in a peculiar arrangement of the parts as hereinafter described and
whereby it is rendered possible to combine the advantages of high speed great
steadiness and great power of traction.
The relative positions of the principal parts (axles boiler valve gear connecting
rods etc) of express locomotives as heretofore constructed render it difficult if not
impossible to combine these qualities in a high degree. The high speed at which
these Engines are required to travel necessitates the employment of wheels of great
diameter. Whilst the hauling power which they are also required to exert renders
it necessary that at least two pairs of wheels should be coupled together. Under
these conditions the boiler which always heretofore has been arranged above the
axles becomes elevated to a position which is objectionable for many reasons and
especially on the score of stability.
According to this Invention the boiler is arranged underneath the driving axles
the necessary space being provided by making the driving wheels of considerable
size (say about fourteen feet for example) By this means a clear space of about
six feet is obtained below the axles which is amply sufficient to contain the locomotive
boiler and its fire box under suitable conditions This space under the boiler may
be economised by making the cylindrical part of the boiler of a relatively small
diameter (which is moreover necessary in order to facilitate placing the boiler between
the wheels as well as to compensate for the great weight of the large wheels) and
by causing the lower part of the fire box to project as little as possible. The
diameter of the large wheels herein before described may thus be reduced to a certain
extent.
The cylinders of the improved locomotive are arranged on the top of the boiler
and occupy the same position in relation to the cranked axle as in ordinary
locomotives.
The cylinders may be arranged internally or externally with regard to the frame
but when possible that is to say when the boiler is hung low enough to give room
for the cranks it is preferable to place them between the wheels in order to counteract
the tendency to rock. By means of this arrangement the following advantages are
obtained viz:
First. Very high speeds may be attained without inconvenience as whilst the

page_text: number of revolutions of the driving wheel per second and the speed of the pistons
remain approximately the same as in Engines with driving wheels of ordinary
dimensions the rate of progression is nearly doubled.
Second. The two pairs of large wheels may be coupled together without
inconvenience
Third. Lastly the stability or steadiness of the improved engine is as great as
can be desired the heaviest part of the structure being placed as low as possible:
In carrying out this Invention the arrangement of the details of the Engine may
vary considerably according to circumstances provided that the general principles of
construction hereinbefore described are observed.
For example supposing an internal frame is employed with ordinary springs it
will be simply necessary to prolong the suspension bolts in order to enable the
boiler to occupy its place underneath the axles of the driving wheels. The axles
being arranged above the frame the horn plates will be turned upwards in place of
downwards and being necessarily somewhat longer than in the ordinary arrange-
ment will require to be made stiffer and to be more strongly stayed accordingly:
When the cylinders and driving gear occupy their usual internal position
relatively to the driving wheels it is necessary to arrange the whole of this mechanism
above the centre line of the boiler and at about the usual distance from the said
centre line. Under these conditions it becomes necessary to provide a support for
the driving gear which is usually directly or indirectly connected with the main
frame of the engine. This support is obtained in this improved arrangement by
employing a supplementary frame shorter than the main frame firmly tied or
connected to the latter by diagonal bars and to the sides of the boiler and
smoke box.
The upper and supplementary frame extends towards the rear of the Engine only
for a sufficient distance to enable it to support the driving mechanism in this direction
but if preferred may be prolonged beyond the axle of the trailing wheels. The
latter arrangement presents the advantage of enabling the horn plates and suspending
bolts to be attached directly to the upper frame and by thus placing these parts
under approximately the same conditions as when pendant horn plates and suspension
bolts arranged underneath the frame are employed they can be made proportionately
lighter.
The frames and horn plates are stayed horizontally by suitable transverse bars
or plates above and below the boiler. The transverse bars above the boiler may be
utilized for supporting a platform for the Engineer to obtain access to the Engine
for the purpose of inspecting and oiling the parts:
The length and arrangement of the steam and exhaust pipes will be necessarily
modified as the cylinders occupy a position relatively to the boiler totally different
from that of the cylinders of ordinary Engines and the steam dome and other
projecting parts on the top of the boiler must be so arranged as not to stand in the
way of the axles: The fore part of the Engine may be supported by a bogey but
it is preferred in order to shorten the base as much as possible to support the fore
part on a single pair of small wheels only, preferably arranged on what is known
as Bissel's system and provided with suitable means for facilitating the passage of
curves.
The hinder part of the Engine may be supported if required by a bogey or by a
single pair of wheels as hereinbefore described with reference to the forepart and
if required a pair of small wheels may be arranged between the two pairs of large
driving wheels.
The various parts of the steam generating apparatus must be of such a length as
to compensate for the necessarily contracted diameter of the boiler.