IMPROVEMENTS APPLICABLE TO LOCOMOTIVE ENGINES
Year: 1871

page_text: PROVISIONAL SPECIFICATION left by Robert Francis Fairlie at the
Office of the Commissioners of Patents, with his Petition, on
the 24th March 1871.
I, ROBERT FRANCIS FAIRLIE, of 9, Victoria Chambers, in the City of
Westminster, Engineer, do hereby declare the nature of the said
Invention for "IMPROVEMENTS APPLICABLE TO LOCOMOTIVE ENGINES," to be as
follows:-
The experience gained from working the bogie engine proves that it
produces great economy in the wear and tear of the permanent way and
substructure generally as well as in the locomotives themselves and in
the other classes of rolling stock. There is also a very marked degree
of safety in the bogie engine when running over bad or imperfect roads
compared with the ordinary rigid engine, and on this ground alone the
bogie system should be universal.
The bogies hitherto employed have had more than one pair of wheels
under each end of the boiler and carrier frame, and these bogies with
more than one pair of wheels can conform to and radiate to any curve
by reason of there being more than two points of contact of the wheels

page_text: to the rails, that is, a bogie with more than one pair of wheels, say 4,
6, 8, or more wheels with parallel axles and fixed wheels, will conform
itself to any curve it may be traversing, providing the length of the
wheel base is not too great for the radius of the curve, but a bogie with
one pair of wheels unless specially guided will not do so, but will as
likely run across the rails at a curve as run properly round it.
The object of my present Invention is to compel a bogie with only
one pair of wheels to radiate truly to any curve it may be traversing,
whether the engine runs backwards or forwards, and therefore properly
guide the engine.
Small engines for working narrow gauge or branch lines, which whilst
requiring the largest possible amount of the whole weight for adhesion
may not need 4 cylinders driving the two bogies giving the whole
weight for adhesion; it is sought, therefore, to gain all the effectiveness
of the present double bogie engine, still maintaining the distinguishing
features of the same, that is, to have a boiler and carrier frame supported
on two bogies, one to be a driving bogie with 4, 6, or more wheels
coupled together in the usual manner, and the other to have one pair
of wheels only as carrying or supporting the end.
I may further describe the engine as a single boiler according to the
Specification of my Patent of 9th December 1865, No. 3185, resting in
the carrier frame as described in the Specification of my Patent of 14th
November 1867, No. 3221, which in turn is supported at or near one
of its ends on a bogie with 2, 3, or more pairs of driving wheels, and at
the other on a bogie with one pair of wheels only not driven. Assuming
the weight of the whole engine to be 16 tons empty, the proportion of
weight on the driving wheels would be 12 tons and on the carrying
wheels 4 tons, that is, two tons would be distributed over 6 driving wheels
and 4 tons over 2 wheels, making the total weight equal over the
whole 8 wheels, or 2 tons per wheel; we thus would have a single
boiler double bogie engine with one pair of cylinders giving 75 per cent.
of its working weight for adhesion, that is, we get an engine with the
driving wheels all under the cylindrical part of the boiler in a bogie
frame giving a very short wheel base and entirely preventing the
galoping motion of tank engines by supporting the foot plate end of
the engine on another bogie, but with one pair of wheels as carriers
only, so that we get complete flexibility with the two bogies, a short.
wheel base for curves, and yet a long wheel base for steady running,

page_text: whilst the centre line of the boiler and carrier frame constitutes a chord
on any curve which the bogics may be traversing, and in this manner
obtain the safety due to the double bogie engine.
Having now stated the nature of my Invention I proceed to explain
the mode or modes in which the axle of the bogie with one pair of
wheels may be made to radiate truly to any curve.
For this purpose
I attach or fix a bell crank to cach side of the fire-box shell of the
boiler, or to the carrier frame, and connect one of the two arms of these
cranks with rods to any suitable part of the trailing end of the bogie
frame which has the driving wheels by preference to each corner of the
bogie, in which are fixed eye bolts to receive the rods for the cranks.
In this manner the driving bogie is connected with the bell cranks,
which move backwards and forwards as the trailing end of the driving
bogie on passing curves alters the parallelism of its centre line and the
centre line of the boiler, which it always does on curves, the bogic
centre line being tangential to the curve, whilst the boiler and carrier
frame form a chord to it. Having thus secured the movement of the
bell cranks, the one having a forward motion and the other a backward
motion, depending upon whether the curve is to the right or to the left.
The next point is to connect the remaining arm of each crank by rods
and joints to the bogic frame with the one pair of wheels, the joint of
the connection being effected with the axle box outside the wheels when
the bearing is outside, or with the guide block of the axle box if the
bearing is inside the wheel. In either case the attachment and the rods
throughout from the one bogie to the other should be in line with the
centre of the single axle of the carriage wheels, which axle works on a
pivot or bogies on a centre similar to the leading wheels of an omnibus,
and in like manner is made to move round to suit curves, only in the
case of the omnibus the movement is secured by the pole which passes
between the horses, whilst in the case of the engine the movement is
secured by the rods attached to the bell cranks, which moving backwards
and forwards pull the axle forward on one side and shove it back on the
other, thus making the axle to radiate to the curve. The amount of
movement in the axle to secure true radiation to the curve is obtained
by the length of the arms of the bell crank, which can be adjusted to
give the exact motion required. The amount of the radiation will
vary according to the distance apart of the pivoting centres of the two
bogies.

page_text: According to another arrangement & transverse bar is fitted imme-
diately behind the back end of the front bogie, and this bogie is provided
with a slotted aperture into which a pin or projection on the said bar
takes. When the front bogie is passing round a curve it acts through
the intermediation of this bar and of bell cranks upon rods at each side
connected with the back bogie.
According to a third arrangement the axle boxes or other suitable
parts of the back bogie are connected with the fire-box or with some
part of the carrier frame at each side by jointed rods, so that when the
engine is passing round a curve the carrier frame shall have a tendency
to draw out these rods on one side and push them in on the other, and
thereby act upon the wheels of the back bogie, causing it to swivel in
accordance with the movements of the front bogic.