IMPROVEMENTS IN THE CONSTRUCTION OF LOCOMOTIVE EN- GINES
Year: 1853

page_text: PROVISIONAL SPECIFICATION left by Jean Joseph Fréchin, at
the Office of the Commissioners of Patents, with his Petition, on
the 26th February 1853.
I, JEAN JOSEPH FRÉCHIN, of Bordeaux, France, and cf 4, South
Street, Finsbury, London, do hereby declare that the nature of the
Invention for "IMPROVEMENTS IN THE CONSTRUCTION OF LOCOMOTIVE EN-
GINES" to be as follows:-
The Invention consists, firstly, in certain improvements in the different
organs of a locomotive engine, in order to obtain a more useful effect
from the steam power; secondly, to lessen the wear and tear; and
thirdly, to facilitate the conducting of the engine by always exhibiting
to the engineer the principal parts of the machinery.

page_text: One of my improvements consists in constructing the engine wit
six wheels of the same diameter, the two driving wheels being placed
at the back of the fire-hole, at a distance equal to their radius. I
order to prevent the wheels making any useless revolution previous to
the starting of the train, I fix two connecting rods at right angles on
the extremity of the moving shaft to unite the middle wheels, thus
preventing any revolution of the wheels without moving the engine.
The same contrivance can be applied to the fore wheels. I likewise
arrange the cylinders obliquely within the boiler, and to secure them by
eccentric rods. They are set up or taken down, when necessary,
an aperture made in the upper part of the boiler, and above each of
them. The aperture is closed by means of a plate fixed by screw bolts.
The parallelism of the piston rods is maintained by a guide adapted
to each engine, and fastened to the cylinder and the frame. The valve
is in the form of a loose plate; a slide-box alone is required, the cylinders
being united inside by stays, so as to form the frame of the slide-box,
which is constructed on the front and back by-plates united to the
frame by means of bolts.
The egress of steam is effected by the same means as in other engines,
with this difference, that, instead of the steam passing through the
chimney, it is delivered freely in the air. The momentum is given to
the slides by means of a handle adapted to the head of the piston rod,
which is guided by a groove; the upper extremity of the opening ex-
tends beyond the small arm of the lever. The long arm of the lever
passes in the slide rod; and the relation of these two levers gives a
trifling advance to the admission; the same effect takes place on the
point of egress.
"
The tapid motion takes place at half-strokes (by the same means
used for the admission) by a permanent handle on the piston rod. At
the second half-stroke this handle meets a stopper, which is connected
by means of a rod with the crank arms, fixed to the same shaft on the
lever. This stopper is kept constantly perpendicular by means of any
suitable spring adapted to the piston rod. When it is intended to
proceed without a tapid motion the rod is disengaged from the crank-
arm by a knob placed between the slide rods by means of an inter-

page_text: mediate lever. Whatever may be the motion of the engine, it does not
in any way alter that of the slides.
A single slide is sufficient for the
two motions of the engine and the two tappets. When, by unforseen
circumstances, it is necessary to stop the engine, either to prevent
accidents or on a declivity, or if the breaks are insufficient, it will be
easy to effect this backing by merely disengaging the ordinary lever
from the moveable groove, and to engage it with the lever, having only
one point. of contact between the slide and its rod, which, in the pre-
ceding case, was in an opposite direction to that of the resistance. To
perform this it is necessary to change the position of the slide axle
This is effected by pushing it backwards, the shaft having a perforated
hole to receive a pin. When it is required to start the engine the slides
must be put in motion by means of the levers, by introducing steam
either above or underneath the pistons, according to the speed neces-
sary; and after one or two revolutions of the wheels, the engine will
continue to work. The feeding pump is fixed on the frame; it occupies
the empty space at the back of the guides, and is put in motion by the
head of the piston. In the event of the draught being insufficient, a
cock is placed, serving to inject into the chimney an additional jet of
steam from the boiler, and which is obtained by extending the back of
the fire grate a few inches from the ground.
Figure VII., section showing the form of the slides.
Figure VIII., plan of the admission ports 0, 0, and the eduction
ports e.
Figure IX. shows a plan of the slides x, x, x, opening, communi-
cating with the escape of the steam; the space Y, communicates with
the escape from the boiler.
The movement of the slides is effected, as herein-before described,
by means of the stoppers a, and b, when the piston has accomplished
its stroke; the square knob A, and the guide G, which is of the same
form at its extremities, engages with the stoppers a, and b, and on its
returning carries with it the guide. When the port is sufficiently
uncovered, the ratchets, provided with a jutting-out part at E, and E',
recede from the guide. The piston effects its complete stroke, and
when it is renewed the same movement takes place.

page_text: When it is required to back the engine the preceding motion is
employed. The ratchets being at rest, the knob not being in contact
with the extremities of the guide, it is necessary to increase one of its
dimensions, and this is done by screwing on the part A, Figure X.