IMPROVEMENTS IN MOTIVE POWER ENGINES
Year: 1855

page_text: PROVISIONAL SPECIFICATION left by Thomas Blackwood and Andrew
Gordon at the Office of the Commissioners of Patents, with their Petition,'
on the 18th January 1855.
We, THOMAS BLACKWOOD and ANDREW GORDON, both of Paisley, in the'
County of Renfrew, North Britain, Engineers, do hereby declare the nature of
the said Invention of "IMPROVEMENTS IN MOTIVE POWER ENGINES" to be as
follows, that is to say :-
This Invention relates to an arrangement or arrangements of engine or
prime mover to be worked by steam or other motive agent, whereby a high
working velocity is secured without the intervention of gearing or speed multi-
plying mechanism of any kind, such engines being especially designed and
adapted for screw propulsion, whilst they are at the same tinic applicable to
other purposes wherein the like properties are advantageous. According
to one modification of the improved engine, three or other convenient number
of steam cylinders are used, these cylinders being precisely like those employed
in ordinary reciprocating steam engines, that is to say, they are each furnished
with pistons,, ports, slide valves, and valve casings, with the usual inlet and
exhaust, passages for the steam. These cylinders are fixed to or carried by a
disc or frame, which is fixed upon the main shaft of the engine, this shaft
being, for example, that upon which the screw propeller is fixed if the engine
is used for screw propulsion. The cylinders are placed equidistantly (or in an
equivalent manner) round the disc, with their axial lines radiating from the
centre of the disc, and the inlet and exhaust passages for the stea'ni are seve-

page_text: rally made to communicate with passages in the disc running to the main shaft,
and extending a short distance along this shaft to two stuffing box connecting
pieces, one fixed upon the steam pipe from the boiler, and communicating, by
means of lateral apertures in the main shaft, with the several internal inlet
passages leading to the cylinder valve casings, whilst the other connecting piece
is fixed on the exhaust pipe leading to the condenser or to the atmosphere,
accordingly as the engine is of the condensing or non-condensing class, and
communicating by another set of lateral apertures in the main shaft with the
several internal exhaust passages leading from the cylinder valve casings.
The steam piston rods may be of the ordinary solid kind, but it is preferred
to have them of the trunk class, the trunks passing through stuffing boxes
either at one end only or at both ends of each cylinder.
The several connecting rods, issuing, by preference, from the inner ends of
the cylinders, are jointed upon a fixed or stationary abutment pin, about which
they are capable of revolving, and this pin is. placed eccentrically to the axis
of the main shaft, to an extent equal to half the stroke of the cylinders. The
action of the engine will be obvious, when it is considered that if the cylinders
were stationary, and the pin to which the pistons are connected capable of
revolving about an axis coincident with that of the frame carrying the cylin-
ders, the steam acting in the cylinders would force round this pin, just as the
crank pin of an ordinary engine is forced round; this pin, however, being
stationary or fixed in the present engine, the motive agency takes effect upon
the moveable frame and shaft carrying the steam cylinders. The valves are
worked by means of an eccentric upon the fixed abutment pin, each valve rod,
according to one plan, being jointed directly to a separate pin loose upon the
eccentric; or instead of this arrangement, the several valve rods may be con-
nected by links to a single ring loose upon the eccentric. The eccentric for
working the valves is made adjustable upon the abutment pin by means of a
lever, or other convenient hand gear, affording a simple and easily workable
means of commanding the action of the engine, as by shifting the eccentric the
engine can be either speedily reversed, made to work expansively to any
extent, or stopped, as circumstances may require. This description of engine
is capable of being worked with safety at a very high velocity, as the parts of
which it is composed have no absolute reciprocating motion, that is to say, the
engine is entirely free from the reciprocation of heavy masses of metal; which
in ordinary engines makes it injurious or impracticable to work them at high
velocities. In the arrangement forming the subject of the present Invention
the cylinders revolve about a centre, thus at the same time working the engine
and acting as its fly wheel. The pistons and valves also revolve about their

page_text: respective centres, and although the pistons are alternately at opposite ends of
their respective cylinders, this apparent or relative reciprocation is merely the
result of the non-coincidence of the centres about which they revolve. The
several details of the arrangement may be variously modified. Thus, for
example, the steam cylinders may be made to oscillate upon the frame which
carries them, in which case their piston rods may be jointed directly upon the
abutment pin, or the abutment pin may be made of comparatively large
diameter, the several piston rods being jointed directly to separate rings upon
it, the cylinders being fixed upon the revolving frame. According to another
modification, the steam cylinders may be carried by the abutment pin, the
pistons being connected to the revolving frame, the valves being in this case
worked by an eccentric upon the revolving frame or main shaft.