OR IMPROVED MODES OF OBTAINING AND TRANSMITTING MOTIVE-POWER AND IN THE MACHINERY OR APPARATUS EMPLOYED THEREFOB
Year: 1866

page_text: PROVISIONAL SPECIFICATION left by Robert Bennett at the Office of
the Commissioners of Patents, with his Petition, on the 10th September
1866.
I, ROBERT BENNETT, Gentleman, of the City of Edinburgh, in the County
of Mid Lothian, North Britain, do hereby declare the nature of the said
Invention for "NEW OR IMPROVED MODES OF OBTAINING AND TRANSMITTING
MOTIVE-POWER AND IN THE MACHINERY OR APPARATUS EMPLOYED THEREFOB," to bu
as follows, that is to say :-
My said Invention has reference to motive-power engines of the recipro-
catory class worked by the confined pressure of steam, air, water, or other
fluid raised, accumulated, and conveyed all by any of the usual manners at
present practised for using the same as motive-power agents for the moving a
piston or pistons and cylinder or cylinders, as the case may be, which is or are
connected in the usual manner by connecting rods to a crank shaft, so as to
convert the reciprocatory motion into circular motion, and transmit the motion
and power for general purposes in the usual manner. And the essential feature
for this my Invention consists in alternately increasing and diminishing the
area of the piston and cylindor or pistons and cylinders, or acting surfaces at
the ends of their strokes (or at the time the crank is turning the two "dead"
centres in a line with the axis of the moving piston or cylinder), so as to act
upon and move the actuating surface, for the time being, with a proportionally
greater force in the direction of motion than in the reverse direction equal to
the said difference made or caused in the area of the actuating surfaces, and
the pressure of steam acting thereon above that of the atmosphero, and by
this means keeps the direct pressure of the steam or other fluid power

page_text: employed constantly acting within the cylinder or cylinders, as the case may
be, without any great or essential escape of the acting fluid or heat therefrom,
as is the case in the present construction of engines, which allows an escape
of the motive-power fluid at the end of every stroke equivalent to the whole
cubical contents of the motive-power cylinder.
The most simple form which has occurred to me of practically carrying out
this my said Invention (say, as to be worked by steam) consists in having a
horizontal or vertical reciprocating cylindrical or other shaped vessel rather
longer than twice the length of stroke, or four times that of the crank, to
which it may either be connected by a single or duplex connecting rod to turn
tle crank and its shaft either on a vertical or horizontal axis. This cylinder
bas close ends and two longitudinal rectangular slots formed on its opposito
sides with recesses corresponding extending a considerable distance into the
two close ends; these long slots as the cylinder reciprocates work steam-
tight upon two longitudinal area contracting plungers, blocks, or, slides at each
end rather longer than the length of stroke, and projecting some distance
beyond the ends of the cylinder at its extreme traverse either way; and these
contracting slides work or slide laterally out through steam-tight recesses
formed in the slides or faces of two portions of the main steam boilers, or two
vessels in direct connection therewith, upon or between which the cylinder
works at the two sides steam-tight, and which form the main framing of the
reciprocating cylinder. The steam is admitted to the cylinder at the centre
by a pipe or pipes through the longitudinal slots at the sides from the steam
vessels, between divisions forming the adjacent end guides at the centre for
the area contracting slides as they are laterally introduced or withdrawn from
the cylinder by any ordinary mechanical means or movements.
One means
being cams on shafts for the purpose geared directly to the crank shaft, or
otherwise by levers worked from tappets projecting from the moving cylinder.
Two parallel rods are connected to each contracting slide near their extreme
ends, passing out through stuffing boxes in the steam chambers at the sides
where they are attached to a cross head outside. The sides of the slides
working within the steam chambers have the same pressure of steam acting
on them as on the sides working inside the cylinder, so that little is
required to move the two lateral slides into the cylinder when it has reache
its extreme outward end stroke in either direction from the centre, so as to
contract the area of the reactionary end of the cylinder, for the time being,
during its return stroke towards the centre or annular division where the
steam enters the cylinder; but for drawing out the two slides at the other end
of the cylinder, which takes place at the same time as those at the other
power

page_text: end are pushed in, to enlarge the area of the acting end of the cylinder for
the time being during the outward stroke from the centre some considerable
power is required, as a greater portion of the outer surface of these two slides
at this end are outside of the cylinder, therefore not exposed to the extra
pressure of the steam as they are on that of the inside of the steam chambers,
but only exposed to the pressure of the atmosphere, and therefore the cross
heads of the ends of the parallel guiding rods of these slides may be attached
to counterbalancing pistons of steam cylinders sufficiently large to balance and
move them, steam being let into these cylinders at the proper time for that
purpose a short time and distance before the main cylinder reaches the out-
ward end of its stroke by a tappet on the main moving cylinder and tilting
weighted lever action, or otherwise the valves of the counterbalancing cylinders
may be worked by excentrics or cams, on the crank shaft. The lateral open-
ings in the ends of the cylinder, for the contracting blocks to work into, are
covered by steam-tight slides working on steam-tight faces on the inside ends
of the cylinder, and made to follow and work steam-tight up against the face
of the slides by guides, or by springs pressing them assunder or against tho
said working faces. In this way the pressure of the steam being constant and
greater within the steam vessel and cylinder than tho pressure of the atmo-
sphere outside the cylinder moves in the outward direction from the centro
with the enlarged end surface area advancing forward by the greater pressure
of steam acting on it until it reaches its extreme outward stroke, when the
converse action of the lateral enlarging or contracting blocks takes place, that
is, the two lateral slides at that end of the cylinder, now at the outside, aro
pressed inwards and contract the area and capacity of that end of the cylinder,
while the two slides at the other end are drawn out so as to enlarge its
capacity and area, when the cylinder then moves outwards in the opposito
direction to that of the former motion and stroke to complete a revolution of
the crank shaft, and so on, so long as the lateral slides are thus alternately
moved out and in at the extreme ends of the stroke of the cylinder. In place
of the cylinder moving, as just described, the cylinder may be made stationary,
and two pistons made to traverse too and fro in it, one at each end fast on the
same piston rod. In this modification the two ends of the cylinder must be
bored out to suit the two pistons, the steam entering at the centre of the
cylinder, as in the former modification, so as to act on the inside surfaces of
the pistons and force them out alternately from the centre as the area of the
pistons are enlarged and contracted. The cylinder in this case may either be
worked with or without ends or covers, but open to the atmosphere; the inside
of these ends, and the central annular division form slides or guides, or ends

page_text: of the steam-tight recesses for the four longitudinal contracting slides working
transversely between the cylinder and the steam chambers, two contracting
blocks or slides working into each end of the cylinder as in the former
arrangement. The pistons having deep recesses or notches formed in them
at each side to work or slide longitudinally upon the laterally contracting
blocks or slides, with vanes or slides working or sliding in the notches or over
the face of them in steam-tight contact with the piston and against the face
of the contracting blocks, so as to prevent all escape of steam at the recesses
through the pistons as the blocks traverse laterally into or out of the recesses
while contracting the capacity and area of the cylinder and pistons. The
action in this case would be the same as in the former modification described,
namely, the area of each acting surface or piston in this case being enlarged
as it reaches the centre for the outward stroke by the drawing out of the
lateral sliding blocks, at the same time as the area of the other piston was
contracted by pushing the slides at that end of the cylinder inwards in
readiness for the inward reactionary stroke, and so on alternately, as each
piston reaches their inward and outward stroke to complete the revolution of
the crank shaft, connected in this case to the piston rod by a connecting rod
or otherwise in any of the usual manners now in use for that purpose. The
latter modification might be worked with close ends on the cylinder having
steam introduced between the contracted piston and its end cover, while the
space between the other end of the cylinder and the enlarged piston was
opened to the atmosphere, or to a condenser by slide or other valves in the
usual manner, so as to combine the working of my improvements in the same
motive-power engine along with those at present in use for the like purpose,
and so make the same engine double-acting on each piston, and work to nearly
double the power it would do by only allowing the steam to act effectively on one
piston at a time. In all these arrangements I prefer to cover in the cylinders
by non-conducting materials, such as wool and wood, to prevent radiation or
condensation in the cylinders, when steam or other heated elastic fluids are
employed as the motive-power agent in the cylinders, to which I also attach
small escape valves or cocks at their lower sides or ends when steam is used
to carry
off any water which may bo condensed or collected therein.