CERTAIN NEW AND USEFUL IMPROVEMENTS IN MACHINERY FOR PROPELLING VESSELS, SOME OF WHICH ARE APPLICABLE TO OTHER PURPOSES
Year: 1878

page_text: LETTERS PATENT to Sydney Pitt, of Sutton, in the County of Surrey, for the
Invention of "CERTAIN NEW AND USEFUL IMPROVEMENTS IN MACHINERY FOR
PROPELLING VESSELS, SOME OF WHICH ARE APPLICABLE TO OTHER PURPOSES."
A communication from abroad by John Baird, of New York, in the United
States of America, Mechanical Engineer.
Sealed the 12th July 1878, and dated the 23rd May 1878.
COMPLETE SPECIFICATION filed by the said Sydney Pitt at the Office of the
Commissioners of Patents on the 23rd May 1878.
SYDNEY PITT, of Sutton, in the County of Surrey. CERTAIN NEW AND USEFUL
IMPROVEMENTS IN MACHINERY FOR PROPELLING VESSELS, SOME OF WHICH ARE
APPLICABLE TO OTHER PURPOSES." A communication from abroad by John Baird,
of New York, in the United States of America, Mechanical Engineer.
The improvements constituting the subject of this Patent have reference more
particularly to the propulsion of water, craft, but some of them are applicable to
other purposes.
For convenience of description the Invention may be divided into two_principal
divisions or heads, the first division comprehending those parts of the Invention
which have reference to the construction of the vessel itself and the combination
thereof with the propeller and propeller shaft; while the second division com-
prehends those parts of the Invention which have reference to the engine for driving
the propeller.
The improvements comprehended under the first division of my Invention are
represented in Sheet 1 of the accompanying Drawings, and have for their object the
obviation of two defects which have been found to exist in propeller vessels. The

page_text: .
first of these defects is that the propeller is not immersed deep enough as a whole,
and the second defect is that the rubbing surfaces of vessels exposed to currents of
water cut away rapidly, especially in such ships as frequently enter or navigate
continuously shallow waters, or waters much defiled with silt or sand.
The improvements described under this first head conduce to obviate both these
defects, and at the same time leave the propeller and rudder in the relative positions
which long practice has sanctioned as the best, viz., with the propeller in front of
the rudder.
In ordinary propeller ships there is a shoe connecting the true stern post or after
end of the keel with the lower end of the false or rudder stern post, and the lowest
part of the propeller must lie about the top of this shoe. This shoe forms part of
the attachment of the false stern post of the vessel, and prevents this part from
being bent rearwards, or sidewise, or in, diagonally, to these directions, and such shoe
is, so far as known, always used in vessels where the rudder is as usual behind the
propeller.
The first two improvements consist in doing away with this shoe, and supporting
the false stern post by the propeller shaft, as herein-after explained, so that the
lowest part of the propeller may be immersed as deeply or even deeper than the
keel if desired; and when the false stern post is thus supported by the shaft, it is
preferred to use a false stern post and a rudder which do not descend as low as the keel
(see Figure 4, Sheet 1), thus securing the rudder and its post from shocks when the
vessel grounds, and at the same time relieving them in part from that shock which
occurs whenever a blade of the propeller passes the rudder post. This shortening
of the rudder will produce no inconvenience, as it is now generally acknowledged
that the lower part of the rudder has comparatively little steering power, and even
if this acknowledgement be incorrect, the rudder can be made wide enough to secure
the required amount of surface.
Although it is preferred thus to shorten the rudder and its post, it is con-
templated sometimes using a rudder and post of the usual length.
The other improvements of this first division consist of means for preventing sand
or silt from entering between the rubbing surfaces of the propelling mechanism and
vessel.
All the Drawings on Sheet 1 show the improvements of the first division in their
preferred forms, which however may be modified as found expedient.
Figure first is an elevation of the body of a vessel with the improvement applied
thereto.
Figures second and third are respectively an end elevation and section through a
boss on the true stern post on a large scale.
Figure fourth is a vertical central section through Figure first.
Figure fifth is an end elevation of the rudder stern post.
· Figures sixth and seventh are views of the propeller and its shaft.
Figure eighth is a plan of the bottom of the rudder.
Figure ninth is a transverse section.
Figure tenth is a horizontal section through the rudder stern post, showing the
brass for the end of the propeller shaft mounted therein, the sleeve on the end
of the propeller shafs, and the collar on that sleeve on a larger scale.
Figures eleven and twelve are respectively a side and an end elevation of the
rudder stern post, and views of the brass which supports the end of the propeller
shaft on the same scale as Figure tenth.
Figure thirteenth is a plan of the bottom of the rudder stern post, including the
lower eye for the support of the rudder; and Figures fourteenth and fifteenth are
respectively an elevation of the sleeve or the end of the propeller shaft, and a
plan of one half thereof.
In the Drawings the propeller is shown at a, the true stern post at b, the false or
rudder post at c, and the rudder itself at d.
Figures 1 and 5 show the preferred relative positions of the rudder and its post

page_text: with reference to the keel of the vessel and the propeller. If this rudder post were
supported only at top, it would be liable to bend, the face of the water acting
against the rudder tending to bend the post, as before stated. As the propeller
shaft is the strongest piece of metal at the stern of the vessel, the rudder post is
according to this Invention supported by this shaft. In order to do this the shaft
is prolonged, so that it will enter into the rudder post (see Figures 4, etc.) and
revolve in a bearing there. This construction will prevent sidewise bending of the
rudder post; and in order to prevent the rudder post from bending backwards there
is applied to the propeller shaft a sleeve e (represented on a larger scale in Figure 10),
which is provided on its exterior with projecting rings f, f, and this sleeve revolves
in a brass g set in the rudder post, and secured by flanges from moving endwise
therein. This brass may be made of any convenient form on the outside, and
necessarily in at least two pieces, and is with the sleeve to be placed in the rudder
post (which is made in at least two pieces, as shown in the Drawings) before the
pieces composing the post are rivetted or bolted together. After these parts are in
place, the propeller shaft is shoved out through the true stern post through the eyo
of the propeller, and into the sleeve, and is keyed or otherwise secured therein, by
preference by a key as at h. Under this construction the sleeve will revolve with
the shaft in the brass, and the projecting rings on the sleeve entering corresponding
grooves in the brass (sce specially Figures 4 and 10) will provent the brass and
consequently the rudder post from bending backwards unless the post carries the
shaft endwise with it. This cannot happan, as the shaft is always provided with
collars in the ship, which prevents endwise motion of the former, and could not
happen when the propeller was driving the ship ahead, even if there were no collars
in the ship, because at that time the tendency of the propeller and its shaft is to
move inward or forwards.
In order to prevent a current of water carrying silt or sand from entering
between the sleeve and its brass, a collar j is applied to the shaft itself, or preferably
upon a prolongation of the sleeve, and this collar is made in at least two pieces, as
plainly shown in the Drawing, and secured in place by flanges and grooves, and two
bolts, which unite the two halves of the collar into a whole after it is placed upon
the sleeve. This collar revolves with the shaft, and has projecting inwards from it a
ring k, which overlaps the flange on the brass in the rudder post.
It is preferred to make the ring separate from the collar, and to slip it into
place after the collar is put into position, and to secure the ring to the collar by
screws. This collar may be made in one piece with the sleeve e provided the key
sloth be cut through it. This arrangement prevents a current of water from
flowing between the rubbing surfaces of the sleeve and the brass in the rudder post
because there is a water-tight joint between the ring and the collar, and because the
direction of the current is such that it does not flow practically between the ring
and the brass in the rudder post. As an additional precaution it is preferred to
close up the after end of the brass in the rudder post, as seen at m, in consequence
of which even if a current should tend to enter at the front part of the brass there
could be no appreciable current passing through the brass. This closure of closing
piece of the after end of the brass may be cast with the parts of the brass, as shewn
in the Drawings (Figure 10), or it may be a separate piece of metal properly
supported in position. It is intended if found expedient to use the ring without
the closing piece, and the closing piece without the ring, but it is preferred to use
both.
In order to prevent a current of water from entering the support of the propeller
shaft inside of the vessel, a boss n is applied to the stern post, and is bolted on to
the true stern post, and there is applied to its exterior and overlapping the boss of
the propeller a ring o similar to the ring k.
In large vessels it may sometimes be useful to apply other support than the
propeller shaft, to prevent the bending of the rudder post, although this may never
be necessary, but in case it becomes requisite, two braces p, p, attached at one end

page_text: to the stern of the ship, and at the other and lower end to the rudder post, WILL
prevent bending of the post.
It is intended sometimes to dispense with the sleeve, and permit the surface
of the propeller shaft to bear directly in the brass in the rudder post, and in such
case there is applied to the end of the shaft behind the rudder post a flange, whose
forward surface will bear against the rear or after surface of the brass in the rudder
post. This flange is to be firmly secured to the shaft, and where the rudder post
tends to bend rearwards, such tendency will be resisted by this flange. This con-
struction is regarded as an inferior one. The sleeve keyed to the propeller shaft
and the brass may be used without the devices for preventing currents of water
from flowing between their rubbing surfaces, but these devices as applied to the
after end of the rudder post or to the front thereof, will be of little or no use, except
when a rudder post is used without a shoe connecting its lower end to the keel,
because the ordinary practice, when the shoe is employed, is to use a shaft so short
that it will not enter the rudder post.
-
The improvements claimed under this division of the Invention are,-
First. The combination of a propeller shaft with the rudder post of a vessel sub-
stantially in the manner described, so that the shaft prevents the bending of the
rudder post in the manner specified.
Second. In combination with a propeller shaft and a sleeve secured thereon, a
brass in the rudder post, the three being so made and combined substantially as
specified, that the shaft prevents the bending of the post as set forth.
Third. A ring so applied substantially as described between the propeller and
the front part of the rudder post, that said ring shall operate to prevent currents of
water flowing between the rubbing surfaces enclosed in the rudder post.
Fourth. The metallic closing piece which shuts up the after end of the brass in
the rudder post, made and operating substantially as described. .
Fifth. The ring applied between the propeller and the stern post, in combination
with a boss upon the stern post, substantially in the manner and for the purpose
set forth..
The improvements comprehended under the second division. of the Invention
consist,―
First. Of a new arrangement and combination of the parts of the Wolfe engine,
invented about 1806, and now under various forms in common use, under the desig-
nation of compound engine.
Second. Of a new combination of valves and valve chest.
And, Third. Of a new construction of pillow block.
These improvements are used by preference in connection with the improvements
described under the first division or head of the Invention, but the improvements of
either division may be used separately from those of the other, and the improve-
ments of the second division may be used for other purposes than the propulsion of
water craft or vessels.
Before the improvements of this second division are described, it is proper to
state that engines existed prior to this Invention, provided with two cylinders and
their accessories, a lever beam, a crank and connecting rod, in which engines, the low-
pressure or larger cylinder stood under one end of the beam, and was connected
thereto, while the high-pressure or smaller cylinder was located, so that its links
took hold of the beam between the beam centre pin and the beam pin of the con-
necting rod, which latter was applied at the end of the beam farthest from the low-
pressure cylinder, and took hold of a crank located under this same end of the beam
outside of the high-pressure cylinder, or in other words, this old engine was an
ordinary low-pressure beam engine, having added thereto a high-pressure cylinder
located between the crank and the condenser, and connected to the beam between
the connecting rod pin and the beam centre pin.
In this old engine, the stroke of the high-pressure cylinder was of necessity only
about half that of the low-pressure cylinder, and room was wasted because the

page_text: crank at points in its throw projected out beyond the end of the beam. In the
improved engine constructed according to this Invention, some room is saved, the
pistons may have the same length of stroke, and they and their rods and links
move with equal velocities. These are advantages, but the great end attained by
this part of the Invention is that by reason of it, a compound beam engine can be
used with advantage in a propeller ship. In such ships the shaft usually lies in the
centre of the vessel, and if the crank be outside of either the high or the low
pressure cylinder, both cylinders and the whole length of the beam must be located
on one side of the shaft. Hence such an engine would with difficulty, if at all, be
got into a ship, and then only with a very short beam and consequently short
stroke; and when in place, its weight would all be on one side of the vessel. By
the improvement herein-after described, the crank lies under the beam centre or
thereabouts, between lines passing through the centres of the two cylinders; the
engine straddles the propeller shaft with one cylinder on each side of the shaft, has
only one half of its beain on each side of the shaft, can be got into any ship, can
have a long beam if desired, and when in the ship, has its centre of gravity nearly
over the keel of the vessel.
This improved engine is therefore peculiarly adapted for use in propellers, but
may with advantage be employed wherever beam engines of any kind are now
used.
Sheets 2 and 3 of the accompanying Drawings represent the preferred mode of
constructing the said improved engine in connection with the other improvements
of this second division of the Invention.
In the Drawings Figure 1 is a vertical longitudinal sketch of an engine partly in
section, partly in elevation; Figure 2 is a plan of parts of the same, partly in
section; Figure 3 is a transverse elevation of parts of the same engine; Figure 4 is
a vertical section through the exhaust valves and valve chest of the low-pressure
cylinder of the same engine; Figure 5 is an end elevation of the high-pressure
cylinder of the same engine.
Figure 6 is a vertical longitudinal sketch of a modification of the engine mounted
upon a wooden frame.
Figure 7 is a plan of parts of Figure 8; Figure 8 is a vertical longitudinal
elevation of a modification mounted upon an iron frame; Figure 9 is a partial end
elevation of Figure eight.
All the other Figures, which are on a larger scale, are details of the improvements
in brasses for pillow blocks.
In all the Drawings the high-pressure cylinder is shown at a, and its valve chests
at a. The low-pressure cylinder is shown at b, its valve chest or chests at b¹, the
beam having a fixed bearing for its centre pin as usual at c, the crank or cranks at d,
the connecting rod or rods at ce, the condenser at f, and the air pumps at g; and it
will appear from inspection of the Drawings that the high-pressure cylinder is con-
nected at one end of the beam, or nearly so, and the low-pressure cylinder at the
other;
while in all cases the axis passing through the crank shaft lies underneath
the beam centre pin, or nearly so, so that the engine lies partly on each side of the
shaft or straddles it. This peculiar arrangement of the parts necessitates a beam in
which the centre pins for the connecting rod are out of the straight line, passing
through the beam centre pin, and the pins for the links of the cylinder.
In Figures 1, 2, and 3 (Sheet 2), this arrangement of the pins is secured by the
use of two rocking arms or supplementary beans c', c', which are keyed upon the
main beam centre, and carry the connecting rod pins h, h, this plan involving
the use of two connecting rods and a centre shaft, each end of which carries a
crank.
In the modification shown in Figures 6 and 8, Sheet 3, the same end is attained
by so forming the beam that the pin for the connecting rod may be secured thereto,
below the straight line which passes both through the centre pins for the beam, and
through those for the cylinder links.

page_text: In the modification of Figures 1, 2, and 3, Sheet 1, the connecting rods and
cranks are outside of the frame, and therefore do not conflict in working with any
other parts of the engine.
In the modification of Figures 6, 7, 8, and 9, Sheet 3, two small air pumps I, I,
are used instead of a single large pump, and these small pumps are located close to
one of the cylinders, and the connecting rod plays between the links which move
the cross heads of the pumps. The same end, viz., the movement of the connecting
rod without interfering with other parts of the engine, might be attained by using
a single pump with a yoke in its link, through which the connecting rod could
pass, or by the use of an independent air pump, or one moved by an excontric or
crank on the main shaft.
These engines may be furnished with any known kinds of condensers, air pumps,
valves, valve chests, and valve gear; moreover the engines may be mounted upon
any appropriate framing either of wood or metal
It is preferred to use puppet valves, as they work well in engines, running up to
60 or 70 revolutions per minute, and as they are more easily handled by the
engineer in stopping, starting, and backing, than any other valves; and when using
puppet valves it is preferred to use two or more pair of balanced puppet valves, all
for steam, or all for exhaust in a single valve chest; such valves are shown applied
to the low-pressure cylinder at h, k, l, in Figures 2 and 4, Sheet 2.
The pairs both of steam and exhaust valves may be located in the same chest,
one for the top, and another for the bottom of the cylinder; the steam and exhaust
having nozzles common to both as usual, but it is preferred to have separate chests
for the steam valves, and separate chests for the exhaust valves, with separate
nozzles, and located on opposite sides of the cylinder, as shown in Figures 1, 2,
and 4, Sheet 2. In these Figures, the pipe which conveys exhaust steam from the
high-pressure cylinder to the induction valve chest of the low-pressure cylinder is
shown at m, and two pairs of balanced puppet induction valves for each end of the
low-pressure cylinder, and three pairs of balanced puppet eduction or exhaust valves
for each end of the same cylinder are also shown.
It is a fact well known to engineers that puppet valves must be lifted to a certain
height in order to secure a passage equal to the area of the aperture in the seat, and
that a large valve must be lifted higher than a smaller one; for instance, in round
numbers, a 12-inch valve must be lifted about 3 inches, while a 4-inch valve need
be lifted only a little more than 1 inch. Three 74-inch valves have more area
than one 12-inch valve; and in order to give free passage to the steam, the former
need be lifted only two inches, while the area of the valve chest between the valves
when seated and the bore of the cylinder is less for the three 7-inch valves
than the one 12-inch valve. Hence it follows that there is less loss of steam with
the three 7-inch valves than the one 12 inch valve.
It ought further to be stated that with the puppet valve engines now in use in
propellers running, say, to 60 revolutions per minute, the steam valves must rise
and fall when the engine is running at its usual period of cut-off during a time
which is only one-fifth, or one-sixth of that of a stroke of the piston, or one-
tenth or one twelfth of a revolution, hence the great necessity for an induction valve
or valves with comparatively small rise and fall.
It is believed that two inches is about the limit to which double beat or balanced
puppet valves can be raised with success in such engines.
Further, in such engines where the steam is highly expanded there must be very
large exhaust openings in order to avoid back pressure, and thrce and a half inches
is about the safe limit of lift for exhaust valves of such fast-running engines.
An additional advantage of the use of multiple balanced valves in place of a
single balanced valve is, that the chests may be made circular, as represented in
the Drawings, so that room is saved, owing to the small projection of the chest
from the cylinder; and in addition to this, it is a well-known fact that small valves
are more easily kept tight than large ones.

page_text: Great practical advantages therefore follow from the combination of several
balanced puppet valves, all for steam or all for exhaust, with a single valve chest
or chests common to all the valves.
The last improvement relates to pillow blocks, and this improvement, although
specially useful in engine pillow.blocks, may be applied to pillow blocks generally.
This improvement is represented at Figures 10 to 14 inclusive, Sheet 3.
Figure 10 is a side elevation of the pillow block and brasses; Figure 11, an end
elevation of the same; Figure 12 is an elevation and section of one of the keys;
Figure 13, an elevation of and cross section through one of the adjusting screw
supports; and Figure 14 is a plan of one of the screws. In these Figures the
block itself is shown at o, o, and the cap at p. The brasses are shown at q. These
may be of any suitable metal, or Babbet metalled, and, of any ordinary con-
struction, save at the surfaces u, u, which surfaces are inclined to the top of one
brass and the bottom of the other (see Figure 10), and are also rebated so as to
receive the keys, Figure 12 (see loft hand of Figure 11, where the key ris repre-
sented in place). These rebates may be of any form; or the surfaces may be
simply inclined across the block, so as to receive a wedge key; the face of which
nearest the shaft is narrower than the face furthest from the shaft, the object being
to keep the keys firm in place; and in some cases it is intended to dispense with
the rebates or their equivalents.
The keys are so clearly represented as to need no further description, except to
say, that they are bored out, and have a screw nut formed in the bore, as shown in
Figure 12. Upon the ends of the pillow blocks are secured two screw supports 8, 8,
one of which is represented in place in Figure 11. These supporters it is proferred
to make of two pieces of metal provided with holes, through which the screws that
fasten them to the block pass, and each having a recess, which when the pieces of
metal are put together form a single recess to receive the collar v of the screw.
When the brasses are in place, also the keys, the screws, and the screw sup-
porters, the turning of the screws in one direction or the other will move the keys
endwise, and cause the brasses to recede from or approach to each other, so that in
case of wear of either brasses or shaft the two may be properly adjusted to each
other. Such adjustment is specially necessary in fast-running engines of great
power, even when running slowly, as the least play of the shaft in the brasses
causes a thump.
It has been found by trial that a brass a sixteenth of an inch greater in internal
diameter than the external diameter of the shaft best avoids jars, and works with
least friction, and this plan is the only one known by which such proper relation
of shaft and brasses can be secured.
It has been found also by trial that ordinary brasses as they get worn tend to
pinch the shaft at those points of the upper and lower brass which are nearest each
other.
Experience has proved that the above-described combination of keys with the
brasses remedies the difficulty. These brasses are best adjusted by setting the cap
down tight, and then causing the keys to shove the brasses apart a little, slackening
the binder screws, if necessary; and as the brasses become worn a liner may be
introduced under the lower brass.
What is claimed under the second division of the Invention is,―
First. The combination herein-before described of two cylinders, a beam with a
fixed bearing for its centre pin, a crank, crank shaft, and connecting rod, all arranged
substantially as described; that is to say, with the axis of the shaft substantially
under the beam centre pin, and between lines passing through the centre lines of
the two cylinders, as herein-before set forth.
Second. The combination with a valve chest of a set of balanced or double beat
puppet valves, all for steam, or all for exhaust, located in that chest, substantially
in the manner and for the purpose specified.
Third. The combination with the brasses of a pillow block keys applied between

page_text: the brasses, constructed and capable of operating as specified, the combination being
substantially as described.
In witness whereof, I, the said Sydney Pitt, have hereunto set my hand and
seal, this Fourteenth day of May, in the year of our Lord One thousand
eight hundred and seventy-eight.
Signed & sealed by the said
Sydney Pitt in the pre-
sence of
CHARLES BROOK,
St. Andrew's Street,
Holborn Circus.
SYDNEY PITT. (L.S.)