Improvements in or connected with Ships' Propeller Shafts.
Year: 1897

page_text: Improvements in or connected with Ships' Propeller Shafts.
I, WILLIAM BRUCE CUMMING, of 16, Brunswick Street, Liverpool, in the County
of Lancaster, Consulting Engineer, do hereby declare the nature of this invention
to be as follows:
This invention has reference to ships' propeller shafts, that is to say, that
part of the shaft on which the screw propellers are mounted, generally called
the "tail-shaft"; and the invention has chiefly for its object to provide a con-
struction by which the breakage of such shafts, which is so constantly happening
at the present time (and which is found to be largely due to the corrosion or
pitting of such shaft), shall be prevented.
According to the usual construction of tail shafts of screw propellers, water is
admitted to the surface of the ordinary steel or iron tail shaft through spaces
in the bearing, but according to the present invention water so admitted is pro-
vented from acting upon the iron or steel surface of the whole of the tail shaft
between the bearings to which salt water has access by encasing it with a brass or
other suitable metal casing made up in several parts, and applied and constructed
as described. The casing is in one construction made up in three parts, i.e. three
casings, the intermediate one of which is of brass or equivalent metal and the
end ones of wrought iron (or brass or other metal if desired); and outside these
casings at the tail end and the fore part, viz. at the parts constituting the journals
of the shaft which work in the bearings, brass liners, which fit and work in the
bearings, are provided; and the inner ends of these, and the abutting edges of
them are so arranged in relation to each other, that the inner ends of the outer
liners overlap the butt joints, so that these journal brass liners make a lap or
joint over these meeting parts, and produce a complete water tight joint, that is,
a joint through which it is impossible for water to work into.
Acording to one construction, the lengths of the casing of the shaft body which
lie between the brass journal liners, and the shaft, are of wrought iron; while
the length which extends between these brass journal liners is made of brass or
other suitable equivalent metal. In the manufacture of the shafts, the shaft
surface is turned all over; and the brass or wrought iron casings are truly bored
to the required diameter, and secured on the shaft by shrinking them on; and
afterwards they are turned up all over where they are on the shaft. Over these
truly turned parts of the casings, at either end of the shaft, the brass journal
liners being first truly bored-are placed, and shrunk on; their inner adjacent
ends overlapping, as stated, the abutting edges of the ends of the wrought iron
and brass casings. Then, having been shrunk on in this way, they are turned
externally as usual, and fastened with pins.

page_text: At the front end of the shaft, the body is, in some cases of greater diameter
where the front bearing journal of the shaft comes, and the casing which fits
over this part will, correspondingly, be made larger than the other casings,
internally; while the end of the intermediate brass casing which abutts up against
this casing, and which is overlapped by the outer brass liner, is made thicker
to fill the space between the shuft surface, and the even inside surface of the
liner; and so that its outer surface will be the same diameter as that of the front
wrought iron casing.
In a modified construction of shaft according to this invention, the shaft, at the
part forming the forward working journal, is swelled by forging out 50 much
larger than the rest, that its surfaco is the same diameter as, and will be flush
with, the end of the brass casing forming the intermediate piece or casing in the
aforesaid construction; and the journal brass liner will fit directly over this
swelled part of the shaft, and over the end of the said intermediate piece, making
joint with the latter as in the former case. Thus, in this case, at this part of
the shaft the inside casing of wrought iron is not used.
CHEESBROUGH & ROYSTON,
Applicant's Patent Agents, 15, Water Street, Liverpool.
Improvements in or connected with Ships' Propeller Shafts.
I, WILLIAM BRUCE CUMMING, of 16, Brunswick Street, Liverpool, in the County
of Lancaster, Consulting Engineer, do hereby declare the nature of this invention
and in what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement:-
"
-
This invention has reference to ships' propeller shafts, that is to say, that
part of the shaft on which the screw propellers are mounted, generally called
the tail-shaft"; and the invention has chiefly for its object to provide a con-
struction by which the breakage of such shafts, which is so constantly happening
at the present time (and which is found to be largely due to the corrosion or
pitting of such shaft), shall be prevented.
According to the usual construction of tail shafts of screw propellers, water is
admitted to the surface of the ordinary steel or iron tail shaft, through spaces
in the bearing, but, according to the present invention, water, so admitted, is pre-
vented from acting upon the iron or steel surface of the whole of the tail shaft
between the bearings to which salt water has access, by encasing it with a brass, or
other suitable metal casing, made up in several parts, and applied and constructed
as described.
The drawings hereto annexed illustrate three modifications under the invention.
The Figures 1, 2, and 3 shew the three respective modifications in part sectional
elevation.
Taking these in the order of the figures, the shaft between the tail end a, on
which the propeller boss fits, and the part of which fits and revolves in the
stem tube gland, is encased by a wrought iron casing b at the aft end, a
wrought casing c at the fore end, and an intermediate brass, or equivalent metal
casing d, between these casings c and b; the adjacent ends of the parts c d and þ d
being arranged to touch each other, so that the three together, form a complete
casing of the shaft between the shank or base of the tail a, and the point a¹.
Around the abutting ends of these parts a, b, and c; and outside the wrought iron

page_text: casings b and c, and the ends of the casing d, are brass or equivalent metal
casings e and f, which cover and close the butt joints of c and d and band d,
and also serve as journals or bearing liners, on which the whole shaft is borne
and revolves on its bearings.
The fore part of the shaft at a³, on which the casing c is applied, is of slightly
greater diameter than the body of the shaft aft of it; and this enlarged part
enables this casing to be slid on into position readily from the tail end; and
the whole of the shaft is truly turned all over.
«
"
This wrought iron casing connected with the part a³ is first bored, and then
shrunk on
the shaft, in any known suitable way of "shrinking on
"Buch
things. When it is "shrunk on it is then truly turned externally all over.
After this the brass casing d is passed on to the shaft; and this casing, similarly
G₁ is first bored, and then "shrunk on the shaft; and, when on, is turned at
the ends where the casings or liners e and f fit over it.
to
"
The aft wrought iron casing b is bored; then placed and shrunk on the shaft;
and then turned truly all over.
By this mode of constructing and securing the casings on the shaft, they
become immovable on it and practically form one with it
When these are in
position, the brass liners or casings e and f are placed over b, c, and d, and make
an absolute closing of the butt joints between the ends of the casings, by their
being arranged to over-lap on d, as shown.
These casings or liners, similarly to the other casings, are bored, and then
shrunk on; and secured with brass pins to the shaft butt, in any known suitable
way, and then turned.
The effect of the whole construction is, as stated, that the water, which is
admitted to the outer surface of the tail shaft in the usual way, is entirely
prevented from acting upon the iron or steel surface of the whole shaft; and the
casings on which it does act being entirely of brass, no corrosion of any kind
detrimental to the shaft takes place.
In some cases, if desired, a suitable packing, as a rubber ring, may be provided
between the propeller boss and the outer surface of the liner e to prevent access
of water to any portion, or the shank portion, of the part a.
In the modification shewn in Figure 2, the construction is similar to that in
Figure 1, except that in lieu of the wrought iron casing c being used over the
portion a, as in that figure, the shaft at this part, a³, is enlarged in diameter,
and made equal with the diameter of the end of the casing d, so that the outer
brass liner will be bored and directly shrunk on over the part a³, and the end
of next it.
Referring now to the modification in Figure 3, in this case, the fore end casing
and construction is similar to that shewn and set forth in reference to Figure 2;
but at the aft end, that is the part which forms the journal and revolves in the
stem tube bearing (which may be of any known suitable form), is directly
encased by and in a brass casing b; the end of which butts up against the end
of d, as in Figures 1 and 2, while the butt between the parts 6 and d is covered
with a short outer brass casing e, closing this joint, and making the whole case
water-tight. In other respects it is the same as those above described.
Having now particularly described and ascertained the nature of this inven-
tion and in what manner the same is to be performed, I declare that what I
claim is:
1. The herein described improvement connected with ships' propeller tail
shafts, namely, a tail shaft of iron or steel, encased within a number of casings
of metal of the kind specified, shrunk on the shaft, and the ends of which
abutt against each other, or with parts of the shaft, being closed by outer casings
shrunk over same; substantially as and for the purposes set forth.
2. The ships' propeller tail shafts, made up of parts arranged, constructed, and

page_text: adapted to act as set forth with reference to and shewn in Figure 1, Figure 2,
and Figure 3, respectively; for the purposes specified.
Dated this 1st day of January 1898.
CHEESBROUGH & ROYSTON,
Applicant's Patent Agents, 15, Water Street, Liverpool.