Improvements in and connected with Stern Tube Bearings for Screw Propeller Shafts.
Year: 1893

page_text: Date of Application, 11th Mar., 1893
Complete Specification Left, 11th Jan., 1894-Accepted, 10th Mar.. 1894
PROVISIONAL SPECIFICATION.
Improvements in and connected with Stern Tube Bearings for
Screw Propeller Shafts.
JOHN FRAME KITCHING, Marine Engineer of 4 Hart Road, West Hartlepool,
and ROBERT COULSON, Shipyard Manager of Fountain Terrace, West Hartlepool,
do hereby declare the nature of this invention to be as follows
The propeller shaft marked on plan "P. S." is lined with a casing of brass
marked "F," this casing or sleeve can be fitted in one piece or put on in two
pieces and afterwards burned together, this sleeve tightly contracted on to the
shaft will prevent the sea water from coming in contact with the material of the
shaft.
The sleeve "F" rigidly attached to the propellor shaft will work inside a
cylindrical brass bush "D" lined with strips of lignum vitæ, and the bush "D"
will be made of such a length as will permit of its being drawn out from the stern
post "S. P." for purposes of inspection.
The brass bush "D" is supported by means of a cast iron stern tube "C"
fitted to the stern post "S. P." and secured with wrought iron nut "N." outside
of stern post, and attached at forward end to a recess bulkhead "B." this bulk-
head forms a water tight compartment "W. T. C.," the opposite side being
bulkhead "A," the latter bulkhead supports a stuffing box "S. B'." in the usual
manner.
A second stuffing box "S. B." is however applied in our invention on bulk-
head "B," a brass neck ring "E" being fitted inside the stern tube "C," forming
part of the stuffing box, this brass ring can be lengthened to meet the bush "D,'
and also fitted with strips of lignum vitæ, making a continuous bearing from
bulkhead "B" to stern post "S. P."
The only exposed part of propeller shaft is the part marked "S" within the
water tight compartment "W. T. C.," this part of the shaft would be well painted,
and could be examined at any time by opening the door "O." in bulkhead "A."
The advantages gained by this method of fitting propeller shafts are :-
(I.) A considerably shorter length of shaft, with brass casing in one piece
running entire length of stern tube, effectually preventing water from coming in
contact with any part of shaft, thus preventing corrosion.
(II.) The outer end "P" upon which propeller fits can be examined by easing
back the propeller when its boss is out of water, the whole of propeller shaft and
brass casing can be examined without disconnecting or being drawn into the vessels
tunnel.
(III.) The brass bushes "D" and "E" forming the journal for supporting the
propeller shaft, can be lengthened to the entire length of stern tube "C.," thus
giving a great bearing surface, and continuous support for propeller shaft.
Dated this 10th day of March 1893.
ARTHUR BARRETT,
Agent.

page_text: Improvements in and connected with Stern Tube Bearings for
Screw Propeller Shafts.
We, JOHN FRAME KITCHING, of Hart Road, West Hartlepool, in the
County of Northumberland, Marine Engineer, and ROBERT COULSON, of
Fountain Terrace, West Hartlepool. aforesaid, Shipyard Manager, 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 of improvements in and connected with stern tube bearings for
screw propeller shafts, has for object to provide a stern tube bearing of greater
efficiency and shorter length than usual and whereby the bearing and the tail
end or rear length of the propeller shaft can be readily examined and renewed as
we will now proceed to explain by reference to the drawing left with our
Provisional Specification and that filed herewith, each of which shows partly in
longitudinal section and partly in side elevation, the stern portion of a ship fitted
with a stern tube bearing constructed and arranged according to this invention.
In the first mentioned drawing PS is the tail end or rear length of the propeller
shaft provided with a brass sleeve or casing F, which may be fitted in one piece, or
be put on in two pieces and afterwards united by burning together. This sleeve is
contracted on to the shaft so as to form a water tight joint therewith and thus
prevent the sea water from coming in contact with that portion of the shaft which
it surrounds. The sleeve F thus rigidly attached to the propeller shaft, is arranged
to work within a cylindrical brass bush D, that is fitted into the stern tube C, is
lined with strips of lignum vitæ and is made of such a length as to permit of its
being drawn end ways out of the stern tube and laterally from the opening in the
stern post SP for purposes of inspection. The stern tube C which thus carries
the brass bush D and tail end of the propeller shaft and may be of cast iron, is
fitted to the stern post SP to which its rear end is secured by means of a wrought
iron nut N secured thereon outside the stern post, its forward end being attached
to a recessed bulkhead B. This bulkhead forms with the ordinary bulkhead A at
the end of the shaft tunnel, a water tight compartment W. T. C.; the bulkhead A
supports a stuffing box S B' in the usual manner.
A second stuffing box S B is, however, according to this invention, applied to
the forward end of the stern tube where it is attached to the bulkhead B. The
stuffing box is formed by fitting a brass neck ring E inside the forward end of the
stern tube C which also forms part of the stuffing box. This brass ring is
preferably made of such a length as to meet, or nearly meet, the bush D, as in the
modified construction shown in the drawing filed herewith, and the said ring which
then becomes a tube or bush is preferably fitted with other strips E' of lignum vita
as shown in the said accompanying drawing. By this construction a practically
continuous bearing is provided for the propeller shaft, extending from the bulk-
The
head B to the stern post S P and therefore of greater length than usual.
strips of lignum vitæ in the bushes D and E may be each made in lengths extending
from the stuffing box S B to the stern post S P. A guard ring, shown at G in the
accompanying drawing, and attached to outer end of stern tube (by means of set
screws, serves to prevent the strips of lignum vitæ from working outwards.
The only exposed part of the length PS of the propeller shaft, is the part
marked S which is within the water-tight compartment W. T. C. and which would
usually be well painted; this part of the shaft can he readily examined at any
time on opening the door ( in the bulkhead A. K is the after peak water ballast
tank; I the stool or carriage for supporting the rear end of the main length of the
propeller shaft extending from the engine; and J the top of the propeller shaft
tunnel.

page_text: A portion of the bulkhead A in front of the bulkhead B, may advantageously
be removed as shown in the modified construction illustrated in accompanying
drawing, a floor being in this case provided at B' to form the bottom of the
compartment or recess W. T. C., which in this case is in free communication with
the shaft tunnel J'. By this construction, which is now allowed by the Board of
Trade, the stuffing box S B' of the first arrangement herein described is dispensed
with, and the coupling U between the rearmost length PS of the propeller shaft
and the next forward length P' S₁ of such shaft can, as shown, be placed further
to the rear than in the said first arrangement, thereby enabling the said rear
length PS of the propeller shaft to be made shorter, and therefore lighter and
more easily handled than in the first case and permitting it to be quickly
withdrawn when necessary through the man hole opening in the top J of the
tunnel, instead of its being necessary for this purpose to cut a hole in the said
tunnel top.
By fitting and arranging stern tubes and propeller shafts in the manner described
sea water is prevented from coming in contact with the material of the propeller
shaft, galvanic action and consequent pitting and corrosion of the shaft being
thereby obviated, and the working life of the shaft consequently prolonged; the
rearmost length of the propeller shaft can be made considerably shorter than
usual, which renders it easier to handle and cheaper to renew and as hereinbefore
stated, enables it to be withdrawn through the top of the tunnel without cutting a
special hole for this purpose and temporary coatings of india rubber, paint or the
like on the shaft are not needed.
Furthermore by providing the bushes D and E with lignum vitæ strips as
described, there is provided a practically continuous bearing extending the entire
length of the stern tube and which is capable of lasting much longer than an
ordinary bearing, will afford ample support for the rearmost length of the propeller
shaft and will ensure smooth running of such length.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed we declare that what we
claim is :-
1. A stern tube bearing for a screw propeller shaft, comprising a stern tube
fitted at its rear end to the stern post and at its forward end to a recessed bulk-
head B arranged aft of the ordinary bulkhead A the said stern tube being
provided at its forward end with a stuffing box S B substantially as described for
the purpose specified.
2. The improved stern tube bearing for a screw propeller shaft, constructed and
arranged substantially as hereinbefore described with reference to and shown in the
drawing left with our Provisional Specification, or modified according to the drawing
annexed hereto for the purposes set forth.
Dated this 11th day of January 1894.