An Improved Apparatus for Use in Examining and Repairing Ships' Propellers.
Year: 1895

page_text: Date of Application, 25th June, 1895
Complete Specification Left, 7th Feb., 1896-Accepted, 4th Apr., 1896
PROVISIONAL SPECIFICATION.
An Improved Apparatus for Use in Examining and Repairing
Ships' Propellers.
A communication by ANTON LAURITZ OLSEN, of Helsingör, in the Kingdom of
Denmark, Engineer.
I, WILLIAM PHILLIPS THOMPSON, F.C.S., M.I.M.E., of The Agency for
Foreign Patent Solicitors, 6, Lord Street, Liverpool, and 6, Bank Street,
Manchester, both in the County of Lancaster, 118, New Street, Birmingham, in
the County of Warwick, and 31, High Holborn, in the County of Middlesex,
Civil Engineer, do hereby declare the nature of this invention to be as
follows:-
This invention has for its object an improved apparatus whereby it is possible to
effect repairs to the screw of an ice-breaker or ship in a short time without a dock
and without outside assistance.
For this purpose a round opening is arranged in the ship's hull vertically over
the screw, and is generally kept closed by means of a case or casing. If a damaged
blade of the screw is to be replaced the casing is raised out of the opening, and a
well or caisson in the form of an iron cylinder open at both ends is lowered through
the opening and over the vertically arranged screw blade, until the upper flanged
ring rests on the flange of the opening, and the two flanges are bolted together,
forming a tight joint. Over the opening an air-tight chamber is formed by means
of two bulkheads arranged at the sides of the opening and a hatchway or manhole
is formed in the upper deck, and tightly closed by means of a cover.
Air is then
pumped into this bulkhead chamber by means of an air pump. By this means the
water in the well or caisson, which water was standing before at the same level as
the outside water, is gradually driven back down to the lower edge of the caisson
and the screw blade is exposed. Access can then be had to the screws with which
the blades are attached to the nave or boss, and these screws may be unfastened by
means of a bar screw key which is turned from the bulkhead chamber, the blade
of the propeller being then drawn upwards, and if necessary replaced by a
new one.
When the work is completed the well or caisson is drawn up again and the
opening filled up by its casing. In case a blade which is to be replaced is so bent
that the well will not pass over the same, such a blade is turned to one side and
the well slipped over the next blade. The screws of the bent blade may then be
loosened from the well and the blade pushed away. The nave or boss of the
propeller may be taken off by using this caisson. If the shaft is to be drawn into
the ship, a plate may be screwed over the shaft hole. In an ice breaker provided
with the arrangement hereinbefore described as the blades can be more easily
replaced, said blades may be made weaker in order to insure that, in the event of
a shock the blades and not the shaft or engines will be broken.
The stern of a twin screw warship may be provided with the dry well or caisson;
in this case only one cylinder is necessary and may be used for both screw
propellers. The opening in the ship's hull may be closed from the outside by means
of a simple plate when the caisson is not in use.

page_text: The well or caisson may be also constructed on a barge which may then be
utilized for removing and replacing damaged propellers in other ships.
Dated thie 24th day of June 1895
An Improved Apparatus for Use in Examining and Repairing
Ships' Propellers.
A communication by ANTON LAURITZ OLSEN, of Helsingör, in the Kingdom of
Denmark, Engineer.
1, WILLIAM PHILLIPS THOMPSON F.C.S., M.I.M.E., of The Agency for
Foreign Patent Solicitors, 6 Lord Street, Liverpool, and 6, Bank Street,
Manchester, both in the County of Lancaster, 118 New Street, Birmingham in
the County of Warwick and 31 High Holborn in the County of Middlesex, Civil
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 for its object an improved apparatus whereby it is possible to
effect repairs to the screw of an ice-breaker or ship in a short time without a dock
and without outside assistance.
The invention is shown in the accompanying drawings, in which,
Figure 1 is a vertical longitudinal section, and
Figure 2 a cross section of the well or caisson,
Figures 3 and 4 show the corresponding parts of the ice-breaker with the caisson
removed.
A round opening A is arranged in the ship's hull vertically over the screw C,
and is generally kept closed by means of a case or casing B, Figures 3 and 4.
If
a damaged blade of the screw C is to be replaced, the casing B is raised out of
the opening A, and a well or caisson S in the form of an iron cylinder open at both
ends is lowered through the opening A and over the vertically arranged screw
blade C, until the upper flanged ring rests on the flange D of the opening, and the
two flanges are bolted together, forming a tight joint. Over the opening A an air-
tight chamber F is formed by means of two bulkheads G H arranged at the sides
of the opening and a hatchway or manhole E is formed in the upper deck, and
tightly closed by means of a cover. Air is then pumped into this bulkhead
chamber F by means of an air pump, the pipe of which opens at I. By this means
the water in the well or caisson S, which water was standing before at the same
level as the outside water, is gradually driven back down to the lower edge of the
caisson and the screw blade C is exposed. Access can then be had to the screws K
with which the blades C are attached to the nave or boss, and these screws may be
unfastened by means of a bar screw key, which is turned from the bulkhead
chamber F, the blade C of the propeller being then drawn upwards, and if necessary
replaced by a new one.
When the work is completed, the well or caisson S is drawn up again and the
opening A filled up by its casing B. In case a blade which is to be replaced is so
bent that the well will not pass over the same, such a blade is turned to one side
and the well slipped over the next blade. The screws of the bent blade may then
be loosened from the well and the blade pushed away. The nave or boss of the
propeller may be taken off by using this caisson. If the shaft is to be drawn into
the ship, a plate may be screwed over the shaft hole. In an ice-breaker provided
with the arrangement hereinbefore described, as the blades can be more easily
replaced, said blades may be made weaker in order to insure that, in the event of
a shock the blades and not the shaft or engines will be broken.

page_text: The stern of a twin screw warship may be provided with the dry well or caisson;
in this case only one cylinder is necessary and may be used for both screw
propellers. The opening in the ship's hull may be closed from the outside by means
of a simple plate when the caisson is not in use.
The well or caisson may be also constructed on a barge which may then be
utilised for removing and replacing damaged propellers in other ships.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed, as communicated to me
by my foreign correspondent, I declare that what I claim is :-
An improved apparatus for use in examining and repairing ships' propellers,
characterised by a chamber (F) adapted to be closed airtight, and a well or
caisson (S) adapted to be lowered down to the propellor and to extend thereto from
said chamber, into which latter after it has been hermetically closed air is pumped
so as to expel the water contained in the caisson (S) substantially as hereinbefore
described.
Dated this 6th day of February 1896
WM. P. THOMPSON & Co.,
Agents.