An Improved Method of Sheathing or Protecting Ships' Propeller- shafts and Propellers, Turbine-shafts, and the like against Corrosion and Attrition.
Year: 1897

page_text: An Improved Method of Sheathing or Protecting Ships' Propeller-
shafts and Propellers, Turbine-shafts, and the like against
Corrosion and Attrition.
-
I, MAX WILLENIUS, of 3, Bismarckstrasse, Hamburg, in the German Empire,
Civil Engineer, do hereby declare the nature of this invention to be as follows:-
Driving parts which work in the water, more especially ship's propeller-shafts,
turbine-shafts, and ship's propellers. are very liable to be injured by the action of
the water.
Ship's propeller-shafts which come into contact with the sea-water under a
certain, partly artificially-produced pressure, the shafts of turbines, and ship's
propellers and the like are more especially attacked, that is to say, are consider-
ably eaten or ground away by the water, this being caused both by the chemical
action of the water itself and by the galvanic currents set up by the different
materials, steel, bronze, etc. of which the said parts are made, and by the air
drawn down by the rotation of the shaft, propeller or the like, as well as by the
mechanical action caused by the water, which frequently contains sand, coming
into contact with the rapidly rotating shaft or other part under a certain pressure,
these actions resulting in a weakening of the shaft at various parts so as to cause
fracture to take place.
the same.
Many attempts have already been made to obviate the above mentioned disad-
vantages, but none of the means heretofore employed has been permanently
successful. For example, the shafts have been coated with gutta-percha; it has,
however, been shown that the gutta-percha is rapidly. destroyed and generally
there is no such union thereof with the shaft as to enable it to firmly adhere to
Also the frequently-employed copper sheathing of the shaft is not
trustworthy and even increases the danger in that, notwithstanding an apparently
undamaged copper sheath, the shaft can be attacked since the copper sheath soon
becomes loose. In cases where great power is transmitted, and long shafts are
employed a considerable twisting of the shaft takes place 6 m.m. and more—
which, in steering or manoeuvring by reversing the engine, rapidly alternates in
opposite directions. A non-elastic coating, which is not itself firmly connected
with the material of the shaft, is not able to follow this twisting, and, after a short
time, loosening of the coating takes place which permits access of the sea-water
to the shaft and consequently exposes the same to damage by cutting or grinding
away and by chemical action
The sheathings heretofore proposed are also liable to be damaged by the cutting

page_text: or grinding action of the water and thus soon rendered useless; moreover, to per-
manently unite them with the bearing parts, which frequently consist of different
materials to those of the shaft, presents difficulties, and the sea-water obtains
access to the shaft at this place.
These disadvantages are obviated and a permanent protection obtained for the
shaft by coating it either entirely or partially with hard india-rubber.
This material, by reason of its natural properties, shows itself to be perfectly
suited for reducing the friction between two moving driving parts coming into
contact with each other. If now, in the present case, where a ship's propeller-
shaft is taken as an example, the shaft and the water cannot both be simply
termed bearing surfaces, like a shaft and its bearing, yet their interaction is
similar to that which takes place when two bearing surfaces slide upon one another.
There exists between the water and the shaft, or the sheathing thereof, likewise
considerable sliding friction which gives rise to grinding or wearing away of the
working surface, in the present case, the shaft, in exactly the same manner as
with bearing surfaces, for example, a shaft and its bearing.
Since hard india-rubber is a perfectly suitable material for sheathing working
surfaces, it also gives good results in the present case in which the sheathing also
forms a working surface, in a certain sense, at the parts, which are not. in the
bearing.
The principal advantage of the hard india-rubber sheathing is, however, that
it entirely prevents the formation of galvanic currents.
Further advantages of this material are that, with proper treatment, it unites
very intimately with the shaft, and is sufficiently elastic to be able to follow the
maximum twisting of the said shaft, and by 'reason of its natural properties, it
is adapted to efficiently and permanently resist both the attrition of the water and
the chemical action thereof.
It has also been found to be very advantageous to make the hard india-rubber
layer of different degrees of hardness, in such a manner that the hardness of the
sheathing decreases from the exterior inwards, that is to say, that the hard india-
rubber layer in contact with the shaft itself is the softest and the outermost layer
is the hardest. In this manner great elasticity and resistance of the coating or
sheathing to external mechanical action is obtained.
In applying my said invention to a ship's propeller shaft, I preferably provide
it with an entire sheath of hard rubber, and consequently the bronze bearing
sleeves or liners heretofore generally used, are dispensed with. This arrangement
is particularly advantageous, since the sheath forms a perfectly closed cover, made
in a single piece. In this manner consequently any interruption, jointing or build-
ing up of the cover from separate parts is obviated and therefore the greatest
possible security against the access of water to the shaft is afforded.
The hard rubber is reduced in hardness towards the inside, but on account of the
great pressure which there is at the bearing, it is advisable to make the hard
rubber sheathing perfectly hard at this place.
Since hard rubber produces only extremely little friction, heating of the shaft
or of the bearing can scarcely take place. However even if the bearing should
heat, seizing of the shaft by heating cannot take place, since the hard rubber
sheath of the shaft, by reason of its thermally-insulating properties, prevents the
transmission of heat to the steel shaft.
In consequence of this, the steel shaft will not expand notwithstanding hot
running of the bearing, although the bearing will expand and therefore, after a
short time, the shaft will run casier in the bearing and the heating will abate.
In any case the seizing by heat and expansion of the shaft which frequently take
place with bronze bearings where little cooling water is used and with heavy loads,
cannot occur.
In another arrangement the shaft is provided in the usual way with bronze
bearings and only the intermediate parts are made with a hard rubber sheathing,

page_text: which can either have the hard rubber becoming softer towards the interior, or
be made throughout of the same hardness.
In order to obtain a particularly good union between the hard rubber and the
bronze parts, the hard rubber layer can be allowed to extend partly over the pre-
ferably somewhat rough bearing surface, which can be provided with grooves,
etc., or the place of junction between the bronze part and the hard rubber is tinned,
since tin unites extremely well with both bronze and hard rubber, or the two
processes can be combined. Also the end of the bronze bearing-sleeve or liner
can advantageously be soldered to the steel shaft, whereby the oil or fat applied
between the bronze sleeve and the shaft in drawing on the said sleeve, will not
pass beneath the hard rubber during the vaporization which takes place in the
vulcanisation of the hard rubber sheathing, and destroy this coating or loosen it
from the shaft.
In other cases where the sheathing does not extend over the whole length of the
shaft, the ends of the bronze bearing-sleeve or liner are provided with grooves or
channels in which the hard rubber sheathing engages.
By these or similar means the connection of the bearings with the hard rubber
sheathing can be effected in a very advantageous manner, however the simple
connection is sufficient, as effected in the manner hereinafter mentioned.
cases,
The method of applying the protective sheath to a ship's propeller or screw is
modified according to the material from which the screw is to be made, in most
however, it is sufficient to sheath the places where there is a liability of
danger. With propellers which are made of a metal, which in combination with
the metal of the shaft and the sca-water, produces no electric current, it is suffi-
cient to sheath only with hard rubber the parts liable to be acted upon, so that, by
the special form of the adjacent surfaces, engagement of the hard rubber sheath
into the body of the metal and therefore a mechanical connection is produced.
Also in the sheathing of ship's propellers, the hard rubber sheath can either
be uniformly hard all through or, as above described, becoming softer from the
exterior inwards.
For making or applying the sheathing so-called hard rubber composition is
employed, that is to say, material which yields hard rubber on vulcanising. The
composition of the material is modified according to the nature and application of
the driving parts in question.
The application of the coating is preferably effected in the following manner:-
The raw, unvulcanized hard rubber composition is rolled out into thin sheets of
a few millimeters thick, and these sheets are then applied to the shaft or the like,
which is previously coated with a solution of india-rubber, and the said sheets are
closely rolled on by means of small hand-rollers. The shaft or the like is then
entirely or partly introduced into or surrounded by a steam-pipe or a suitable
casing of corresponding diameter and this pipe or casing made tight or closed.
After this, steam at a pressure of about 2 to 3 atmospheres is introduced into
the steam-pipe or casing and allowed to act on the composition for about two
hours and then the steam pipe or casing is removed.
During the treatment with steam the hard rubber composition hardens and
also unites by the action of the heat closely and inseparably with the shaft or other
metal part.
According to the duration of the treatment with steam, and to the nature of the
composition employed, the said composition hardens either entirely or only partly,
whereby the different degrees of hardness in cross-section are obtained.
101
1
1007
D. YOUNG & Co.,
11 & 12, Southampton Buildings, London, W.C.,
Agents for the Applicant.

page_text: An Improved Method of Sheathing or Protecting Ships' Propeller-
shafts and Propellers, Turbine-shafts, and the like against
Corrosion or Attrition.
I, MAX WILLENIUS, of 3, Bismarckstrasse, Hamburg, in the German Empire,
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:-
Driving parts which work in the water, more especially ship's propeller-shafts,
turbine-shafts, and ship's propellers, are very liable to be injured by the action of
the water.
Ship's propeller-shafts which come into contact with the sea-water under a
certain, partly artificially-produced pressure, the shafts of turbines, and ship's
propellers and the like are more especially attacked, that is to say, are consider-
ably eaten or ground away by the water, this being caused both by the chemical
action of the water itself and by the galvanic currents set up by the different
materials, steel, bronze, etc. of which the said parts are made, and by the air
drawn down by the rotation of the shaft, propeller or the like, as well as by the
mechanical action caused by the water, which frequently contains sand, coming
into contact with the rapidly rotating shaft or other part under a certain pressure,
these actions resulting in a weakening of the shaft at various parts so as to cause
fracture to take place.
Many attempts have already been made to obviate the above mentioned disad-
vantages, but none of the means heretofore employed has been permanently
successful. For example, the shafts have been coated with gutta-percha; it has,
however, been shown that the gutta-percha is rapidly destroyed and generally
there is no such union thereof with the shaft as to enable it to firmly adhere to
the same. Also, the frequently-employed copper sheathing of the shaft is not
trustworthy and even increases the danger in that, notwithstanding an apparently
undamaged copper sheath, the shaft can be attacked since the copper sheath soon
becomes loose. In cases where great power is transmitted, and long shafts are
employed a considerable twisting of the shaft takes place-6 m.m. and more-
which, in steering or manoeuvring by reversing the engine, rapidly alternates in
opposite directions. A non-elastic coating, which is not itself firmly connected
with the material of the shaft, is not able to follow this twisting and, after a short
time, loosening of the coating takes place which permits access of the sea-water
to the shaft and consequently exposes the same to damage by cutting or grinding
away and by chemical action.
The sheathings heretofore proposed are also liable to be damaged by the cutting
or grinding action of the water and thus soon rendered useless; moreover, to per-
manently unite them with the bearing parts, which frequently consist of different
materials to those of the shaft, presents difficulties, and the sea-water obtains
access to the shaft at this place.
These disadvantages are obviated and a permanent protection obtained for the
shaft by coating it either entirely or partially with hard india-rubber.
This material, by reason of its natural properties, shows itself to be perfectly
suited for reducing the friction between two moving driving parts coming into
contact with each other. If now, in the present case, where a ship's propeller-
shaft is taken as an example, the shaft and the water cannot both be simply
termed bearing surfaces, like a shaft and its bearing, yet their interaction is
similar to that which takes place when two bearing surfaces slide upon one another.

page_text: There exists between the water and the shaft, or the sheathing thereof, likewise
considerable sliding friction which gives rise to grinding or wearing away of the
working surface, in the present case, the shaft, in exactly the same manner as
with bearing surfaces, for example, a shaft and its bearing.
Since hard india-rubber is a perfectly suitable material for sheathing working
surfaces, it also gives good results in the present case in which the sheathing also
forms a working surface, in a certain sense, at the parts which are not in the
bearing.
The principal advantage of the hard india-rubber sheathing is, however, that
it entirely prevents the formation of galvanic currents.
Further advantages of this material are that, with proper treatment, it unites
very intimately with the shaft, and is sufficiently elastic to be able to follow the
maximum twisting of the said shaft, and by reason of its natural properties, it
is adapted to efficiently and permanently resist both the attrition of the water and
the chemical action thereof.
It has also been found to be very advantageous to make the hard india-rubber
layer of different degrees of hardness, in such a manner that the hardness of the
sheathing decreases from the exterior inwards, that is to say, that the hard india-
rubber layer in contact with the shaft itself is the softest and the outermost layer
is the hardest. In this manner great elasticity and resistance of the coating or
sheathing to external mechanical action is obtained.
In order to more fully explain the present invention, I have shown in the accom-
panying drawing, some driving parts sheathed in this way as examples.
Figure 1 shows a ship's propeller shaft, which is provided with an entire
sheath a of hard rubber and consequently the bronze bearing sleeves or liners
heretofore generally used, are dispensed with. This arrangement is particularly
advantageous, since the sheath forms a perfectly closed cover made in a single
piece. In this manner consequently any interruption, jointing or building up of
the cover from separate parts is obviated and therefore the greatest possible
security against the access of water to the shaft is afforded.
The varying hardness of the hard rubber layer a is indicated by the different
representations of the cross-section. The black parts show the hard rubber
material which is made quite hard. On account of the great pressure which there
is at the bearing, it is advisable to make the hard rubber sheathing entirely hard
at this place as is also shown in the drawing.
Since hard rubber produces only extremely little friction, heating of the shaft
or of the bearing can scarcely take place. However even if the bearing should
heat, seizing of the shaft by heating cannot take place since the hard rubber
sheath of the shaft, by reason of its thermally insulating properties, prevents the
transmission of heat to the steel shaft.
In consequence of this, the steel shaft will not expand notwithstanding hot
running of the bearing, although the bearing will expand and therefore, after a
short time, the shaft will run easier in the bearing and the heating will abate.
In any case the seizing by heat and expansion of the shaft which frequently take
place with bronze bearings where little cooling water is used and with heavy loads,
cannot occur.
In Figure 2 another arrangement is shown, in which the shaft 6 is provided
in the usual way with bronze liners or bearings c and only the intermediate parts
are made with a hard rubber sheathing a, which can either have the hard rubber
becoming softer towards the interior, or be made throughout of the same hardness.
In order to obtain a particularly good union between the hard rubber and the
bronze parts, the hard rubber layer can be allowed to extend partly over the pre-
ferably somewhat rough bearing surface, which can be provided with grooves, etc.,
or the place of junction between the bronze part or liner and the hard rubber is
tinned, since tin unites extremely well with both bronze and hard rubber, or the
two processes can be combined. Also the end of the bronze bearing-sleeve or
liner can advantageously be soldered to the steel shaft, whereby the oil or fat

page_text: applied between the bronze sleeve and the shaft in drawing on the said sleeve will
not pass beneath the hard rubber during the vaporization which takes place in the
vulcanisation of the hard rubber sheathing, and destroy this coating or loosen it
from the shaft.
In Figure 2 the layer of tin is indicated by e. Figure 2 shows an arrangement
in which the ends of the bronze bearing-sleeve or liner are provided with grooves
or channels in which the hard rubber sheathing a engages.
By these or similar means the connection of the bearings with the hard rubber
sheathing can be effected in a very advantageous manner, however the simple
connection is sufficient, as effected in the manner hereinafter mentioned.
Figures 3 and 4 show unsheathed ship's propellers in a similar manner.
The method of applying the protective sheath to a ship's propeller or screw is
modified according to the material from which the screw is to be made, in most
cases, however it is sufficient to sheath the places where there is a liability of
danger. With propellers which are made of a metal, which in combination with
the metal of the shaft and the sea-water, produces no electric current, it is suffi-
cient to sheath with hard rubber only the parts liable to be acted upon, as shown
in Figure 3, so that, by the special form of the adjacent surfaces, engagement of
the hard rubber sheath into the body of the metal and therefore a mechanical
connection is produced.
Also in the sheathing of ship's propellers, the hard rubber sheath can either be
uniformly hard all through or, as above described, becoming softer from the
exterior inwards.
For making or applying the sheathing, so-called hard rubber composition is
employed, that is to say, material which yields hard rubber on vulcanising. The
composition of the material is modified according to the nature and application of
the driving parts in question. The application of the coating is preferably effected
in the following manner: -
The raw, unvulcanized hard rubber composition is rolled out into thin sheets
of a few millimeters thick, and these sheets are then applied to the shaft or the
like which is previously coated with a solution of india-rubber, and the said
sheets are closely rolled on by means of small hand-rollers. The shaft or the like
is then entirely or partly introduced into or surrounded by a steam-pipe or a suit-
able casing of corresponding diameter and this pipe or casing made tight or closed.
After this, steam at a pressure of about 2 to 3 atmospheres is introduced into
the steam-pipe or casing and allowed to act on the composition for about 2 hours
and then the steam pipe or casing is removed.
During the treatment with steam the hard rubber composition hardens and also
unites, by the action of the heat, closely and inseparably with the shaft or other
metal part.
According to the duration of the treatment with steam and to the nature of the
composition employed, the said composition hardens either entirely or only partly,
whereby the different degrees of hardness in cross-section are obtained.
Having now particularly described and ascertained the nature of my said in-
vention and in what manner the same is to be performed, I declare that what I
claim is:-
1. Driving parts, more particularly ship's propeller-shafts, propellers, turbine-
shafts and the like, which, for protection against the corrosion set up by the action
of the water, the air, galvanic currents, and the like, are entirely or partially
coated or sheathed with hard india-rubber.
2. A shaft, such, for example, as a ship's propeller-shaft, provided with a
sheathing of hard india-rubber which at the same time forms the bearing surface.
3. The modification of my invention in which a thin layer of tin is arranged
between the hard india-rubber sheathing and the bronze liner or other metal
covering of a ship's propeller-shaft or the like, substantially as, and for the pur-
poses herein before described.

page_text: 4. The modification of my invention in which the india-rubber sheathing is
hard at the exterior and is softer towards the interior, certain parts of the said.
sheathing being hard all through if desired.
5. The application of a protective sheathing to a shaft or other driving-part
by a process in which the shaft or other driving-part is first smeared with a solu-
tion of india-rubber and then raw or unvulcanised hard india-rubber composition
is applied, preferably in the form of thin sheets or plates, and is then firmly rolled
on or pressed, after which the hard india-rubber composition is subjected to the
action of steam in order to harden it, in which process various degrees of hardness
of the material can be obtained according to the duration of the action of the
steam, and, if desired, a gradual decrease of hardness can be attained from the
exterior towards the shaft or other driving-part, substantially as, and for the pur-
poses, hereinbefore described.
Dated 11th July 1898.
D. YOUNG & Co.,
11 & 12, Southampton Buildings, London, W.C.,
Agents for the Applicant.