Improved Means for Lubricating the Bearings of Screw Propeller Shafts and for Protecting such Shafts against Corrosion.
Year: 1887

page_text: Date of Application, 13th July, 1887
Specification Accepted, 16th Sept., 1887.
Improved Means for Lubricating the Bearings of Screw Propeller
Shafts and for Protecting such Shafts against Corrosion.
I, FRANS REINHOLD CEDERVALE, Master-workman, Karl Johansgatan 26 Gothenborg,
Sweden, 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 :-
My invention relates to means for lubricating the bearings of screw propeller shafts
and to the protection of said shafts against corrosion.
In the screw bushings hitherto employed it has been customary to give the water
free access to the aft bearing of the bushing and to provide the latter with a lining of
lignum vitae or such like in order to employ only water lubrication, it having moreover
been customary to fill the interior of the bushing with a mixture of oil and tallow in
order to prevent the water from penetrating the bushing itself and to lubricate the
inner bearing of the bushing. In spite of these precautions the water has been found
to penetrate the bushing and occasion a strong corrosion of the shaft particularly when
at weigh in salt water and the oil inclosed in the bushing clogs so that a great friction
is created between the bushing and the shaft.
The present invention has for its purpose to remedy these inconveniences in
placing a protective box with an oil reservoir between the screw and the stern post on
the screw shaft and providing the screw bushing with oil grooves leading to the said
oil reservoir and connecting the bushing with a system of pipes for letting in and out
the oil.
In the accompanying drawings
Figure 1 represents a front elevation of a protective casing constructed according
to the present invention.
Figures 2, 3, and 4 are sections on the lines x, x, y, y and z, z respectively of
Figure 1.
Figure 5 is a vertical longitudinal section of the screw bushing with the protective
box and the pipe system for letting in and out the oil.
Figure 6 is a transversal section on the line ¹¹ Figure 5.
Like letters of reference indicate corresponding parts in all the figures.
A indicates the screw shaft, B the screw bushing, C the screw-centre, D the
stern post, D¹ a strengthening socket, the bushing nut screwed upon the screw

page_text: bushing, and E a protective ring or socket made in two halves and fastened by means
of screw-bolts on the above mentioned bushing nut D¹ this protective ring or socket
preventing ice, ropes and such like from getting in to the protective box.
The protective box, see Figures 1-4 consists of four concentric rings of which the
exterior one F serving as packing box is by means of screws passing through holes F¹
in a flange of the ring fastened at the screw centre C. Into this ring F two other
rings G are screwed and in the space between these rings is placed a separate ring H
engaging likewise in an annular groove of corresponding width in the ring F. The
rings G compress the packings G between the rings F and H. The innermost ring
is made preferably in two halves united by means of dovetail joints and screws, as
shewn in Figure 1. This ring is by means of spiral springs I placed between
the same and the outer ring F pressed against the aft end of the screw bushing B and
is on the wearing surface lined with some suitable anti-friction metal H' or such like,
the surfaces of contact being moreover ground well together. By this arrangement a
light closing is obtained as well in manouvering the engine as when the ship labours
in a heavy sea. Between the rings F G and H and the bushing B an oil reservoir O
is formed which as shown in Figure 5 hereinafter more particularly described can be
fed from the room ahead of the screw bushing bulkhead K. The ring H is compelled
to follow the rotatory motion of the ring F and the screw shaft A owing to hollow
trunnions L projecting from the former and engaging in corresponding bottom holes
in the ring H. The motion of the ring H with relation to the ring F is determined
by the screws M by means of which the box is likewise kept together when being
fastened etc. The heads of these screws can move in the hollow trunnions L. In the
recess N in the ring H closed air bladders N' of india rubber or such like are placed in
order to prevent bursting at the motions of the ring H in case there is a leak and the
box fill with water. In order to be able to empty the box without taking it asunder, a
hole, closed by a screw U is provided in the ring F.
The dispositions of the screw bushing B for employing the above described protective
box is shown in figures 5 and 6 and the aft bearing of the screw bushing is along
its whole length provided with two or more oil grooves P and in the top border
of the central vertical plan with an air groove P¹ those grooves opening in the oil
reservoir of the protective box; from the top of the void B' in the socket B, two
pipes and R and from the the bottom a pipe S are lead forwards through the bulk-
heads K or to any other suitable place, and are there provided with cocks Q¹R¹ and S¹
respectively. At the bulkhead K the screw bushing is in the usual manner closed with
a box gland T.
When the bushing is to be made ready for use the cock R¹ is opened and oil is
poured in through the cock Q' by means of a funnel or a force pump. In proportion
as the oil fills the void in the bushing and through the grooves P runs into the oil
reservoir in the protective box, the air is forced away through the groove P₁, the pipe R
and the cock R. When the oil appears in the cock R' the bushing is filled the cocks Q¹
and R¹ are then closed. This filling of oil need not be repeated more than about twice
a month, while the ship is under weigh. Should the bearing get hot, which however
very seldom occurs as it is so well oiled, the oil is let out through the cock S¹ and
conserved a hose-coupling from a bottom cock or a pump is screwed on the mouth of
the pipe and the box gland T is loosened whereafter water is caused to pass
through the bushing until it has cooled. The oil conserved can then be poured in
again.
If preferred the protective box may of course be attached to the bushing nut D¹ and
rest against the screw centre.
By employing the above protective box with oil reservoir the shaft, the bushing, and
the bearings will be perfectly sheltered from any action of the water and from corrosion.
By means of the arrangement of the bushing obtainable by employing the protective
box, the advantage of the least possible friction and of a great economy of oil is
obtained, and besides the perfect lubrication makes it possible to use very long friction
surfaces in the aft bearing of the bushing, by which the bearing and the shaft will be
by far more durable than before.

page_text: Having now particularly described and ascertained the nature of my said invention
and in what manner the same is to be performed, I declare that what I claim is :
First. The protective box with oil reservoir for screw bushings, consisting of an
outer ring F surrounding the screw shaft and fastened at the screw centre or the
bushing nut D' in which ring F inner ring H retained against the bushing nut D¹ or
the screw centre C by means of spiral springs I can move in the longitudinal direction
of the shaft and which inner ring H is compelled to follow the rotatory motion of the
outer ring by means of trunnions L engaging in the inner ring H a packing G¹
being besides placed between the above mentioned two rings, those rings conjointly
with the shaft and the end of the bushing forming an annular oil reservoir,
from which the oil cannot get out and to which the water cannot get in, the
protective box being moreover surrounded by a protective ring E substantially as
described.
Second. The arrangement of the screw bushing B with the view of employing
the above mentioned protective box, in such a manner that the aft bearing of the
bushing is provided with two or more oil grooves P and an air groove P' opening
in the oil reservoir mentioned in the first claiming clause, the bushing being besides
provided with pipes QS for letting in and out the oil and with a pipe R for letting out
the air, by means of which pipes water can be made to pass through the bushing when
the oil has been let out, substantially as and for the purpose specified.
Dated this 10th day of July 1801.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicant.
HASELTINE, LAKE & Co.,
45, Southampton Buildings, London, W.C.,
Agents for the Applicant.