Improvements in Screw Propellers.
Year: 1892

page_text: Date of Application, 9th Nov., 1892
Complete Specification Left, 20th July, 1893-Accepted, 26th Aug., 1893
PROVISIONAL SPECIFICATION.
Improvements in Screw Propellers.
I JAMES STEPHENS of Stonehouse in the County of Gloucester, Engineer do
hereby declare the nature of this invention to be as follows:-
Improvements in that class of screw propellers for the propulsion of ships or
boats, known as feathering or reversing propellers, (in which each blade of the
propeller is caused to rotate in the boss, on its own axis, through a certain angle
by suitable mechanism), has for its object the production of a stronger propeller;
and also the prevention of the ingress of water to the interior of the propeller.
In carrying out this invention I construct a boss which I attach to a propeller
shaft in any well known manner. I bore holes in this boss transversely to its axis
of rotation for the reception of the shanks of the propeller blades, and each hole
is so far removed from the other as to admit of the shanks of the propeller blades
passing entirely through, or nearly through the boss, and therefore when in
operation revolving in different planes of revolution. Each propeller blade is
secured in its hole so as just to revolve freely on its axis.
A convenient mode of causing the blades to revolve on their axes through the
nescessary angle is as follows. On the shanks of the blades, within the boss and.
about centrally as regards their length, I cut a segment of a spur wheel, and I fit
in recesses within the boss, spur racks which gear into the spur segments on the
shanks of the propeller blades. In order to cause the propeller blades to assume a
different or reverse angle to the axeal line of the propeller it is nescessary to give
these racks a motion in the direction of the axis, and this I do by coupling them to
a rod which passes along the centre of the propeller shaft which I bore to receive
it; when by giving a forward or backward motion to this rod by any convenient
mechanism within the ship or boat, a reversal of the angle of the blades of the
propeller will be effected.
I form annular recesses in the shank holes in the boss for the reception of
annular packing rings of leather or other suitable material, having a U section,
which press outward against the annular recesses and inward against the shanks of
the propeller blades, and by this means I prevent the entrance of water to the
interior of the propeller boss.
Dated this 8th day of November 1892.
COMPLETE SPECIFICATION.
Improvements in Screw Propellers.
I JAMES STEPHENS of Stonehouse, in the County of Gloucester, 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 of improvements in that class of screw propellers for the propulsion
of ships or boats known as feathering or reversing propellers, (in which each blade of
the propeller is caused to rotate in the boss on its own axis through a certain angle
by suitable mechanism,) has for its object the production of a stronger propeller,
and also the prevention of the ingress of water to the interior of the propeller.
In carrying out this invention I construct a boss which I attach to a propeller
shaft in any well known manner. I bore holes in this boss transversely to its axis
of rotation for the reception of the shanks of the propeller blades, and each blade
Price 8d.]

page_text: is so far removed from the other as to admit of the shanks of the propeller blades
passing entirely through or nearly through the boss, and having the support of the
boss on each side of the mechanism by which they are reversed, and therefore when
in operation revolving in different planes of revolution. Each propeller blade is
secured in its hole so as just to revolve freely on its axis.
A convenient mode of causing the blades to revolve on their axes through the
nescessary angle is as follows. On the shank of each of the blades, within the
boss, and about centrally as regards their length, I cut a segment of a spur wheel,
and I fit, in recesses within the boss, spur racks which gear into the spur segments
on the shanks of the propeller blades. In order to cause the propeller blades to
assume a different or reverse angle to the axeal-line of the propeller, it is nescessary
to give these racks a motion in the direction of the axis, and this I do by coupling
them to a rod or shaft which passes along the centre of the propeller shaft, which
is bored to receive it; when by giving a forward or backward motion to this rod
by any convenient mechanism within the ship or boat, a reversal of the angle of
the blades of the propeller will be effected.
I form annular recesses in the shank holes in the propeller boss for the reception
of annular packing rings, of leather or other suitable material having a section,
which press outward against the annular recesses and inward against the shanks of
the propeller blades, and by this means I prevent the entrance of water to the
interior of the propeller boss.
The mode of carrying out this invention will be better understood by reference
to the accompanying drawings of a two bladed propeller in which
Fig. 1 is a vertical longitudinal section of the propeller and of portions of the
propeller shaft, and propeller blades, (the propeller blades and shanks and the rod
or shaft
not being in section).
Fig. 2 is a horizontal section on the line T. U. in Fig. 1 (the rod or shaft G not
being in section).
Fig. 3 is a vertical transverse section on the line R. S. in Fig. 1 (the propeller
blade and shank not being in section).
Fig. 4 is a vertical longitudinal section of a propeller arranged so that the shanks
of the blades do not pass entirely through the boss, (the propeller blades and shanks
and the rod or shaft G not being in section).
The letters of reference denote the same parts in all the figures.
The boss of the propeller is shown at A having holes bored transversely to its
axis for the reception of the shanks of the propeller blades C. Portions of the
propeller blades are shown at B. The shanks of the propeller blades are secured
in their places in the boss so as just to revolve freely by collars D, and have cut on
them at about the centre of their length spur segments shown at E. Spur racks F
gear into these spur segments, and have attached to them a rod or shaft G
arranged to move freely in a longitudinal direction within the hollow propeller
shaft H.
The additional length that is given to the shanks of the propeller blades by
inserting them in the boss in different planes of revolution admits of the annular
recesses shown at I for the reception of the U shaped packings J for preventing
the ingress of water to the propeller boss.
In the arrangement shown in Fig. 4 the shanks of the propeller blades do not
pass entirely through the boss, but have an enlargement upon them shown at K
and are secured in their places by plates L and M that encircle them in the
recess N and are secured to the boss by pins. By this arrangement the plates M
make a watertight joint at the ends of the propeller shanks and one of the
U packings to each shank may be dispensed with.
It will be evident from the foregoing description that by giving a longitudinal
movement to the rod or shaft G by any suitable mechanism within the ship or boat,
in one direction, will cause the blades of the propeller to assume a reverse angle to
that which they will assume if the rod or shaft G is moved in the opposite
direction.

page_text: I wish it to be understood that the rod or shaft G having a longitudinal move-
ment given to it for altering or reversing the angle of the propeller blades within
the hollow propeller shaft, is a convenient mode of accomplishing that object, but
is not essential to my invention, as the same thing may be accomplished by suitable
mechanism operating from the aft end of the propeller.
A three bladed propeller may be made on the same principle by lengthening the
boss so as to admit of the insertion of a third blade and a rack for operating it.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed I declare that what I
claim is :-
1. In a reversible screw propeller the propeller blades arranged to revolve in
different planes of revolution, so as to admit of the shanks of the propeller blades
passing entirely through the propeller boss, and of receiving the support of the
bose on each side of the mechanism by which they are reversed, substantially as
drawn and described.
2. In a reversible screw propeller, the propeller blades arranged to revolve in
different planes of revolution so as to admit of the shanks of the propeller blades
passing nearly through the boss and of receiving the support of the boss on each
side of the mechanism by which they are reversed, substantially as drawn and
described.
Dated this 19th day of July 1893.
JAMES STEPHENS