Improvements in Ships' Propellers.
Year: 1890

page_text: Date of Application, 22nd Apr., 1890
Complete Specification Left, 22nd Dec., 1890-Accepted, 14th Feb., 1891
PROVISIONAL SPECIFICATION.
Improvements in Ships' Propellers.
I, FREDERICK HENRY WHITE, of No. 6 Rylett Road; Shepherd's Bush, in the
County of Middlesex, Clerk in H.M. Civil Service, do hereby declare the nature
of this invention to be as follows:-
My invention relates to an improved construction of ships' screw propellers,
whereby these are also made to effect the steering of the vessel.
For this purpose I extend the propeller shaft beyond the stern post of the vessel
and I connect such extended part to the main shaft, outside the stern post, by a
Hooks joint, that is to say, each part terminates in a fork, which forks are placed
at right angles to each other and are formed with eyes into which are fitted loose
the arms of a cross shaped piece, so that the extension can be moved from a
position in line with the main shaft into an angular position on either side thereof.
The arms of the cross piece which are carried in the eyes of the main shaft-fork
constitute the connecting shaft of two opposite screw propeller blades, which
may be constructed as ordinary propeller blades; and which; when the shaft
extension is in the middle position, in line with the main shaft, are rotated by the
latter in the ordinary manner for propelling the vessel ahead or astern.
When however the shaft extension is moved into an angular position relatively
to the main shaft, such motion being effected in a plane at right angles to the axis
of the propeller blades, it turns such cross piece, and consequently also the arms
that carry the screw blades, in the fork of the main shaft into a corresponding
angular position; and thereby brings the one propeller blade into an increased
angular position relatively to the plane of rotation, and the other blade into a
correspondingly decreased angular position or in other words it increases the pitch
of the one blade and decreases that of the other.
The result of this will be, that as the main shaft and propeller blades rotate, the
propelling action exercised by the one blade when passing through a certain
portion of the circle will be considerably greater than that exercised by the other,
and the one sided thrust thus produced will consequently have the effect of steering
the vessel to port or to starboard according as the extension is moved to the one or
the other side of the axial line of the driving shaft.
It will be seen that when; during the rotation, the axis of the propeller blades
is brought into the position in which it lies in the same plane, as that in which the
extension receives its angular motion; the two blades will assume, symetrical
angular positions, that is to say, they will have the same pitch, and they will
consequently exert equal propelling power; as they move from this position
through a quadrant of the circle, the angular position or pitch of the one blade
will increase and that of the other one will decrease, until the maximum difference
is obtained, and from this point such difference will gradually decrease again
during the following quadrant of the circle, whereupon the second named blade
will gradually have its pitch increased while that of the first named one will be
correspondingly decreased, and so on.
For bringing the end of the shaft extension into the varying angular, positions
for the above named purpose, any suitable mechanism may be employed, thus the
outer end of the extension being carried in a bearing capable of sliding in arc-
shaped guides carried by a suitable support or rudder post; the bearing may be
shifted from the middle position to either side, by a lever worked by suitable gearing
from above, or the bearing may carry a toothed pinion gearing with teeth on the
arc-shaped guides, and be rotated by gearing from above so as to cause it to travel

page_text: in either direction along the guides; or the bearing may be moved by hydraulic
power.
ABEL & IMRAY,
Agents for the Applicant.
COMPLETE SPECIFICATION.
Improvements in Ships' Propellers.
I, FREDERICK HENRY WHITE, of 6 Rylett Road, Shepherd's Bush, London, W.,
Government Clerk, 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 propeller has been designed with the object of enabling it not only to
propel the ship, vessel, launch, boat, or other marine or submarine locomotive to
which it is fitted, but also to steer or assist in the steering of such locomotive.
The propelling shaft, leading from the engines, terminates in an universal
joint which connects it with an extension of itself in the form of a smaller
shaft or tail-piece. The joint can be made in several different forms, but the
principle of each is the same. That which is perhaps the simplest is shown in
Fig. 1, and this form will be used in the general description immediately following
as a type of all the others. The centre- or connecting-piece of the joint shown in
Fig. 1 is in the shape of a rectangular cross. Fig. 2 gives a perspective view of
the same joint.
The screw may have two, three, or four blades; but the case of a two-bladed
screw will be first considered.
The blades are rigidly fixed to the ends of those two arms of the cross (or
connecting-piece of the joint) which are directly held by the main shaft. (See
Fig. 3.) It will then be seen that, (1) while the main shaft, in revolving, acts
directly on the blades, causing them to rotate with an uniform motion in a plane
perpendicular to the shaft, it leaves them free to follow any motion in that plane
which may be imparted to them by the centre-piece of the joint; (2) that by
moving the extension from its normal position as a direct continuation of the main-
shaft, the pitches of the blades can be altered to any extent; and (3) that the
blades being firmly fixed to the centre-piece, and so rigidly connected with one
another, any increase in the pitch of one is accompanied by an equal and
corresponding decrease in that of the other.
શ
When the extension is in its normal position, ¿.e. in one and the same straight line
with the main-shaft, the blades are of equal pitch; and they retain that pitch
throughout the completed revolution of the main-shaft. Suppose the vessel to be
moving ahead, the shaft to be revolving from left to right, and the extension to be
now moved a little to the right of its normal position but in the same horizontal
plane. In this case, when the two blades are in à horizontal position their pitch is
normal and so identical; and when they are in a vertical position the pitch of the
upper blade will be as much greater as that of the lower blade is less than the
normal. In moving from the horizontal to the vertical position the pitch of
the upper blade is gradually increasing and that of the lower blade as gradually
decreasing while in moving from the vertical to the horizontal position the
reverse is the case. Thus, in one half revolution of the propelling shaft, during
which the blades reverse their positions in the horizontal line, the pitch of the upper
blade is greater and that of the lower blade less than normal, the moment of greatest
variation being the same in both cases, viz. when the blades are in a vertical
position. The obvious effect of these changes in the pitch of the blades is that the
stern of the vessel is forced to the left. When therefore it is desired to change the
course of the vessel to the right, the extension is moved horizontally to the right,
its manipulation being thus similar to that of a rudder. . If the, extension be moved

page_text: to the left of its central position the reverse of the above takes place, the course of
the vessel being changed to the left. When the screw is propelling the vessel in a
backward direction the effect of moving the extension to the right or left of its
central position would be similar to, but the exact reverse of that in the cases above
considered.
Not only can the direction of the vessel be changed at will by moving the
extension horizontally to the right or left of its normal position, but, vice versa,
any alteration in the course of the vessel tends to bring the extension into that
position which would of itself cause such an alteration. The natural tendency
of the blades, when fixed as in this propeller, is to so adjust themselves that
the angle which each makes with the direction of the water-flow is the same.
In Figs. 4 & 5 which are horizontal plans, OK represents the shaft, O L the
extension, E F the upper blade, and G H the lower blade, the arrows showing
the course of the water-flow.
were
In Fig. 4 the vessel is going straight ahead, while in Fig. 5 she is turning
to the right. It is seen that, although the position of the extension with respect
to the main-shaft is changed, the angles between the blades and the water-flow
(as marked at G & F) are equal in both cases. Thus, if the extension
removed, and the centre-piece with the blades attached were allowed to run
free, the water-flow would cause the blades to vary in pitch, during a change
in the course of the vessel, in exactly the same way and order as would be the
case were that change produced by the extension itself. It is thus clear that
the work done by the entension is very small, being principally confined to
regulating and governing that motion of the blades which is imparted to them
by the action of the water-current; and that therefore this feathering of the
blades is almost automatic in its nature. The extension would, of course, often
be required to initiate the feathering motion; but the effort necessary for this
would be small and of very short almost momentary-duration. Thus, as no
power is transmitted through the joint, and as the work done by the extension
is so small, the strain on the joint and on the extension is inconsiderable.
The ordinary screw-propeller resists any change in the course of the vessel,
the result being much vibration and loss of power. This invention, however,
assists in the manoeuvring of the vessel, obviates all appreciable vibration during
such manoeuvring, and at the same time retains its full effectiveness as a
propeller, no power being wasted. The wear and tear of such a propeller would
therefore be small.
Although this propeller assists so materially in manoeuvring, it does not affect
the stability of the vessel when following a direct course. The feathering of the
blades is kept under perfect control by the extension, and the vessel can thus be
maintained in a steady course with a smaller expenditure of effort than is required
when the steering is effected by the rudder alone. Moreover, the screw and the
rudder act in conjunction (in a manner to be described hereafter); and as the
steering is done mainly by the former, the action of the latter, tending as it would
to retard the vessel, is reduced to a minimum, being felt principally while the
rudder is actually in motion from one position to another, and then to an almost
inappreciable extent. Another consideration is that the rudder, being connected
with the extension, is similarly affected by the action of the water-flow on the
blades (see above); and tends therefore, during a desired change in the course of
the vessel, to take up such a position as will allow that change. The movements
of the rudder therefore, after the first momentary effort is over, are aided by the
extension.
Figures 1, 2, 6, 7, 8, 9, 10, & 11, deal with a few different forms of joints.
Fig. 1 is a vertical plan, and Fig. 2 a perspective view of an universal joint, the
centre-piece of which is in the form of a right-angled cross. In Fig. 6 the centre-
piece is spherical. Figs. 7 & 8 are a vertical plan and a perspective view
respectively of a solid spherical joint. The boss in this case is larger than in
Fig. 6, and includes within itself the greater part of the four bearings These

page_text: bearings do not then interrupt the spherical form of the boss to so great an extent
as in Fig. 6. In order to imbed the bearings in this manner, parts of the centre-
piece must be cut away to make room for them, the desired shape being given to it
after the different parts of the joint are fitted together. The two arms of the
extension, when made in the form shown in Fig. 9, will interfere little with the
regular shape of the boss; as, although the bearings at the ends of these arms are
as deep as is necessary, the arms themselves are much thinner and thus necessitate
only a very small portion of the boss being levelled off to allow them free play.
The arms of the main-shaft can be fashioned in the same manner. Another form
of joint is that shown in Fig. 10 where the extension swings from within the centre-
piece. Such an extension would be of the shape given in Fig. 11. In this figure
the cross-bar, for the sake of clearness, is drawn in a vertical position; whereas in
Fig. 10 it is lying horizontally, or at right angles to the line joining the central
points of the bases of the two blades. This method of fastening the extension,
however, is not so good practically as that adopted in the other joints already
described; for it would be very difficult to fix the extension in this manner so
accurately as to avoid all looseness or side-play. In the other joints this difficulty
does not exist, ordinary care and precision of workmanship being all that is required
to secure a well-fitting joint.
Coverings or partial coverings can be fitted to these joints if thought desirable.
Fig. 12 shows such a covering made of thin metal. It is fixed to the main-shaft
and its arms, and extends slightly beyond the bearings of the joint. It is of course
open at the rear to allow freedom of motion to the extension. This casing is
suitable for joints of the forms in Figs. 1, 2, 6, & 10. Fig. 13 shows a casing which
would be fixed to the outer parts of the four bearings of the centre-piece, and
would therefore follow the movements of that piece. Besides the four circular
holes which admit the parts to which it is fixed, this casing must be perforated
with four slots through which the arms of the shaft and the extension pass; such
slots being long enough to allow these arms sufficient play. Fig. 14 is a perspective
view of a joint enclosed in this casing. Joints of the form shown in Figs. 1 & 2
could be covered in this way; and similarly any other joint which allows sufficient
room to admit the casing between the centre-piece and the arms of the main-shaft
and extension. In Fig. 15 an additional covering is shown, fitted to the arms of
the shaft and extending to within a short distance of the bearings at the ends of
these arms.
This extra casing could also be used by itself for the joint shown in
Figs. 7 & 8. In Fig. 15 it is furnished with two strips which cover the slots at
the top and bottom of the spherical casing. Neither the casing on the arms of the
shaft nor the strips attached to it are allowed quite to touch the spherical casing.
The two side slots can be similarly covered by strips fastened to the arms of the
extension; but these strips should lie inside the casing. If outside, they would
come into contact, in certain positions of the joint, with the two strips attached to
the arms of the main-shaft. Fig. 16 shows the arms of the main-shaft to which is
fixed the extra casing above referred to, and the two spherically shaped strips.
Numerous other forms of joints more or less suitable for this propeller might be
described; but as they each and all should embody the principle of the joint known
as Hooke's Joint, their method and working would be similar to those above-
mentioned, although their form might be varied and modified in many different
ways.
As regards the means of supporting and guiding the extension thrce methods
will be here described, the first and third being practicable without the assistance
of the ordinary rudder, and the second being used in conjunction with such rudder
In the first of these plans, a frame of the shape shown in Fig. 17 is supported
at two points, one vertically above and the other vertically below the centre of the
joint or boss of the screw, so that it is at liberty to swing horizontally from side
to side at the rear of the screw. This frame supports the shaft-extension in
horizontal position, a circular bore being cut in its central and deepest part to
receive it. The extension is thus free to follow the rotary motion imparted to i

page_text: by the main-shaft, and is at the same time prevented from leaving the horizontal
plane in which the main-shaft lies. In that horizontal plane, however, it swings
from side to side with the frame which supports it. This frame is manipulated
The
and governed from the deck in the same manner as the ordinary rudder.
rear or vertical part of this frame is made flat and deep in order that it may steer
the vessel when steam is shut off and the propeller doing no work. The strain
upon the frame or extension support is very small, as its movements are aided by
the water-flow acting on it through the blades and the extension, as pointed out
above.
In the second plan (ie. when the ordinary rudder is retained in its usual
position, hinged to a post at the rear of the propeller) the extension is supported
in the same way as in the method above described. The supporting frame,
however, not having to act as a rudder and being required to take up as little room
as possible, is no deeper than is necessary for strength and stability. (See Fig. 18.)
It is connected on deck with the rudder so that the two are manipulated together.
It would perhaps be best for the extension support and the rudder to be so
connected that they would move simultaneously through equal angles; as then the
rudder would offer no resistance to the forward motion of the vessel although it
would at the same time tend to keep her evenly in her course, whether that course
were straight ahead or inclining to either side. Fig. 19 shows a simple means of
securing this equal and simultaneous movement. The heads of the rudder and the
When the rudder and the
extension-support are each fitted with a cross-bar.
extension are in one and the same plane, these two cross-bars must be parallel to
one another and perpendicular to the plane of the extension and the rudder.
Connecting links are then fastened to the extremities of these cross-bars, one on
each side. These links, therefore, are also parallel to one another; and the angular
movements of the rudder and the extension will thus necessarily be equal and
simultaneous. If it is required that the rudder shall move through a somewhat
larger angle than the extension, the cross-bar attached to the former should be a
little shorter than that of the latter. An additional connection similar to the
above, but with much shorter cross-bars, might be fixed beneath the extension
frame and the rudder.
In the third plan the supporting frame swings from two points one vertically
above the other, the line connecting them falling however to the rear of the boss
or joint of the screw. The frame could thus take the form and would occupy the
position shown in Fig. 20, and would not, only carry the shaft-extension but would
act as a rudder as well. The extension is supported in a short. tube which, while
fitting it accurately, allows it freedom to revolve. This tube is fixed, above and
below, to the support or rudder; but, as it lies of necessity at all times in the
same direction as the extension, it must have liberty to swing horizontally about
those two points at which it is held by the rudder. In this plan the angular
movement of the rudder is greater than that of the extension; and during any such
movement therefore the supporting tube is caused to slide over a short portion of
the extension. The bracket which holds the lower part of the rudder might be
strengthened by a light upright support connecting it, behind the rudder, with that
part of the vessel above it.
I have as yet said nothing about a three- or four-bladed propeller; but as the
action of these is similar both in principle and effect to that of the two-bladed
propeller a short notice will be sufficient. In a four-bladed propeller (again
taking for the purposes of description and as a type of all the others that joint
of which the centre-piece is in the form of a rectangular cross) the blades are
rigidly fixed to the ends of the four arms of the centre-piece of the joint. It thus
differs from the two-bladed screw already described solely in the addition of two
blades which follow the motion of the arins of the extension in the same way as
the original two blades follow that of the arms of the inain-shaft. And on
submitting the movements of these two additional blades to an analysis similar to
that followed-and described above-in the case of the two-bladed propeller, it

page_text: will be found that their manoeuvring effect is similar to and simultaneous with that
of the two original blades. For example suppose the extension to be moved to the
right. Then, not only will the two additional blades revolve in a plane at right
angles to the extension, but their pitch-which must of course be considered
relatively to that plane-will be constantly varying, that of the upper blade being
less, and that of the lower greater, than normal. When the blades are horizontal
they are of equal pitch; and the moment of greatest variation between the pitch
of one and that of the other is when they are in a vertical position. On con-
sideration it will be seen that these changes tend to turn the vessel to the right.
In the same way if the extension be moved to the left the vessel is turned to the
left. In the case of the two original blades the steering power is due to their
variations in pitch, and is most effective at that moment when the blades are
vertical. But the two additional blades owe their steering effect to the altered
position of their plane of revolution; and the moment of their greatest efficiency
in this respect is when they are horizontal. The four blades therefore act in
harmony with one another; and the work of both couples is at any moment produc-
tive of results exactly similar the one to the other. In a three-bladed propeller
(taking, for the purposes of description a joint with a spherical or solid centre-
piece) it would be best to fix one blade to the centre-piece in exactly the same
position as that of either of the blades in the two-bladed screw shown in Fig. 3.
The two other blades would be based on the centre-piece at equal intervals from
one another and from the first blade, the base-centres of all three lying in that
plane which passes through the four bearing points of the joint, and which, if the
extension be brought into the same straight line with the main-shaft, is at right
angles to that straight line. We have already examined the motion of the first of
these blades and it will be found that the action of each of the others is com-
pounded of the movements of any two of the blades-taken consecutively-of the
four-bladed propeller. Thus, if the extension be moved from its central position
the steering effect of the first blade is entirely due to its feathering motion; while
that of the other two is due partly to their feathering motion and partly to the
inclined position of their plane of revolution. As they are based much nearer the
bearing points of the extension than to those of the main-shaft their motion
partakes more of the character of that of the two additional blades in the four-
bladed screw than of that of the two original blades. The work of each of the
three blades is, however, at any moment productive of exactly similar effects; and
the three-bladed propeller therefore resembles the two previously described in the
harmony and effectiveness of its action.
In describing this screw-propeller, I have in every case mentioned certain points
on the connecting-piece of the joint which would seen to be the most suitable base-
centres for the blades. As a matter of fact, however, the blades can be fixed, with
similar but perhaps not with equal effect, at any other points on the centre-piece
provided that these points are equidistant from one another on their circle of revolu-
tion, and that when the extension and the main-shaft are in one and the same
straight line the blades revolve in a plane at right angles to the main-shaft.
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 :-
(1) In a marine or ship's screw propeller, the construction at the end of the
propelling shaft of an universal joint (embodying the principle of the joint known
as Hooke's joint) by which the main-shaft is connected with a short additional
shaft or small extension of itself, the centre- or connecting-piece of this joint being
taken as the base from which the blades of the propeller spring and to which they
are rigidly fixed; all substantially as described or indicated above, and for the
purpose there specified.
(2) An upright frame or rudder pivoted (with liberty to swing from side to side
at the rear of the propeller described in claim 1 and above) at two points one

page_text: vertically above the other, the straight line between these points passing, in one
instance, through the centre of the joint of the propeller and in another instance
falling a short distance inmediately behind that central point; this frame being
under control from the deck of the vessel, and supporting and carrying the shaft
extension in a horizontal plane; all substantially as set forth and described above,
whether the supporting frame take the form and position shown in Fig. 17 or that
shown in Fig. 18 or that in Fig. 20.
Dated this 22nd day of December 1890.