Improvements in Screw Propellers and Apparatus connected therewith.
Year: 1890

page_text: Date of Application, 1st Nov., 1890
Complete Specification Left, 5th June, 1891-Accepted, 25th July, 1891
PROVISIONAL SPECIFICATION.
Improvements in Screw Propellers and Apparatus connected
therewith.
I, ROBERT MCGLASSON of 39, Dagnall Park, Selhurst, in the County of Surrey,
Gentleman, do hereby declare the nature of this invention to be as follows:-
My invention consists of a reversible screw-propeller for ships whereby the
direction in which the vessel is propelled may be reversed merely by altering the
position of the blades without reversing the engines thereby enabling the valve
reversing gear to be dispensed with and avoiding the loss of time and the strains
incidental to stopping and restarting the engines and the reversed torsional strains
to which the shaft is exposed. With this object the blades of the screw are so
connected to the boss that each may be turned on its own axis so as to alter its
angle in such wise as to convert the screw from a right to a left handed one or vice
versa. Or the blades may be placed in a fore and aft position in order to offer less
impediment to the navigation of the vessel under sail alone. Each blade accord-
ingly springs from a circular head or base plate received and firmly secured in a
corresponding socket in the boss with freedom to turn therein, the blades being
acted on by a moving part mounted on the boss or shaft and connected to the blades
by and actuated by a system of levers and connections from the deck or bridge.
By the facility for adjusting the angle of the blades thus obtained, a war ship may
be maneuvred at any required speed ahead or astern as required without altering
the engines. In some cases where variation of speed is not required the two blades
might be fixed on the same spindle passing transversely through the boss.
Dated t
37
1
1000
R. MCGLASSON.
By A. M. & Wm. Clark,
53, Chancery Lane, London, Patent Agents.
R. MCGLASSON.
By A. M. & Wm. Clark,
53, Chancery Lane, London, Patent Agents.
COMPLETE SPECIFICATION.
Improvements in Screw Propellers and Apparatus connected
therewith.
I, ROBERT MCGLASSON, of 39, Dagnall Park, Selhurst, in the County of Surrey,
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:-
My invention relates to screw propellers, and has, first, for its object to enable
the obliquity of the blades to be reversed as quickly as may be desired so as to
convert the propeller from a right to a left handed one, or vice versa, whilst it is
revolving, whereby the direction in which the propulsive action is exerted is reversed
without reversing the direction of rotation of the screw and consequently without
reversing the engines, thus avoiding the loss of time and the risk involved in the
transmission of orders to, and their execution in, the engine-room and the reversed
torsional and other strains incidental to the stopping and re-starting of the engines
and propeller shaft.
As the engines would always run in one direction, the ordinary reversing gear
may be dispensed with, if deemed expedient.
Besides the above mentioned capability of reversal of the blades from full pitch
in the one direction to full pitch in the other direction, the pitch of the blades may
be varied to suit the draught, trim, or condition of bottom, of the vessel or any

page_text: other circumstances affecting its propulsion, and in some cases the blades may be
set in a fore and aft position in order to offer less impediment to the navigation of
the vessel when under sail alone.
The blades may therefore be set to propel the vessel at any required speed ahead
or astern or be set so as to cut the water and stop or steady the vessel.
The invention comprises certain features of construction of the screw whereby
adequate strength is ensured and whereby the rotation of the blades, each on its
own axis, for the purpose of altering the angle of the blade as above mentioned, is
rendered possible whilst the screw is at work, and also various arrangements of
mechanism whereby the performance of this operation is effected from the deck or
captain's bridge or other convenient point inboard without the necessity of first
communicating with the engine room.
The invention also comprises a special construction of reversible screw, suited for
launches and the like.
Reference is to be had to the accompanying drawings, forming part of this
Specification, wherein I have illustrated a few typical examples of the methods of
carrying my invention into effect, it being understood that I do not limit myself to
the precise arrangements and details therein represented but reserve to myself the
right of making such modifications of arrangement and construction as may be
requisite, according to the particular circumstances of the case.
Figure 1 is a central vertical section of a screw, the blades of which are capable
of being reversed or of being varied in pitch when going either ahead" or "astern,"
the blades and their operating gear being, for the sake of simplicity, supposed to be
in a mid-position between full-forward and full-backward pitch.
Figure 2 is a section of same, on line 1-1 Figure 1.
Figure 3 is an axial cross-section in the plane on which the boss is (in this
example) supposed to be divided.
Figures 4 and 5 are respectively part sectional elevations of reversing gears for
large ships.
Figure 5 is a detail.
Figures 6 and 7 represent other arrangements for reversing small screws, such
as those of launches.
. The same letters of reference denote like parts in all the figures.
Referring to Figures 1 to 3, which illustrate the preferred mode of carrying out
the invention as applied to large screws, cach blade A of the screw is fitted to
rotate on its own axis in the boss B, the blade, for this purpose, springing from a
circular base or Hange a taking a circumferential bearing upon a corresponding seat
in the boss and having a shank or journal A fitting in a corresponding socket in
the boss and terminating in a flange a', steel or other balls a² (or it may be rollers
mounted in loose carrying rings) being introduced between the base and flange a a
and, their respective seats in the boss, to reduce the friction and so enable the blade
to be rotated upon its axis with greater facility. The boss is constructed in halves
bolted together by bolts after the blade shanks have been placed in their seats in
the boss.
I have shewn the boss split transversely, but it will be understood that it may be
split longitudinally, if preferred.
The preferred form of connection between the blades and their operating
mechanism, consists of oppositely-directed arms A² on the blade journals A coupled
by links to a longitudinally-sliding part operated from inboard. This longi-
tudinally-sliding part is a crosshead Con the end of a rod D passing through the
propeller shaft E which is made tubular, the crosshead and links being housed
within a cap B' forming part of the boss. The crosshead C may be situated beyond
the end of the propeller shaft, as shewn, or it might pass through longitudinal slots
therein if the shaft be continued rearwards to a bearing in the rudder post.
In Figures 5, 6, and 7, the longitudinally-sliding part from which the screw-blades
receive their pivotal motion, is a collar M on the propeller shaft, and, in Figure 5,
instead of links and arms on the blade shanks, very strong racks N slide through

page_text: guides in the boss and gear with circumferential teeth n on the blade journals.
This collar is embraced by the forked end o of a sliding rod O which may be rack-
toothed and actuated through pinion and worm gear P from a vertical shaft Wi
operated by bevel or other gear we from a hand wheel W on deck. The wheel shaft
may be screw-threaded to actuate a sliding index 2 whereby to shew at all times
the pitch and direction of the screw blades. This index is shewn in plan in
Figure 5 but any other form of indicator may be used. In this arrangement, the
reversal of the blades being effected through the arcs 1, 1, 2, 2, it will be obvious
that the blades may be placed in an intermediate position fore and aft when the
vessel is under sail alone.
Instead of the rod O being a rack, it may be screw-threaded, as shewn at Q,
Figure 4, actuated by a combined sprocket wheel and nut y driven by an endless
chain R (or other gear) from the shaft to which motion is imparted by the hand
wheel W as before.
It is to be understood that in all cases where a hand wheel W is referred to for
operating the gear from the bridge, deck, or elsewhere, that such hand wheel may
be replaced by a small motor of any suitable kind similarly situated and fulfilling
the same functions as the hand wheel.
In operating the reversal, or setting of the blades of small screws, various com-
binations and arrangements of gear, levers, and other connections, may be used for
transmitting the necessary motion from the bridge, deck, or other point, to the collar
or cross-head to which the blade shanks are connected as above described.
According to the arrangement shewn in Figure 6, the said collar M is in rear,
instead of in front, of the screw as in the former arrangement and it is engaged
directly by a forked bell-crank lever S, mounted on the rudder post and connected
by a link's passing directly up through a well to a pin on a worm segment T
operated through a worm t by the handwheel W on deck.
Instead of a handwheel, a hand lever U (Figure 7) provided with a spring bolt
engaging with a notched quadrant u, may pass directly down to, and be engaged
by its forked end with, the sliding collar M.
When a variation of pitch and alteration of speed by the screw, is not required
the two blades A. A may be connected or fixed on the same spindle passing
completely through the boss, as in Figure 6.
I am aware that screw propellers have heretofore been made with pivoted blades
for the purpose of feathering and placing in position for sailing, and therefore I
do not claim the swivelling of the screw blades. But no means have been heretofore
provided whereby the obliquity of the blades may be reversed and the blades be
held in any position between full-pitch in the one direction and full-pitch in the
other direction, in the manner herein described, or the pitch of the blades altered
to suit the condition of the vessel at any moment, or to vary their propulsive action
and the speed of the vessel, or to nullify it for the purpose of stopping or steadying
the vessel whilst the screw is in operation, this capability of adjustment when in
operation including "feathering" the blades or placing them in position for sailing
only.
Although my invention has been described with reference to propellers driven by
steam engines, it will be evident that it is equally applicable to propellers driven
by electric or other power.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manuer the same is to be performed, I declare that what I
claim is
1st. The combination, with a screw-propeller having its blades pivoted to swivel
in the boss and connected by arms and links or toothed and rack or other gear with
a longitudinally-sliding part in the form of a cross-head or collar, of gear, sub-
stantially as herein described and illustrated in the drawings, such gear actuating
the said longitudinally-sliding part and effecting the complete reversal or alteration
of pitch of the screw blades, and, consequently, the reversal or alteration of

page_text: propulsive effect, without stopping and reversing the propelling engines and screw-
shaft, substantially as herein specified.
2nd. The combination, with a swivel or reversible-bladed screw, such as herein
described, and with a longitudinally-sliding part coupled or geared to the blade
journals, as specified, of an auxiliary or donkey engine or other motor and of
mechanism, such as described, whereby the said longitudinally-sliding part may be
actuated as required for the purpose of reversing or altering the pitch of the screw
without reversing the main engines, as specified.
3rd. The combination, with a swivel or reversible-bladed screw, such as herein
described, and with a longitudinally-sliding part coupled or geared to the blade
journals, as specified, of the various arrangements of manually operated gear
whereby the reversal or alteration of pitch of the screw, may be effected without
reversing the engines, as specified.
4th: The combination, with a swivel-bladed screw, of ball or rolling bearings
interposed between the blade journals and their seats in the boss, substantially as
and for the purpose specified.
Dated this 4th day of Tune 1901
R. MCGLASSON.
By A. M. & Wm. Clark,
53, Chancery Lane, London, Patent Agents.