Improvements in Screw Propellers and Apparatus connected therewith.
Year: 1891

page_text: Date of Application, 31st Jan., 1891
Complete Specification Left, 6th July, 1891-Accepted, 5th Sept., 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 relates to screw-propellers the blades of which are capable of
being quickly reversed so as to convert the screw from a right to a left handed
inclination, or vice versa, whilst the propeller is revolving, whereby the direction in
which it exerts its propulsive action may be reversed without reversing the
direction of its rotation and consequently without reversing the engines, thus
avoiding the loss of time 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 restarting of the engines and propeller shaft.
As by my invention the engines would always run in one direction, the ordinary
valve 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 other circumstances affecting its propulsion, or the blades may be set in a fore
and aft position in order to offer less impediment to the navigation of the vessel
under sail alone.
The invention comprises certain features whereby the rotation of the blades,
cach 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 this operation may be performed from the
deck or captain's bridge or other convenient point inboard without the necessity
of first communicating with the engine room, the said mechanism being actuated
either by the main engines or by auxiliary steam or hydraulic engines and com-
bined with means whereby not only will the racing of the main engine which would
be liable to occur during the operation of reversal be prevented, but the engines
may be kept running at practically the same speed with only the necessary
expenditure of steam at whatever augle the blades may be placed.
In carrying out the invention as applied to large screws, each blade is fitted to
rotate on its own axis in the boss, the blade for this purpose springing from a
circular base or flange taking a circumferential bearing upon a corresponding seat
upon the boss and having a solid or hollow shank or spindle fitting in a corre-
sponding socket or on a stud on the boss, the necessary freedom of motion being
obtained by the introduction of ball or roller bearings between the base flange and
its seat and also between the shank and the boss. The boss is constructed in
halves and provided with internal spaces for the reception of the connections
between the shanks of the blades and the mechanism by which the setting of the
blades at different angles is effected, the preferred form of such connections being
oppositely directed arms on the two blade shanks coupled by links to a
longitudinally-sliding part operated from inboard. This longitudinally-sliding part
may be an inner shaft or rod contained within the propeller shaft which is made
tubular for its reception and terminates at its outer end in a crosshead to which
the said links are connected, the crosshead and links being housed within the
hollow boss and the crosshead being situated either beyond the extremity of the
propeller shaft or passing through longitudinal slots therein should the shaft

page_text: be continued to a bearing in the rudder post. Or the longitudinally-sliding part
may be a collar upon the propeller shaft to which the links are connected.
The longitudinal motion may be imparted to the crosshead and its sliding inner
shaft from the main engines or from auxiliary steam or hydraulic engines. For
this purpose, the said sliding inner shaft terminates inboard in a crosshead passing
through longitudinal slots in the propeller shaft and connected to a sliding collar
thereon, which, if operated by an auxiliary engine, would be coupled, by a fork or
a pair of levers or other means permitting of its rotation, with a pair of links con-
nected to a crosshead on the piston rod of a direct acting cylinder. Or the collar
might be attached directly to the piston of a cylinder through which the propeller
shaft passes axially. The distribution of motive fluid to the cylinder would be
governed by a suitable valve, and in the case of hydraulic power the locking of the
water in the cylinder would suffice to hold the propeller blades rigidly at whatever
angle they may be set. Instead of directly coupling the collar to the piston, an
ordinary donkey engine or pair of engines may be used, or an engine, similar to a
steam or hydraulic steering engine, operating the collar through worm or other
gear with provision for the prevention of over-running as usual in the latter class
of engine, or as hereafter described in driving from the propeller shaft. In
operating the said collar by the main engines, the auxiliary cylinder would be
replaced by a sliding rod operated by a screw or worm motion on a counter shaft
capable of being geared through the medium of a friction clutch and reversing
spur friction or band gear with the propeller shaft, the friction clutch being thrown
into gear with the one or other set of spur or other gear through the medium of
connecting rods levers rack worm spur or other gear operated by hand from the
bridge or other point, an indicator being there provided, shewing at all times the
then position of the blades of the screw.
In order to prevent over running, a sort of "hunting gear" is combined with the
sliding rod operated by the counter-shaft screw motion and with the clutch
whereby, on the complete reversal of the blades being effected, the friction clutch
is automatically thrown out of gear so as to prevent injury to the screw-reversing
mechanism. This hunting gear" may be in the form of a link operated by the
screw motion and acting on the clutch lever on reaching the extremities of its
course.
The same arrangements for setting the blades of the screw by power whether of
the main engines or of auxiliary engines of any description may be applied to
actuate the external sliding collar to which the shanks of the screw blades are
directly connected by links or racks, as above mentioned. In either case, the
"hunting gear," if used, or some other part of the mechanism for transmitting the
longitudinal motion required for setting the screw blades, would be connected
with a throttle valve on the steam pipe to the main engines whereby the said
engines would be slowed down, without being actually stopped, in the operation of
reversing the screw for the purpose either of preventing the racing of the main
engines if the screw blades, in the operation of reversing, are turned through such
an angle as to be presented edgewise to the water, or of preventing undue strain
being thrown on the screw blades if presented flatwise to the water.
Dated this 31st day of January 1891.
K. M'GLASSON.
By A. M. & Wm. Clark,
53, Chaucery Lane, London, Patent Agents.

page_text: Improvements in Screw Propellers and Apparatus connected
therewith.
1, 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 improvements in the means of operating the blades and
controlling the engines of reversible screw-propellers such as those described in a
previous application for Letters Patent dated the 1st day of November 1890,
No. 17566; that is to say propellers whose blades are capable of being reversed
so as to convert the screw from a right to a left handed one or vice versa whilst the
propeller is revolving, the object being to enable the direction of propulsion to be
reversed without reversing the direction of rotation of the engines and screw, and
thus to avoid the loss of time and also the reversed torsional and other strains
consequent on stopping and restarting the engines and propeller shaft.
the capability of reversal from full pitch in one direction to full pitch in the other
direction for the purpose of reversing the direction of propulsion the blades may be
adjusted at any intermediate pitch as may be required.
Besides
The present invention relates to power-operated mechanism for accomplishing
this, actuated either by the main engines or by a direct acting auxiliary cylinder
or other engine and controlled from the bridge conning tower or deck as well as
from the engine room so that the propulsion of the vessel ahead or astern is brought,
in case of great emergency only, under the direct control of the captain or other
officer on duty independently of the engineer, thus avoiding, in case of urgent
need, the loss of time incidental to the transmission of orders to, and their execution
in, the engine room although for ordinary working the control over the direction
of propulsion would still remain with the engineer to whom orders would be
transmitted in the ordinary way. With this power-operated screw-reversing gear
is combined means for preventing the racing of the main engines which would be
liable to occur during the reversal of the blades of the screw.
Reference is to be had to the accompanying drawings, forming part of this
Specification, wherein Figures 1. 2. and 3. are sections of the preferred construction
of reversible-bladed screw. Figure 4 is an elevation of mechanism operated by
the power of the main engines; and Figures 5. and 6. are elevations of a direct
acting cylinder for the purpose of varying or reversing the pitch of the screw-
blades whilst the propeller is revolving; these two mechanisms being typical
examples of power operated gear for this purpose. Figure 7 illustrates one form
of the special throttle-valve herein referred to.
Referring to Figures 1. 2. and 3. the screw-blades A have strong pivots A¹
received in sockets in the boss B with ball or roller bearings at the flanges a a¹
and the pivots have oppositely directed crank arms A coupled by links c to a
crosshead C fixed to the end of a rod D passing through the propeller shaft and
terminating in a crosshead (Figure 6) free to slide in longitudinal slots e in
the propeller shaft E, the ends of the said crosshead being engaged by a collar H
free to slide upon the shaft, said collar being engaged by a pair of levers. G
pivoted at g.
The mechanism shewn in Figure 4 is operated from the propeller shaft E (and
therefore by the power of the main engines) through the medium of a double
friction or other clutch I upon a countershaft the clutch being capable of putting
the countershaft J into gear with the propeller shaft E through one or other of
two sets of oppositely-acting spur gear K or K' as the case may be, the one set' K
gearing the countershaft directly to the propeller shaft and the other set through
an intermediate wheel. This countershaft J is screw-threaded and actuates a nut

page_text: pivoted on the pair of levers G engaging the collar H which as before mentioned
is connected to the sliding rod D.. According as the clutch I is engaged with the
one or other set of spur gear the power of the main engines is applied, through
the countershaft screw gear levers collar and sliding rod D, to turn the blades of
the screw upon their pivots that is to say to alter their pitch or reverse the
direction of propulsion as may be required. Although I have shewn spur gear
at K K it will be obvious that friction, band, or other gear may be substituted.
The clutch lever I' is operated from a hand or power operated wheel W on the
bridge or deck through the medium of connecting rods and levers or shafting and
rack, worm, spur, or other gear whereby the necessary motion may be imparted to
the cluch lever to throw the clutch into gear in the one or other direction, an
indicator being provided as hereafter described shewing at all times the angle of
the screw-blades. In this example the clutch lever I is connected to a sliding
rod geared by rack and pinion with a vertical shaft W₁ geared by bevel gear
with the hand wheel W. In order to prevent over running, the double lever G is
connected with the clutch lever I by a slotted link L engaging with a stud / on
the lever whereby on the propeller blades reaching the position of full pitch in
either direction the pressure of the clutch lever is relieved by the end of the slotted
link L throwing the clutch out of action (so that injury to the screw-reversing
mechanism is avoided) this action being due to the motion of the lever G in the
opposite direction to that in which the lever I was moved to put the clutch in gear.
In Figures 5. and 6. the sliding rod D is operated by the piston of a cylinder F
worked by steam hydraulic or other fluid pressure, whose rod is connected to the
pair of levers Gengaging with the collar H. The distribution of the motive
Huid to the cylinder F would be controlled by a valve whose rod is manually or
power operated from any point on the bridge or deck in the same way as the
mechanism before described. If hydraulic power be employed in the cylinder F
the locking of the water therein will hold the propeller blades at whatever angle
they may be set whilst if steam or other elastic fluid be used it will also serve as a
"cushion."
In each of the above described arrangements, the double lever G or some other
part of the mechanism is connected by a rod or otherwise to a special throttle
valve or valves on the steam pipe or pipes of the main engines, the said throttle
valve or valves being so constructed as to diminish, without entirely shutting off,
the supply of steam so as to slow down the main engines (without however stopping
them) or keep them running at the same speed, and thus prevent them "racing
when in the operation of reversing, the pitch of the screw diminishes so that the
blades are presented more edgewise to the water, the valve opening again as the
pitch of the screw increases in the reverse direction. For this purpose the valve
or valves proper, which may be of the throttle, double beat slide or other form
may either fit loosely in the bore of the valve casing or it may have a hole or holes
through it, or as seen in Figure 7 segments may be removed from the edge of
the valve or be otherwise made so as to be incapable of cutirely preventing the
passage of the steam to the main engines when the blades are in the mid position.
If however the screw is so constructed that the blades in the operation of reversal
of pitch, are presented more flatwise to the water, which it will be readily under-
stood they may be, the slowing down of the engines will prevent undue strain on
the blades.
Instead of operating the collar H by the propeller shaft, as in Figure 4, or
coupling it directly to a piston, as in Figures 5 and 6, it may be operated through
worm or other gear by a donkey engine or pair of engines or an engine similar to
a steam or hydraulic steering engine or any other motor, as will be readily under-
stood without further illustration, provision being made for the prevention of over
running as above described and the said engine being controlled by gear such as
herein referred to manually or otherwise operated from the bridge or other distant
point. The lever G, Figure 4, instead of acting on the friction clutch lever. I
might, in the case when the reversing of the screw is effected by a donkey engine,

page_text: be made to act on the reversing shaft of the donkey engine so as to gradually stop
the latter when the screw blades reach full pitch ahead or astern. In this case, no
friction clutch and toothed or other gear, such as referred to in Figure 4, are
necessary, the donkey engine driving the screwed shaft J direct, the clutch lever 11
becoming the reversing lever of the donkey engine which lever is controlled by the
officer on bridge, deck or elsewhere by the system of levers and connections shown
or substantially similar arrangements so that the motion of the engine may be
stopped when the blades have assumed the desired position. Suitable means (which
it is unnecessary to describe in detail) would also be provided whereby the within
described gears may be controlled by the engineers in the engine room or orders
transmitted by the ordinary engine room telegraph or otherwise from the officer on
bridge or deck.
Having now particularly described and ascertained the nature of the said inven-
tion and in what manner the same is to be performed declare that what I
claim is--
1. The combination with a reversible-bladed screw such as herein described and
with the longitudinally-sliding part coupled to the blade journals, of mechanism
such as described or substantially similar whereby the said longitudinally sliding
part may be actuated at required times and to the required extent directly from
the screw shaft itself for the purpose of applying the power of the main engines to
effect the operation of altering the pitch or of reversing the direction of propulsion
without stopping and reversing the engines, the operation of such mechanism being
controlled from any desired point, as specified.
2. The combination, of a reversible bladed screw such as herein described and
with the longitudinally-sliding part coupled to the blade journals, of a fluid pressure
cylinder and piston coupled directly to and actuating the said longitudinally-sliding
part and screw blades substantially as herein specified the valve of the cylinder
being controlled from any suitable point for the purpose of reversing or altering
the pitch of the blades and holding the blades in the altered position without
stopping and reversing the main engines and screw shaft, as described.
3. The combination, with a reversible-bladed screw such as herein described and
with the longitudinally-sliding part coupled to the blade journals, of an auxiliary
or donkey engine or other motor and of mechanism such as described whereby the
blades may be actuated as required for the purpose of reversing or altering the
pitch of the screw without reversing the main engines such auxiliary engine or
motor being controlled from any desired point, as specified.
4. The combination with a reversible-bladed screw such as herein described and
with each of the herein described mechanisms (or substantially similar mechanisms)
for operating the same, of a special throttle or other valve or valves on the main
steam pipe or pipes so constructed and operated by the screw-reversing mechanism
as to vary the supply of steam to the main engines concurrently with the alteration
of pitch and to an extent proportional or approximately proportional to the power
required to drive the screw at whatever angle the blades may for the time being be
placed whereby racing" of the engines is prevented, substantially as specified.
ROBT. MCGLASSON.
By A. M. & Wm. Clark,
53, Chancery Lane, London, Patent Agents.