improvements in the Combination and Arrangement of Screw Propellers.
Year: 1893

page_text: Date of Application, 12th Oct., 1893
Complete Specification Left, 18th Jan., 1894-Accepted. 10th Mar.,
1894
PROVISIONAL SPECIFICATION.
improvements in the Combination and Arrangement of Screw
Propellers.
I, SAMUEL GRIFFIN of Kingston Iron Works Bath in the County of Somerset
Engineer do hereby declare the nature of this invention to be as follows:-
My invention relates to improvements in the combination and arrangement of
screw propellers for propelling, reversing and stopping boats or other floating craft,
without the necessity for stopping or reversing the driving motor itself, and is
specially suitable to work in combination with petroleum or gas motors of any
kind in which a continuous motion in one direction is essential or desirable.
For this purpose I arrange two propellers concentric with each other on the end
of the propeller shaft, each propeller being independent and free to revolve on the
said propeller shaft. These two said propellers have their blades arranged with
opposite pitch i.e. right and left hand and are separately engaged or disengaged
with the said propeller shaft at will, by means of any suitable mechanism, during
the motion of the driving motor or otherwise. It is advantageous to arrange the
forward propeller next the rudder, and the backward propeller next the keel.
The action of this arrangement is as follows:-
To effect the forward propulsion of the boat, the propeller near the rudder will
be connected with the propeller shaft by means of the before mentioned mechanism
thus giving the necessary forward motion, at the same time the propeller next the
keel (being free on the shaft and having its blades of opposite pitch) will revolve
in an opposite direction without hindrance to the motion of the boat. To reverse
the motion of the boat it is only necessary to connect the propeller next the keel
with the shaft at the same time disconnecting the forward propeller by means of
the before mentioned mechanism, when the reverse action to that already described
for forward propulsion will take place. To entirely stop the boat it is only
necessary to disconnect both propellers by means of the before mentioned
mechanism, when the shaft simply revolves loosely in them without imparting
motion to either.
It might be advantageous in certain cases to connect the aforesaid propellers
with each other by means of any suitable gearing so that the motion of one
propeller may be communicated to the other, driving it in the opposite direction.
Dated this 11th day of October 1893.
SAMUEL
GRIFFIN.
Tongue & Birkbeck,
Agents for the Applicant.
CUMI LEID
Improvements in the Combination and Arrangement of Screw
Propellers.
I, SAMUEL GRIFFIN of Kingston Iron Works, Bath, Somerset, 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 for boats ships or other floating vessels

page_text: (all of which for the take of brevity I shall hereinafter term "boats") and has for
its object to enable such boats to be started or reversed (i.e. propelled ahead or
astern) or stopped without any necessity for stopping or reversing the driving
motor itself or the driving shaft connected therewith and my present invention
is specially suitable to work in conjunction with petroleum or gas motors of
any suitable kind in which a continuous motion in one direction is essential or
desirable.
For this purpose I arrange two propellers concentric with each other on the end
of the propeller shaft each propeller being independent and free to revolve on the
said propeller shaft. These two said propellers have their blades arranged with
opposite pitch (i.e. right and left hand) and are separately engaged or disengaged
with the said propeller shaft at will by means of any suitable mechanism during
the motion of the driving motor or otherwise.
It is advantageous to arrange the forward propeller next the rudder and the
backward propeller next the keel but I do not limit myself thereto.
The action of this arrangement is as follows:-
To effect the forward propulsion of the boat the propeller near the rudder will
be connected with the propeller shaft by means of the before mentioned mechanism
(i.e. any suitable clutch or connecting gear) thus giving the necessary forward
motion at the same time the propeller uext the keel (being free on the shaft and
having its blades of opposite pitch) will revolve (by the action of the water on
its blades) in an opposite direction without sensible hindrance to the motion of the
boat. To reverse the direction of travel of the boat it is only necessary to connect
the propeller next the keel with the shaft at the same time disconnecting the
forward propeller by means of the before mentioned mechanism when the reverse
action to that already described for forward propulsion will take place. To
entirely stop the boat it is only necessary to disconnect both propellers by means
of the before mentioned mechanism when the shaft simply revolves loosely and idly
in them without imparting motion to either propeller.
It might be advantageous in certain cases to connect the aforesaid propellers with
each other by means of any suitable gearing so that motion from one propeller may
be communicated to the other driving it in the opposite direction.
In certain cases it might be advantageous to fix the clutch or other suitable
means for engaging and disengaging the above mentioned propellers with the
driving shaft in the interior of the boat instead of between the propellers as above
described.
According to this arrangement one propeller would be mounted on a hollow shaft
passing through the stern into the interior of the boat the other propeller being
carried by a separate shaft passing through the said hollow shaft also into the
interior of the boat these two shafts being respectively and independently connected
and disconnected with the driving shaft by any suitable clutch or other suitable
means arranged in the interior of the boat in any convenient position.
Referring to the drawings hereunto annexed: -
Figs. 1 and 2 are sectional elevation and plan of propeller shaft and propellers
showing arrangement of clutch and mechanism for actuating same.
Fig. 3 shows a portion of stern of boat fitted with propellers and mechanism
connected therewith.
a a¹ are propellers having right and left hand blades respectively.
6 6¹ are loose rings carried by the boss c and fitting corresponding recesses in the
propeller bosses a a' and divided by the wedge shaped slots d'd'.
c is a boss firmly fitted to the propeller shaft g and slotted longitudinally through
the propeller shaft to receive the bolt e.
The bolt e (which I will term the "clutch bolt") has wedge shaped ends e¹ e² to
correspond with slots d d' and has a longitudinal motion in connection with the
rod which passes through the centre of the hollow propeller shaft g. This
rod is actuated by the sliding boss to which it is connected by the key or
piu i.

page_text: The hand lever (Fig. 3) communicates a sliding motion to the boss b by means
of the link k and lever through the rocking shaft m to the forked lever n which
operates in the recess h¹ in said sliding boss h.
dotted lines showing position of lever j in forward and backward gear
respectively.
oo' collars fitted tight to propeller shaft g.
The mode of operation is as follows:-
The hand lever j being at midgear as shown the clutch bolt e through the inter-
vention of the mechanism kln mh if will be at mid-travel between the rings bb' and
as these rings fit loosely in the recesses of the respective bosses of the propellers a a¹
the propeller shaft g and boss e will revolve without communicating motion to the
said propellers which are loose on the said propeller shaft being held in position
against the boss c by the tight collars o o'. In this position therefore it is obvious
that the propeller shaft will revolve without propelling the boat in either
direction.
In order to propel the boat "ahead" the lever j is moved into the position
indicated by the dotted lines j¹ the clutch bolt e will consequently (through the
intervention of the connecting mechanism k l m n hi f) be moved into such a
position that its taper end e will be forced into the corresponding taper
slot d in the ring thus causing the latter to expand forcibly against its corre-
sponding recess in the boss of the propeller a. A powerful frictional contact
is thus established between the said propeller a and the shaft g and boss c in
connection with which it continues to revolve propelling the boat "ahead." The
reverse propeller u being at the same time loose upon the shaft will by reason
of the action of the water upon its blades revolve freely in an opposite direction
to that of the shaft g and without sensible obstruction to the progress of the
buat.
In order to propel the boat astern it is only necessary to move the lever j into
the position shown by the dotted lines when it is obvious the reverse action to
that already described will take place. The reverse movement of the clutch bolt e
at once releasing the propeller a and at the same time establishing a corresponding
frictional contact between the propeller a¹ and shaft g. The boat is consequently
in virtue of the reverse pitch of the propeller blades propelled "astern."
The propeller a being now disengaged revolves freely in an opposite direction to
that of the shaft g as before described in reference to the propeller a'.
It will thus be seen that by the simple movement of the lever ; either into
forward backward or mid-gear the various operations respectively of starting
reversing and stopping the motion of the boat can be effected without stopping or
reversing the motion of the propeller shaft g or motor which actuates it.
Fig. 4 shows a mechanically equivalent arrangement to the two propellers on one
shaft in Figs. 1 to 3 :-
Fig. 4 being a sectional side view showing arrangement of the two propellers of
opposite pitch each rigidly fixed on a separate shaft and these two said shafts
concentric to each other with clutch or connecting and disconnecting mechanism
placed in the interior of the boat for actuating either one shaft or the other
or neither and thereby revolving either one screw or the other or neither-as
desired.
A A are propellers having right and left hand blades respectively.
B B' solid and hollow shafts respectively-having the propellers A A¹ rigidly
fixed thereto respectively.
CC' recessed bosses fixed respectively to the shafts B B'.
D is a boss receiving motion through the boss E from the driving shaft F-this
boss D being grooved longitudinally to receive the conical ended bolt G which
engages or disengages alternately with the split rings H and H.
I is a sliding collar on shaft F which is actuated by a suitable lever (not shown)
in connection with the collar Z and communicates a longitudinal motion to the bolt G
through the link J rocking lever K and link L.

page_text: The operation of this arrangement is as follows :-—
This arrangement is in all respects similar in action to that already described
and illustrated in Figs. 1 2 and 3 the hollow shaft B¹ and shaft B passing
through it being essentially prolongations of the bosses respectively of the
propellers A A.
The position of the conical ended bolt G being as shown in the drawings midway
between the rings H'and H the shaft F and boss E will revolve without communicating
motion to either of the recessed bosses C₁C and consequently the propellers will
be idle.
When the collar I is moved (by any convenient mechanism) towards the
propellers the bolt G through the intervention of the mechanism L K J will
expand the ring H into the corresponding recess of the boss C thus communicating
motion through the shaft B to the propeller A the propeller A' being at the same
time free to revolve (by the action of the water on its blades) in an opposite
direction, and in so doing this propeller A being fixed on the hollow shaft B' will
revolve said shaft together with tlie recessed boss C¹ fixed on said shaft.
By moving the collar I in the opposite direction to that already described the
bolt G will engage with the ring H₁ causing it to expand in the recess of the boss C¹
and thus through the hollow shaft B' revolve the propeller A' the propeller A
being by the same movement released and free to revolve (by the action of the
water thereon as before described) together with the shatt B upon which it is fixed
and the recessed boss C carried on said shaft B.
I do not limit myself to the precise details herein described-as these may be
modified without departing from the nature of my invention.
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. The combination of two screw propellers having their blades of right and
left hand pitch respectively fitted loosely to the same shaft concentric with each
other and each adapted to either revolve freely upon the said shaft or be revolved
by and with it and independently of the other propeller substantially in the manner
and for the purposes herein before set forth.
2. The combination of two screw propellers having their blades of right and
left hand pitch respectively fitted to revolve freely upon the same driving shaft and
concentric with each other and each propeller capable of being independently
connected with or disconnected from the driving shaft substantially in the manner
and for the purposes hereinbefore described.
3. The combination of two screw propellers having their blades of right and left
hand pitch respectively each being capable of revolving in connection with or
independently of the driving shaft in such a manner that the independent connection
of one propeller or shaft carrying same with the main driving shaft will propel the
boat "ahead" while the independent connection of the other propeller or the shaft
carrying same with said main driving shaft will propel the boat astern the dis-
connection of both propellers or shafts carrying same from the said main shaft
leaving the latter revolving or free to revolve without revolving either of the
propellers substantially as and for the purposes herein before described.
4. The combination of two screw propellers having their blades of right and left
handed pitch respectively each such propeller being mounted and revolving con-
centric to the other one such propeller fitted upon and revolved by a hollow shaft
and the other propeller fitted upon and revolved by a second and separate sha't the
latter mounted within and concentric to said hollow shaft and means to impart
rotary motion to either the said inner or outer shaft or to stop both without
necessarily stopping or reversing the driving motor substantially in the manner and
for the purposes hereinbefore described.
5. The improved arrangement and combination of two screw propellers-acting
in conjunction with means to start and stop each such propeller independently of

page_text: the other the whole arranged combined and acting substantially in the manner and
for the purposes herein before described and illustrated in the drawings hereunto
annexed.
Dated this 18th day of January 1894.
TONGUE & BIRKBECK,
34, Southampton Buildings, Chancery Lane, London, W.C.,
Agents for the Applicant.