Improvements in Apparatus for Propelling Boats and other Navigable Vessels and Driving Gear therefor.
Year: 1898

page_text: Date of Application, 3rd Nov., 1898
Complete Specification Left 29th Aug 1899 Accepted. 30th Sept. 1899
PROVISIONAL SPECIFICATION.
Improvements in Apparatus for Propelling Boats and other Navigable
Vessels and Driving Gear therefor.
I, HENRY BARCROFT, of The Glen, Newry, in the County of Armagh, Ireland,
Director of the Dundalk and Newry Steam Packet Company, do hereby declare
the nature of this invention to be as follows:-
My invention relates principally to that description of apparatus for propelling
boats in which two sets of screw propeller blades are mounted on the ends of
radial arms carried by concentrically arranged shafts, situated above the water
line, and driven in opposite directions, the screw blades of the one set being
arranged at an opposite angle to those of the other set, so that each set counter-
acts the lateral thrust exercised by the other one arising from the fact that the
propellers are only partially immersed.
Apparatus of this kind are described in the Specification to my Patents
Nos. 13019 of 1889 and 20,638 of 1889.
My present invention has mainly for its object to enable such propeller apparatus
to be employed with advantage for navigating shallow water ways, where only a
comparatively small extent of immersion of the propeller blades can be obtained.
In order in such cases to enable a considerable propelling power to be exercised
by the propelling apparatus, I employ two or more pairs of such propellers,
arranged side by side at the stern of the boat, all driven by one and the same
driving shaft of a motor engine. For this purpose I drive the shafts of the pro-
pellers by chain and chain wheel gear in the following manner. Assuming that
three such pairs of propellers are employed, one pair being in the line of the
keel while the others are on each side thereof.
The tubular shaft of the one propeller of each pair has a chain wheel, and
these three chain wheels are all driven by one and the same chain and chain
wheel, on the engine shaft. The inner shaft of each pair, that carries the second
propeller, has on its extension beyond the tubular shaft, another chain wheel,
and these three chain wheels are also all driven by a second chain and chain
wheel on the engine shaft, but in such manner that these propeller shafts revolve
in the contrary direction to the respective tubular propeller shafts first referred to.
The chain gear can be arranged in a variety of ways for effecting the above
described mode of driving. According to one arrangement, the chain for driving
the tubular shafts passes from the underside of the driving chain wheel at an
angle up to the chain wheels of the two outer propeller shafts, and after passing
partly round these, it is led first under two guide pullies and then over the chain
wheel of the middle propeller shaft; the propeller shafts being thus all driven in
the same direction.
The above described arrangement may be modified by dispensing with the
guide pullies, and passing the chain from the upper side of the two lateral chain

page_text: wheels to the underside of the middle one which would thus be driven in the
contrary direction to the other two.
For driving the inner shafts, the chain passes first over the top of the driving
chain wheel, then down under two guide pullies and thence up to the chain wheels
of the two outer propeller shafts, the arrangement being otherwise the same as
before. Thus it will be seen that in this case the propeller shafts will be driven
in the opposite direction to that of the other shafts.
According to another arrangement, the chain for the tubular shafts passes
from the underside of the driving chain wheel, first up to the chain wheel of the
one outer shaft, and from this it is led over guide pullies to the wheel of the
other outer shaft.
After passing partly round this it is led over the top of and partly round the
chain wheel of the middle shaft, from which it passes down to the opposite side
of the driving chain wheel.
With this arrangement it will be seen that the middle shaft is driven in the
opposite direction to that of the outer shafts.
For driving the inner propeller shaft of each pair, the chain passes from the
underside of the driving chain wheel up to the same side of the chain wheel of
the middle shaft, from the top of this to the underside of the chain wheel of one
outer shaft, thence across to the other outer shaft, and thence down to a guide
pulley, from which it passes to the driving chain wheel again.
Although I have described the arrangement of chain gear as applied to three
propeller shafts, it will be evident that any number of propeller shafts may be so
arranged and driven, the propellers being either in line with each other or
arranged in different planes, one behind the other.
A similar arrangement of chain gear may also be employed with advantage for
driving the concentric shafts of a single pair of propellers.
In this case the one shaft is driven by a chain and chain wheels arranged in
the ordinary way for driving the shaft in the same direction as the driving shaft.
For driving the second shaft, the chain passes from the one side of the driving
chain wliecl to the opposite side of the chain wheel of the shaft, and thence over a
guide pulley down to the driving chain wheel again. Or in this case instead of
driving both shafts by chains and chain wheels, the shaft that is driven in the
contrary direction to the driving shaft may be driven by means of ordinary spur
gearing.
Although the above described mode of driving two or more propeller shafts
from one engine shaft by chain wheel gear is principally applicable to propellers
of the kind herein before referred to, yet it will be evident that it is also applicable
for driving two or more ordinary submerged propeller shafts by means of one
engine shaft, the propellers of those shafts that are driven in opposite direction
to the other being made with a corresponding opposite pitch.
Another improvements relates to a mode of securing the first above described
arms of the propeller blades to the boss of the propeller shafts, whereby they are
securely fixed when adjusted to the correct angular position, by means of a
keying device so arranged as to admit of such angular adjustment.
The arm of the propeller blade has its end formed with a screw thread screwed
into a socket on the boss. The threaded part of the arm has a longitudinal key-
way or flat cut into or on it and a corresponding key-way of some depth is cut
into the socket. A key, or series of keys is or are provided, the two faces of
which are slightly inclined to each other in the transverse direction.
The pro-
peller arm having been adjusted to its correct position, the said key is inserted and
behind it there is inserted in the key-way of the socket a wedge, fitting the more
or less inclined rear face of the key and securing it in position.
It will be seen that according as, by the angular adjustment of the propeller arm
the bottom face of its key-way has assumed a slight angle in the one direction
or the other relatively to the key-way of the socket, the key, in being inserted

page_text: with its transverse taper in the corresponding direction, can be made to fit the
angle of the key-way and thus secure the arm in the adjusted position.
The wedge is secured in position, by a screw-nut screwed on the arm beyond
the end of the socket, which nut also acts as a lock nut to the screw thread secur-
ing the arm in the socket.
Improvements in Apparatus for Propelling Boats and other Navigable
Vessels and Driving Gear therefor.
I, HENRY BARCROFT, of The Glen, Newry, in the County of Armagh, Ireland,
Director of the Dundalk and Newry Steam Packet Company, 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 principally to that description of apparatus for propelling
boats in which two sets of screw propeller blades are mounted on the ends of
radial arms carried by concentrically arranged shafts, situated above the water
line, and driven in opposite directions, the screw blades of the one set being
arranged at an opposite angle to those of the other set, so that each set counter-
acts the lateral thrust exercised by the other one arising from the fact that the
propellers are only partially immersed.
Apparatus of this kind were described in the specification to my Patents
Nos. 13,019 of 1889 and 20,638 of 1889.
My present invention has mainly for its object to enable such propeller apparatus
to be employed with advantage for navigating shallow water ways, where only a
comparatively small extent of immersion of the propeller blades can be obtained.
In order in such cases to enable a considerable propelling power to be exercised
by the propelling apparatus, I employ two or more pairs of such propellers,
arranged side by side at the stern of the boat, all driven by one and the same
driving shaft of a motor engine. For this purpose I drive the shafts of the pro-
pellers by chain and chain wheel gear in the following manner. Assuming that
three such pairs of propellers are employed one pair being in the line of the
keel while the others are on each side thereof.
The tubular shaft of the one propeller of each pair has a chain wheel, and
these three chain wheels are all driven by one and the same chain and chain
wheel, on the engine shaft. The inner shaft of each pair, that carries the second
propeller, has on its extension beyond the tubular shaft, another chain wheel,
and these three chain wheels are also all driven by a second chain and chain
wheel on the engine shaft, but in such manner that these propeller shafts revolve
in the contrary direction to the respective tubular propeller shafts first referred to.
The chain gear can be arranged in a variety of ways for effecting the above
described mode of driving.
Figs. 1, 2 and 3 on the accompanying drawings shew one such arrangement
for driving three sets of double propellers. Fig. 1 shews a diagrammatic plan
of the three sets of propeller shafts and their chain gear. Fig. 2 shews a diagram-
matic elevation of the inner propeller shafts and engine shaft with their chain
gear, and Fig. 3 shews the same view of the outer shafts and their connection
with the engine shaft. A A A are the three inner propeller shafts on which are

page_text: fixed the propellers B B B. C is the engine shaft on which is fixed the chain
wheel D while on the shafts A A A are fixed the chain wheels D¹ D¹ D' over which
is passed the pitch chain E, this being passed round the underside of wheel D.
Guide wheels Fare provided for affording the necessary grip of the chain wheels
upon the chain. On the outer tubular shafts A' A¹ A¹ carrying the propellers B¹
BB are fixed chain wheels G G G, and on the engine shaft C is fixed a second
chain wheel H. The pitch chain I is passed over the chain wheels G, as before,
but instead of being passed under the chain wheel H it is led by the guide
wheels F over the same. From this arrangement it will be seen, that the engine
shaft C being driven in the direction of the arrow, it will drive all the shafts A
and their propellers B in the same direction while the shafts A¹ and their pro-
pellers B will all be driven in the contrary direction.
The above described arrangement may be modified by dispensing with the upper
guide wheels F and passing the chain from the upper side of the two lateral
chain wheels to the under side of the middle one which would thus be driven
in the contrary, direction to the other two.
Figs. 4 and 5 shew a different arrangement of the chains E and I, for imparting
motion in contrary directions to the inner and outer propeller shafts A A¹ from
the engine shaft C; in this case also the middle propeller shaft will be driven
the contrary direction to the two outer shafts.
Although I have described the arrangement of chain gear as applied to three
propeller shafts, it will be evident that any number of propeller shafts may be
so arranged and driven, the propellers being either in line with each other or
arranged in different planes, one behind the other.
Thus Figs. 6 and 7 shew an arrangement similar to Figs. 1 and 2 for driving
two sets of double propeller shafts A A¹ instead of three. C is the engine shaft
and F are guide wheels.
Although I have shown the engine shaft arranged below the propeller shafts,
it will be obvious that the invention is equally applicable to cases where the
engine shaft is arranged above the propeller shafts.
The above described mode of driving two or more propeller shafts from one
engine shaft by chain wheel gear is principally applicable to propellers of the
kind herein before referred to; it will be evident however that it is also applicable
for driving two or more ordinary propeller shafts by means of one engine shaft,
the propellers of those shafts that are driven in opposite direction to the others,
being made with a corresponding opposite pitch.
Another improvement relates to a mode of securing the first above described
arms of the propeller blades to the boss of the propeller shafts, whereby they
are securely fixed when adjusted to the correct angular position by means of a
keying device so arranged as to admit of such angular adjustment.
This arrangement is shewn in vertical section at Fig. 8 and in sectional plan
at Figs. 9 and 10.
The arm K of the propeller blade has its end formed with a screw thread screwed
into a socket L on the boss. The threaded part of the arm has a longitudinal key-
way or flat K¹ cut into or on it and a corresponding key-way of some depth is
cut into the socket L. A key M or series of keys is or are provided, the two
faces of which are slightly inclined to each other in the transverse direction.
The propeller arm having been adjusted to its correct position, the said key is
inserted and behind it there is inserted in the key-way of the socket a wedge N
fitting the rear face of the key M and securing it in position.
It will be seen that according as, by the angular adjustment of the propeller
arm the bottom face of its key-way has assumed a slight angle in the one direction
or the other relatively to the key-way of the socket as shewn in the two positions
Figs. 9 and 10 the key M in being inserted with its transverse taper in the corre-
sponding direction, can be made to fit the angle of the key-way and thus secure
the arm in the adjusted position.
The wedge is secured in position, by a screw nut 0 screwed on the arm beyond

page_text: the end of the socket, which nut also acts as a lock nut to the screw thread secur-
ing the arm in the socket.
Having now particularly described and ascertained the nature of this invention
and in what manner the same is to be performed, I declare that what I claim is :-
1. Driving gear for imparting motion from one and the same driving shaft to
two or more sets of double propeller shafts consisting of two chain wheels fixed
on the driving shaft, which drive chain wheels on inner and outer propeller shafts
in contrary direction by means of pitch chains one of which is led round the under-
side of the one chain wheel on the driving shaft, while the other is led round
the upperside of the other chain wheel, substantially as described.
2. Driving gear for imparting motion from one and the same driving shaft to
two or more sets of double propeller shafts, arranged and operating substantially
as and for the purpose herein described with reference to the drawings.
3. Securing propeller arms in their bosses by means of keys such as M and
wedges such as N so arranged that the keys can be made to fit the key-ways of
the propeller arm notwithstanding that the angular position of the propeller arm
in the boss may vary, substantially as herein described.
Dated this 29th day of August 1899.
ABEL & IMRAY,
Agents for the Applicant.