Improvements in Sorew Propellers.
Year: 1895

page_text: Date of Application, 5th Mar., 1395-Accepted, 10th Aug., 1895
Improvements in Sorew Propellers.
I, CHARLES ROMEO PURNELL, a citizen of the United States, residing at
No. 2555 Sepviva Street, in the City of Philadelphia, in the County of Phils-
delphin and State of Pennsylvania, Mechanic, 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 has relation to screw propeller wheels or blades for steamships
and other crafts; and in such connection it relates particularly to the construction
and arrangement of the blades and their location on a shaft to constitute the
propeller wheel or screw for said purposes.
The principal objects of my invention are first, to provide a screw propeller in
which the greatest possible efficiency or impelling power is derived therefrom, with
friction and slip lessened; second, to provide a propeller wheel or screw for ships
or other crafts, in which the blades are disposed one after the other and so as to
describe in position on a hub engaging a feathered shaft, a true screw formation
and contacting with each other at their junction at the hub in order to induce
impelling power or force in a body or volume of water and with slip and resisting
friation lessened in the working of the same; and third, to provide a screw
propeller having reversely curved or pitched wing blades arranged in advance of
one another on a bub or hubs mounted on a feathered shaft and each without being
influenced by the other, in working performing its functions to derive a maximum
impelling power or force due to the particular construction and arrangement and
imanner in which the blades thereof enter and leave the body or volume of water
and displace the same in their travel therethrough.
My invention stated in general terms, consists of a screw-propeller constructed
and arranged in substantially the manner hereinafter described and claimed.
The nature, objects and scope of my invention will be more fully understood from
the following description taken in connection with the accompanying drawings
forming part hereof; and in which
Figure 1, is a perspective view of a screw-propeller, showing the formation,
particular arrangement or position of the blades in connectiou with a solid hub
adapted to be mounted on a propeller shaft and embodying characteristic features
of my present invention.
Fig. 2, is an elevational view of the hub and a sectional view through the curved
and reversoly pitched wing-shaped blades of the screw propeller, arranged one in
advance of the other and describing in outline a true screw formation and so as to
act independently of one another in action.
Fig. 3, is an end elevational view of a slightly modified form of a screw-propeller
of my invention with the respective wing-shaped blades arranged on separate hubs
engaging a feathered shaft and provided with keys or pins engaging openings
provided in their companion hub or hubs to receive the same; and
Fig. 4, is a side elevation showing the hubs detachably supported on a feathered
shaft, to illustrate the manner of detaching one from the other thereon.
Referring to the drawings A, is the propeller shaft as shown in Figs. 3 and 4,
provided with a longitudinal feather a, to which is secured against turning thereon
a complemental hub B, provided with an internal longitudinal groove or channel b,
as illustrated in Figs. 1 and 2, of the drawings. C, are the blades set into or

page_text: formed integral with a solid hub B, as illustrated in Figs. 1 and 2. These
blades C, in the form of wings are slightly curved or pitched from the hub to the
end, and increase in width from the hub to said end o, thereof. In shape or form
each of the blades has a convex outline c', from the hub to the end c, such being
the outer contour thereof, while the inner line &, of each blade is concavo-convex
to the end c, thereof. Each blade occupies a position in connection with the
hub B, at a diagonal plane c, thereto and contacting with each other at their
junction at the said hub in such manner as that each blade in its position or
connection with said hub B, describes a true screw in formation and in order
that the respective blades may each be permitted to perform its function inde-
pendently of the others in creating an impelling force or power against a body
or volume of water, with back lash or slip and resisting friction upon the blades
lessened in the body of water.
Hitherto as screw propellers have been arranged, they tended to retard the
individual blades thereof as each was brought into action through the rotation of
the same in a body of water, but a propeller constructed according to my
invention acts in a contrary manner, whereby a maximum energy, as a propelling
force against a body or volume of water to be displaced is ensured; and hence
a far greater rate of speed than was hitherto possible, is obtained. In a word,
appreciably increasing the speel of the ship or other craft, which is entirely due
to the particular construction and arrangement of the blades on the hub or hubs
thereof Practice has demonstrated that five or more knots per hour greater
speed can be readily obtained with my propeller as compared with the best wheel
now in use on ships or similar crafts, as a means of moving the same through a
volume or body of water.
In Figs. 3 and 4, the construction and arrangement of the series of blades C,
of the propeller are the same as hereinbefore described, with this exception, that
instead of forming them with a solid hub B, they are secured to or formed
integral with separable hubs B', B' and B', mounted on a shaft A, provided with
a feather a. The hubs B' and B', are each provided with a series of end pius or
keys, adapted to enter complemental openings 6 and 6*, provided in the end
walls of the hub B', as clearly illustrated in Fig. 4, whereby the respective hubs
with their curved or pitched wing blades C, arranged one in advance of the other,
nay be quickly locked to required position on the feathered shaft A, against
longitudinal movement and also against individual rotary movement and so as to
permit each to perform its function, while independent of one another with
geometrical precision as to their entry of the body or volume of water one after
the other, thus ensuring a maximum energy or impelling power to be derived and
far greater speed than was hitherto possible. One end of the shaft A, may be
threaded at a', for the reception of a nut a', as shown in Fig. 4, or the shaft may
have formed integral therewith a cap or nut in order that the hub member 13, may
bear against the same and thoroby to prevent displacement in action.
Having now particularly described and ascertained the nature of any said inven-
tion, and in what manner the same is to be performed, I declare that what 1
claim is :-
1. A screw propeller provided with a feathered shaft, three blades conuected
with an internally grooved hub mounted on said shaft, each of said blades having
convex and concavo-convex outlines and said blades also being arranged so that
they follow each other after the manner of an interrupted screw and contact with
each other at their junction at the hub, the construction being such as to induce a
propelling forco against a body of water and with slip and resisting friction on the
bludes lessened, substantially as described.
2. A screw propeller provided with a feathered shaft, internally grooved
separable hubs locking by means of pins and openings mounted on said shaft, and
each hub provided with a blade having convex and concavo-convex outlines and

page_text: the said blades in normal position diagonally positioned to their hubs, one aft the
other so as to act independently of one another in inducing a propelling force.
against a body of water, substantially as described.
Dated at Philadelphia, Pa., this 6th day of February A.D. 1895.
CHARLES ROMEO PURNELL,
Per J. G. Lorrain, M. Inst. E.E., M. Inst. M.E.,
Chartered Patent Agent.