Improvements in Screw Propellers. to a by screws, or screw bolt
Year: 1893

page_text: Date of Application, 9th Oct., 1893-Accepted, 11th Nov., 1893
Improvements in Screw Propellers.
A communication by MARTIN DAVIES, of 88, Sussex Street, Jersey City, in the
County of Hudson and State of New Jersey, United States of America,
Machinist.
I, WILLIAM PHILLIPS THOMPSON F.C.S. M.I.M.E. of the Agency for
Foreign Patent Solicitors, 6, Lord Street, Liverpool, and 6, Bank Street,
Manchester, both in the County of Lancaster and 323, High Holborn in the
County of Middlesex, Civil Engineer, do hereby declare the nature of this inven-
tion and in what manner the same is to be performed, to be particularly described
and ascertained in and by the following statement :-
screw
This invention is an improvement in the class of "
blades or flukes are secured to a hub by screws, or screw bolts.
"
propellers, whose
It has been the usual practice to insert screws through the base of the blades or
Hlukes, from the outer side thereof, so that the inner ends of the screws enter
threaded sockets formed in the hub. This mode of fastening has been found to be
insecure, and the improved substitute hereinafter described has been devised, the
leading feature of which consists in inserting screw bolts through the hub from
the inner side, and then through the bases of the propeller blades, nuts being then
applied to their projecting outer ends. The heads of the bolts are countersunk in
the interior of the radially bored hub, and are also preferably arranged to form
part of the smooth hub bearing for the propeller shaft.
Reference is to be had to the accompanying drawings forming a part of this
Specification, in which similar figures and letters of reference indicate corresponding
parts in all the views.
Figure 1 is a side elevation of the improved propeller.
Figure 2 is a section taken through the hub and opposing blades, the section
being taken on the line 2-2 of Figure 1; and
Figure 3 is a horizontal section taken essentially on the line 3-3 of
Figure 2.
In carrying out the invention, the hub A may be made of any desired material,
or may be given any approved shape. In the drawings, the hub is illustrated as
being provided with four faces 10, each of which is adapted to have attached to it
a propeller blade or fluke B. Each blade receiving face of the hub is preferably
provided with a recess 11, ordinarily of circular shape, and in one wall of the said
recess a feather 12, is formed. The flukes or blades B are provided with the usual
base 13, and above the base the blade or fluke has preferably produced in it a
pocket 14, which pocket may be of any desired length and extends longitudinally
The base of each blade or
of the blade to the base, as shown in Figures 1 and 2.
fluke B is provided with a boss 15, adapted to enter the recess 11 in the face of the
hub receiving the blade. Therefore, the hub recesses 11 and the bosses 15 of
the flukes or blades are of the same cross sectional shape, and each boss 15 is
provided with a recess adapted to receive the feather 12 of the hub recess in which
the boss is introduced. It will be understood that the feather may be formed
upon the boss of a fluke and the receiving recess be produced in the wall of the
boss-receiving recess of the hub, if in practice it is found desirable.
Each propeller blade or fluke is secured to the hub by means of a screw bolt 16,
by inserting its shank through a radial bore or perforation in the hub, from the
inner side of the latter, and then through the base 13 of the blade, a nut a being
then applied to the threaded end of the bolt which projects through said base as
shown. A jam nut a' may be employed if desired. The head of the bolt fits in a

page_text: countersink formed in the interior of the hub, as shown in Figure 2.
connection between the bolt and hub is thus made the most secure possible.
The
The nut a being turned down with great force, the blade is clamped and fastened
in place with a corresponding degree of security, and yet, if occasion requires, it
may obviously be detached with convenience and despatch.
Practical test of the invention in actual use has demonstrated superiority in
respect to these qualities.
Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, as communicated to me by
any foreign correspondent, I declare that what I claim is :-
1. The combination with the hub having radial bores which are countersunk on
the inner side, and propeller blades having a perforated base, of screw bolts whose
heads are fitted in the countersinks, their shanks projecting outward through the
hub and bases of the blades as shown and described."
2. The combination with the hub having radial bores which are countersunk on
the inner side and recesses on the outer side which are provided with feathers, and
the blades having bosses 15, and recesses to receive said feathers, of the screw
bolts whose heads are fitted in the countersinks and their shauks extending
outward through the hub bores and bases of the blades, and nuts applied to said
shanks, as shown and specified.
Dated this 7th day of October 1893.
WM. P. THOMPSON & Co.,
Agents for the Applicant.