Improvements in Marine Screw Propellers.
Year: 1896

page_text: Date of Application, 23rd Dec., 1896-Accepted, 17th Apr., 1897
COMPLETE SPECIFICATION.
Improvements in Marine Screw Propellers.
We, WILLIAM STELLNER of 277 Elizabeth Street, Melbourne in the Colony of
Victoria, Engineer and JAMES ALFRED COOPER of 287-289 Elizabeth Street,
Melbourne, in the Colony aforesaid. Hardware Merchant, dp 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 :-
The object of our invention is to provide a propeller the blades of which are not
only easily detachable from and adjustable on the arms which carry them but by
means of which a greater speed is obtained. In the screw propellers hitherto in use
it has generally been necessary when the pitch of the blades required altering or a
broken blade replacing to seud down a diver or to dock the vessel. But with our
invention the delay and expense attendant on this operation is not incurred since if
the after part of the ship be lightened it will rise sufficiently to expose the blades
above the water. From which one at a time they can be approached by punts or
rafts for either replacement or adjustment.
Our invention which is applicable to one two three or four bladed screw propellers
consists of blades which in contour resemble the segments of a circle and which are
detachable from arms protruding from the propeller boss. In order to stiffen the
said blades and also to ward off any ropes, chains or other floating or falling
obstructions which might cross the propeller's pathway there are placed between
the leading ends of each blade connecting staуs. An unbroken circle is thereby
formed on the leading side of the propeller the blades of which are adjustable in
three ways. Radially from the boss, longitudinally on the arms and also as regards
their pitch. The radial and longitudinal adjustment is effected by cross shaped
holes in the blades whilst the pitch is varied by a pitch adjusting wedge (also
having cross shaped holes) situated between the blades and the arms. The bolts or
rivets passing through these holes are locked in any required position by a chock
or chocks cut to fit into the holes.
But in order that our invention may be better understood we will now refer to
the accompanying sheet of drawings which are to be taken as part of this
specification and read herewith.
Figure 1 represents an elevation of a four bladed screw looked at from the aft or
driving side.
Figure 2 represents a side elevation of the same shewing the connecting stays
which as will be seen are attached to the back of the leading ends of the blades.
Figure 3 represents an elevation of the screw looked at from the forward or
leading side.
Figure 4 represents on an enlarged scale a view of one of the blades looked at
from its driving side.
Figure 5 shews a sectional plan of a blade between which and the arm is the pitch
adjusting wedge.
Figure 6 represents a front view of the wedge.
Figure 7 represents a perspective view of the chocks which are placed in the
elongated holes shewn in Figure 5. Similar letters of reference indicate similar or
corresponding parts where they occur in the several views. On reference to the
drawings it will be seen that A is the boss to which are integrally attached the
arms B. The fore and aft edges of these arms as shewn in Figure 2 are not square
P

page_text: with the axis of the boss but trail aft at the outside end. The sides of the arms
may be at any angle with the aforesaid axis which angle is governed by the pitch.
At the end of the arms are connected the blades C each one of which in contour is
a perfect segment of a circle. These are preferably secured by bolts which pass
through the recessed cross shaped holes D.
Attached to the leading end of the blades by bolts, rivets or other means are the
rectangular sectioned connecting stays H. These extend from blade to blade and
at both ends in order not to reduce the area of the driving side are secured to the
trailing face or back of the said blades.
The longitudinal and radial adjustment of the blades is effected by the cross
shaped holes D. These permit them to be moved either fore or aft and either from
or to the boss. When the desired position is ascertained the space around the bolt
or rivet E is filled by the chocks such as F which effectually lock both bolt and
blade. The heads of the said bolts or rivets by the recessed holes shewn are suuk
beneath both the blade and the arm.
The adjustment of the pitch is effected by the insertion or withdrawal of the
wedge G which is also provided with cross shaped holes to permit of such
adjustment. When the wedge is driven inwardly the pitch of the blade is increased
whereas when it is withdrawn it is diminished.
We do not bind ourselves to a wedge of the particular inclination shewn nor to
the shape of the holes within it since these particulars will all vary with the
different conditions under which each propeller is constructed.
The blades, which can be attached to existing propellers may also be either
curved or flat the amount of the curvature depending upon the diameter and. the
pitch.
Having now particularly described and ascertained the nature of our said
invention and in what manner the same is to be performed, we declare that what
we claim is.
1st. In marine screw propellers a pitch adjusting wedge as G interposed between
the blade and the arm as and for the purposes herein before described and as
illustrated in the drawings.
2nd. In marine screw propellers a blade as C forming a complete segment of a
circle and detachable from an arm as B integral with the boss as and for the
purposes herein before described and as illustrated in the drawings.
3rd. In marine screw propellers a detachable blade as C, having recessed cross
shaped holes as D the bolts or rivets in which are locked by chocks as F all as and
for the purposes hereinbefore described and as illustrated in the drawings.
4th. In marine screw propellers and in combination a blade as C forming a
complete segment of a circle having recessed cross sectioned holes as D, a pitch
adjusting wedge as G and an arm as B all as and for the purposes hereinbefore
described and as illustrated in the drawings.
5th. In marine screw propellers and in combination a boss as A having integral
arms as B to which are detachably connected blades as A having recessed cross
sectioned holes as D with chocks as F; and between said blades and arms a pitch
adjusting wedge as G the blades being stiffened by connecting stays as H all as
and for the purposes herein before described and as illustrated in the drawings.
Dated this 23rd day of December 1896.
c
WHEATLEY & MACKENZIE,
40 Chancery Lane, London, W.C., Agents.