Improvements in and Connected with Screw Propeller Bosses and their Shafts.
Year: 1887

page_text: Improvements in and Connected with Screw Propeller Bosses and
their Shafts.
I, THOMAS DOBIE, of Elie Villa, Tighnabruaich, Argyleshire, Engineer, do
hereby declare the nature of my invention and in what manner the same is to be
performed, to be particularly described and ascertained in and by the following
statement in writing, reference being had to the accompanying sheet of Drawings,
and to the letters and figures marked thereon, that is to say :-
Heretofore the parts of scrow propeller shafts and their bosses exposed to the action
of the water have been subject to rapid corrosion and wear, caused by the salt water
getting into the bearing parts of the eye of the boss and the shaft and its keys and
liner, causing the propeller boss to get loose on its shaft, and consequent greatly
trouble in keeping it tight.
This invention has for its object the prevention of the foregoing evils, and
comprises certain improved fittings to be applied to the forward end of the boss to
prevent the water getting in to the eye of the boss or behind the liner.
The nature and novelty of my invention consist in forming or fitting a water tight
stuffing box and gland on the forward end of the propeller boss and over the brass
liner. The stuffing box may be jointed to the boss, or cast or formed solid with the
boss bored out; and fitted with a screw tightening up gland, and india rubber, hemp
or other packing, and having the necessary screw studs or bolts and holes for
securing it to the boss. Which improved devices or fittings will prevent the present
corrosion and wear to which screw propeller shafts and bosses are liable when
exposed to the action of sea water.
And in order that my said invention, and the manner of performing or carrying
the same into effect or practice may be properly understood, I have hereunto appended.
an explanatory sheet of Drawings, in which the same reference letters are used to
indicate corresponding parts in all the Figures where shown. Figure 1 shows a
sectional side elevation of a propeller boss A as fitted in position on its shaft S with

page_text: .
parts of its blades B, and tightening up nut B' in the stern frame T of a ship, with
à part of the boss in section, showing the application of one arrangement of my
improvements of applying a portable stuffing box C screwed to the forward end of
the boss A, as suitable for being applied to older or present propellers. Figure 2 is a
transverse section corresponding to, and taken on the line 1--1 of Figure 1. And
Figure 3 shows a side elevation with the lower half in section of another propeller
boss A¹ as fitted on its shaft S having my new or improved stuffing box C₁ as formed
or turned solid on the forward end of the boss A¹, and which would be the preferable
manner of applying my improvements to new propellers.
Referring to Figures 1 and 2 of these Drawings which represents the ordinary
boss A of a propeller, S is the shaft, and shows the after end of the stern bearing
brass liner which usually passes some little distance into the eye of the boss A, but by
my improvements I turn a groove a round it at its inner end in the boss A, and fit
and bolt a stuffing box C water-tight on the forward end of the boss A, round the
liners, projecting out over the liner towards the stern bearing, and bored sufficiently.
larger than the liner to allow room for packing, and I fit on its outer end a brass
tightening up gland c secured to the stuffing box C preferably by sunk headed screw
pins c¹, the gland fitting the liner within the recess and the stuffing box, all so that
when screwed up it will compress the packing within the stuffing box C and the
groove in the eye of the boss at a, and thus prevent the water from getting into the
S, and
eye of the boss at a¹, and its bearings on the shaft or the key a² within the liner
prevent them from being eaten away or getting oxidised or corroded from the effects
of salt water and the galvanic action of the liners and iron.
Referring to Figure 3, this shows the stuffing box. C as formed, turned, and bored
solid on the forward end of the boss A¹, and the tightening up gland and the
screws c¹ fitted to the stuffing box C otherwise substantially as described and shown
in Figures 1 and 2. The stern screw nut B' would always be fitted so tight as to
prevent water from getting in between it and the after end of the propeller boss A
or A¹.
Having now particularly described and ascertained the nature of my said invention,
and in what manner the same is to be performed, I declare that what I claim is :-
The fitting of a water-tight stuffing box and gland, or equivalent device, on the
forward end of propeller bosses, substantially as and for the purposes and advantages
herein, described in reference to and shown in the accompanying Drawings.
Did this 21st day of March 1887