A New or Improved Manufacture of Thrust Shafts.
Year: 1892

page_text: Date of Application, 29th July, 1892-Accepted, 3rd Sept., 1892
QUALI LID DINOLE ICATION.
A New or Improved Manufacture of Thrust Shafts.
I, THOMAS PUTNAM, Director of the Darlington Forge Co. Limited, Darlington,
in the County of Durham, do hereby declare the nature of this invention
and in what mauner the same is to be performed, to be particularly described
and ascertained in and by the following statement:-
This invention relates to a new or improved manufacture of thrust shafts, such
as are used in the line of marine engine screw shafts to receive and withstand
the end pressure or thrust of the screw propellor, and the object in view is to
obtain a stronger and more efficient thrust shaft than those now in use.
:
Hitherto thrust shafts have usually been made of iron, and forged solid or
with an axial hole through them; and also of cast steel but cast solidly and
sometimes shafts have been forged or cast solidly and an axial hole bored out
subsequently. In my improved manufacture of thrust shafts, I make a mould of
suitable size and form, and insert therein an axial core, and fill the mould with
molten steel in any known manner.
This improved thrust shaft is therefore a cast steel hollow or tubular shaft,
made without subsequent boring, so far as the internal space is concerned. It
has the advantage of being stronger than a corresponding solid shaft, the torsional
moment of the cast hollow shaft exceeding that of the solid shaft by about
two per cent. The cast hollow shaft has the further advantage of having the metal
evenly and equibly distributed so that in cooling no undue strains are set up by
the unequal contraction of diverse masses of metal; the inner and the outer surfaces
consolidate the metal between and tend to obviate unsoundness; while the surfaces
of the metal at the thrust collars and bearings being more compact and dense, al
clean working surface is produced which reduces friction.
In further description, reference is made to the accompanying drawings in
which
Fig. 1 is a longitudinal elevation (with a portion in section) of a thrust shaft cast
with the thrust collars roughly shaped in two forms; and
Fig. 2 is an end elevation of the same.
Fig. 3 is a longitudinal elevation (with a portion in section) of a thrust shaft,
cast of the full diameter at the thrust bearing portion of the shaft, in which
the collars and grooves-forming the journal-are turned out of the solid material,
and
Fig. 4 is an end elevation of the same.
In the upper half of Fig. 1, a, a, represents the exterior line of the shaft, after
it has been cast and taken from the mould, and immediately beneath it is a dotted
linc b, b, which indicates the finished size after it has been turned in the lathe to
the required dimensions and form. In that portion, however, shown in section, the
outer or dotted line a' represents the exterior line of the shaft before turning, while
the full line indicates the finished size and form after turning. In the lower
half of Fig. 1 the outer or full line e represents the exterior line of the shaft before
turning, while the dotted line d represents the finished size and form after turning.
It will be seen that in the upper half of Fig. 1 the thrust collars are cast in a
square form, while in the lower half they are more or less rounded or convoluted
at the outer and inner angles of the collars.
In Fig. 3 the full line a denotes the outer form throughout as cast, while the
dotted line denotes the finished size and form throughout. In this figure it will
be seen that the thrust collars and journal between are turned out of the solid or
enlarged portion of the shaft, as is indicated by the dotted lines. The axial cavity
го
.

page_text: or bore, as cast upon a core in the well known manner, is indicated by e in all the
figures.
It is to be understood that 1 do not claim any particular method of casting or
forming the said cast steel thrust shaft except as herein described and illustrated
by the drawings, and as restricted by the claiming clause hereto, but
Having now particularly described and ascertained the nature of the said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is
As a new article of manufacture, a steel thrust shaft, cast hollow upon a core in
a mould, substantially as and for the purpose herein described, and shown by the
accompanying drawings.
י
C T 1
1003
FAIRFAX & WETTER,
433, Strand, London, Agents for the Applicant..