Improved Means of Seeuring in a Readily Detachable Manner Bosses or Sleeves on Shafts, such as the Bosses of Screw Propellers, Couplings for Shafting, Railway Wheels, Flywheels, and the like.
Year: 1898

page_text: Date of Application, 24th Jan., 1898
Complete Specification Left, 15th Sept., 1898-Accepted, 29th Oct., 1898
PROVISIONAL SPECIFICATION.
Improved Means of Seeuring in a Readily Detachable Manner Bosses
or Sleeves on Shafts, such as the Bosses of Screw Propellers,
Couplings for Shafting, Railway Wheels, Flywheels, and the like.
I, JOHN BALLOT, of No. 113, Cannon Street, in the City of London, Gentle-
man, do hereby declare the nature of this invention to be as follows:-
My invention relates to improved means for securing bosses or sleeves on
shafts in such manner that while the parts are securely fixed to each other for
driving in either direction, they can, when required, be easily and rapidly
separated from each other. For this purpose I form on the periphery of the
shaft, at the part where it is to be connected to the boss or sleeve, a series of
cam-shaped projections extending in a helical longitudinal direction, the con-
figuration of such projections being preferably similar to that of ratchet teeth,
that is to say, with a more or less radially placed face and a curved surface of
gradually decreasing distance from the centre of the shaft.
The boss or sleeve has similarly shaped helical recesses, so that when fitting
the two parts together, the shaft will enter the boss with a screwing motion the
projections of the former fitting accurately the recesses of the latter, like the male
and female threads of a screw and nut of very quick pitch.
Thus it will be seen that when a shaft and its boss or coupling sleeve have
been fitted together in this way, they can be readily uncoupled by simply turning
them relatively to each other in the direction for unscrewing.
In order however to enable shafts to be driven in either direction, I prevent
the unscrewing motion by the following means.
In the curved periphery of the said projections on the shaft, as also in the
curved surfaces of the recesses of the boss, I cut longitudinal grooves in such
manner that when the two parts are fitted together as described, the grooves of
the one part will be exactly opposite those of the other part, and into these com-
bined grooves I then drive accurately fitting keys, so that by this means the
two parts are so locked together that it will not be possible to turn them rela-
tively to each other in that direction in which they unscrew.
I prefer to make the said grooves and keys with a slight amount of taper,
making the grooves slightly wider than the keys, so that when these are driven
in, they will exercise a slight wedging action in a peripheral direction, tending
to tighten the contact of the surfaces of the projections of the shaft with the
recesses of the boss or sleeve. For locking the keys in their driven position,
and enabling them to be readily removed when the shaft and boss or sleeve are
o be disconnected, I employ the following arrangement. The keys are of such
length that when driven, they project to a certain extent beyond the face of
he boss or sleeve, and are there formed with a notch, head or eye by means of
which they can be withdrawn. Over these projecting ends I fit a washer of a
hickness about equal to such projections, the washer having notches into which
he said projecting ends fit, and I then screw upon a threaded projecting end

page_text: two parts are so locked together that it will not be possible to turn them rela-
tively to each other in that direction in which they unscrew.
I prefer to make the said grooves and keys with a slight amount of taper,
making the one groove slightly wider than the key, as will be presently explained,
so that when these are driven in, they will exercise a wedging action in a
peripheral direction, tending to tighten the contact of the surfaces of the curved
projections of the shaft with the recesses of the boss or sleeve.
I will proceed to describe my said invention with reference to the accom-
panying drawings, which shew by way of example various applications of the
invention to the fixing of screw propellers on their shafts, for coupling lengths
of shafting together, and to other purposes.
Referring to Figures 1, 2 and 3, which shew respectively a sectional side view,
an end view and a longitudinal section on line a Figure 2, of an application
of the invention to the fixing of a pulley on a shaft, the shaft A has formed upon
it at the place where the pulley B is to be fixed, three curved or cam shaped
projections a, a, a, each of which extends in a helical longitudinal direction.
partly round the shaft. The one face of each of these projections is formed
radial to the centre of the shaft, while the other face is formed with a curvature
which is preferably a circular arc struck from a centre a¹ slightly excentric to
the centre of the shaft. The boss of the pulley B is, on the other hand, formed
with three correspondingly shaped grooves or recesses b extending in the same
helical direction.
The projections a and recesses 6 consequently constitute an infinite series of a
peculiar form of male and female screw threads of very steep or quick pitch,
so that if the shaft be pushed longitudinally into the boss, it will pass in with
a screwing motion. It will be found however that the longitudinal motion can
at any point be arrested, if on holding the boss B stationary there be applied
more or less suddenly to the shaft a force in the circumferential direction indi-
cated by the arrow Figure 2; by the application of that force, the curved sur-
faces of the projections a will be firmly jammed or wedged against the corre-
sponding curved surfaces of the recesses b, and the frictional resistance to longitudinal
motion produced by such jamming action will, with a sufficiently steep pitch
of the helice or screw, be found to be greater than the force tending to produce
a longitudinal motion of the boss or shaft by the screw action.
Thus, assuming the shaft to have been screwed into the boss of the pulley until
the helical projections of the former are situated entirely within the recesses
of the latter, and the one part or the other then have a force applied to it in
the before mentioned circumferential direction so as to produce the before men-
tioned jamming action of the curved surfaces, the pulley will be firmly fixed on
the shaft for transmitting power when rotated by the shaft in that direction.
If on the other hand a force be applied to the one or the other part in the contrary
circumferential direction, the jam of the curved surfaces will be released, and
as the radial surfaces of projections will then bear against the radial surfaces of
the recesses, a screwing action will be produced causing the pulley to screw
longitudinally off the shaft. In order therefore to enable my invention to be
employed for the transmission of rotary motion in either direction, I form longi-
tudinal keyways respectively in the shaft A and in the boss B in such positions
that when the curved surfaces of a and b fit tightly against each other as
described the grooves of a will be exactly opposite the grooves of b, so that
accurately fitting keys C can be inserted into them. With this arrangement
it will be seen that if a force be applied to shaft A in the rotary direction contrary
to that of the arrow Figure 2, any such screwing motion as above referred to
will be stopped by the keys C, which will consequently in this case take the
strain in the rotary direction. But these keys will not be subject to the total
strain thus exerted, for the following reason.
Referring to Figure 3, it will be seen that owing to the helical direction of
the projections a in combination with the curvature of their surface, a longi-

page_text: described, but would require to be first fitted on the one shaft, and the end of the
other shaft would then have to be screwed into it.
My invention is applicable with particular advantage to the fixing of screw
propellers on their shafts.
Figures 7, 8 and 9 shew two such applications. In the arrangement shewn
in longitudinal section at Figure 7 and end view at Figure 8, the helical pro-
jections a and recesses are not made to extend along the whole length of the
joint, the middle portion of the boss being hollowed out, and the middle part
of the projections a on the shaft being omitted for facilitating the fitting. The
projections and recesses may however be carried right through; the projections a
and recesses b at the inner and outer ends are however made to constitute parts
of the same helices.
In this application, the screw propeller being made with a right hand pitch,
the helices of the projections and recesses are made to run to the left hand,
so that the torsional strain when going ahead tends to screw the boss tightly
against the thrust collar D of the shaft in addition to producing the before
described jamming action between the curved surfaces of the projections a and
recesses b, thus producing an exceedingly firm grip of the propeller boss upon
the shaft. It will also be seen that as the circular arcs constituting the
generatrices of the helical curved surfaces of a are all struck from points lying
in a small circle surrounding the centre of the shaft as shewn at Figure 2, the
tortional strain is practically taken by the whole of the metal of the shaft, and
there is no shearing action such as would occur with an ordinary screw thread.
When driving astern on the other hand the propeller thrust tends to draw the
propeller off the shaft; this however is prevented on the one hand by the keys C
which prevent the unscrewing motion, and on the other hand by the tapering
enlargement in the outward direction of the shaft, any tendency to outward
motion being effectually checked by the longitudinal wedging of the boss of the
propeller upon the shaft as explained with reference to Figure 3, and herein-
after again referred to.
Any loosening of the keys C is in this case prevented by fitting upon the outer
end of the propeller boss a washer E having notches into which project the outer
ends of the keys C, and against the washer is screwed a nut F screwed upon
the projecting threaded end of the shaft A and locked by any suitable known
means. For unshipping the propeller, the nut is unscrewed, the washer is
removed, and the keys are withdrawn, their projecting ends being notched for
this purpose, as shewn, after which, on turning the propeller to the left hand on
the shaft, it will readily screw off the latter. In order to allow of this, the stern
post of the ship can be made with a corresponding recess at X Figure 10.
In order to facilitate such removal of the propeller the parts can be kept well
oiled, by providing an oil chamber formed by the cap G enclosing the front end
of the boss and shaft, packing rings H being provided at the thrust collar D and
between the cap G and the boss. The cap is provided with a screw valve at G¹
on removing which it can be charged with lubricant.
Figures 11 and 12 shew respectively a longitudinal section, and a part sectional
end view of the nave of a road wheel constructed according to my invention,
with a view to providing the wheel with ball bearings in such a manner that
the wheel can be removed without disturbing the adjustment of the ball bearings.
For this purpose the usual taper axle has fitted upon it with ball bearings a
box I which is secured by the nut J on the threaded end of the axle. The outer
surface of this box, which constitutes a tubular shaft, is provided with the same
helical cam-shaped projections as the previously described constructions, and
the metal bush K, which fixed in the wooden nave L, is provided with the corre-
sponding helical grooves so that on screwing this upon the box or tubular shaft I
and driving the keys M the nave will be securely fixed upon the box by the
jamming action of the helical projections and recesses as before described, and
also by the outwardly increasing taper of these parts resisting any longitudinal

page_text: direction. In this application, it is preferred to provide the forward shaft or
rod with a thrust collar at the lower end of the coupling, as in the case of the
propeller shaft described, and the keys are secured at the upper end by a washer
and screw nut screwing on a thread of the shaft, also as there described.
I am well aware that curved or cam-shaped projections on shafts have already
been employed in combination with corresponding recesses in bosses or sleeves
for the purpose of securing the two parts together by a jamming action, such
projections having been made to extend parallel with the axis of the shaft. But
such an arrangement cannot accomplish the functions that are performed by
my invention as above described, namely the essential feature of a tapering form
of shaft enabling a jamming effect to be obtained in a longitudinal direction,
as also the facility of the fixing on and removing of the boss or sleeve by a
screwing action.
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:
1. Effecting the connection of a shaft with a boss or sleeve by forming on the
shaft one or more helical projections of quick or steep pitch, such projections
having a curved or cam shaped surface and a straight radial surface, while the
boss or sleeve has one or more corresponding recesses with curved and radial
surfaces, so that on the application of a torsional strain in one direction the
curved surfaces of the projections will jam upon the curved surfaces of the boss
or sleeve to a sufficient extent to prevent a longitudinal screwing motion, the
parts being secured in that position by one or more keys driven in grooves formed
in both of them, substantially as described.
2. In the construction of coupling referred to in the first claim, forming
the key or keys with a taper so arranged that on driving them in, they produce
a circumferential strain, whereby the jamming or wedging action of the said
curved surfaces upon each other is increased, substantially as described.
3. A coupling for a shaft and boss or sleeve wherein helical projections formed
on the shaft are caused by a circumferential strain in one direction, to jam with
convex curved surfaces against corresponding concave surfaces of helical recesses
in the boss or sleeve, the two parts being prevented from turning on each other
in the contrary direction by keys driven in grooves therein, while the longi-
tudinal tapering surfaces formed by the helical curved projections and recesses
also tend to produce a wedging action in a longitudinal direction, substantially
as described.
4. In a
coupling for a shaft and boss or sleeve, such as is referred to in the
preceding claims, securing the keys in position by means of a washer having
netches fitting over the projecting ends of the keys, and secured by a screw
nut screwed on to a threaded part of the shaft or by any other suitable device,
substantially as described.
5. Coupling devices for uniting a boss or sleeve on a shaft combined and
operating as herein described with reference to the drawings.
Dated this 15th day of September 1898.
ABEL & IMRAY,
Agents for the Applicant.