Improvements in and relating to Clutches for Screw-propeller Shafts.
Year: 1893

page_text: Date of Application, 16th Feb., 1893
Complete Specification Left, 16th Nov., 1893-Accepted, 23rd Dec., 1893
PROVISIONAL SPECIFICATION.
Improvements in and relating to Clutches for Screw-propeller
Shafts.
THOMAS BARNFATHER, Engineer, 13 Phillipsburg Avenue, Fairview in the
County of Dublin, and CHARLES KÜBLER, Brush Maker, Windsor House,
Windsor Avenue, Fairview, in the County of Dublin do hereby declare the nature
of this invention to be as follows:-
The apparatus consists of
1. A compound ratchet box with right hand and left hand ratchets, on the face
of the propellershaft.
2. Paul holder boxes containing four right hand and four left hand pauls, on the
face of the crankshaft.
All are made of steel.
The ratchet box on the propellershaft is a fixture. The pauls on the face of the
crankshaft are movable; they are pinioned in the centre and are held firmly in the
ratchet box by means of springs..
The pauls thus connect the two shafts and transmit to the propellershaft the
motion of the crankshaft; they are therefore the actual carriers of the propeller;
they are safe and reliable and easily moved by the touch of a lever, which will
become necessary for a reversing motion.
Great injury is often done to the driving shafts, but chiefly to the propellershaft,
by the continued working of the propeller after steam has had to be shut off
suddenly. Sometimes the propellershaft even breaks. The shafts should work
separately.
By disconnecting the shafts the propeller could at this crisis do no harm, as the
propellershaft would work independently of the stationary crankshaft. On shutting
off the steam the centrifugal force of the propeller releases the pauls from the
ratchets; they force back the springs and the ratchet box is carried past them until
the motion is run out. On again turning on the steam the crankshaft moves again
and the pauls in their turn re-gain their position in the ratchet box, yielding to the
pressure from their springs and thus the two shafts are re-connected.
The occasion for using this apparatus with full benefit would arise at the moment
In this
when, through stress of weather, the propeller works free of the water.
position, unless steam is shut off, the propeller's motion is considerably accelerated
as the engines meet no resistance and grave consequences may follow. To avoid
danger the engineer turns off the steam sharply. The stoppage immediately acts
on the crankshaft, being nearest; but the propeller cannot be stopped at once,
owing to the momentum acquired by its own weight and velocity. Its centrifugal
force acts on its shaft, which, being under the present system bolted to the now
stationary crankshaft, it tries to carry with it. The crankshaft is inert from want
of motive power and it is held firmly, while the propellershaft has at its other end
the power of the still revolving propeller. The consequence is that one of the
shafts, but generally the propeller shaft, either twists and opens or at once breaks
at some place and the vessel with her burden of human lives and property becomes
like an unmanageable log in the water or she may possibly be wrecked and lost.
By disconnecting the two shafts, which is automatically done by this apparatus
(as it does away with the connecting bolts now in use) any danger arising from the
cause mentioned is completely averted. The pauls leave their hold on the ratchets
on the propellershaft, owing to the centrifugal force of the propeller, the moment
steam is shut off and the crankshaft has become stationary. The propeller and its

page_text: shaft may then safely continue their motion until run out or steam is again turned
on, when, the crankshaft moving again the pauls naturally resume their places in
the ratchets on the propellershaft by means of their springs without any assistance
whatever.
For the reversing motion of the steamer a lever will be attached to change the
working of the pauls, as required.
Dated this 15th day of February 1893.
COMPLETE SPECIFICATION.
Improvements in and relating to Clutches for Screw-propeller
Shafts.
We, THOMAS BARNFATHER, Engineer, 13 Phillipsburgh Avenue, Fairview,
and CHARLES KÜBLER, Brush Maker, of Windsor House, Windsor Avenue,
Fairview, in the County Dublin, Ireland do 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:-
This invention has reference to an improved apparatus for the purpose of averting
injury from the driving shafts of screw steamers.
According to the present system of connecting the propeller shaft with the crank
or driving shaft which consists essentially in securing the coupling plates tightly
together by means of bolts and nuts-considerable rigidity is produced along the
entire length of shafting, and in the event of the engine or driving end being
suddenly stopped or arrested in its rotatory motion, the propeller end (owing to the
momentum acquired by the propeller) will continue for some time to rotate carrying
the entire shaft round producing what may be described as torsion and exerting a
tendency to twist or open, and thus weaken or impair the efficiency of the
shaft.
In practice the frequent occurrence of this contingency so deteriorates the shaft
that eventually a break occurs rendering the propeller inoperative and thus
disabling the steamer.
Our invention is designed to obviate this danger by producing means whereby
the shaft is automatically divided, or in other words, the propeller end automatically
disconnected from the driving end, and the shaft thus released from undue straining
or tendency to twist in the case of a sudden stoppage of the engine, or the driving
end of shaft.
The method whereby we propose to accomplish this object, we will now proceed
to describe, with the assistance of the accompanying drawings:-
Fig. 2,
Fig. 1, is a plan showing the various parts of our improved apparatus ;
is a longitudinal section of same; and Figs. 3 and 4 detail views hereinafter more
fully described.
Similar letters of reference indicate corresponding parts in each of the views.
On the face of the ordinary coupling plate of the propeller shaft A, we propose
to form a compound ratchet box with right and left-hand ratchets as shown in
Fig. 3.
In suitable recesses round the face of the coupling plate of the crank or driving
shaft B, we mount four right-hand, or forward pauls 1. 2. 3 and 4, and four left-
hand pauls 5. 6. 7. and 8. Each paul is hinged suitably on radial pivots, and is
supported on small spiral springs 21 and provided with small lateral screw pins 22,
for the purpose presently described.
Around the paul coupling is arranged a collar 9, through which the lateral screw
pins 22 project, those of the four right-hand or forward pauls through small slots,

page_text: and the four left-hand or backward pauls through open cuts as described
later on.
The four right-hand or forward pauls are operated by the longitudinal movement
of collar 9, which is connected by rods c to the disk 10 forming part of the
sleeve 11, mounted on the driving shaft B. The four left-hand or backward pauls
pass as already stated through the open cuts in collar 9, thence through slots in
arms 12, 13, 14 and 15 whereby they are operated-said arms being connected to
the disk 16 which forms part of the outer sleeve 17.
Levers 18 and 19 are shown (Fig. 1) for the purpose of moving the two sleeves,
and a feather 20 (Fig. 2) passes from shaft B, through elongated slots to admit of
longitudinal movement while securing rotatory motion with the shaft.
The action of our invention is briefly as follows:-
As shown in Figs. 1 and 2, the apparatus is in its normal condition, that is to
say, the right-hand or forward pauls engage with the ratchet coupling plate, thus
locking the propeller shaft with the driving shaft for forward motion.
Meanwhile the left-hand or backward pauls are drawn within their respective
recesses by the backward set of sleeve 17.
As thus manipulated it is obvious that so long as shaft B is rotated it will carry
round shaft A, but should the speed of the former be suddenly checked, shaft A,
will be free to revolve independently, since the ratchet coupling plate will ride
freely over the right-hand or forward pauls; thus the momentum acquired by the
propeller is allowed to exhaust itself independently, and its tendency of exercising
any deteriorating influence on the shafting is obviated. When the speed of shaft B,
is again accelerated the pauls will re-engage and restore the normal condition for
forward driving.
To manipulate the apparatus for reversing the propeller, the set of left or back-
ward pauls are caused to engage with the ratchet coupling plate by thrusting
forward sleeve 17, while the right-hand or forward pauls are drawn within their
recesses by the backward movement of sleeve 11. In this position should shaft B,
be suddenly arrested in its motion, shaft A will be free to rotate independently :-
the ratchet coupling plate riding freely over the left-hand or backward pauls, as
in the first described instance.
From this explanation it will be obvious that in order to attain the object of our
invention namely, to enable the propeller to revolve independently of the driving
shaft in the event of the latter's speed being suddenly checked-only one set of
pauls should engage the ratchet coupling plate at one time, thus the right-hand or
forward set for forward motion and the left-hand or backward set for reversing.
Should however it be desirable to lock the propeller with the driving shaft for
intermittent motion in both directions, it is only necessary to press forward both
sleeves, thus causing both sets of pauls to engage the ratchet coupling plate and
thereby lock the shafts rigidly together.
This position may be found necessary when in harbour for instance, or engaged
in trial, or other manœuvres.
Having now particularly described and ascertained the nature of our said
invention, and in what manner the same is to be perforined, we declare that what
we claim is :-
First. In the construction and coupling up of the propeller shaft with the driving
shaft of screw steamers, the use and application of apparatus consisting of a
ratchet coupling plate, in combination with a coupling plate carrying two sets of
pauls with means for operating same, substantially in the manner and for the
purpose herein described.
Second. In screw steamers, the use and application of apparatus whereby the
driving shaft is caused to engage with the propeller shaft for rotatory motion in
either direction, in such a manner that the latter may become automatically
disconnected and revolve independently in the event of the speed of the former
being suddenly checked substantially as herein described.

page_text: Third. In screw steamers, the use and application of apparatus, constructed,
arranged and operating substantially in the manner and for the purpose as herein
specified and set forth.
Dated the 15th day of November 1893.
J. K. FAHIE & SON,
9, Westland Row, Dublin, Agents for Applicants.