IMPROVEMENTS IN THE CONSTRUCTION OF THRUST-BEARINGS FOR THE SHAFTS OF SCREW-PROPELLERS
Year: 1883

page_text: LETTERS PATENT to George Davies of 4 Saint Ann's Square Manchester in
the County of Lancaster Consulting Engineer and Patent Agent for an
Invention of "IMPROVEMENTS IN THE CONSTRUCTION OF THRUST-BEARINGS
FOR THE SHAFTS OF SCREW-PROPELLERS" communicated to him from abroad
by Francis Jackson of San Francisco California in the United States of
America.
PROVISIONAL SPECIFICATION left by the said George Davies at the Office
of the Commissioners of Patents on the 29th October 1883.
GEORGE DAVIES of 4 St Ann's Square Manchester in the County of Lancaster
Consulting Engineer and Patent Agent IMPROVEMENTS IN THE CONSTRUCTION OF
THRUST-BEARINGS FOR THE SHAFTS OF SCREW PROPELLERS (& Communication to
me from abroad by Francis Jackson of San Francisco California in the United
States of America)
The object of this invention is to construct such bearings so that the friction is
greatly reduced, and that the thrust is not borne by the metallic surfaces revolving
in contact but by hydraulic means that is by a surface of compressed water, oil or
other liquid.
A resisting block capable of bearing all the necessary strain is bolted or otherwise
firmly fixed to the keelson of the vessel.
In the rear side of this resisting block is formed an eight sided or octagonal
chamber, in which is fitted a bearing or plummer block (made in two halves) so
mounted as to be capable of a certain amount of horizontal movement.
Between
the two halves of this plummer block passes the propeller shaft, the latter being
made with several collars fitting into corresponding recesses made in the inside of
the two halves like an ordinary thrust bearing.
The amount of horizontal movement which the bearing or plummer block is
capable of inside the octagonal chamber is limited, firstly by means of an octagonal
ring placed behind the plummer block within the mouth of the chamber and
screwed or bolted thereto, and secondly by a similar ring placed inside the chamber
between the front of the plummer block and the closed end of the chamber. This
latter ring is fitted with screws passing out through the resistance block by means

page_text: of which (if at any time requisite) it is possible to jam the plummer block forwards
against the other ring so that it becomes practically fast inside the resistance
block, and it then acts as an ordinary thrust-bearing. This would only be
necessary in the event of the hydraulic part of the apparatus (hereinafter described)
getting out of order.
The propeller shaft is also provided (inside the octagonal chamber) with an
additional collar the front face of which works against the rear edge of a gland
which passes water tight through the front end of the resistance block, outside
which it is provided with a flange through which are bored two or more holes, and
through these holes pass bolts screwed into the front of the resistance block, spiral
springs being placed on the said bolts and pressing against the flange so as to
allow of a certain amount of longitudinal movement of the gland, and at the same
time to keep its rear edge always pressed against the collar on the propeller shaft.
The gland is bored out larger than the propeller shaft to avoid friction.
At a convenient distance from the rear end of the resistance block a strong disc
or cylindrical block is fixed onto the propeller shaft. The outside of this disc or
block is turned cylindrical and the rear end of the resistance block opposite to it is
also turned to the same diameter. On each of these cylindrical parts is fitted a
broad ring, and the edges of these two rings meet about midway between the two
blocks so as to form a liquid tight joint, thus enclosing the rear end of the
resistance block. The adjacent edges of the two rings are lipped inside so that
upon water or other liquid under pressure being admitted into the chamber it will
compress the edges of the two rings tightly together.
The ring on the disc or block revolves with the propeller shaft but is capable of
a slight end wise movement and is pressed against the edge of the other ring by an
india rubber ring behind it. The other ring does not revolve, but is capable of
being set forwards or backwards by set screws bearing against its front edge.
Thus it will be seen that the plummer block which forms the bearing for the
propeller shaft is placed in a liquid tight chamber wherein it is capable of a certain
amount of endwise movement; holes are bored through the plummer block from
front to back so as to form a communication between the chamber in front and
that at the back of the same, and it will be evident that upon water oil or other
liquid under pressure being admitted to fill these two chambers, the resistance to
the thrust of the propeller will be borne by the liquid so that the friction is reduced
to a minimum.
The only rubbing surfaces of metal are the adjacent edges of the two broad
rings, and the front of the additional collar on the rear edge of the gland and these
do not bear any thrust but are merely pressed together sufficiently to prevent the
liquid from escaping.
The tube which supplies the liquid under pressure is provided with a valve and
this valve is so connected to a spring piston working in a cylinder open to the
tube that should the pressure at any time be excessive the piston rises and closes
the valve. It is also fitted with a pressure indicator. Or, I sometimes mount a
broad ring on the rear end of the resistance block so that it can slide end ways and
fit springs behind it.
In this case an arm is fitted on the ring and connected by a small rod to a tap
on the hydraulic tube, so that should the pressure become excessive the ring can
recede and this will cause the rod to open the tap and release the pressure.
In some cases I make the resistance block with a cylindrical chamber through
the centre of which passes the propeller shaft. A piston fixed on the propeller
shaft tits in about the middle of the chamber, and the water, oil or other fluid
under pressure is admitted through a branched pipe to both sides of this piston.
The cylinder ends are bored out larger than the propeller shaft, and inside each
of them a smaller piston is also tixed on the propeller shaft.
All three pistons are made with grooves round the edge in which is fitted a
metallic ring having a circumferential recess in which to contain an india rubber
packing ring.

page_text: The pistons revolve with the propeller shaft but the metallic rings with the india
rubber packing do not revolve.
On the propeller shaft in front of the resistance block is fitted a ring (or a
portion of a ring, say two thirds) between two collars, so that it has a tendency to
turn with the shaft but its movement is limited by two pins or stops.
This ring is fitted with two pins, and hanging above the ring between these two
pins is a lever connected to a small spindle ou which are three valves; one of the
valves is fitted into each of the branch pipes and the third is a relief valve. There
are also back pressure valves between the branch pipes and the pressure gauge.
When the propeller shaft is revolving in the direction to "go ahead
the ring
moves with it till one of its pins comes against the hanging lever and causes it to
open the valve in one branch pipe and close the valve in the other thus admitting
the compressed water, oil or other fluid into the chamber in front of the main
piston so as to resist the thrust and relieving the pressure in the buck chamber,
but as soon as the engine is reversed, the ring moves in the opposite direction and
reverses the valves so as to admit the compressed water or other fluid at the back
of the said piston and relieve the pressure from the other end.
In cases where the propeller shaft is not connected directly with the Engine,
and its forward end does not consequently require to pass through the resistance
block.
The latter requires only a very small internal chamber in which fits & piston
fixed on the end of the propeller shaft. The disc or block is not fixed tight on the
propeller shaft but is screwed tight, by means of a cap, onto a ball made on the
said shaft. The disc or block is bored out larger than the shaft to allow for any
springing of the shaft. The broad rings, covering the space between the disc or
block on the shaft and the rear end of the resistance block, are the same as in the
first described arrangement, and the resisting medium for receiving the thrust
is water, oil or other fluid forced under pressure into the chamber in front of the
piston.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said George Davies in the Patent Office on the 29th April 1884.
GEORGE DAVIES of 4 Saint Ann's Square Manchester in the County of Lancaster
Consulting Engineer and Patent Agent IMPROVEMENTS IN THE CONSTRUCTION OF
THRUST BEARINGS FOR THE SHAFTS OF SCREW PROPELLERS (a Communication to
me from abroad by Francis Jackson of San Francisco California in the United
States of America)
The object of this invention is to construct such bearings so that the friction is
greatly reduced and that the thrust is not borne by metallic surfaces revolving in
contact but by hydraulic means that is by a surface of compressed water oil or
other liquid.
Such being the nature and object of the said invention I will now proceed to
describe in detail the manner in which the same is to be or may be performed or
carried into practical effect, and in order that the same may be clearly understood I
have annexed hereunto two sheets of drawings illustrative thereof, and have
marked the same with figures and letters of reference corresponding with those in
the following explanation thereof.
In the annexed drawings Fig 1. sheet 1 is a longitudinal section of one
modification of the invention and Fig. 2 is a transverse section through the
line A. B in Fig. 1.
A resisting block a a capable of bearing all the necessary strain is bolted or
otherwise firmly fixed to the "keelson" of the vessel. In the rear side of this
resisting block is formed an eight sided or octagonal chamber b, b in which is
fitted a bearing or plummer block c, c (made in two halves) so mounted as to be
capable of a certain amount of horizontal movement. Between the two halves of
this plummer block c, c passes the propeller shaft d, d the latter being made with
soverul collars e, e fitting into corresponding recesses made in the inside of the two
halves c, c like an ordinary thrust bearing. The amount of horizontal movement
which the bearing or plummer block is capable of inside the octagonal chamber b, b
is limited first by means of an octagonal ring f.f placed behind the plummer
block c, o within the mouth of the chamber b, b and screwed or bolted thereto, and
secondly by a similar ring 9, 9 placed inside the chamber between the front of the
plummer block c, cand the closed end of the chamber. This latter ring g, g is
fitted with screws h, h passing out through the resistance block a, a by means of
which (if at any time requisito) it is possible to jam the plummer block c, c
forwards against the other ring f, (as shown in Fig 1.) so that it becomes
practically fast inside the resistance block a, a and it then acts as an ordinary
thrust bearing. This would only be necessary in the event of the hydraulic part of
the apparatus (hereinafter described) getting out of order At other times the
screws h, h are partially unscrewed and the ring g, g is free to slide forwards. The
propeller shaft d, d is also provided (inside the octagonal chamber b, b) with an
additional collar i, i the front face of which works against the rear edge of a
gland k, which passes watertight through the front end of the resistance
block it, a outside which it is provided with a flange l, through which are bored
two or more holes, and through these holes pass bolts screwed into the front of the
resistance block a, a; spiral springs m, m being placed on the said bolts and
pressing against the flange 1, 7 so as to allow of a certain amount of longitudinal
imovement of the gland k, and at the same time to keep its rear edge always
pressed against the collar i, i on the propeller shaft. The gland k, k is bored out
larger than the propeller shaft to avoid friction. At a convenient distance from
the rear end of the resistance block a, a a strong disc or cylindrical block n, n is

page_text: fixed onto the propeller, shaft d, d. The outside of this disc or block n, n is turned
cylindrical and the rear end of the resistance block at a, a opposite to it is also
turned to the same diameter. On each of these cylindrical parts is fitted a broad,
ring o and o¹ and the edges of these two rings meet about midway between the
two blocks so as to form a liquid tight joint at **thus enclosing the rear end of
resistance block. The adjacent edges of the two rings are lipped inside so that
upon water or other liquid under pressure being admitted into the chamber it will
compress the edges of the rings o, and o' tightly together.
The ring o, o on the disc or block n, n revolves with the propeller shaft d, d
but is capable of a slight endwise movement and is pressed against the edge of the
other ring by an india rubber ring p, p behind it. The other ring o', o' does not
revolve, but is capable of being set forwards or backwards by set screws q, q
bearing against its front edge. Thus it will be seen that the plummer block c, c
which forms the bearing for the propeller shaft d, d, is placed in a liquid tight
chamber b, b wherein it is capable of a certain amount of end wise movement, holes
r, rare bored through the plummer block c, c from front to back so as to form a
communication between the chambers 6 in front and b' at the back of the same,
and it will be evident that upon water, oil, or other liquid under pressure being
admitted to fill these two chambers b and b¹ the resistance to the thrust of the
propeller will be borne by the liquid so that the friction is reduced to a minimum.
The only rubbing surfaces of metal are the adjacent edges of the two broad rings o
and o', and the front of the additional collar i, i on the rear edge of the gland k, k
and these do not bear any thrust but are merely pressed together sufficiently to
prevent the liquid from escaping. The tube 8, s which supplies the liquid under
pressure is provided with a valve t, and this valve t, is so connected to a spring
piston u, u working in a cylinder v, v open to the tube 8, & that should the
pressure at any time be excessive the piston rises and closes the valve t; It is also
fitted with a pressure indicator w, Or, I sometimes mount the broad ring o', o¹ on
the rear end of the resistance block, so that it can slide endways and fit springs
behind it removing the set screws q, q. In this case an arın x, x is fitted on the
ring o', o¹ and connected by a small rod y, y to a tap z, on the hydraulic tube, so
that should the pressure become excessive the ring can recede and this will cause
the rod to open the tap and release the pressure.
In some cases (see Fig 5 Sheet 2) I make the resistance block a, a with a
cylindrical chamber 6, 6 through the centre of which passes the propeller shaft d, d.
A piston c, c fitted on the propeller shaft d, d fits in about the middle of the
chamber b, b and the water, oil, or other fluid under pressure is admitted through
a branched pipe to both sides of this piston. The cylinder ends are bored out
larger than the propeller shaft d, d and inside each of them a smaller piston k, k, is
also fixed in the propeller shaft. All three pistons are made with grooves round
the edge in which is fitted a metallic ring having a circumferential recess in which
to contain an india rubber packing ring. The pistons revolve with the propeller
shaft but the metallic rings with the india rubber packing do not revolve. On the
propeller shaft d, d in front of the resistance block a, a is fitted a ring 1. 1. (or a
portion of a ring say two thirds) between two collars 2, 2 so that it has a tendency
to turn with the shaft d, d but its movement is limited by two pins or stops 3. 3
see transverse (section Fig 6). This ring 1, 1, is fitted with two pins 4. 4. aud
hanging above the ring between these two pins is a lever 5, 5, connected to a small
spindle 6, 6, on which are three valves; one of the valves is fitted into each of the
branch pipes 8, 8 and the third is a relief valve 7. 7. There are also back pressure
velves 8. 8. between the branch pipes and the pressure gauge.
"
When the propeller shaft d, d is revolving in the direction to go ahead" the
ring 1. 1. moves with it till one of its pins 4. 4. comes against the hanging lever
5, 5 and causes it to open the valve in one branch pipe s, & and close the valve in
the other, thus admitting the compressed water, oil or other fluid into the chamber
in front of the main piston c, c so as to resist the thrust and relieving the pressure
in the back chamber 6, 6' but as soon as the engine is reversed a ring 1.1 moves

page_text: in the opposite direction and reverses the valves so as to admit the compressed
water or other fluid at the back of the said piston and relieve the pressure from the
other end.
In cases where the propeller shaft d, d is not connected directly with the engine
and its forward end does not consequently require to pass through the resistance
block a, a (as shown at Figs 3 and 4 Sheet 1), the latter requires only a very small
internal chamber b, b in which fits a piston c, c fixed on the end of the propeller
shaft d, d. The disc or block n, n is not fixed tight on the propeller shaft d, d
but is screwed tight by means of a cap onto a ball i, i made on the said shaft. The
disc or block n n is bored. out larger than the shaft to allow for any springing of
the shaft. The broad rings o, and o¹ covering the space between the disc or block
on the shaft and the rear end of the resistance block a, a are the same as in the
first described arrangement, and the resisting medium for receiving the thrust is
water, oil, or other fluid forced under pressure into the chamber b, b in front of the
piston c, c.
It it will be evident that the use of thrust bearings made according to this
invention is not confined to propeller shafts, but they are also equally applicable to
other horizontal shafts or to vertical shafts where there is a great pressure to be
sustained.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed I wish it to be under-
stood that I clain as the invention Communicated to me by the said Francis
Jackson the construction of thrust bearings substantially as herein before described
and illustrated by the drawings annexed wherein the thrust is not borne by
metallic surfaces revolving in contact, but by hydraulic means, that is by a surface
of compressed water oil or other liquid. In witness whereof I the said George
Davies have hereunto set my hand and seal this twenty eighth day of April in the
year of our Lord one thousand eight hundred and eighty four.
GEORGE DAVIES