Improvements in Bearings.
Year: 1895

page_text: PROVISIONAL SPECIFICATION.
Improvements in Bearings.
FREDERICK EDWARD SHEAN, 360, Upland Road, S.E. Engineer, do hereby
declare the nature of this invention to be as follows:-
To prevent the friction, and wearing down of bearings under heavy loads by
supporting such loads upon an oil, or liquid surface, enclosed (where the motion is
rotatory) between the journal or neck, and a cavity in the bearing-bed, or brass;
and, under such supplied pressure as shall by its constant lifting effort neutralize
the effect of the load upon the bearing.
Dated this 11th day of September 1895.
FRED. E. SHEAN.
improvements in Dearings.
FREDERICK EDWARD SHEAN, 360, Upland Road, East Dulwich, S.E.
Engineer, 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 :-
The prevention of friction, and wearing down of bearings, under heavy loads,
by supporting such loads upon an oil or liquid surface, enclosed between the
journal or neck, and a cavity in the bearing-bed or brass; the said oil, or liquid
within the cavity being under such supplied pressure, as shall, by its constant
lifting effort, neutralize the effect of the load upon the bearing.
In an ordinary bearing block, shewn in longitudinal and transverse section
(Figs. 1 & 2, Sheet No. 1) the journal is 30 inches in length, and 17 inches in
diameter; the lower brass, A A having, therefore, a horizontal sectional area of
510 sq. inches.
The neck, or journal, B B. which revolves on this bearing carries a weight of,
say 70 tons.
From the bottom bearing surface of the lower brass, (A Fig. 3) take away a square
foot, by forming therein, a rectangular cavity, (a) having a length of 24 inches,
and a breadth of 6 inches. Its depth may be from half an inch, to an inch (seen
in section, at a a Figs. 1 & 2, Sheet No. 1).
Then, the neck, or journal, lying, with its load of 70 tons, upon this cavity,
closes it, more or less completely, according to the fitting.
And, if the cavity, a, communicate with a force-pump, the pressure within it
being that under the ram, gives a lifting effort under that part of the journal
which covers the cavity, and, which also, has a horizontal sectional area of
one sq. foot. Therefore, equilibrium results, & the effect of the whole 70 tons is
counteracted, and neutralized, when the pressure in the cavity is 1088 lbs. per
sq. inch, or, that produced by a ram of one sq. inch worked by 36 inches of
piston-area (equal to a piston of 6.75 in. diameter, nearly) with a pressure of
30 lbs. pr. sq. inch.
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page_text: And, it is obvious, that, if there were no leakage, of ram, or cavity, the
counteraction of the whole, or any desired portion of the weight on the bearing,
would be obtained by the mere static pressure of the ram; and, that the approach
to such perfection would depend upon the fitting.
This method applies to any bearings subject to great pressure, and especially
to those of marine propeliers, to prevent their wearing down, and getting out
of line.
For these important bearings, (the tendo Achillis of a ship) being, for long
periods, out of sight, and beyond the possibility of control, or adjustment, are
often a source of great auxiety, at sea, and of expense in port.
As, independently of the material quality of propeller shafts, there are,
probably, two main causes of their breaking; one, predisposing, and gradual;
the other, immediate.
The first is the propeller being "down."
When employed in a wholly metallic propeller bearing, the cavity method is
simply as seen in the lower brass, A. A. Figs. 1, 2, & 3 Sheet 1.
When employed in a bearing, fitted otherwise ordinarily with lignum vitæ strips,
the cavity is seen at a a, Fig. 4; a, Fig. 5; a, Fig. 6; and, a a, Fig. 7, Sheet 2,
the figs. in which are,-
Fig. 4 the after end of a propeller shaft, and its bearing, in longitudinal section.
Fig. 5, cross section through A B, at any point, between a & a, Fig. 4. Fig. 6, a
segment of the stern-tube, with shaft removed; but, with lignum vitæ strips
remaining. Fig. 7, a horizontal section through the segment, Fig. 6, showing,
in plan, the bearing, or lifting area of the cavity, a a, and its confines, or
buttresses, bb bb, k k.
Generally,
a, is the lifting, or bearing cavity.
b, buttress rib, between cavity and lower lignum vitæ strip.
c, lignum vitæ strips.
d, division, or containing ribs of L.V. strips.
e, sleeve of shaft.
, clearance between sleeve, & ribs.
.9, keep-ring at after end.
h, flange of stern tube.
i, stern tube.
k, end buttresses of cavity.
1, containing ribs of inner ends of lower lignum vitæ strips, & continuations
of bb, but lower, by the extent of the clearance, f.
m, butt-ring, for lignum vitæ strip-ends.
o, shaft.
Here, a portion of the bottom lignum vitæ has been substituted by a bearing
cavity, which is formed in the casting, for that purpose. (This does not preclude
the adaptation of existing lignum vitæ-fitted bearings.)
In Figs. 5 & 6, the buttress, 6, is shewn to touch the sleeve, in common with the
adjacent lignum vitæ strips, on either side, instead of having the clearance, f,
between it and the sleeve, as in the cases of all the other ribs (d), and which is the
usual practice when the lignum vitæ is worn down, under the revolution of a shaft
end, which, in addition to its own weight, carries that of the propeller.
But, in this case the lignum vitæ is not worn down under that weight, because it
does not support it.
That is done by the lifting effort of the fluid pressure in the cavity; and the
wear down" of the lignum vitæ, and the buttress, are ordinarily nil.
A fluid bearing, of this kind, virtually eliminates the lignum vitæ element, in so
far as relates to its function of support; and, with suitable metal for shaft and
bearing, may do so absolutely; since it has the further advantage of ensuring
perfect lubrication at any time, if so desired.

page_text: REMARKS.
In propeller bearings, whether wholly metal, or fitted with lignum vitæ, the
pressure may be supplied, either by a small steam pumping engine, or by a water-
engine, worked from the propeller shaft.
With the propeller, and shaft end weighing 30 tons, the neutralizing pressure in
the cavity (Sheet 2) would be 525 lbs. pr. sq. in. (the area being 32 × 4), and.
with unity as ram area, and 36 inches of piston area as before the pressure thereon.
would be 14'6 lbs. pr. sq. inch.
The liquid, for the cavity pressure is generally sea water, roughly filtered
through bunting. But provision may be made, on the suction side of the pump,.
for an oil vessel in case it may be at any time desirable to to use a lubricant, or
prevent marine growths.
The supply pipe may enter the stern tube wherever convenient, and pass through
the buttresses m & k, into the cavity.
With the object of enabling the cavity to be washed out at any time, the supply
pipe, before passing out of the "tunnel," may divide into two branches which enter
the stern tube singly, and pass into the cavity on opposite sides of it. One of the
branches has a valve on the after side of the breech, and before the after bulk-
head; abaft this valve, there is a test-pipe leading from the same branch; this
test pipe, too, has a valve in it.
When the first named valve is open, (and the second is closed) both portions of
the breech communicate with the cavity; but, when that valve is closed, only the
pipe which has no valve can do so.
If, now, the second valve be opened (i.e. the one on the test pipe) the cavity.
communicates with the tunnel, and, if the pump be working, water is driven out of
the cavity, and may be caught, and examined.
In other bearings, the liquid in the cavity may be oil, or water, with, or without
unguent, as found desirable.
The pressure may be obtained by either, a steam, or water engine.
For cleaning out the cavity, there is an outlet pipe, by which the liquid may be
blown through.
This pipe may be at the opposite end to the pressure pipe, or, the same end, but
on the opposite side of the cavity.
"
The "horns or sides of the brass would not be eased away, as usual when they
are liable to "
seize," through heating; for, in such a bearing there should be no
heating, as there need be no friction to cause it.
Having, now, particularly described, and ascertained the nature of my said inven--
tion, and, in what manner the same is to be performed, I declare, that, what I
claim is,
Prevention of the wearing down of bearings, under heavy loads or weights, by
supporting such loads upon an oil, or liquid surface, enclosed in a cavity in the
bearing-bed, or brass, by the neck, or journal, which revolves upon that brass,.
the said liquid, enclosed within the cavity, being under such pressure, supplied
from without, as shall, or may, by its constant lifting effort, counteract the weight
upon the bearing, ensure perfect lubrication, and, practically, impose a veto upon.
friction, heating, and wearing down.
Dated this 9th day of July 1896.