Improved Means for Lubricating Cranks.
Year: 1899

page_text: Date of Application, 23rd Aug., 1899-Accepted, 7th Oct., 1899
[Communicated from abroad by THE SINGER MANUFACTURING COMPANY, of New
York, United States of America, Sewing Machine Manufacturers.]
Improved Means for Lubricating Cranks.
I, JOHN KING MACDONALD, Manager of The Singer Manufacturing Company,
Kilbowie, Dumbartonshire, do hereby declare the nature of this invention and in
what manner the same is to be performed, to be particularly described and ascer-
tained in and by the following statement:-
This invention has for its object to provide means whereby the oil, which is
applied to a rapidly rotating crank, to lubricate the bearing or joint between such
crank and the eye of the pitman which it operates, will be retained in the bearing
or joint by centrifugal action and will also be caused to circulate in such bearing or
joint by such action, instead of being expelled or thrown off, as heretofore, leaving
the bearing or joint dry. Much difficulty has been encountered in the operation
of high speed sewing machines running at from eighteen hundred to twenty-five
hundred or more stitches per minute (representing from eighteen hundred to
twenty-five hundred or more rotations of the driving shaft per minute) by the
heating of the crank of the driving shaft at its joint with the pitman connecting
said shaft with the shuttle-shaft below, this difficulty arising from the fact that
the lubricating oil was quickly thrown off or expelled from the joint by centri-
fugal action, leaving the joint dry. I have remedied this difficulty by making
the pitman strap or eye wider than that part of the crank against which it bears
and providing the said pitman strap or eye, at the sides of the bearing portion
of the crank, with oil grooves or pockets forming receptacles into which the oil,
which would otherwise be thrown off by centrifugal action, is forced by such
action into these receptacles as the crank revolves, these oil-grooves or pockets
having imperforate outer walls and being preferably connected, across the crank
bearing, by transverse oil-grooves or ducts so that the oil can freely circulate in
the joint or bearing, as will be hereinafter more fully explained.
In the accompanying drawings, Fig. 1 is a sectional elevation illustrative of
my invention, and Fig. 2 is a transverse section of the same on line 2-2, Fig. 1.
Fig. 3 is a detail inside view of the pitman cap.
A denotes a portion of a rotary shaft provided with a crank b having a convex
or ball-like bearing portion c encircled by the strap or eye of a pitman & The
bearing or acting portion c of the crank, instead of being made as a complete
or nearly complete ball, as heretofore, is narrowed or cut away at its sides, and
the eye of the pitman instead of being narrower than the ball or bearing portion
of the crank, as is usual, is made wider, and at the sides of the ball or bearing
portion of the crank grooves or oil pockets e are formed in the interior of the
eye of the pitman. These grooves e have imperforate outer walls and are prefer-
ably annular so as to be continuous around the inside of the eye of the pitman
and said annular grooves are preferably connected with each other across the

page_text: bearing portions of the pitman eye or strap, and consequently across the bearing
portion of the crank, by transverse grooves of formed in the interior of said eye
or strap and opening at their ends into the annular grooves or oil pockets e.
From the foregoing it will be understood that any oil which is applied to
the crank, to lubricate the same, will, when the said crank is in rotation, be
forced outward by centrifugal action into the annular grooves or oil pockets e in
the eye of the pitman, and this same centrifugal force will have a tendency to
cause the oil to seek to reach the higher or outer portions of the ball and socket
bearing of the crank and strap, this tendency of the oil to enter and remain in the
bearing being assisted by the transverse grooves f. Owing to the fact that the
bearing portion of the crank not only turns or rotates on its own axis but also
revolves in an orbit around the axis of the shaft A, the oil in the oil-grooves or
- pockets e, f, will be kept in constant movement or circulation when the crank
is in operation, being forced against or away from the surface of the bearing
portion c of the crank according to whether such surface may be at any time on
the outer or inner side of the orbit. (denoted by the dotted circle a in Fig. 2)
described by the axis of the bearing portion of the crank. This action will be
understood from Fig. 2 from which it will be seen that in the positions of the
parts in full lines the tendency of the oil will be to move to the left, so that the
oil in the grooves f on right or inside part of the bearing or joint
will be forced against the ball or bearing portion of the crank,
to keep the same lubricated; while when the crank has travelled around to the
position denoted by dotted lines in Fig. 2 the oil in the grooves f at the left of
the bearing will be forced against the ball or bearing portion of the crank. Also
this same action is constantly going on with reference to other positions of the
revolving crank. Thus the oil in the grooves f in the top of the pitman cap d',
and which, when the crank is at the top of the dotted circle a, is forced away
from the ball or bearing portion c of the crank, is thrown against said ball or
bearing portion c when the crank is at the bottom of its orbit of rotation; and
the oil in the bottom portion of the pitman strap or eye, and which is forced
upward against the bearing portion c, when the crank is at the top of its orbit,
will be thrown downward when the crank reaches the bottom of its orbit.
C
From the foregoing it will be understood that my invention provides means
whereby centrifugal force, which has heretofore served to expel the lubricating
oil from the crank bearing, is utilized to retain the oil in the bearing or joint, and
cause it to circulate therein, so that when oil has once been applied to the crank
it will stay there indefinitely and the difficulty arising from want of lubrication
of rapidly rotating cranks is wholly avoided, as has been demonstrated by practice.
I do not wish to be understood as limiting my invention to the details herein
shown and described, as the invention is capable of use in connection with other
forms of cranks or rotating devices for operating pitmen than that herein illus-
trated. Also the proportional sizes of the oil pockets or grooves may be varied,
as may be required; or the said grooves may be of different forms; or the trans-
verse grooves might run diagonally or across each other; all without departing
from the essence of the invention.
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. The combination with a rotating crank, of a pitman having an eye or strap
which is wider than the bearing portion of said crank, and the interior of which
eye or strap is provided with oil grooves or pockets at the sides of the said bear-
ing portion of said crank and which oil grooves or pockets have imperforate outer
walls, so that the oil will be retained therein by centrifugal force.
2. The combination with a rotating crank, of a pitman having an eye or strap
which is wider than the bearing portion of said crank, and the interior of which
eye or strap is provided with oil grooves or pockets at the sides of the said bear-

page_text: ing portion of said crank, said eye or strap being also provided with interior
transverse oil grooves or pockets connecting said first-named grooves or pockets.
3. The combination with a rotating crank having a convex or ball-like bearing
portion, of a pitman having an eye or strap which is wider than the said bearing
portion of said crank and the interior of which eye or strap is provided with
annular oil grooves or pockets at the sides of said bearing portion, and which
oil grooves or pockets have imperforate outer walls so that the oil will be
retained therein by centrifugal force.
4. The combination with a rotating crank having a convex or ball-like bear-
ing portion, of a pitman having an eye or strap which is wider than the said
bearing portion of said crank and the interior of which eye or strap is provided
with annular oil grooves or pockets at the sides of said bearing portion, said eye
or strap being also provided interiorly with transverse oil grooves or pockets
connecting said annular grooves.
WALLACE FAIRWEATHER,
Of the Firm of Cruikshank & Fairweather,
Chartered Patent Agents, 62, Saint Vincent Street, Glasgow,
Agent for the Applicant.