Improved Pitman and Connected Parts.
Year: 1899

page_text: Date of Application, 23rd Aug., 1899-Accepted, 16th Dec., 1899
(Communicated from abroad by THE SINGER MANUFACTURING COMPANY, of New
York, United States of America, Sewing Machine Manufacturers.)
Improved Pitman and Connected Parts.
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
ascertained in and by the following statement:--
This invention has for its object to provide a novel ball-bearing pitman, of
simple construction, for use in sewing machine stands and for other purposes.
To this end the improved pitman comprises a rod or bar one end of which is
provided with a strap on which is preferably formed one part of the pitman ball-
race, the other part of the pitman ball-race being formed on an adjustable ring
or cap which has a screw-threaded engagement with the strap and which serves
to hold the balls in place. To prevent lateral movement or displacement of the
pitman, in operation, the crank, in connection with which the pitman is to
operate, is preferably provided with an annular groove which forms the crank
ball-race. The ball-bearing strap portion of the pitman may, if desired, be
made oil retaining and dust-proof, as by the use of felt or other washers applied
in any suitable or well-known manner. For connection to a treadle the lower
end of the pitman is provided with a ball forming part of an adjustable ball
and socket joint preferably comprising an oil pocket in which the ball end of the
pitman is held by a cup-screw which may be adjusted to take up wear.
In the accompanying drawings Fig. 1 is a sectional elevation of the improved
pitman and connecting parts, and Fig. 2 is a view at right angles to Fig. 1 with
the crank in section and the ball-retaining ring or cap removed.
Referring to the drawings A denotes a rod or bar, forming the body of the
pitman, provided at its lower end with a ball a. B is a strap consisting pre-
ferably of an internally threaded steel ring the central opening in which is
greater in diameter than the crank so that, in assembling the parts, the pitman
strap may be readily passed over the crank. The interior of the ring or strap
has a concaved or bevelled part forming a portion of the ball race and the said
strap has a lig having a threaded hole for the reception of the threaded upper
end of the rod A, thus providing for an adjustment in the length of the pitman.
C is a screw ring or cap the inner edge of which is concaved or bevelled to
form a part of the race for the circular series of balls which are retained in
place by the said ring or cap. To afford a strong screw connection between the
strap or ring B and the cap C, without making the former objectionably thick,
an annular recess or groove 6 is preferably formed in the said strap or ring
outside of the ball-race part thereof, to receive a lip or flange c of the screw-
threaded ring or cap C.
E is a crank adapted for use in a sewing machine stand and to which a driving
wheel or pulley (not shown) is to be affixed; this crank having at its central

page_text: portion an annular groove e forming part of the race for the balls d; said
groove preventing lateral displacement of the pitman, when the parts are
assembled, as will be understood.
F denotes a part of a treadle provided with a cup f to receive the ball a on
the rod or bar A, the interior of said cup being adapted to serve as an oil pocket,
as well as a socket for the ball a. The ball a on the rod or bar A is held in the
cup by a cup-screw having a screw-threaded connection with the cup f
and provided with flaring sides which allow the pitman to swing back and forth
as the crank E rotates..
The cup-screw g can be turned down, when necessary, to take up any wear of
the ball and socket joint formed by the ball «, the pocket in the cup f and the
cup-screw ; while any wear of the ball-bearing at the upper end of the pitman
can be readily taken up by simply screwing in the ring C, slightly, by a wrench
or tool adapted for engagement with the recesses c¹ formed in the outer face
of the said ring. The ring C may be retained in any proper position of adjust-
ment by a set screw and the cup-screw g may be similarly retained in place
by a set screw g².
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. In a pitman, the combination with a pitman rod or bar, of a strap at one
end thereof and in the inner portion of which is formed a part of a ball-race,
said strap being provided with an annular groove outside of said ball-race part,
a ring or cap having a screw-threaded connection with said strap and provided
with a portion of a ball-race and with an annular flange or lip extending into
said annular groove in said strap, and a series of balls between said cap and
strap.
2. The combination with a crank having an annular groove, of a pitman rod
or bar, a strap at one end of said pitman rod or bar and on the inner portion
of which strap is formed a part of a ball race, said strap being provided with an
annular groove outside of said ball race part, a ring or cap having a screw-
threaded connection with said strap and provided with a portion of a ball race
and with an annular flange or lip extending into said annular groove in said
strap, and a series of balls between said cap, strap and crank.
3. The combination of a crank having an annular groove, of a pitman rod or
bar provided at its lower end with a ball a, a strap at the upper end of said
pitman rod or bar and on the inner portion of which strap is formed a part of a
ball-race, said strap being provided with an annular groove outside of said
ball race part, a ring or cap having a screw threaded connection with said strap
and provided with a portion of a ball race and with an annular flange or lip
extending into said annular groove in said strap, a series of balls between said
cap, strap and crank, a horizontal treadle part having an oil cup or pocket, and
means for securing the lower end of said pitman in said oil cup or pocket.
Dated this 22nd day of August 1899.
WALLACE FAIRWEATHER,
Of the Firm of Cruikshank & Fairweather,
Chartered Patent Agents, 62, Saint Vincent Street, Glasgow,
Agent for the Applicant.