A NEW OR IMPROVED EXPANSIBLE PIVOT
Year: 1872

page_text: LETTERS PATENT to Alexander Melville Clark, of 53, Chancery Lane,
in the County of Middlesex, for the Invention of "A NEW OR
IMPROVED EXPANSIBLE PIVOT."
Sealed the 6th September 1872, and dated the 20th July 1872.
COMPLETE SPECIFICATION filed by the said Alexander Melville Clark
at the Office of the Commissioners of Patents, with his Petition
1
and Declaration, on the 20th July 1872, pursuant to the 9th
Section of the Patent Law Amendment. Act, 1852.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, ALEXANDER
MELVILLE CLARK, of 53, Chancery Lane, in the County of Middlesex,
'send' greeting.
WHEREAS I am in possession of an Invention for "A NEW OR
IMPROVED EXPANSIBLE. PIVOT," and have petitioned Her Majesty to grant
unto me, my executors, administrators, and assigns, Her Royal Letters
Patent for the same, and have made solemn Declaration that I am the
true and first. Inventor thereof.

page_text: Figure 2 is a longitudinal section of same applied to a sewing
machine. Figure 3 and 4 are transverse sections on the lines x, x,
and y, y, of Figure 2.
.
Figure 5 is a detail perspective view of one of the ratchet
keys.
Similar letters of reference indicate corresponding parts.
A in the Drawing represents the pivot pin made prismatic, three or
or more sided, at that part where it receives the greatest strain while the
machinery to which it pertains is in motion. The straight sides a, a, of
the prismatic portion are toothed ratchet fashion, and upon them are
placed toothed plates b, b, whose teeth correspond with those of a.
The
outer sides of the plates b, b, are rounded, so that when applied to the
pin they make it of cylindrical form, as shown in Figure 3. A split
spring tube or ring B is placed around the plates b, b.
C is a sleeve sup-
porting the pin A and placed around the round portion of the pin A, and
made adjustable longitudinally by means of a nut D that is screwed
upon the pin A. Projecting ribs d on A fit into grooves within the
slceve C, as in Figure 4, and prevent the same from turning. The

page_text: sleeve C bears against the inner ends of the plates b, whose outer ends do
not quite reach a nut e or washer ƒ held by e, that bears against the
split ring B and holds it in place. When the pivot is applied the
spring ring B furnishes the wearing surface. When the pivot wears
smaller or the eye of the wheel larger the nut D is turned against the
sleeve C, the nut e being at the same time unscrewed in an equal
degree. The nut D forces the sleeve C toward e and thereby moves
the ratchet plates lengthwise, causing them to ride upon the higher
parts of the teeth a, and thereby to expand the ring B.
Having described the nature of the Invention, and in what manner
the same is to be performed, I declare that what I claim as the Inven-
tion and desire to secure by Letters Patent is, the pin A having the
toothed section a, and combined with the ratchet plates 6, nut D,
sleeve C, spring ring B, and nut e, all arranged as set forth.
In witness whereof, I, the said Alexander Melville Clark, have
hereunto set my hand and seal, this Twentieth day of July,
in the year of our Lord One thousand eight hundred and seventy.
two
0 Witness,
W. G. E. SwINNOCK,
53, Chancery Lane,
London.
A. M. CLARK. (L.S.)