IMPROVEMENTS IN THE MANUFACTURE OF CRANK AXLES
Year: 1878

page_text: LETTERS PATENT to Sir Joseph Whitworth, Baronet, of Manchester, for the
Invention of "IMPROVEMENTS IN THE MANUFACTURE OF CRANK AXLES."
:
PROVISIONAL SPECIFICATION left by the said Sir Joseph Whitworth at
the Office of the Commissioners of Patents on the 18th July 1878.
Sir JOSEPH WHITWORTH, Baronet, of Manchester.
MANUFACTURE OF CRANK AXLES."
"
IMPROVEMENTS IN THE
This Invention has for its object improvements in the manufacture of crank
axles.
Instead of forging the crank axle from a single block of metal I build it up of
separate pieces; these pieces are screwed together and further secured by keys if
necessary.
་
For the purpose of obtaining still closer attachment of the separate parts I heat
the pieces in which the female screw is cut, and then screw the parts together,
and thus avail myself of the cohesion due to the contraction of the metal on
cooling.
For cranks intended to work only one way I sometimes cut the screws in a taper
form.
By the use of the screw threads as above described I am able to increase the area
of the surfaces in contact, and I can therefore reduce the thickness of the sides of
the sweeps to a minimum.
I prefer to form a hole or passage along the centre of the shaft and through the
crank pins, as is described in the Specification of my former Patent, No. 4937, in
the year 1876.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed
by the said Sir Joseph Whitworth in the Great Seal Patent Office on the 17th
January 1879.
Sir JOSEPH WHITWORTH, Baronet, of Manchester.
MANUFACTURE OF CRANK AXLES."
" IMPROVEMENTS IN THE
This Invention has for its object improvements in the manufacture of crank axles.
Instead of forging the crank axle from a single block of metal I build it up of
separate pieces; these pieces are screwed together and further secured by keys if
necessary.
For cranks intended to work only one way I sometimes cut the screws in a taper
form, so that the tendency of the two parts in contact is always to tighten them-
selves against each other.
In order that the manner in which I carry out my Invention may be fully under-
stood I will proceed to describe the accompanying Drawings.
Figure 1 is a longitudinal section of a built-up crank axle, showing the different
parts of which it is composed screwed together; Figure 2 is a transverse section of
the same taken through the centre of the crank pin.
Figure 3 is a longitudinal section of a built-up crank axle to work only one way,
the sweeps being connected to the body of the crank axle by taper screws;
Figure 4 is a transverse section of the same taken through the centre. of the
crank pin.
For the purpose of obtaining a still closer attachment of the separate parts I heat
the pieces in which the female screw is cut, and then screw the parts together,
and thus avail myself of the cohesion due to the contraction of the metal on
cooling.
By manufacturing crank axles from separate pieces of metal they can be more
readily forged and roughed out in the lathe or other machine, thus securing a great
saving in labour, and at the same time obtaining a better manufactured material,
and by using the screw threads as above described I am able to increase the area
of the surface in contact, and also reduce the liability of the separate pieces from
being forced sideways out of their respective places.
By inserting keys between the body of the shaft and the sweeps they are pre-
vented from being turned round.
I prefer to form a hole or passage along the centre of the axle and through the
crank pins, as is described in the Specification of my former Patent, No. 4937, in
the year 1876.
In cases where additional strength is required I avail myself of the hole or
passage made, as above described, through the centre of the crank shaft and crank
pin to still further strengthen the shaft or pin when necessary by fitting into it, by
screwing or otherwise, a bar of steel of greater strength than the steel of which the
crank itself is made.
Having thus described the nature of my said Invention and the manner of per-
forming the same, I would have it understood that I claim,-
First. The manufacture of crank axles, consisting of parts screwed together, sub-
stantially as described.
Second. The combination of parts constituting my crank axles, constructed sub-
stantially as described, and illustrated by the annexed Drawings.
In witness whereof, I, the said Sir Joseph Whitworth, have hereunto set my
hand and seal, this Fifteenth day of January, in the year of our Lord One
thousand eight hundred and seventy-nine.
TASED WHITWODTU
Gal