IMPROVEMENTS IN THE MANUFAC- TURE OF STEEL CRANK AXLES
Year: 1876

page_text: LETTERS PATENT to Sir Joseph Whitworth, Baronet, of Manchester, in the
County of Lancaster, for the Invention of "IMPROVEMENTS IN THE MANUFAC-
TURE OF STEEL CRANK AXLES."
Sealed the 1st June 1877, and dated the 21st December 1876.
"
PROVISIONAL SPECIFICATION left by the said Sir Joseph Whitworth at the
Office of the Commissioners of Patents on the 21st December 1876.
Sir JOSEPH WHITWORTH, Baronet, of Manchostor, in the County of Lancaster.
IMPROVEMENTS IN THE MANUFACTURE OF STEEL CRANK AXLES."
This Invention has for its object improvements in the manufacture of steel crank
axles.
I manufacture crank axles from cast steel. I forge the shaft, and 1 drill or form
holes through the centro of the shaft from end to end, and through the centre of
each of the crank pins or portions of the crank embraced by the connecting rod.
Afterwards I harden and improve the metal by heating it, and plunging it in oil.
The holes drilled as above described serve two purposes; by removing the metal
from the neutral axis they render the shaft better fitted to withstand severe strains,
and save weight and metal, and they allow of the hardening process to be more
effectually performed than would otherwise be practicable, owing to access being
afforded to inner as well as outer surfaces of the steel.
In order to obtain cranks of the greatest possible strength and soundness I use
my fluid compressed steel.
By employing the system of manufacture above described I obtain greater
strength and ductility with less weight of metal than by any other system hitherto
adopted.
For cranks intended to be used when running at high velocities I balance the
checks of the crank throws by prolonging them on the side opposite to the crank
pin,

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent nied by
the said Sir Joseph Whitworth in the Great Seal Patent Office on the 21st
June 1877.
Sir JOSEPH WHITWORTH, Baronet, of Manchester, in the County of Lancaster.
"IMPROVEMENTS IN THE MANUFACTURE OF STEEL CRANK AXLES."
This Invention has for its object improvements in the manufacture of steel crank
axles.
I manufacture crank axles from cast steel. I forge the shaft, and I drill or form
holes through the centre of the shaft from end to end, and through the centre of
cach of the crank pins or portions of the crank embraced by the connecting rod.
Afterwards I harden and improve the metal by heating it and plunging it in oil.
The holes drilled or formed as above described serve two purposes; by removing
the metal from the neutral axis they render the shaft better fitted to withstand
severe strains, and save weight and metal, and they allow of the hardening process
to be more effectually performed than would otherwise be practicable owing to access
being afforded to inner as well as outer surfaces of the steel.
In order to obtain cranks of the greatest possible strength and soundness I use
my fluid compressed steel.
By employing the system of manufacture above decribed I obtain greater
strength and ductility with less weight of metal than by any other system hitherto
adopted.
The manner in which I carry out this Invention will be readily understood from
the accompanying Drawings, which I now proceed to describe.
Figure 1 is a casting of a hoop or hollow ingot.
Figures 2, 3, 4, 5, and 6 show the various forms it takes after each operation.
Figure 7 is an end view showing the crank shaft when complete.
The casting, Figure 1, is heated in a furnace in the usual manner, and then forged
or swaged by hydraulic pressure between suitable blocks until the hole in the centre
is nearly closed.
To prevent the hoop elongating whilst being closed hydraulic or other apparatus
may be used to give the necessary resistance endways to prevent it. When it is
desirable to revolve the forging ready for the next stroke the end pressure is released
and again applied for the following stroke. I then cut the metal away from
the middle portion and from each end by slotting or parting in the lathe, as in
Figure 3. This Figure and those which follow are drawn as for a two-throw crank,
but I am able in a similar manner to make single, double, or other throw crank
shafts from steel hoops or hollow ingots.
Figure 4 shows the metal in the middle and at each end forged down to the
required diameter and length.
Figure 5 shows the crank with the portions to form the sweeps twisted to their
relative positions.
Figure 6 shows the crank with the metal cut away to form the sweeps, which is
performed in the usual manner by turning in a lathe or other suitable machine.
Figure 7 is an end view of the complete crank, showing the sides of the sweep of
an oval form; this allows of their being made thinner, owing to the increased cross
sectional area, by which means the bearings can be brought nearer together, and so
greater stability obtained.
Before the crank is finished turned I prefer to bore or drill a hole through the
centre of the shaft and the crank pins, and also through the cranks. Afterwards the
metal is improved by heating and plunging in oil, and when it comes out of the oil
it is again heated in a furnace until the oil is "blazed off." The holes drilled, as
above described, allow of the hardening process to be more effectually perforined,
owing to the oil acting on the inner as well as the outer surfaces of the steel. The
crank is then finished in the usual manner.
By the above method of manufacture it will be readily seen that every part of

page_text: the casting is thoroughly forged, and by using my fluid pressed steel a sound,
ductile, and perfectly reliable crank is obtained.
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 steel crank axles, with holes formed in them, and har-
dened and improved substantially as described.
Second. The method of forging and forming steel crank axles from cast hoops or
hollow ingots, substantially as described.
Third. The manufacture of steel crank axles, substantially as described.
In witness whereof, I, the said Sir Joseph Whitworth, have hereunto set my
hand and seal, this Twentieth day of June, in the year of our Lord One
thousand eight hundred and seventy-seven.
JOSEPH WHITWORTH. (L.S.)