IMPROVEMENTS, IN STEAM HAMMERS
Year: 1857

page_text: LETTERS PATENT to Elizabeth McDowall, of Johnstone, in the County.
of Renfrew, North Britain, Widow, for the Invention of "IMPROVEMENTS,
IN STEAM HAMMERS."-A communication from her late husband, John
McDowall, of Johnstone aforesaid, Engineer, deceased..
Sealed, the 22nd December 1857, and dated the 28th October 1857.
PROVISIONAL SPECIFICATION left by the said Elizabeth McDowall at
the Office of the Commissioners of Patents, with her Petition, on
the 28th October 1857:
I, ELIZABETH MCDOWALL, of Johnstone, in the County of Renfrew, North:
Britain, Widow, do hereby declare the nature of the said Invention for "IM-
PROVEMENTS IN STEAM HAMMERS," a communication to me from my late husband,
John McDowall, of Johnstone afsd, Engineer, deceased, to be as follows:-
This Invention relates to the arrangement of the parts of steam hammers
and to the system or mode of actuating the hammer.
The stationary parts of the machine consists of a rectangular cast-iron base,
which supports a column or pillar; to the upper part of this column is bolted
a plummer block, which carries a segmentally ended lever, or a beam some-
what similar to the beam of the early pumping engines, and in like manner
vibrating upon a central axis. The beam projects over the front part of the

page_text: base, and in a vertical line below it is a grooved plate, which forms the guide
for the hammer block to work in; the guide plate is fixed to a frame which
projects from the front part of the fixed column or standard. Below the
inner end of the segmentally ended lever or beam, and in a vertical line
therewith to one side of the central column, is fitted a steam cylinder, which
is bolted to the base of the machine; the cylinder. is made single acting,
and the induction and eduction ports are made in the upper part of the
cylinder above the piston. The hammer block is attached by a broad strap,
or by a chain, or other suitable flexible connection, to an eye at the outer end
of the overhead lever, and a strap or chain is passed over the opposite or inner
curved end of the vibrating beam, and the lower end of this strap or chain is
attached to the piston rod. Below the hammer block, and on the side opposite
to that on which the steam cylinder stands, is fixed an anvil, similar to those
ordinarily used for steam hammers. The admission of the steam into the
cylinder is controlled by a hand lever and the valve of the exhaust pipe by a
wheel or other suitable arrangement, to enable the attendant to regulate the
emission of the steam; the hammer block is raised by admitting the steam to
the cylinder upon the upper side of the piston, which is thereby forced down-
wards, and carries with it the belt or chain which is attached to the segmen-
tally ended lever connected to the hammer block; the hammer descends by
its own gravity, the force of the blow being regulated by the velocity with
which the steam is allowed escape from the cylinder, the emission of the
steam being under the control of the attendant who has charge of the wheel
or other arrangement by means of which the exhaust valve is regulated.
The eduction port.is, made of sufficient area to allow of the steam escaping
suddenly from the cylinder when the whole force of the hammer block is
required; on the contrary, by checking the escape of the steam from the
cylinder, the blow may be modified according to the nature of the work to
be forged.