Improvements in Direct Acting Engines.
Year: 1895

page_text: Date of Application, 16th July, 1895
Complete Specification Left, 29th Oct., 1895-Accepted, 7th Dec, 1895
PROVISIONAL SPECIFICATION.
[Communicated from abroad by FRANK HERBERT, of Castlemaine, in the Colony
of Victoria, Australia, Engineer.]
Improvements in Direct Acting Engines.
1, CHARLES HERBERT, of Landore, in the County of Glamorgan, Engineer, do
hereby declare the nature of this invention to be as follows:-
This invention relates to means of equalising the power delivered by the piston
of an engine worked by elastic fluid, throughout its stroke, notwithstanding the
reduction of pressure on the piston due to expansion. For this purpose, I joint to
the piston crosshead one end of a lever, the middle of which is jointed to a radius
mounted to revolve around a fixed centre, and the other end of which is jointed or
linked to the rod of a piston working in a secondary cylinder having its axis at
right angles to that of the main cylinder. This secondary cylinder being supplied
with fluid under pressure, which may be the working fluid of the engine, or may be
water pumped by the engine, the operation is as follows. During the first part of
the stroke of the main piston, when it is subject to high pressure, it has the
secondary piston opposing it. During the latter part of the stroke of the main
piston, when the pressure acting on it is low, the secondary piston acts in conjunc-
tion with and aiding it. The power delivered by the main piston throughout i
stroke is thus approximately equalised. The linking of the main to the secondary
piston may be so arranged as to constitute a parallel motion for both pistons, or it
may be otherwise arranged so as to work the valve of the main cylinder.
Dated this 16th day of July 1895.
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ABEL & IMRAY,
Agents for the Applicant.
Improvements in Direct Acting Engines.
1, CHARLES HERBERT, of Landore in the County of Glamorgan, Engineer,
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 relates to means of equalising the power delivered by the piston
of an engine worked by elastic fluid, throughout its stroke, notwithstanding the
reduction of pressure on the piston due to expansion. For this purpose I joint to
the piston crosshead one end of a lever, the middle of which is jointed to a radius
mounted to revolve around a fixed centre, and the other end of which is jointed or
linked to the rod of a piston working in a secondary cylinder having its axis at
right angles to that of the main cylinder. This secondary cylinder being supplied
with fluid under pressure, which may be the working fluid of the engine, or may be
water pumped by the engine, the operation is as follows. During the first part of
the stroke of the main piston when it is subject to high pressure, it has the

page_text: secondary piston opposing it. During the latter part of the stroke of the main
piston when the pressure acting on it is low, the secondary piston acts in conjunc-
tion with and aiding it... The power delivered by the main piston throughout its
stroke is thus approximately equalised. The linking of the main to the secondary
piston may be so arranged as to constitutela parallel motion for both pistons, or it
may be otherwise arranged so as to work the valve of the main cylinder.
Fig. 1 of the accompanying drawings is a side elevation of a direct acting
pumping engine provided with secondary cylinder according to this invention, this
cylinder being shewn in section; and the links being so arranged as to form a
parallel motion. Fig. 2 is a similar view of an engine in which there is a modified
arrangement of links, and their movement is utilised to work the cut off valve.
Referring first to Fig. 1, the crosshead G of the main piston rod is jointed to
one end U. of an equal armed lever E the middle O of which is jointed to a radius F
mounted to revolve around a fixed centre N, the opposite end' T of the lever E is
jointed to a piston B working in a secondary cylinder A which is supplied with
steam by a pipe J. The pivot N being in the same horizontal line with U and in
the same vertical line with T, and the arms of E being each equal to the radius F,
the points and T are guided in straight lines as by a parallel motion. As the
main piston is making the first part of its stroke, the piston B is forced into the
cylinder A in opposition to the steam pressure, and the effective power of the main
piston is thus reduced. As the main piston is making the latter part of its stroke,
the piston B is forced out of the cylinder A adding its power to that of the main
piston, the effective power of which throughout its stroke is thus approximately
equalised.
As shewn in Fig. 2, the arms of the lever E are not equal to the radius F nor to
one another, and the pivot N not being in the same horizontal line with U the
end' T of the lever is connected to the portion B by an oscillating link D, a suitable
point of which is linked to the cut off valve rod V. The pressure communicated
by the pipe J to the secondary cylinder A is that of the water pumped by the
engine or of the air in the air vessel of the pump.
Obviously the invention is applicable generally to direct acting engines worked
by any elastic fluid expanding in the cylinder, and whether these engines be applied
for pumping 'or for other work.
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 :-
In combination with the main piston of an engine worked by elastic fluid
expanding in the cylinder, a piston subject to pressure in a secondary cylinder and
linked to the main piston in such a manner as to resist the main piston during the
first part of its stroke when the pressure on it is great, and to assist the main piston
during the latter part of its stroke when the pressure on it is small, substantially
as described.
Dated this 29th day of October 1895.