Improvements in Steam and other Fluid Pressure Engines.
Year: 1892

page_text: Date of Application, 15th Feb., 1892
Complete Specification Left, 15th Nov., 1892-Accepted, 4th Feb., 1893
PROVISIONAL SPECIFICATION.
Improvements in Steam and other Fluid Pressure Engines.
I, JOHN HENRY HOLMES, of Portland Road, Newcastle on Tyne in the County
of Northumberland Electrical Engineer do hereby declare the nature of this
invention to be as follows:-
This invention relates to improvements in steam and other fluid pressure engines,
and has for its object to construct double-acting reciprocating engines in such a
manner as to attain some of the advantages which are usually considered to be
features of single acting engines only, more especially absence of need for constant
adjustment to compensate for wear in the brasses of the connecting rod and freedom
from the noise usually noticeable in reciprocating double acting engines after such
wear has taken place.
To attain these ends I arrange the parts so that the pressures brought to bear
upon the crank pin and crosshead brasses are always acting in the same direction,
that is to say always acting so as to tend to force the brasses into closer contact
with the pins upon which they bear.
As an example of the way in which my invention may be carried out in practice
I will describe it as applied in the case of an inverted single cylinder steam engine
having the cylinder above the crankshaft. In this type of engine I desire to
construct it in such a manner that the upper crank pin brass shall always be pressed
in a downward direction, and the lower brass always in an upward direction.
With this object I fit the cylinder with two pistons each piston having its own
piston rod and connecting rod or rods. When the engine is working the upper
piston is always subject to a pressure tending to keep it down, and this pressure is
transmitted as a thrust through its piston rod and connecting rod to the top brass
of the crank pin. The lower piston on the other hand is subject to a pressure
tending always to force it upwards and this pressure is transmitted as a pull
through the other piston rod and connecting rod to the bottom brass of the
crank pin. The two pistons traverse the cylinder together always moving together
in a similar direction and therefore act as one piston of an ordinary engine
acts. The steam distribution may therefore be effected in the usual manner by
means of a slide valve and ports or other well known methods. When the brasses
wear, the slack is taken up by the two pistons moving closer together so that it is
essential that when the engine is first put together the pistons be arranged with
sufficient space between them to admit of this movement taking place. I bring the
piston rod of the lower piston through a stuffing box in the bottom cylinder cover
and attach it to a crosshead with slipper sliding in the usual guides.
This rod however differs from the ordinary rod in being made hollow so as to
admit of a solid rod from the upper piston passing right through it. I make this
latter rod a good fit in the hollow rod at the crosshead end so that it is not necessary
to provide a second slipper in the guides as the side thrust of the connecting rod
is transmitted directly to the slipper attached to the other crosshead. When the
engine is at work the solid or centre piston rod is always in thrust and has a
connecting rod attached to it so as to transmit this thrust to the upper crank pin brass
and always keep it in close contact with the crank pin. The hollow piston rod is
always in tension and is attached preferably to two light connecting rods which
transmit this tension to the lower crank pin brass and always tend to keep it in
close contact with the side of the crank pin which happens to be lowest. These
tension connecting rods may be forked at the lower end so as to embrace the crank
pin and its upper brass, and then be attached to the lower brass only. The crank
pin brasses are made so that each covers less than half the circumference of the

page_text: crank pin thus allowing slack to be taken up without the brasses coming into
contact, and the brasses of the upper end of the connecting rod are also arranged
so that wear may be similarly compensated for.
.
As it is desirable that the pressure in the space between the pistons shall be kept
as nearly as possible at the atmospheric pressure and as leakage of steam past the
pistons would be detrimental to this, I arrange a communication with this chamber
and the atmosphere by means of the hollow piston rod mentioned above. This is
accomplished by making longitudinal chanuels or grooves in either the solid rod or
the inside surface of the tubular one. In some cases it may be more desirable to
make a communication with the chamber between the pistons and the exhaust steam
pipe rather than the atmosphere and to accomplish this I may close in the crank
chamber and connect it to the exhaust pipe; or I can prevent communication by
way of the hollow piston rod and provide instead a tube screwed into a hole through
the upper piston and passing through a stuffing box in the upper cylinder cover
into a chamber communicating with the exhaust.
When the steam is turned off from the engine the pressure upon the pistons is
relieved and the lower piston may fall by the action of gravity and cause a knock when
slowing down besides exposing the surface of the lower crank pin brass to dust, &c.
I therefore prefer to provide a spring pressure tending always to draw the pistons
together. For this purpose tension springs may be placed between the pistons, or
compression springs between the outer ends of the piston rods or crossheads.
Dated this 13th day of February 1892.
JOHN H. HOLMES.
COMPLETE SPECIFICATION.
Improvements in Steam and other Fluid Pressure Engines.
I, JOHN HENRY HOLMES, of Portland Road, Newcastle-on-Tyne, in the
County of Northumberland, Engineer do hereby declare the nature of this inven-
tion 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 improvements in steam and other fluid pressure engines,
and has for its object to construct double acting reciprocating engines in such a
manner as to attain some of the advantages which are usually considered to be
features of single acting engines only, more especially absence of need for constant
adjustment to compensate for wear in the brasses of the connecting rod and freedom
from the noise usually noticeable in reciprocating double acting engines after such
wear has taken place.
To attain these ends, I arrange the parts so that the pressures brought to bear
upon the crank pin and cross head brasses are always acting in the same direction,
that is to say, always acting so as to tend to force the brasses into closer contact
with the pins upon which they bear.
As an example of the way in which my invention may be carried out in practice,
I will describe it as applied in the case of an inverted vertical single cylinder steam
engine having the cylinder above the crank shaft. In this type of engine, I desire
to construct it in such a manner that the upper crank pin brass shall always be
pressed in a downward direction, and the lower brass always in an upward
direction.
It is best explained by aid of the accompanying drawings, in which-
Figure 1 is a vertical section of an engine •

page_text: before the two pistons come in contact. This space is ventilated through grooves
being formed in the inside of piston rod E or outside of piston rod D, which other-
wise closely fit each other at the ends.
Or, instead of this manner of ventilating, the plan set forth in Figure 3 can be
used, by which any steam escaping into F can be brought at once to the condenser
or exhaust. In this figure, the piston rod D fits the rod E accurately where it
passes through piston C, and is extended beyond piston B through a stuffing box
into a chamber G, as shown, which is connected at H, by a pipe, (not shown with
the condenser.
Piston rod D is linked at I to connecting rod J, which bears on the upper
surface of upper crank pin bearing K: piston rod E, on the other hand, is attached
to a cross head L. M M are two connecting rods working on the pins of this cross
head, and carrying the lower bearing N of the crank pin. P is a spring bearing
on the outer piston rod E and the cross head L at the one end, and the jaws of
piston rod D at the other end. This spring keeps the two pistons as near together
as the machinery will admit, and, consequently, the two bearings K N tightly
grasping the crank pin even when the steam is off and the piston C, rods M M and
bearing N would otherwise (when the engine stopped in position shown) fall down.
It will be seen, from the above, that, when the engine is working, the upper
piston B is always subject to a pressure tending to keep. it down, and this pressure
is transmitted as a thrust through its piston rod D and connecting rod J to the top
brass K of the crank pin. The lower piston C, on the other hand, is subject to a
pressure tending always to force it upwards, and this pressure is transmitted as a
pull through the other piston rod E and connecting rods M to the bottom brass N
of the crank pin.
The two pistons traverse the cylinder together, always moving together in a
similar direction, and therefore act as the one piston of an ordinary engine acts.
The steam distribution may, therefore, be effected in the usual manner by means
of a slide valve and ports or other well known methods.
When the brasses wear, the slack is taken up by the two pistons moving closer
together, so that it is essential that, when the engine is first put together, the
pistons be arranged with sufficient space between them to admit of this movement
taking place.
I bring the piston rod of the lower piston C through a stuffing box in the bottom
cylinder cover and attach to it a cross head with slipper sliding in the usual
guides.
This rod, however, differs from the ordinary rod in being made hollow so as to
admit of a solid rod from the upper piston passing right through it. I make this
latter rod a good fit in the hollow rod at the cross head end, so that it is not
necessary to provide a second slipper in the guides, as the side thrust of the
connecting rod is transmitted directly to the slipper attached to the other cross
head. When the engine is at work, the solid or centre piston rod is always in
thrust and has a connecting rod attached to it, so as to transmit this thrust to the
upper crank pin brass and always keep it in close contact with the crank pin.
The hollow piston rod is always in tension, and is attached preferably to two
light connecting rods which transmit this tension to the lower crank pin brass,
and always tend to keep it in close contact with the side of the crank pin which
happens to be lowest. These tension connecting rods may be forked at the lower
end so as to embrace the crank pin and its upper brass and then be attached to the
lower brass only.
The crank pin brasses are made so that each covers less than half the circum-
ference of the crank pin, thus allowing slack to be taken up without the brasses
coming into contact and the brasses of the upper ends of the connecting rods, and
also arranged so that wear may be similarly compensated for. The space between
the pistons is connected with the atmosphere or condenser, as already described,
because leakage of steam into this space would be detrimental and soon form a
pressure antagonistic to spring P. This spring is useful as, when the steam is

page_text: turned off from the engine, the pressure upon the pistons is relieved and the lower
piston might otherwise fall by the action of gravity and cause a knock when
slowing down, besides exposing the surface of the lower crank pin brass to dust,
etcetera. The spring P could be placed between the pistons, if preferred.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
1. In steam or other fluid pressure engines in which the actuating fluid is
introduced alternately at each end of the cylinder, the use or employment of two
pistons in the same cylinder, one of these pistons being connected with one of the
crank pin brasses or its equivalent, and the other with the other crank pin brass or
its equivalent, substantially as and for the purposes described.
2. The arrangement of engine with duplicate pistons in one cylinder substantially
as herein described and illustrated, whether the cylinders be horizontal, inclined,
vertical or oscillating.
*7001 QUANTO CON TALT O
WM. P. THOMPSON & Co.,
Of Liverpool, Manchester, Nottingham, and London, Patent Agents.