IMPROVEMENTS IN APPARATUS FOR CONTROLLING THE PRESSURE OF STEAM OR OTHER FLUID USED FOR APPLYING THE BREAKS OF RAILWAY BREAK APPARATUS, APPLICABLE ALSO FOR CONTROLLING THE PRESSURE OF STEAM OR OTHER FLUID USED FOR OTHER PURPOSES." PROVISIONAL SPECIFICATION
Year: 1879

page_text: LETTERS PATENT to Bowman Malcolm, of Belfast, in the County of Antrim,
for the Invention of "IMPROVEMENTS IN APPARATUS FOR CONTROLLING THE
PRESSURE OF STEAM OR OTHER FLUID USED FOR APPLYING THE BREAKS OF
RAILWAY BREAK APPARATUS, APPLICABLE ALSO FOR CONTROLLING THE
PRESSURE OF STEAM OR OTHER FLUID USED FOR OTHER PURPOSES."
PROVISIONAL SPECIFICATION left by the said Bowman Malcolm at the
Office of the Commissioners of Patents on the 8th November 1879.
BOWMAN MALCOLM, of Belfast, in the County of Antrim. "IMPROVEMENTS IN
APPARATUS FOR CONTROLLING THE PRESSURE OF STEAM OR OTHER FLUID USED FOR
APPLYING THE BREAKS OF RAILWAY BREAK APPARATUS, APPLICABLE ALSO FOR
CONTROLLING THE PRESSURE OF STEAM OR OTHER FLUID USED FOR OTHER PURPOSES."
For the purpose of controlling the pressure of steam, or it might be other fluid,
used for applying the breaks of railway break apparatus, I employ a piston capable
of moving to and fro in a cylinder; above the piston is situated a double seated or
equilibrium valve, closing valve seats formed at the end of the steam supply pipe.
When the piston is lifted a projection from its upper end comes against the bottom
of the valve and lifts it from its seats, but when the piston moves downwards away
from the valve, the valve is pressed down and closed by a spring pressing upon it
at the top. When the valve is raised steam issues from the end of the steam
supply pipe into a chamber by which it is surrounded. From this chamber a pipe
passes to the cylinders of the steam breaks, the upper end of the cylinder before
mentioned is also open to the interior of the chamber. A rod or spindle is passed
up through the bottom of the cylinder and by it the piston can be lifted. When
the breaks are to be applied the rod is moved upwards by means of a spring, and it
then lifts the piston and the valve above it; steam is thus allowed to pass from the
steam supply pipe into the chamber, and from thence to the break cylinders. The
pressure of steam in the chamber acts opon the top of the piston, and when the
pressure upon the piston is sufficient to overcome the spring by which it is held up,
the piston is forced downwards and the valve at once closes, and no more fsteam
passes from the steam supply pipe to the pipe leading to the breaks. The force
with which the breaks are applied will consequently be governed by the strength
of the spring by which the piston is held up.

page_text: When the breaks are to be taken off the upward pressure of the spring is taken
off and the piston is then forced down by the steam above it, and as it descends it
passes below and so uncovers an exhaust port from which the steam in the chamber
and pipe leading to the breaks can escape.
I prefer that the rod or spindle used for lifting the piston should be jointed to a
léver, which at its end is connected by a coiled spring with one arm of a bell crank
lever, the other arm of the lever being connected by a link either to a lever which
can be set and held in any desired position by a catch locking into a notched
quadrant, or that it should be connected to a screw by which it can be drawn back
and held in any desired position, but other mechanism may be used for putting any
required amount of tension on the spring when the breaks are to be applied.
The arrangement of apparatus above described is also applicable for controlling
the pressure of steam or other fluid used for other purposes.

page_text: SPECIFICATION in pursuance of the conditions of the Letters Patent filed by
the said Bowman Malcolm in the Great Seal Patent Office on the 7th May
1880.
BOWMAN MALCOLM, of Belfast, in the County of Antrim. "IMPROVEMENTS IN
APPARATUS FOR CONTROLLING THE PRESSURE OF STEAM OR OTHER FLUID USED FOR
APPLYING THE BREAKS OF RAILWAY BREAK APPARATUS, APPLICABLE ALSO FOR
CONTROLLING THE PRESSURE OF STEAM OR OTHER FLUID USED FOR OTHER
PURPOSES."
For the purpose of controlling the pressure of steam, or it might be other fluid,
used for applying the breaks of railway break apparatus, I employ a piston capable
of moving to and fro in a cylinder; above the piston is situated a double seated or
equilibrium valve, closing valve seats formed at the end of the steam supply pipe.
When the piston is lifted a projection from its upper end comes against the bottom
of the valve and lifts it from its seats, but when the piston moves downwards,
away from the valve, the valve is pressed down and closed by a spring pressing
upon it at the top. When the valve is raised steam issues from the end of the
steam supply pipe into a chamber by which it is surrounded. From this chamber
a pipe passes to the cylinders of the steam breaks, the upper end of the cylinder
before mentioned is also open to the interior of the chamber. A rod or spindle is
passed up through the bottom of the cylinder and by it the piston can be lifted.
When the breaks are to be applied the rod is moved upwards by means of a spring,
and it then lifts the piston and the valve above it; steam is thus allowed to pass
from the steam supply pipe into the chamber, and from thence to the break
cylinders. The pressure of steam in the chamber acts upon the top of the piston,
and when the pressure upon the piston is sufficient to overcome the spring by
which it is held up, the piston is forced downwards and the valve at once closes,
and no more steam passes from the steam supply pipe to the pipe leading to the
breaks. The force with which the breaks are applied will consequently be governed
by the strength of the spring by which the piston is held up.
When the breaks are to be taken off the upward pressure of the spring is taken
off and the piston is then forced down by the steam above it, and as it descends it
passes below and so uncovers an exhaust port from which the steam in the chamber
and pipe leading to the breaks can escape.
I prefer that the rod or spindle used for lifting the piston should be jointed to a
lever which at its end is connected by a coiled spring with one arm of a bell crank
lever, the other arm of the lever being connected by a link, either to a lever which
can be set and held in any desired position by a catch locking into a notched
quadrant, or that it should be connected to a screw by which it can be drawn back
and held in any desired position, but other mechanism may be used for putting any
required amount of tension on the spring when the breaks are to be applied.
The arrangement of apparatus above described is also applicable for controlling
the pressure of steam or other fluid used for other purposes.
In order that my said Invention may be most fully understood and readily carried
into effect I will proceed to describe the Drawings hereunto annexed.
DESCRIPTION OF THE DRAWINGS.
Figure 1 is a side elevation, Figure 2 is a front elevation, Figure 3 is a plan,
Figure 4 is a longitudinal section, and Figures 5 and 6 are transverse sections of a
pressure controlling apparatus constructed according to my Invention.
a is a valve chamber containing the double seated valve b; the inlet for the
steam or other fluid under pressure is at c, and the outlet by which the fluid
passes from the valve chamber into the pipe leading to the break apparatus or
mechanism is marked d; e is a light spring tending to hold the valve b down to its

page_text: seats; is a piston working in a cylinder which forms part of the valve chamber a.
This piston is separate from the valve b, and may descend in the cylinder after the
valve b has come to its seats; the piston then uncovers an outlet g in the side of the
cylinder and so the valve chamber and the pipe passing from it to the breaks are
relieved from pressure; h is a rod or pusher passing through the end cover of the
cylinder it serves to move the piston upwards when required, and then a projection f¹
on the top of the piston comes into contact with the valve b and lifts it from its
seats.
The
The steam or fluid then enters the valve chamber until it establishes a pressure
therein sufficient to thrust back the piston and pusher. The pusher h is actuated
by a lever i, and a coiled spring k connects the outer end of this lever with one arm
of a bell crank l. The other arm of the bell crank is connected by a rod with a
hand lever provided with a locking bolt taking into notches in a fixed arc.
lever may thus be retained in any position to which it may be brought, and it will
thus be seen that the tension of the spring k will be increased or diminished
according to the position given to the hand lever. The tension of the spring
regulates the amount of support given to the piston f on its underside, and on this
again the pressure in the valve chamber and pipes and apparatus connected
therewith depends. The lever i and the bell crank are connected also by a slotted
link m which serves two objects; when the hand lever is moved to its full extent in
one direction it raises the pusher h, independently of the spring k, and then the full
pressure is admitted to the valve chamber, and again it withdraws the pusher h
when the hand lever is moved to its full extent in the other direction. The breaks
are then taken off the piston f, falling and uncovering the outlet g, thereby
completely relieving from pressure the valve chamber and the parts in connection
therewith. It is obvious that in place of the hand lever other mechanism may be
employed by which the operator can at pleasure act through the spring k and link
m upon the lever i and pusher h in the manner stated.
Having thus described the nature of my said Invention and the manner of
performing the same, I would remark that I am aware that some of the parts:
aforesaid have before been employed in combination, but simply as a reducing valve
without the relief outlet g, which the piston is free to cover and uncover whilst the
valve b is seated, and without the means described for varying the tension of the
spring and for acting upon the pusher independently of the spring, I would
therefore have it understood that I limit my claim to,-
First. The combination consisting of the valve chamber a, its double valve b, and
passages c and d, and piston f, with the relief outlet g, over which the piston works,
serving as a valve to open and close the outlet, substantially as described.
Second. The combination with the parts a, b, c, d, f, g, h, and k, of a hand lever
or other like control apparatus by which the tension of the spring k can be varied
at pleasure, and by which also the pusher h can be moved, substantially as
described.
Third. My pressure controlling apparatus, substantially as described and illustrated
by the annexed Drawings.
In witness whereof, I, the said Bowman Malcolm, have hereunto set my hand
and seal, this Seventeenth day of March, in the year of our Lord One
thousand eight hundred and eighty.